Albidah [48] investigated the effect of replacing limestone aggregate by RAP aggregate in metakaolin-based GPC mixes under different Albidah [48] 研究了在不同条件下，在以偏高岭土为基础的 GPC 混合料中用 RAP 骨料替代石灰石骨料的效果。
replacement ratios. The results indicated that the compressive strength decreased from 56.7 MPa to 32.45 MPa with 25 % replacement of RAP for the limestone portion of the aggregate. Further increasing the percentages of RAP replacement to 50%50 \% and 100%100 \% resulted in even larger reductions in strength. Preethi et al. [49]similarly observed the use of coarse RAP aggregate as a replacement for natural coarse aggregate in fly ash/slag-based GPC. The study showed that incorporation of RAP resulted in 5.9 % less, 8.7%,11.8%8.7 \%, 11.8 \%, and 23.2%23.2 \% decrease in strength over control mix for replacement levels of 20%,40%,60%20 \%, 40 \%, 60 \%, and 80%80 \%, respectively. 替代率。结果表明，在石灰石部分骨料的 RAP 替代率为 25% 时，抗压强度从 56.7 兆帕降至 32.45 兆帕。进一步将 RAP 替代率提高到 50%50 \% 和 100%100 \% 后，强度下降幅度更大。Preethi 等人[49]同样观察了在基于粉煤灰/矿渣的 GPC 中使用粗 RAP 骨料替代天然粗骨料的情况。研究表明，在替换水平为 20%,40%,60%20 \%, 40 \%, 60 \% 和 80%80 \% 时，掺入 RAP 会导致强度比对照混合料分别降低 5.9%、 8.7%,11.8%8.7 \%, 11.8 \% 和 23.2%23.2 \% 。
Wongkvanklom et al. [50] examined how the characteristics of alkali-activated materials were affected by the use of RAP at replacement levels of 20%20 \% and 40%40 \% and liquid alkaline/ash ratios of 0.65 and 0.75 . According to the study, compressive strength and elastic modulus decreased as RAP content increased from 0%0 \% to 40%40 \%. In particular, it was discovered that the range of compressive strength losses with 40%40 \% RAP replacement, contingent on the liquid alkaline/ash ratio, was 29.7-51.1 %. The addition of RAP had a positive impact on other attributes in spite of these decreases in mechanical qualities. It led to decreased thermal conductivity, decreased porosity, and decreased water absorption. Furthermore, the use of RAP enhanced the material’s resistance to acid attack and surface abrasion, highlighting its potential for improving durability in specific applications. Wongkvanklom 等人[50] 研究了在 20%20 \% 和 40%40 \% 的替代水平以及 0.65 和 0.75 的液体碱/灰比率下使用 RAP 如何影响碱活性材料的特性。研究表明，随着 RAP 含量从 0%0 \% 增加到 40%40 \% ，抗压强度和弹性模量都有所下降。特别是，研究发现，根据液碱/灰的比例， 40%40 \% RAP 替代的抗压强度损失范围为 29.7-51.1%。尽管机械质量有所下降，但添加 RAP 对其他属性也有积极影响。它降低了导热性，减少了孔隙率，降低了吸水性。此外，使用 RAP 还增强了材料的耐酸侵蚀性和表面耐磨性，突出了其在特定应用中提高耐久性的潜力。
1.1. Research gap 1.1.研究差距
While the use of RAP in traditional concrete has been researched, its incorporation into AAC, especially for structural applications beyond pavement construction, has received limited attention. Most existing studies focus on RAP as a replacement for natural aggregates, but few have explored its interaction with GF in AAC systems, particularly regarding the combined impact on durability and mechanical strength. The performance of RAP-enhanced AAC at higher curing temperatures is also not well documented in the literature, and nothing is known about how RAP affects characteristics like compressive strength, flexural strength, and freeze-thaw resistance. Moreover, it is unclear what ratios of RAP and GF are best for balancing mechanical performance with environmental sustainability. The microstructural characteristics of AAC and its interaction with GF are not well understood, particularly in the context of RAP at higher replacement levels. To address these gaps, this study examines the mechanical, durability, and microstructural properties of AAC reinforced with GF and RAP. It offers new insights into sustainable construction materials with enhanced performance features. 虽然对 RAP 在传统混凝土中的使用进行了研究，但将其纳入 AAC（轻质混凝土与加气混凝土）中，特别是用于路面施工以外的结构应用，受到的关注却很有限。现有的大多数研究都将 RAP 作为天然集料的替代品，但很少有研究探讨 RAP 与 AAC 系统中 GF 的相互作用，尤其是对耐久性和机械强度的综合影响。RAP 增强型 AAC 在较高固化温度下的性能在文献中也没有很好的记录，而且 RAP 如何影响抗压强度、抗弯强度和抗冻融性等特性也一无所知。此外，目前还不清楚 RAP 和 GF 的最佳比例是多少，以平衡机械性能和环境可持续性。人们对 AAC 的微观结构特征及其与 GF 的相互作用还不甚了解，特别是在 RAP 替代水平较高的情况下。为了填补这些空白，本研究考察了用 GF 和 RAP 增强的 AAC 的机械性能、耐久性和微观结构特性。它为具有更高性能特点的可持续建筑材料提供了新的见解。
1.2. Research significance 1.2.研究意义
The importance of this study is in its contribution to the creation of high-performance and environmentally friendly building materials. RAP and GF are incorporated into AAC in this study to solve urgent environmental issues like waste management and the depletion of natural resources. The need for substitute materials that can lessen the industry’s carbon footprint is highlighted by the building sector’s reliance on natural aggregates, increasing RAP generation from road maintenance, and worries about the depletion of river sand. The possibility of replacing river sand with RAP and improving mechanical qualities by adding glass fibers are both investigated in this study. The creative method used in this study shows that, even at high curing circumstances, the combination of RAP and GF can produce environmentally friendly AAC with enhanced durability, compressive strength, and resistance to freeze-thaw cycles. This work opens the door for the creation of more economical, long-lasting, and environmentally friendly building materials by effectively integrating RAP into AAC. The findings of this study are also relevant to the construction industry, highlighting the potential of recycling waste materials to develop eco-friendly composites with high structural integrity. This study adds to the expanding corpus of research on geopolymer composites and offers insightful information on 这项研究的重要性在于其对创造高性能环保建筑材料的贡献。本研究将 RAP 和 GF 纳入 AAC，以解决废物管理和自然资源枯竭等紧迫的环境问题。建筑行业对天然骨料的依赖、道路养护产生的 RAP 不断增加以及对河沙枯竭的担忧，都凸显了对可减少行业碳足迹的替代材料的需求。本研究探讨了用 RAP 替代河沙和通过添加玻璃纤维提高机械质量的可能性。本研究采用的创新方法表明，即使在高固化条件下，RAP 和 GF 的组合也能生产出具有更高的耐久性、抗压强度和抗冻融循环能力的环保型 AAC。这项研究通过将 RAP 有效地融入 AAC 中，为创造更经济、更持久、更环保的建筑材料打开了大门。这项研究的结果也与建筑行业相关，突出了回收废料开发具有高结构完整性的环保型复合材料的潜力。本研究为不断扩大的土工聚合物复合材料研究资料库增添了新的内容，并就以下方面提供了深刻的信息
how to best combine sustainability, mechanical performance, and durability by maximizing RAP content and fiber reinforcement. 如何通过最大限度地提高 RAP 含量和纤维加固，将可持续性、机械性能和耐久性最好地结合起来。
2. Experimental program 2.实验计划
2.1. Materials 2.1.材料
In the geopolymers produced in this study, ground blast furnace slag (GBFS) was used as the main binder. GBFS has a specific gravity of 2.84 and a specific surface area of 5800cm2//g5800 \mathrm{~cm} 2 / \mathrm{g} based on the Blaine technique. Grain size distribution of GBFS is shown in Fig. 1a, whereas mineralogical characteristics are shown in Fig. 1b. As seen in Fig. 1a, the smallest particle size below 10%10 \% of the volume (d_(10))\left(\mathrm{d}_{10}\right) is below ∼3mum\sim 3 \mu \mathrm{~m}. The size reaching 50%50 \% of the volume ( d_(50)\mathrm{d}_{50} ) is around 10 mum10 \mu \mathrm{~m}. This indicates that half of the mixture consists of particles below this value. The size corresponding to 90%90 \% volume ( d_(90)\mathrm{d}_{90} ) is around 40 mum40 \mu \mathrm{~m}. Fig. 1a shows a sigmoid curve. Most of the particles are concentrated in a certain size range, indicating that the slag is ground homogeneously. The region where the curve rises rapidly ( ∼1-50 mum\sim 1-50 \mu \mathrm{~m} ) indicates that the distribution is quite narrow and larger-sized particles are limited. The distribution also exhibits a log-normal trend. This indicates that the natural grinding and manufacturing processes characterize the material. A low d_(50)\mathrm{d}_{50} (around 10 mum10 \mu \mathrm{~m} ) indicates that the slag has a high specific surface area. This increases the reactivity and enables it to react more efficiently with alkaline activators. Fig. 1b shows a broad peak, especially in the range 20^(@)-35^(@)20^{\circ}-35^{\circ}. This broad and weak peak indicates that the amorphous phase is dominant. The amorphous structure of GBFS indicates a high activation potential, which makes it suitable for reaction with alkaline activators. The amorphous phase facilitates the rapid dissolution of Ca,Si\mathrm{Ca}, \mathrm{Si} and Al ions and the formation of binder phases (C-S-H or N-A-S-H) during the geopolymerization reaction. The absence of distinct sharp peaks in the XRD pattern indicates no significant amount of crystalline phase in the material. This indicates that GBFS inhibits crystallization during the grinding and cooling and acquires an amorphous structure. The chemical characterization of GBFS determined by XRF method is presented in Table 1. 在本研究生产的土工聚合物中，磨碎的高炉矿渣（GBFS）被用作主要粘合剂。根据布莱恩技术，GBFS 的比重为 2.84，比表面积为 5800cm2//g5800 \mathrm{~cm} 2 / \mathrm{g} 。GBFS 的粒度分布见图 1a，矿物学特征见图 1b。从图 1a 中可以看出，体积 (d_(10))\left(\mathrm{d}_{10}\right) 的 10%10 \% 以下的最小粒度低于 ∼3mum\sim 3 \mu \mathrm{~m} 。达到体积 50%50 \% 的粒度（ d_(50)\mathrm{d}_{50} ）约为 10 mum10 \mu \mathrm{~m} 。这表明混合物中有一半由低于此值的颗粒组成。与 90%90 \% 体积 ( d_(90)\mathrm{d}_{90} ) 相对应的大小约为 40 mum40 \mu \mathrm{~m} 。图 1a 显示了一条曲线。大部分颗粒都集中在一定的粒度范围内，表明炉渣是均匀研磨的。曲线快速上升的区域（ ∼1-50 mum\sim 1-50 \mu \mathrm{~m} ）表明分布范围很窄，较大尺寸的颗粒受到限制。分布也呈现对数正态分布趋势。这表明自然研磨和制造过程是材料的特征。 d_(50)\mathrm{d}_{50} 较低（约 10 mum10 \mu \mathrm{~m} ）表明炉渣具有较高的比表面积。这提高了反应活性，使其能够更有效地与碱性活化剂发生反应。图 1b 显示了一个宽峰，尤其是在 20^(@)-35^(@)20^{\circ}-35^{\circ} 范围内。这个宽而弱的峰值表明无定形相是主要的。GBFS 的无定形结构表明其活化电位较高，因此适合与碱性活化剂反应。在土工聚合反应过程中，无定形相有利于 Ca,Si\mathrm{Ca}, \mathrm{Si} 和铝离子的快速溶解以及粘合剂相（C-S-H 或 N-A-S-H）的形成。 XRD 图谱中没有明显的尖锐峰，表明材料中没有大量的结晶相。这表明 GBFS 在研磨和冷却过程中抑制了结晶，并获得了无定形结构。表 1 列出了用 XRF 方法测定的 GBFS 化学特征。
River aggregate and reclaimed asphalt aggregates (RAP) were used to produce geopolymer. The specific gravity of the stream aggregate is 2.62 , and the 24 -hour water absorption is 1.22%1.22 \%. A road that was constructed approximately five years ago had its upper structure removed by a milling machine, and the discarded material was used to harvest the RAP aggregate. Under controlled laboratory settings, the RAP aggregate was crushed in a stone crusher and sieved with a 0-4mm0-4 \mathrm{~mm} sieve aperture. After 24 hours, the water absorption of RAP aggregate is 河水骨料和再生沥青骨料（RAP）被用来生产土工聚合物。河水骨料的比重为 2.62，24 小时吸水率为 1.22%1.22 \% 。一条大约五年前修建的道路被铣刨机拆除了上部结构，废弃的材料被用来采集 RAP 骨料。在受控实验室环境下，RAP 骨料在碎石机中粉碎，并用 0-4mm0-4 \mathrm{~mm} 筛孔过筛。24 小时后，RAP 骨料的吸水率为
calculated to be 1.35%1.35 \%, and its specific gravity is measured at 2.66. RAP aggregates were not surface-treated. The results of sieve analysis of aggregates according to ASTM C33 are given in Fig. 2. 1.35%1.35 \% ，其比重测量值为 2.66。RAP 集料未经表面处理。根据 ASTM C33 对集料进行筛分分析的结果见图 2。
The geopolymer samples were prepared using NaOH and Na_(2)SiO_(3)\mathrm{Na}_{2} \mathrm{SiO}_{3} solutions. NaOH flakes of 98%98 \% purity were used for the NaOH solution. Twenty-four hours before casting, a 12 M NaOH solution was prepared with distilled water. The Na_(2)SiO_(3)\mathrm{Na}_{2} \mathrm{SiO}_{3} solution comprises 15.4%Na_(2)O,30%15.4 \% \mathrm{Na}_{2} \mathrm{O}, 30 \%SiO_(2)\mathrm{SiO}_{2} and 56%56 \% water (by mass). The specific gravity of Na_(2)SiO_(3)\mathrm{Na}_{2} \mathrm{SiO}_{3} is about 1.58 , and that of 12 M NaOH is 1.43 . In this study, alkali-resistant glass fibers (GF) were used to improve the mechanical properties of geopolymer blends. Technical properties of glass fibers are presented in Table 2. 使用 NaOH 和 Na_(2)SiO_(3)\mathrm{Na}_{2} \mathrm{SiO}_{3} 溶液制备土工聚合物样品。NaOH 溶液使用纯度为 98%98 \% 的 NaOH 片。浇铸前 24 小时，用蒸馏水配制 12 M NaOH 溶液。 Na_(2)SiO_(3)\mathrm{Na}_{2} \mathrm{SiO}_{3} 溶液由 15.4%Na_(2)O,30%15.4 \% \mathrm{Na}_{2} \mathrm{O}, 30 \%SiO_(2)\mathrm{SiO}_{2} 和 56%56 \% 水（按质量计）组成。 Na_(2)SiO_(3)\mathrm{Na}_{2} \mathrm{SiO}_{3} 的比重约为 1.58，12 M NaOH 的比重为 1.43。本研究使用耐碱玻璃纤维 (GF) 改善土工聚合物混合物的机械性能。表 2 列出了玻璃纤维的技术特性。
2.2. Mixing, casting, and curing 2.2.混合、浇注和固化
GBFS, preferred as the main binder in all mixtures, was used at a 750kg//m^(3)750 \mathrm{~kg} / \mathrm{m}^{3} dosage. RAP was used 25%25 \%, 50%50 \% and 100%100 \% by volume instead of river aggregate. Similarly, GF was added to the mixture at 0.5 and 1%1 \% by volume. In this context, 12 different mixtures were prepared for this study. Mixing ratios and the amount of materials used in the production of geopolymer samples are given in Table 3. An alkaline solution ( NaOH+Na_(2)SiO_(3)\mathrm{NaOH}+\mathrm{Na}_{2} \mathrm{SiO}_{3} ) equal to 84%84 \% of the amount of GBFS was added to the mixture. The alkaline solution was kept high since GBFS has a very fine-grained structure. Since no extra water was used in the mixtures, workability was achieved with alkaline solutions. A_(2)Na_(2)SiO_(3)//\mathrm{A}_{2} \mathrm{Na}_{2} \mathrm{SiO}_{3} / NaOH ratio 2.5 was preferred to prepare all geopolymer samples. In preparing geopolymer samples, GBFS, stream aggregate and RAP were mixed at low speed ( 145 rpm ) for 2 minutes. In the second step, liquid alkali solutions were added to the mixture, stirring at low speed for 1 minute and at high speed ( 280 rpm ) for 2 minutes. In the last step, GF was added to the mixture and stirred at low speed for 1 minute and at high speed for 2 minutes. Two different curing processes were applied for the fresh geopolymer mortars in the molds. The first curing condition consisted of thermal curing at 80^(@)C80^{\circ} \mathrm{C} for 8 hours. For this, an oven with a heating rate of 5^(@)C5{ }^{\circ} \mathrm{C} was used. After 8 hours of thermal curing, the specimens were allowed to cool down in the oven and the specimens were tested 24 hours after casting. The specimens were subjected to ambient curing for 24 hours in the second curing condition. After 24 hours, the specimens were removed from the molds and subjected to tests. GBFS 是所有混合物中首选的主要粘结剂，使用量为 750kg//m^(3)750 \mathrm{~kg} / \mathrm{m}^{3} 。使用 RAP 以 25%25 \% 、 50%50 \% 和 100%100 \% 的用量代替河骨料。同样，在混合物中添加了 GF，添加量为 0.5 和 1%1 \% 。在这种情况下，本研究共制备了 12 种不同的混合物。表 3 列出了生产土工聚合物样品时所用材料的混合比例和用量。在混合物中加入相当于 GBFS 用量 84%84 \% 的碱性溶液（ NaOH+Na_(2)SiO_(3)\mathrm{NaOH}+\mathrm{Na}_{2} \mathrm{SiO}_{3} ）。由于 GBFS 具有非常细的颗粒结构，因此碱性溶液的浓度较高。由于混合物中没有使用额外的水，因此碱性溶液可实现可操作性。 A_(2)Na_(2)SiO_(3)//\mathrm{A}_{2} \mathrm{Na}_{2} \mathrm{SiO}_{3} / 在制备所有土工聚合物样品时，首选 NaOH 比率为 2.5。在制备土工聚合物样品时，将 GBFS、流骨料和 RAP 以低速（145 rpm）混合 2 分钟。第二步，向混合物中加入液碱溶液，低速搅拌 1 分钟，高速（280 转/分）搅拌 2 分钟。最后一步，向混合物中加入 GF，低速搅拌 1 分钟，高速搅拌 2 分钟。对模具中的新鲜土工聚合物砂浆采用了两种不同的固化工艺。第一种固化条件是在 80^(@)C80^{\circ} \mathrm{C} 温度下进行 8 小时的热固化。为此，使用了加热速率为 5^(@)C5{ }^{\circ} \mathrm{C} 的烘箱。热固化 8 小时后，让试样在烘箱中冷却，浇铸 24 小时后对试样进行测试。在第二种固化条件下，试样在环境中固化 24 小时。24 小时后，将试样从模具中取出并进行测试。
2.3. Test methods 2.3.测试方法
All geopolymer samples were assessed according to ASTM C642[51]. 所有土工聚合物样品都根据 ASTM C642[51] 进行了评估。
Fig. 1. Characterization of GBFS (a) Particle size distribution (b) XRD pattern. 图 1.GBFS 的特征 (a) 粒度分布 (b) X 射线衍射图。
Table 1 表 1
Chemical composition of GBFS (% by weight). GBFS 的化学成分（重量百分比）。
Cube specimens measuring 50 xx50 xx50mm50 \times 50 \times 50 \mathrm{~mm} were tested for apparent porosity and water absorption. The samples were further cured in ambient and thermal conditions for 24 hours, following which measurements of the physical properties were carried out. The flexural strength test on the 40 xx40 xx160mm40 \times 40 \times 160 \mathrm{~mm} geopolymer specimens was done following standard ASTM C348[52]. After these tests, we tested the compressive strength of fractured specimens under ASTM C349[53] standard. The weight of each sample was measured before tests to calculate the density. The measurement of three replications is summarized as average. The specimens were tested for mechanical properties after cooling (around 24 hours of casting). According to TS EN 1015-18[54], the transport properties of geopolymer samples were evaluated. 50 mm cube samples were prepared for this purpose. 对测量 50 xx50 xx50mm50 \times 50 \times 50 \mathrm{~mm} 的立方体试样进行了表观孔隙率和吸水率测试。试样在环境和热条件下进一步固化 24 小时，然后进行物理性质测量。 40 xx40 xx160mm40 \times 40 \times 160 \mathrm{~mm} 土工聚合物试样的抗弯强度测试是按照标准 ASTM C348[52] 进行的。测试结束后，我们按照 ASTM C349[53] 标准测试了断裂试样的抗压强度。测试前测量了每个试样的重量，以计算密度。三次重复测量的结果汇总为平均值。试样冷却后（浇铸 24 小时左右）进行机械性能测试。根据 TS EN 1015-18[54]，对土工聚合物样品的运输性能进行了评估。为此制备了 50 毫米的立方体样品。
Capillary water absorption values were determined from three specimens. 从三个试样中测定了毛细吸水率。
To evaluate their resistance against high temperatures, geopolymer samples were heated at 200^(@)C,400^(@)C200^{\circ} \mathrm{C}, 400^{\circ} \mathrm{C}, and 600^(@)C600^{\circ} \mathrm{C}. Their performance was assessed based on compressive strength and weight loss. These tests used cube specimens measuring 50 mm on a side. A muffle furnace operating at a heating rate of 10^(@)C//min10^{\circ} \mathrm{C} / \mathrm{min} was employed for sample burning. Following a 120 -minute incubation period, samples were allowed to achieve the desired temperature before gradually cooling down. The investigation into high-temperature degradation aims to evaluate the thermal stability and mechanical resilience of slag-based alkali-activated composites (AAC). This study specifically assesses the behavior of composites exposed to elevated temperatures, providing crucial insights into their suitability for applications in fire-prone environments, industrial facilities, and high-temperature operations. Understanding high-temperature degradation is essential for identifying the limitations and optimizing the performance of AAC formulations under extreme conditions. These findings are particularly important for advancing the use of eco-friendly AAC in scenarios where traditional materials may fail. Moreover, the study sheds light on the role of reclaimed asphalt pavement (RAP) and glass fibers (GF) in mitigating thermal damage, offering strategies for enhancing the durability and structural integrity of AAC exposed to heat. The freeze-thaw resistance of geopolymer specimens was tested according to ASTM C666[55]. To that end, 50 xx50 xx50mm50 \times 50 \times 50 \mathrm{~mm} cube specimens were cast. The specimens were subjected to 50 cycles, each involving holding at -20^(@)C-20^{\circ} \mathrm{C} in the air for 14 hours and thawing in water at +4^(@)C+4^{\circ} \mathrm{C} for approximately 10 h . The samples were weighed between individual frost tests, and their compressive strength was measured after completing all planned freeze-thaw procedures (i.e., an extra load along with preceding applications was applied). 为了评估它们的耐高温性能，在 200^(@)C,400^(@)C200^{\circ} \mathrm{C}, 400^{\circ} \mathrm{C} 和 600^(@)C600^{\circ} \mathrm{C} 下对土工聚合物样品进行了加热。根据抗压强度和重量损失来评估它们的性能。这些测试使用的是边长为 50 毫米的立方体试样。样品燃烧采用了加热速率为 10^(@)C//min10^{\circ} \mathrm{C} / \mathrm{min} 的马弗炉。经过 120 分钟的保温期后，样品达到所需的温度，然后逐渐冷却。高温降解调查旨在评估矿渣碱活性复合材料（AAC）的热稳定性和机械回弹性。这项研究专门评估了复合材料在高温下的行为，为了解复合材料在易燃环境、工业设施和高温作业中的应用提供了重要依据。了解高温降解对于确定 AAC 配方在极端条件下的局限性和优化其性能至关重要。这些发现对于在传统材料可能失效的情况下推进环保型 AAC 的使用尤为重要。此外，该研究还揭示了再生沥青路面（RAP）和玻璃纤维（GF）在减轻热损伤方面的作用，为提高暴露在热环境中的 AAC 的耐久性和结构完整性提供了策略。根据 ASTM C666[55] 测试了土工聚合物试样的抗冻融性。为此，浇铸了 50 xx50 xx50mm50 \times 50 \times 50 \mathrm{~mm} 立方体试样。对试样进行了 50 次循环，每次循环包括在 -20^(@)C-20^{\circ} \mathrm{C} 空气中保持 14 小时，然后在 +4^(@)C+4^{\circ} \mathrm{C} 水中解冻约 10 小时。 在两次霜冻试验之间对样品进行称重，并在完成所有计划的冻融程序后测量其抗压强度（即在之前的试验中施加额外荷载）。
3. Results and discussion 3.结果和讨论
3.1. Compressive strength 3.1.抗压强度
Fig. 3 displays the effects of glass fiber (GF) content, ambient and 80^(@)C80^{\circ} \mathrm{C} curing temperatures for 24 hours, and replacing river sand (RS) with RAP on the compressive strength of slag-based alkali-activated composites (AAC) mixtures. Increasing the curing temperature from ambient to 80^(@)C80^{\circ} \mathrm{C} led to a significant improvement in the compressive strength of AAC mixtures, with gains ranging from 26%26 \% to 60%60 \%, independent of GF and RAP content. The mixture with 100%100 \% RAP and 0%0 \% GF showed the smallest strength increase, while the mixture with 0%0 \% 图 3 显示了玻璃纤维 (GF) 含量、24 小时环境温度和 80^(@)C80^{\circ} \mathrm{C} 固化温度以及用 RAP 替代河砂 (RS) 对矿渣碱活性复合材料 (AAC) 混合物抗压强度的影响。将固化温度从常温提高到 80^(@)C80^{\circ} \mathrm{C} 后，AAC 混合物的抗压强度显著提高，提高幅度从 26%26 \% 到 60%60 \% 不等，与 GF 和 RAP 含量无关。含有 100%100 \% RAP 和 0%0 \% GF 的混合物强度提高幅度最小，而含有 0%0 \% RAP 和 0%0 \% GF 的混合物强度提高幅度最大。
Table 3 表 3
Material weights and mixing ratios (kg//m^(3))\left(\mathrm{kg} / \mathrm{m}^{3}\right). 材料重量和混合比 (kg//m^(3))\left(\mathrm{kg} / \mathrm{m}^{3}\right) .
Fig. 3. The compressive strength of the mixes after 24 hours of curing at room temperature and 80^(@)C80^{\circ} \mathrm{C}. 图 3.混合料在室温和 80^(@)C80^{\circ} \mathrm{C} 条件下固化 24 小时后的抗压强度。
RAP and 1 % GF demonstrated the greatest strength enhancement. RAP contains bituminous material, which has lower chemical reactivity compared to natural aggregates like river sand. This can limit the strength development even at elevated temperatures, as RAP may not participate effectively in the geopolymerization process. As a result, the mixture with 100 % RAP and 0 % GF sees the least strength improvement. The bituminous content in RAP can reduce the bond between the aggregate and the alkali-activated binder, leading to a weaker matrix structure. This limits the potential for strength gains when exposed to higher curing temperatures. The mixture with 0%0 \% RAP has a more cohesive and chemically reactive matrix since natural aggregates (e.g., river sand) bond better with the geopolymer binder. The absence of RAP ensures that there is no interference from the bituminous material, allowing the matrix to fully benefit from the elevated curing temperature, resulting in the highest strength enhancement. GF enhance the tensile strength and improve the crack resistance of the matrix by bridging micro-cracks and distributing stresses more evenly. In the mixture with 1%GF1 \% \mathrm{GF} and 0%RAP0 \% \mathrm{RAP}, the fibers provide additional reinforcement, leading to greater strength improvement when subjected to elevated curing temperatures. RAP 和 1 % GF 的强度提高幅度最大。RAP 含有沥青材料，与河沙等天然集料相比，其化学反应活性较低。由于 RAP 可能无法有效参与土工聚合过程，因此即使在高温条件下也会限制强度的提高。因此，含有 100 % RAP 和 0 % GF 的混合物的强度提高幅度最小。RAP 中的沥青含量会降低集料与碱激活粘结剂之间的粘结力，导致基体结构变弱。这就限制了在较高的固化温度下提高强度的潜力。含有 0%0 \% RAP 的混合物具有更强的内聚力和化学反应基质，因为天然集料（如河沙）与土工聚合物粘结剂的粘结性更好。不使用 RAP 可确保不受沥青材料的干扰，使基质充分受益于较高的固化温度，从而达到最高的强度增强效果。GF 通过桥接微裂缝和更均匀地分布应力，提高了基质的抗拉强度和抗裂性能。在与 1%GF1 \% \mathrm{GF} 和 0%RAP0 \% \mathrm{RAP} 的混合物中，纤维可提供额外的增强作用，从而在固化温度升高时提高强度。
The significant increase in compressive strength when raising the curing temperature from ambient to 80^(@)C80^{\circ} \mathrm{C} for AAC mixtures can be attributed to several key factors. Alkali-activated materials (AAMs) rely on the geopolymerization process, where the binder forms a stable, hardened matrix. Higher temperatures accelerate the dissolution of aluminosilicate materials (such as fly ash, slag, or metakaolin), leading to faster formation of the geopolymer gel (C-S-H or N-A-S-H). This results in a denser and stronger matrix at elevated temperatures [17,26]. At 80^(@)C80^{\circ} \mathrm{C}, the reaction rate between the alkali activators and the binder components is much faster than at ambient temperatures. This leads to more complete hydration and bonding in a shorter period, which translates to higher compressive strength. The higher curing temperature contributes to lower porosity in the AAC mixtures due to more effective binding of the particles. Reduced porosity helps improve the overall compressive strength by minimizing voids within the matrix [56]. 将 AAC 混合物的固化温度从环境温度提高到 80^(@)C80^{\circ} \mathrm{C} 时，其抗压强度会明显增加，这可归因于几个关键因素。碱活性材料（AAM）依赖于土工聚合过程，在此过程中粘结剂形成稳定的硬化基体。较高的温度会加速硅酸铝材料（如粉煤灰、矿渣或偏高岭土）的溶解，从而加快土工聚合物凝胶（C-S-H 或 N-A-S-H）的形成。这使得基体在高温下更加致密和坚固[17,26]。在 80^(@)C80^{\circ} \mathrm{C} 温度下，碱活化剂与粘结剂成分之间的反应速度比常温下快得多。这将在更短的时间内实现更完全的水化和粘结，从而获得更高的抗压强度。较高的固化温度可更有效地结合颗粒，从而降低 AAC 混合物的孔隙率。孔隙率的降低有助于最大限度地减少基质中的空隙，从而提高整体抗压强度[56]。
For the mixtures ambient cured with 0%0 \% GF content, it was found that those containing 25%,50%25 \%, 50 \%, and 100%100 \% RAP experienced strength enhancements of 20.81%,7.98%20.81 \%, 7.98 \%, and 4.17%4.17 \%, respectively, compared to the reference mixture (A0G0). The strength enhancements observed in the ambient-cured mixtures with 0%0 \% GF content and varying amounts of RAP substituted for RS can be attributed to several factors: 对于 GF 含量为 0%0 \% 的常温固化混合物，发现与参考混合物（A0G0）相比，含有 25%,50%25 \%, 50 \% 和 100%100 \% RAP 的混合物的强度分别提高了 20.81%,7.98%20.81 \%, 7.98 \% 和 4.17%4.17 \% 。在采用 0%0 \% GF 含量和不同数量的 RAP 替代 RS 的常温固化混合物中观察到的强度增强可归因于几个因素：
RAP may act as a filler, improving the packing density of the alkaliactivated matrix. This enhanced particle packing can reduce voids in the concrete, leading to increased compressive strength, particularly at lower replacement levels (e.g., 25%25 \% ).The presence of RAP could improve the interaction between the alkali-activated binder and the aggregates, potentially resulting in a stronger bond, especially in the early stages of strength development. The residual bituminous material in RAP might contribute to the mix by providing additional stiffness, which could explain the strength enhancement, particularly at lower RAP percentages. However, at higher RAP contents, this effect may diminish, explaining the lower strength gains at 50%50 \% and 100%100 \% RAP replacement. RAP 可充当填料，提高烷基活化基质的堆积密度。这种增强的颗粒堆积可以减少混凝土中的空隙，从而提高抗压强度，尤其是在较低的替代水平下（例如 25%25 \% ）。RAP 的存在可以改善碱活化粘结剂与集料之间的相互作用，从而可能产生更强的粘结力，尤其是在强度发展的早期阶段。RAP 中的残余沥青材料可能会提供额外的刚度，从而有助于混合料的强度提高，特别是在 RAP 百分比较低的情况下。然而，当 RAP 含量较高时，这种效果可能会减弱，这也是 50%50 \% 和 100%100 \% RAP 替代率较低时强度增益较低的原因。
For the mixtures cured at 80^(@)C80^{\circ} \mathrm{C} with 0%GF0 \% \mathrm{GF} content, those incorporating 25%25 \%, and 50%50 \% RAP showed strength increases of 13.67%13.67 \%, and 3.32%3.32 \%, respectively, compared to the reference mixture (A0G0). However, the mixture with 100%100 \% RAP showed a strength reduction of 11.35%11.35 \% compared to the reference mixture. The mixture containing 25 % RAP demonstrated the highest strength at both ambient curing and 80^(@)C80^{\circ} \mathrm{C} curing conditions. It appears that the mixtures containing RAP exhibited poorer compressive strength performance at 80^(@)C80^{\circ} \mathrm{C} compared to those cured at ambient temperature. RAP contains bituminous materials, which may soften at elevated temperatures, such as 80^(@)C80^{\circ} \mathrm{C}. This softening can weaken the overall bond between the RAP aggregates and the alkali-activated matrix, leading to reduced strength development, especially at higher RAP replacement levels (e.g., 100 % RAP). While lower RAP contents (e.g., 25%25 \% and 50%50 \% ) show some strength improvement at elevated temperatures, likely due to the matrix still benefiting from the reactivity of the remaining natural aggregates, the use of 100%100 \% RAP results in a strength reduction because the bituminous nature of RAP becomes a limiting factor at high temperatures, weakening the matrix. This explains why RAP-containing mixtures performed worse at 80^(@)C80^{\circ} \mathrm{C} compared to ambient curing conditions[57]. 对于在 80^(@)C80^{\circ} \mathrm{C} 下固化的 0%GF0 \% \mathrm{GF} 含量的混合物，与参考混合物 (A0G0) 相比，含有 25%25 \% 和 50%50 \% RAP 的混合物的强度分别增加了 13.67%13.67 \% 和 3.32%3.32 \% 。然而，与参考混合物相比，含有 100%100 \% RAP 的混合物强度降低了 11.35%11.35 \% 。在常温固化和 80^(@)C80^{\circ} \mathrm{C} 固化条件下，含有 25 % RAP 的混合物强度最高。与在环境温度下固化的混合物相比，含有 RAP 的混合物在 80^(@)C80^{\circ} \mathrm{C} 条件下的抗压强度表现较差。RAP 含有沥青材料，在 80^(@)C80^{\circ} \mathrm{C} 等高温条件下可能会软化。这种软化会削弱 RAP 集料与碱激活基质之间的整体粘结力，导致强度降低，尤其是在 RAP 替代水平较高（例如 RAP 含量为 100%）的情况下。虽然较低的 RAP 含量（如 25%25 \% 和 50%50 \% ）在高温下显示出一定的强度改善，这可能是由于基质仍然受益于剩余天然集料的反应性，但使用 100%100 \% RAP 会导致强度降低，因为 RAP 的沥青性质在高温下成为限制因素，从而削弱了基质。这就解释了为什么含 RAP 的混合物在 80^(@)C80^{\circ} \mathrm{C} 环境固化条件下的性能比常温固化条件更差[57]。
The addition of 0.5%0.5 \% and 1%1 \% GF reduced the compressive strength of the AAC mixtures cured at ambient and 80^(@)C80^{\circ} \mathrm{C} for 24 h , irrespective of RAP content, when compared to the mixtures without GF. At higher fiber content, clumping or uneven dispersion of the glass fibers may occur, leading to weak zones or micro voids in the matrix. These weak points can reduce the compressive strength of the mixture, as the load is not evenly distributed across the matrix[58]. The introduction of fibers, particularly at higher percentages, can disrupt the continuity of the alkali-activated matrix. The fibers may interfere with the geopolymerization process by creating voids or hindering the bonding between the binder and aggregates, leading to lower compressive strength. The addition of GF can introduce additional porosity into the geopolymer matrix, either due to poor compaction or air entrapment around the fibers. Increased porosity reduces the material’s density and compressive strength, as voids act as weak zones where cracks can initiate under compressive loads [59,60]. 与不添加玻璃纤维的混合物相比，添加 0.5%0.5 \% 和 1%1 \% 玻璃纤维会降低在常温和 80^(@)C80^{\circ} \mathrm{C} 条件下固化 24 小时的 AAC 混合物的抗压强度，而与 RAP 含量无关。在纤维含量较高的情况下，玻璃纤维可能会结块或分散不均匀，从而导致基体中出现薄弱区域或微空隙。这些薄弱点会降低混合物的抗压强度，因为荷载没有在基体中均匀分布[58]。纤维的引入，尤其是较高比例的纤维，会破坏碱激活基质的连续性。纤维可能会产生空隙或阻碍粘结剂与集料之间的粘结，从而干扰土工聚合过程，导致抗压强度降低。添加 GF 可能会在土工聚合物基体中引入额外的孔隙率，原因可能是压实不良或纤维周围夹带空气。孔隙率的增加会降低材料的密度和抗压强度，因为空隙会成为薄弱区域，在抗压负荷作用下会产生裂缝[59,60]。
For the mixtures ambient cured with 0.5%0.5 \% GF content, those containing 25%25 \% and 50%50 \% RAP exhibited strength increases of 20.83%20.83 \% and 6.18%6.18 \%, respectively, compared to the mixture (A0G0.5). However, the mixture with 100%100 \% RAP experienced a very slight strength reduction of 0.09%0.09 \% compared to the mixture without RAP. Similarly, Strength increases of 26.75%26.75 \% and 10.08%10.08 \% were observed for mixtures with 25%25 \% and 50%50 \% RAP, respectively, after curing at 80^(@)C80^{\circ} \mathrm{C} with 0.5%0.5 \% GF content, compared to the mixture (A0G0.5). In contrast, the mixture with 100%100 \% RAP showed a 3.6 % reduction in strength compared to the mixture A0G0.5. The mixture with 25%25 \% RAP performed better under elevated curing temperature (80^(@)C)\left(80^{\circ} \mathrm{C}\right), showing a larger strength gain. This suggests that the higher curing temperature enhances the geopolymerization process more effectively in the presence of moderate RAP content, leading to stronger matrix development and bonding. Similar to the 25 % RAP mixture, the 50 % RAP mixture also benefited more from the higher curing temperature, but the improvement was less pronounced than with 25%25 \% RAP. The moderate increase in strength at 80^(@)C80^{\circ} \mathrm{C} indicates that higher RAP content begins to diminish the positive effect of 对于 GF 含量为 0.5%0.5 \% 的常温固化混合物，与混合物 (A0G0.5) 相比，含有 25%25 \% 和 50%50 \% RAP 的混合物的强度分别增加了 20.83%20.83 \% 和 6.18%6.18 \% 。然而，与不含 RAP 的混合物相比，含有 100%100 \% RAP 的混合物强度略有下降，降幅为 0.09%0.09 \% 。同样，与混合物（A0G0.5）相比，含有 25%25 \% 和 50%50 \% RAP 的混合物在 80^(@)C80^{\circ} \mathrm{C} 和 0.5%0.5 \% GF 含量下固化后，强度分别增加了 26.75%26.75 \% 和 10.08%10.08 \% 。相反，与 A0G0.5 混合物相比，含有 100%100 \% RAP 的混合物强度降低了 3.6%。含有 25%25 \% RAP 的混合物在较高的固化温度 (80^(@)C)\left(80^{\circ} \mathrm{C}\right) 下表现更好，显示出更大的强度增益。这表明，在 RAP 含量适中的情况下，较高的固化温度能更有效地促进土工聚合过程，从而使基体发展和粘结更强。与 25% RAP 混合物类似，50% RAP 混合物也从较高的固化温度中获益更多，但与 25%25 \% RAP 相比，改善并不明显。 80^(@)C80^{\circ} \mathrm{C} 时强度的适度增加表明，RAP 含量越高，RAP 的积极作用就越小。
elevated curing on compressive strength. The 100 % RAP mixtures showed strength reductions under both curing conditions, but the drop was more significant at 80^(@)C80^{\circ} \mathrm{C}. This suggests that high RAP content is detrimental to compressive strength, particularly at elevated temperatures, likely due to the bituminous material in RAP softening at higher temperatures, weakening the bond between RAP and the matrix. 固化温度升高对抗压强度的影响在两种固化条件下，100% RAP 混合物的强度都有所下降，但在 80^(@)C80^{\circ} \mathrm{C} 条件下下降更为明显。这表明高 RAP 含量不利于抗压强度，尤其是在高温条件下，这可能是由于 RAP 中的沥青材料在高温下软化，削弱了 RAP 与基体之间的粘结力。
For the mixtures cured at ambient temperature with 1%GF1 \% \mathrm{GF} content, those with 25%25 \% and 50 % RAP showed strength increases of 53.12 % and 44.28%44.28 \%, respectively, compared to the mixture (A0G1). In contrast, the mixture with 100%100 \% RAP experienced a slight strength reduction of 4.08 % compared to the mixture without RAP. Likewise, after curing at 80^(@)C80^{\circ} \mathrm{C} with 1%GF1 \% \mathrm{GF} content, strength gains of 27.93%27.93 \% and 18.88%18.88 \% were observed in the mixtures with 25%25 \% and 50%50 \% RAP, respectively, compared to the mixture (A0G1). In contrast, the mixture with 100%100 \% RAP exhibited a 10.55 % reduction in strength compared to A0G1. The inclusion of 1%1 \% GF improved the strength of mixtures containing RAP, especially under ambient conditions. However, the elevated temperature curing (80^(@)C)\left(80^{\circ} \mathrm{C}\right) appeared to limit the positive effect of glass fibers, particularly in the presence of higher RAP content. The increase in strength at 25 and 50%50 \% RAP was attributed to improved particle packing and densification in the matrix as a function of partial RAP inclusion that balanced the stiffness and bonding. However, at 100 % RAP, binderaggregate adhesion weakens due to the absence of a natural aggregate and the predominance of bitumen-coated surfaces, hence the lower strength. Increased curing ( 80^(@)C80^{\circ} \mathrm{C} ) hastens the geopolymerization process and increases strength at moderate RAP levels, whereas it tends to soften bitumen when RAP is at 100%100 \%, further weakening the matrix and increasing its porosity. GF enhance tensile strength, but their advantages are limited in 100 %RAP mixtures due to inferior matrix integrity[61]. 对于在常温下固化的 1%GF1 \% \mathrm{GF} 含量的混合物，与混合物 (A0G1) 相比，含有 25%25 \% 和 50 % RAP 的混合物的强度分别增加了 53.12 % 和 44.28%44.28 \% 。相反，与不含 RAP 的混合物相比，含有 100%100 \% RAP 的混合物强度略微降低了 4.08%。同样，在 80^(@)C80^{\circ} \mathrm{C} 和 1%GF1 \% \mathrm{GF} 含量下固化后，与混合物 (A0G1) 相比，含有 25%25 \% 和 50%50 \% RAP 的混合物的强度分别增加了 27.93%27.93 \% 和 18.88%18.88 \% 。相反，与 A0G1 相比，含有 100%100 \% RAP 的混合物强度降低了 10.55%。 1%1 \% GF 的加入提高了含有 RAP 的混合物的强度，尤其是在环境条件下。然而，高温固化 (80^(@)C)\left(80^{\circ} \mathrm{C}\right) 似乎限制了玻璃纤维的积极作用，尤其是在 RAP 含量较高的情况下。RAP 含量为 25% 和 50%50 \% 时强度的增加归因于部分 RAP 的加入改善了基体中的颗粒堆积和致密化，从而平衡了刚度和粘结力。然而，当 RAP 含量达到 100% 时，由于缺乏天然骨料，沥青涂层表面占主导地位，粘结剂与骨料的粘附性减弱，因此强度降低。增加固化（ 80^(@)C80^{\circ} \mathrm{C} ）可加速土工聚合过程，并在中等 RAP 水平下提高强度，而当 RAP 达到 100%100 \% 时，固化往往会软化沥青，进一步削弱基质并增加其孔隙率。GF 可提高拉伸强度，但由于基体完整性较差，其优势在 100% RAP 混合物中受到限制[61]。
3.2. Flexural strength 3.2.挠曲强度
Fig. 4 illustrates the effects of GF content, ambient and 图 4 说明了 GF 含量、环境温度和温度的影响。80^(@)C80^{\circ} \mathrm{C} curing temperatures for 24 hours, and the use of RAP instead of RS on the flexural strength of AAC mixtures. The inclusion of GF in AAC mixtures contributed positively to flexural strength due to their ability to resist tensile forces and delay crack propagation [62]. As GF content increases from 在 AAC 混合物中加入 GF 对抗弯强度有积极作用，因为它们能够抵抗拉力并延迟裂缝扩展 [62]。在 AAC 混合物中加入 GF 会对抗弯强度产生积极影响，因为 GF 具有抵抗拉力和延迟裂纹扩展的能力 [62]。随着 GF 含量从0%0 \% to 至1%1 \%, the flexural strength of the AAC mixtures also increases across both curing regimes (ambient and 此外，在两种固化条件下（常温和低温），AAC 混合物的抗折强度都会增加。80^(@)C80^{\circ} \mathrm{C} ). Increasing the GF content improved flexural strength, with ).增加 GF 含量可提高抗折强度，其中1%1 \% GF showing the best performance. The fibers enhanced crack resistance and load distribution, particularly when combined with RAP. Curing at GF 的性能最佳。纤维增强了抗裂性和载荷分布，尤其是与 RAP 结合使用时。固化温度80^(@)C80^{\circ} \mathrm{C} led to higher 导致
flexural strength due to accelerated geopolymerization, better bonding, and improved microstructure[17]. RAP and GF benefited most under these conditions. RAP improved the flexural strength by providing better particle packing, flexibility, and energy absorption. A 由于加速了土工聚合、提高了粘结性并改善了微观结构，因此抗折强度更高[17]。在这些条件下，RAP 和 GF 受益最大。RAP 可提供更好的颗粒堆积、柔韧性和能量吸收，从而提高抗弯强度。A25%25 \% RAP content appears to be optimal for maximizing flexural strength, especially under elevated curing temperatures. Under ambient curing, the flexural strength values are lower due to the slower geopolymerization process. However, even at ambient conditions, the incorporation of GF and RAP still provides noticeable strength improvements, demonstrating the potential of these materials to perform well under less aggressive curing regimes. The higher curing temperature likely enhanced the bonding between the RAP particles and the alkali-activated binder, leading to a stronger and more resilient composite. This improvement is more pronounced in the mixtures with RAP 含量似乎是最大化抗折强度的最佳选择，尤其是在固化温度升高的情况下。在常温固化条件下，由于土工聚合过程较慢，抗折强度值较低。不过，即使在常温条件下，加入 GF 和 RAP 仍能显著提高强度，这表明这些材料在侵蚀性较小的固化条件下也有很好的表现潜力。较高的固化温度可能会增强 RAP 颗粒与碱激活粘合剂之间的粘合力，从而使复合材料更坚固、更有韧性。这种改善在含有以下成分的混合物中更为明显0.5%0.5 \% and 和1%GF1 \% \mathrm{GF}, where the enhanced fiber-matrix interaction under high-temperature curing further boosts the flexural strength. 在高温固化条件下，纤维与基质之间的相互作用增强，从而进一步提高了抗弯强度。
At 0%0 \% GF content, the flexural strength is the lowest across all RAP replacement levels. This is expected because GF provide additional reinforcement, and their absence results in lower flexural strength. Even with RAP substitution, there is limited crack resistance in the absence of GF. Flexural strength increased with rising RAP content for both ambient and 80^(@)C80^{\circ} \mathrm{C} curing, displaying moderate strength values. All RAPcontaining mixtures demonstrated higher flexural strength compared to the reference mixture at both curing temperatures. The mixture containing 25%25 \% RAP, when cured at 80^(@)C80^{\circ} \mathrm{C}, exhibited the highest flexural strength, showing an improvement of 18.54%18.54 \% over the reference mixture. Under ambient curing, the mixture with 100 % RAP showed the greatest strength, reflecting a 20.72%20.72 \% increase compared to the reference mixture. 在 0%0 \% GF 含量下，抗折强度在所有 RAP 替代水平中都是最低的。这在意料之中，因为 GF 提供了额外的加固，而没有 GF 会导致抗弯强度降低。即使用 RAP 替代，在没有 GF 的情况下，抗裂性也很有限。在常温和 80^(@)C80^{\circ} \mathrm{C} 固化条件下，抗折强度随着 RAP 含量的增加而增加，显示出中等强度值。与参照混合物相比，所有含 RAP 的混合物在两种固化温度下都表现出更高的抗折强度。含有 25%25 \% RAP 的混合物在 80^(@)C80^{\circ} \mathrm{C} 温度下固化时，显示出最高的抗折强度，比参考混合物提高了 18.54%18.54 \% 。在常温固化条件下，含有 100 % RAP 的混合物强度最大，与参考混合物相比提高了 20.72%20.72 \% 。
At 0.5%0.5 \% GF, there was a noticeable increase in flexural strength compared to 0%GF0 \% \mathrm{GF}. The inclusion of GF enhanced crack resistance and improved the composite’s ability to withstand flexural stresses. Both ambient and 80^(@)C80^{\circ} \mathrm{C} curing conditions showed this improvement. The mixture with 50%50 \% RAP, cured at 80^(@)C80^{\circ} \mathrm{C}, achieved the highest flexural strength, displaying a 22.92 % improvement over the reference mix (A0G0.5). In contrast, under ambient curing conditions, the mixture with 25 % RAP showed the greatest strength, with a 12.92 % increase compared to the reference mix. All mixtures containing RAP showed higher flexural strength than the mixture without RAP at both curing temperatures, except for the mixture with 100%100 \% RAP cured under ambient conditions. The poor performance of the 100%100 \% RAP mixture under ambient conditions is likely due to a weaker bond between the RAP and the matrix, which results in lower flexural strength. 与 0%GF0 \% \mathrm{GF} 相比， 0.5%0.5 \% GF 的抗弯强度明显提高。GF 的加入增强了抗裂性，提高了复合材料承受弯曲应力的能力。常温和 80^(@)C80^{\circ} \mathrm{C} 固化条件都显示了这种改善。含有 50%50 \% RAP 的混合物在 80^(@)C80^{\circ} \mathrm{C} 条件下固化后，抗折强度最高，比参考混合物（A0G0.5）提高了 22.92%。相比之下，在常温固化条件下，含有 25% RAP 的混合物强度最大，与参考混合物相比提高了 12.92%。所有含有 RAP 的混合物在两种固化温度下都比不含 RAP 的混合物显示出更高的抗折强度，但在环境条件下固化的 100%100 \% RAP 混合物除外。在环境条件下， 100%100 \% RAP 混合物的性能较差，这可能是由于 RAP 与基体之间的结合力较弱，导致抗折强度较低。
At 1%GF1 \% \mathrm{GF}, the flexural strength reached its peak, with both curing regimes showing significantly higher values compared to 0%0 \% and 0.5%0.5 \% GF content. The higher GF content increased the crack-bridging capability, resulting in better overall flexural performance. The improvement between 0.5%0.5 \% and 1%GF1 \% \mathrm{GF} was more moderate, suggesting a possible saturation point beyond which the benefits of adding more fibers diminish. The mixtures with 25 and 50 %RAP exhibited larger strength but the mixture with 100 %RAP had lower strength than the mixture without RAP at both curing temperature. The mixture containing 25%25 \% RAP achieved the highest flexural strength, showing an improvement of 24.27 % and 12.65 % over the reference mix (A0G1) under ambient and 80^(@)C80^{\circ} \mathrm{C} curing conditions, respectively. In contrast, the mixture with 100%100 \% RAP exhibited the lowest strength, with reductions of 9.56%9.56 \% and 8.93%8.93 \% under ambient and 80^(@)C80^{\circ} \mathrm{C} curing, respectively, compared to the mix without RAP. The mixture with 1%1 \% GF and 25 % RAP achieves the best flexural strength due to optimal fiber reinforcement, improved crack resistance, and a balanced amount of RAP that enhances flexibility without disrupting the matrix. However, the 100 % RAP mixture performs poorly because the excessive asphalt binder weakens the matrix, leading to insufficient bonding between the geopolymer matrix and the reinforcing fibers, especially under ambient curing. 在 1%GF1 \% \mathrm{GF} 时，抗折强度达到峰值，两种固化条件下的抗折强度值都明显高于 0%0 \% 和 0.5%0.5 \% GF 含量。较高的 GF 含量提高了裂缝桥接能力，从而改善了整体抗折性能。 0.5%0.5 \% 和 1%GF1 \% \mathrm{GF} 之间的改善程度较为适中，这表明可能存在一个饱和点，超过该点，添加更多纤维的好处就会减少。含有 25%RAP 和 50%RAP 的混合物强度较大，但含有 100%RAP 的混合物在两种固化温度下的强度都低于不含 RAP 的混合物。含有 25%25 \% RAP的混合物获得了最高的抗折强度，在常温和 80^(@)C80^{\circ} \mathrm{C} 固化条件下分别比参考混合物（A0G1）提高了 24.27 % 和 12.65 %。相比之下，含有 100%100 \% RAP 的混合物强度最低，在常温和 80^(@)C80^{\circ} \mathrm{C} 固化条件下，与不含 RAP 的混合物相比，强度分别降低了 9.56%9.56 \% 和 8.93%8.93 \% 。含有 1%1 \% GF 和 25 % RAP 的混合物可达到最佳抗折强度，这是因为纤维加固效果最佳，抗裂性得到改善，而且均衡的 RAP 含量可在不破坏基质的情况下增强柔韧性。然而，100% RAP 混合物的性能较差，因为过量的沥青粘结剂会削弱基质，导致土工聚合物基质与增强纤维之间的粘结力不足，尤其是在常温固化条件下。
Fig. 4. The flexural strength at ambient and 80^(@)C80^{\circ} \mathrm{C} for 24 h . 图 4.环境和 80^(@)C80^{\circ} \mathrm{C} 条件下 24 小时的抗弯强度。
3.3. Oven dry density 3.3.烘箱干燥密度
Fig. 5a displays the effects of glass fiber (GF) content, ambient and 80^(@)C80^{\circ} \mathrm{C} curing temperatures for 24 hours, and RAP substitution for RS on the oven dry density of alkali-activated composites (AAC) mixtures. The mixes dried at room temperature have dry densities ranging from 2040 to 2168kg//m^(3)2168 \mathrm{~kg} / \mathrm{m}^{3}. The mixes dried at 80^(@)C80^{\circ} \mathrm{C} have dry densities ranging from 1934 to 2155kg//m^(3)2155 \mathrm{~kg} / \mathrm{m}^{3}. The mixtures with 25%25 \% RAP exhibited the largest dry density at both curing conditions regardless of GF content. It seems that 25 % RAP provides an ideal balance between RS and RAP, promoting optimal particle packing and compaction at both curing conditions, which leads to the highest dry density. 图 5a 显示了玻璃纤维 (GF) 含量、24 小时的环境温度和 80^(@)C80^{\circ} \mathrm{C} 固化温度以及 RAP 替代 RS 对碱活性复合材料 (AAC) 混合物烘干密度的影响。在室温下干燥的混合物的干密度在 2040 到 2168kg//m^(3)2168 \mathrm{~kg} / \mathrm{m}^{3} 之间。在 80^(@)C80^{\circ} \mathrm{C} 下干燥的混合物的干密度范围为 1934 到 2155kg//m^(3)2155 \mathrm{~kg} / \mathrm{m}^{3} 。无论 GF 含量如何，含有 25%25 \% RAP 的混合料在两种固化条件下都表现出最大的干密度。看来，25% 的 RAP 在 RS 和 RAP 之间达到了理想的平衡，在两种固化条件下都能促进最佳的颗粒堆积和压实，从而获得最高的干密度。
The mixtures cured under ambient conditions displayed higher dry density compared to those cured at 80^(@)C80^{\circ} \mathrm{C}, regardless of the GF content. Additionally, the inclusion of GF led to a reduction in dry density. Ambient curing promoted slower geopolymerization and more uniform matrix consolidation, leading to higher dry density. 80^(@)C80^{\circ} \mathrm{C} curing accelerated the geopolymerization process but can lead to micro cracking and voids due to rapid moisture loss and internal stresses, reducing the overall density. GF reduced dry density because of their lower mass compared to the geopolymer matrix and natural aggregates, and the introduction of voids during mixing and curing[63]. 与在 80^(@)C80^{\circ} \mathrm{C} 条件下固化的混合物相比，在环境条件下固化的混合物显示出更高的干密度，无论 GF 含量如何。此外，加入 GF 会导致干密度降低。常温固化可减缓土工聚合速度，使基质固结更均匀，从而提高干密度。 80^(@)C80^{\circ} \mathrm{C} 固化加速了土工聚合过程，但会因水分快速流失和内应力而导致微裂缝和空隙，从而降低整体密度。与土工聚合物基体和天然集料相比，GF 的质量较小，而且在混合和固化过程中会产生空隙，因此会降低干密度[63]。
For the ambient-cured mixtures containing 0%0 \% GF, all RAPincorporated mixtures showed a slightly higher dry density compared to the reference mixture without RAP. Notably, the mixture with 25%25 \% RAP had the highest density, showing an improvement of about 2.4%2.4 \% over the reference mixture (A0GO). In the case of mixtures cured at 80^(@)C80^{\circ} \mathrm{C} with 0%0 \% GF, those containing 25%25 \% and 50%50 \% RAP exhibited marginally higher densities, while the mixture with 100%100 \% RAP had a slightly lower density, with a reduction of 3.72%3.72 \% compared to the reference mixture. RAP typically contains a mix of aggregates and aged binder, which may improve particle packing and interlock within the matrix. In the ambient-cured mixtures, the addition of RAP could enhance the compaction efficiency, leading to slightly higher dry densities compared to the reference mixture without RAP. The mixture with 25 % RAP might have struck an optimal balance between the natural aggregates and RAP, maximizing the packing density, hence the 2.4%2.4 \% increase in density. Curing at 80^(@)C80^{\circ} \mathrm{C} accelerates the geopolymerization process. For the mixtures with 25%25 \% and 50%50 \% RAP, this accelerated reaction likely improved the binder structure, leading to marginally higher densities than the reference. However, the mixture with 100 % RAP exhibited a reduction in density. This could be due to the absence of natural aggregates, which typically have higher strength and density compared to RAP materials. The rapid geopolymerization at high temperatures could 对于含有 0%0 \% GF 的常温固化混合物，与不含 RAP 的参考混合物相比，所有添加 RAP 的混合物的干密度都略高。值得注意的是，含有 25%25 \% RAP 的混合物密度最高，比参考混合物（A0GO）高出约 2.4%2.4 \% 。在使用 0%0 \% GF 在 80^(@)C80^{\circ} \mathrm{C} 下固化的混合物中，含有 25%25 \% 和 50%50 \% RAP 的混合物密度略高，而含有 100%100 \% RAP 的混合物密度略低，与参考混合物相比降低了 3.72%3.72 \% 。RAP 通常包含集料和老化粘结剂的混合物，这可能会改善基质内的颗粒堆积和互锁。在常温固化混合物中，添加 RAP 可提高压实效率，从而使干密度略高于不添加 RAP 的参考混合物。添加 25% RAP 的混合物可能在天然集料和 RAP 之间达到了最佳平衡，使堆积密度最大化，因此密度 2.4%2.4 \% 有所增加。在 80^(@)C80^{\circ} \mathrm{C} 条件下固化可加速土工聚合过程。对于含有 25%25 \% 和 50%50 \% RAP 的混合物，这种加速反应可能会改善粘结剂结构，从而使密度略高于参考值。然而，含有 100% RAP 的混合物密度有所降低。这可能是由于没有天然集料的缘故，而天然集料通常比 RAP 材料具有更高的强度和密度。高温下的快速土工聚合可能会导致
also cause micro-cracking or increased void content due to faster moisture loss and internal stresses, contributing to the 3.72 % reduction in density for the 100%100 \% RAP mixture. 此外，由于水分损失和内应力的加快，也会导致微裂缝或空隙含量增加，从而使 100%100 \% RAP 混合物的密度降低 3.72%。
For the ambient-cured mixtures containing 0.5%GF0.5 \% \mathrm{GF}, the mixture with 25 % RAP showed a slightly higher density, while those with 50 % and 100 % RAP had slightly lower densities compared to the mixture without RAP. In contrast, all RAP-incorporated mixtures cured at 80^(@)C80^{\circ} \mathrm{C} displayed higher densities compared to the mixture without RAP. 对于含有 0.5%GF0.5 \% \mathrm{GF} 的常温固化混合物，与不含 RAP 的混合物相比，含有 25 % RAP 的混合物密度略高，而含有 50 % 和 100 % RAP 的混合物密度略低。相反，与不含 RAP 的混合物相比，在 80^(@)C80^{\circ} \mathrm{C} 条件下固化的所有 RAP 加入混合物的密度都较高。
For the ambient and 80^(@)C80^{\circ} \mathrm{C}-cured mixtures with 1%GF1 \% \mathrm{GF}, the mixtures containing 25 and 50 % RAP had a slightly higher density, whereas the mixtures with 100 % RAP showed slightly lower density compared to the mixture without RAP. 与不含 RAP 的混合物相比，含 25% 和 50% RAP 的常温和 80^(@)C80^{\circ} \mathrm{C} 固化混合物的密度略高，而含 100% RAP 的混合物密度略低。
In Fig. 5b, the dry density and compressive strength show a significant exponential relationship ( R2=0.86\mathrm{R} 2=0.86 and 0.90 ). Accordingly, dry density could be a good indicator of the materials’ compressive strength. 在图 5b 中，干密度与抗压强度呈显著的指数关系（ R2=0.86\mathrm{R} 2=0.86 和 0.90）。因此，干密度可以很好地反映材料的抗压强度。
3.4. Porosity and water absorption 3.4.孔隙率和吸水性
Fig. 6a illustrates how the porosity of AAC mixes is affected by the GF concentration, the curing temperatures of ambient and 80^(@)C80^{\circ} \mathrm{C} for 24 hours, and the replacement of RS with RAP. While combinations cured at 80^(@)C80^{\circ} \mathrm{C} had porosities ranging from 7.09%7.09 \% to 10.22%10.22 \%, those cured at room temperature have porosities ranging from 7.65%7.65 \% to 11.12%11.12 \%. The mixtures cured at 80^(@)C80^{\circ} \mathrm{C} showed lower porosity compared to those cured at ambient temperature, regardless of the RAP content or GF content. Higher curing temperatures accelerated the geopolymerization process, leading to a faster and more complete chemical reaction between the aluminosilicate materials and the alkaline activators. This results in the formation of a more dense and compact matrix, reducing the amount of unreacted material and, consequently, the overall porosity [64]. 图 6a 说明了 AAC 混合料的孔隙率如何受到 GF 浓度、24 小时固化温度（环境温度和 80^(@)C80^{\circ} \mathrm{C} 温度）以及用 RAP 替代 RS 的影响。在 80^(@)C80^{\circ} \mathrm{C} 温度下固化的混合物的孔隙率在 7.09%7.09 \% 到 10.22%10.22 \% 之间，而在室温下固化的混合物的孔隙率在 7.65%7.65 \% 到 11.12%11.12 \% 之间。与在环境温度下固化的混合物相比，无论 RAP 含量或 GF 含量如何，在 80^(@)C80^{\circ} \mathrm{C} 温度下固化的混合物孔隙率都较低。较高的固化温度加快了土工聚合过程，使硅酸铝材料与碱性活化剂之间的化学反应更快、更完全。这就形成了更加致密和紧凑的基体，减少了未反应材料的数量，从而降低了整体孔隙率[64]。
Regardless of GF content, the mixtures containing 25 % RAP consistently showed the lowest porosity under both curing conditions. The 25 % RAP content achieved an optimal balance between RAP and RS, facilitating effective particle packing and matrix formation. The RAP’s binder and particle characteristics, coupled with efficient geopolymerization (especially at 80^(@)C80^{\circ} \mathrm{C} ), lead to the lowest porosity levels across both curing conditions, regardless of the GF content. On the other hand, the mixtures containing 100%100 \% RAP showed the highest porosity under both ambient and 80^(@)C80^{\circ} \mathrm{C} curing conditions, regardless of the GF content. RAP has a more porous and rough surface texture compared to natural aggregates like river sand (RS). The aged asphalt coating on RAP particles introduces micro voids into the mix, making it difficult to achieve a tightly packed, dense structure, leading to higher overall 无论 GF 含量如何，含有 25% RAP 的混合物在两种固化条件下的孔隙率都是最低的。25% 的 RAP 含量实现了 RAP 和 RS 之间的最佳平衡，有利于有效的颗粒堆积和基质形成。RAP 的粘结剂和颗粒特性，加上高效的土工聚合（尤其是在 80^(@)C80^{\circ} \mathrm{C} 时），使得在两种固化条件下，无论 GF 含量如何，孔隙率水平都最低。另一方面，含有 100%100 \% RAP 的混合物在常温和 80^(@)C80^{\circ} \mathrm{C} 固化条件下的孔隙率最高，与 GF 含量无关。与河砂（RS）等天然集料相比，RAP 的表面纹理更加多孔和粗糙。RAP 颗粒上的老化沥青涂层会给混合料带来微小空隙，使其难以形成紧密的致密结构，从而导致总体孔隙率升高。
Fig. 5. Oven dry density at ambient and 80^(@)C80^{\circ} \mathrm{C} for 24 h . b) Compressive strength vs. oven dry density. 图 5.b) 压缩强度与烘干密度的关系。
Fig. 6. The porosity of the mixtures at ambient and 80^(@)C80^{\circ} \mathrm{C} for 24 h . b) Compressive strength vs. porosity. 图 6.b) 压缩强度与孔隙率的关系。
porosity [41]. The inclusion of glass fibers (GF) increased the porosity of the mixtures, regardless of the curing temperature or RAP content. This can be due to the inclusion of GF introduces voids around the fibers, interferes with particle packing, and may cause distribution and bonding issues, all of which contribute to increased porosity in the mixtures, regardless of curing conditions or RAP content. 孔隙率[41]。无论固化温度或 RAP 含量如何，加入玻璃纤维 (GF) 都会增加混合物的孔隙率。这可能是由于玻璃纤维的加入会在纤维周围产生空隙，干扰颗粒堆积，并可能导致分布和粘结问题，所有这些都会导致混合物的孔隙率增加，而与固化条件或 RAP 含量无关。
Fig. 6b shows high R^(2)\mathrm{R}^{2} values for both curing conditions, indicating a strong correlation between porosity and compressive strength. The R^(2)\mathrm{R}^{2} value for 80^(@)C80^{\circ} \mathrm{C} curing is slightly higher (R^(2)=0.89)\left(R^{2}=0.89\right) than for ambient curing ( R^(2)=0.86\mathrm{R}^{2}=0.86 ), suggesting that compressive strength is more predictably influenced by porosity when cured at elevated temperatures. 图 6b 显示，两种固化条件下的 R^(2)\mathrm{R}^{2} 值都很高，表明孔隙率和抗压强度之间有很强的相关性。 80^(@)C80^{\circ} \mathrm{C} 固化条件下的 R^(2)\mathrm{R}^{2} 值略高于常温固化条件下的 (R^(2)=0.89)\left(R^{2}=0.89\right) 值（ R^(2)=0.86\mathrm{R}^{2}=0.86 ），这表明在高温固化条件下，抗压强度受孔隙率的影响更可预测。
Fig. 7 illustrates the effects of GF content, curing temperatures (ambient and 80^(@)C80^{\circ} \mathrm{C} for 24 hours), and the substitution of RAP for RS on the water absorption of AAC mixtures. The water absorption of the mixtures cured at ambient temperatures ranges from 4.03%4.03 \% to 7.64%7.64 \%, while those cured at 80^(@)C80^{\circ} \mathrm{C} range from 2.40%2.40 \% to 6.89%6.89 \%. Regardless of RAP or GF content, mixtures cured at 80^(@)C80^{\circ} \mathrm{C} consistently exhibited lower water absorption compared to those cured at ambient temperature. Higher curing temperatures promote faster and more efficient 图 7 说明了 GF 含量、固化温度（常温和 80^(@)C80^{\circ} \mathrm{C} 24 小时）以及用 RAP 替代 RS 对 AAC 混合物吸水性的影响。在常温下固化的混合物的吸水率在 4.03%4.03 \% 到 7.64%7.64 \% 之间，而在 80^(@)C80^{\circ} \mathrm{C} 下固化的混合物的吸水率在 2.40%2.40 \% 到 6.89%6.89 \% 之间。无论 RAP 或 GF 含量如何，与在环境温度下固化的混合物相比，在 80^(@)C80^{\circ} \mathrm{C} 下固化的混合物始终表现出较低的吸水性。较高的固化温度可促进更快、更有效的
Fig. 7. The water absorption of the mixtures cured at ambient and 80^(@)C80^{\circ} \mathrm{C} for 24 h . 图 7.在环境和 80^(@)C80^{\circ} \mathrm{C} 条件下固化 24 小时的混合物的吸水性。
geopolymerization, which leads to a denser and more compact matrix. This reduced the number of voids or micro-pores in the structure that could allow water to be absorbed. Curing at 80^(@)C80^{\circ} \mathrm{C} improves the matrix’s density, reduces voids and capillary pores, and enhances particle bonding, which together significantly lower the water absorption compared to mixtures cured at ambient temperatures. Similar to the porosity results, the mixtures containing 25%25 \% RAP consistently exhibited the lowest water absorption under both curing conditions, regardless of GF content. The 25%25 \% RAP content provides an optimal blend of particle packing, matrix formation, and geopolymerization, resulting in a denser structure with fewer voids and pathways for water, thereby reducing water absorption under both curing conditions. Conversely, the mixtures containing 100%100 \% RAP demonstrated the highest water absorption under both ambient and 80^(@)C80^{\circ} \mathrm{C} curing conditions, irrespective of the GF content. The high porosity of RAP, poor particle packing, weak matrix formation, and inefficient geopolymerization in 100 % RAP mixtures result in higher water absorption, regardless of the curing conditions or GF content. 地聚合，从而使基质更致密、更紧凑。这就减少了结构中可能吸水的空隙或微孔的数量。在 80^(@)C80^{\circ} \mathrm{C} 条件下固化可提高基质的密度，减少空隙和毛细孔，并增强颗粒间的粘结力，与在环境温度下固化的混合物相比，吸水率明显降低。与孔隙率结果类似，无论 GF 含量如何，含有 25%25 \% RAP 的混合物在两种固化条件下的吸水率都是最低的。 25%25 \% RAP 含量实现了颗粒填料、基质形成和土工聚合的最佳混合，使结构更加致密，空隙和水通道更少，从而降低了两种固化条件下的吸水率。相反，无论 GF 含量如何，含有 100%100 \% RAP 的混合物在常温和 80^(@)C80^{\circ} \mathrm{C} 固化条件下的吸水率都最高。在 100% RAP 混合物中，RAP 的孔隙率高、颗粒堆积差、基质形成弱、土工聚合效率低，因此无论固化条件或 GF 含量如何，吸水率都较高。
3.5. Sorptivity 3.5.吸附性
Fig. 8a illustrates the effects of GF content, curing temperatures (ambient and 80^(@)C80^{\circ} \mathrm{C} for 24 hours), and the substitution of RAP for RS on the sorptivity of AAC mixtures. The sorptivity of the mixtures cured at ambient temperatures ranges from 0.6%0.6 \% to 1.99%1.99 \%, while those cured at 80^(@)C80^{\circ} \mathrm{C} exhibit values between 0.43%0.43 \% and 1.65%1.65 \%. Overall, the mixtures cured at 80^(@)C80^{\circ} \mathrm{C} demonstrated lower sorptivity than those cured at ambient temperatures, irrespective of the RAP or GF content. Curing at 80^(@)C80^{\circ} \mathrm{C} promotes more rapid chemical reactions within the AAC mixtures. This leads to a more efficient formation of the alkali-activated products, resulting in a denser and stronger matrix compared to mixtures cured at ambient temperatures. The elevated temperature enhances the development of a compact microstructure, effectively reducing the porosity of the mixtures. A lower porosity generally leads to decreased sorptivity, as there are fewer pathways for water to penetrate. Irrespective of the GF content and curing temperature, the mixtures with 25 % RAP consistently exhibited the lowest sorptivity under both curing conditions and the mixtures with 100 %RAP had the largest sorptivity values. At 25%25 \% RAP content, the mixture likely achieves an optimal balance between RAP aggregates and fresh materials (such as natural aggregates and cementitious binders). This balance promotes better compaction and less porosity, reducing the pathways for water ingress, which leads to lower sorptivity. The asphalt in RAP is hydrophobic, which decreases 图 8a 说明了 GF 含量、固化温度（常温和 80^(@)C80^{\circ} \mathrm{C} 24 小时）以及用 RAP 代替 RS 对 AAC 混合物吸附性的影响。在常温下固化的混合物的吸附性介于 0.6%0.6 \% 和 1.99%1.99 \% 之间，而在 80^(@)C80^{\circ} \mathrm{C} 下固化的混合物的吸附性介于 0.43%0.43 \% 和 1.65%1.65 \% 之间。总的来说，无论 RAP 或 GF 含量如何，在 80^(@)C80^{\circ} \mathrm{C} 下固化的混合物都比在常温下固化的混合物吸水率低。在 80^(@)C80^{\circ} \mathrm{C} 下固化可促进 AAC 混合物内部更快的化学反应。这导致碱活化产物的形成更加有效，与在环境温度下固化的混合物相比，基质更加致密和坚固。温度升高可促进微观结构的紧密发展，有效降低混合物的孔隙率。孔隙率降低通常会导致吸水率降低，因为水渗入的途径减少了。无论 GF 含量和固化温度如何，含有 25 % RAP 的混合物在两种固化条件下的吸水率都是最低的，而含有 100 % RAP 的混合物的吸水率值最大。当 RAP 含量达到 25%25 \% 时，混合物可能会在 RAP 骨料和新鲜材料（如天然骨料和水泥基粘结剂）之间达到最佳平衡。这种平衡可提高压实度，降低孔隙率，减少进水途径，从而降低吸水率。RAP 中的沥青具有疏水性，可降低
Fig. 8. The sorptivity at ambient and 80^(@)C80^{\circ} \mathrm{C} for 24 h . b) Compressive vs. sorptivity. 图 8.b) 压缩率与吸附率的关系。
water absorption. At 25 % RAP, this coating may be sufficient to effectively reduce moisture penetration without negatively impacting the overall bond between the cement paste and aggregates. With 100 % RAP, there is a larger presence of aged asphalt-coated aggregates, which may not bond as effectively with the cementitious matrix compared to natural aggregates. This can create a more porous structure with less cohesion, allowing more water to penetrate, thus increasing sorptivity. A full replacement of natural aggregates with RAP could result in a more porous structure because RAP aggregates may contain micro-cracks or voids that are inherent due to aging and weathering. These voids increase the capillary pathways, raising the sorptivity. At higher percentages of RAP, the bituminous material might degrade or break down during mixing and compaction, especially under certain curing conditions, leading to higher permeability and sorptivity. While low to moderate RAP contents (like 25 %) provide benefits like a hydrophobic effect and pore refinement, high RAP contents (100 %) might reverse these advantages due to excessive asphalt-coated particles, which create discontinuities in the cement matrix. At 100 % RAP, the integrity of the overall matrix is compromised because the cementitious material may not fully encapsulate the RAP particles, leading to higher sorptivity. 吸水性。在使用 25% RAP 时，这种涂层可能足以有效减少水分渗透，而不会对水泥浆和集料之间的整体粘结力产生负面影响。如果使用 100% 的 RAP，则会出现更多的老化沥青涂层集料，与天然集料相比，这些集料可能无法与水泥基质有效结合。这会产生内聚力较低的多孔结构，使更多的水渗入，从而增加吸水率。用 RAP 完全替代天然集料可能会产生更多孔的结构，因为 RAP 集料可能含有因老化和风化而固有的微裂缝或空隙。这些空隙会增加毛细通道，提高吸水率。如果 RAP 的比例较高，沥青材料可能会在搅拌和压实过程中降解或分解，特别是在某些固化条件下，从而导致渗透性和吸水率升高。中低浓度的 RAP 含量（如 25%）具有疏水效果和细化孔隙等优点，而高浓度的 RAP 含量（100%）则可能会由于过多的沥青涂层颗粒在水泥基质中产生不连续性而使这些优点发生逆转。当 RAP 含量达到 100%时，整个基质的完整性会受到影响，因为胶凝材料可能无法完全包裹 RAP 颗粒，从而导致吸水率升高。
Fig. 8b confirms the well-known inverse relationship between compressive strength and sorptivity. The stronger correlation under 80^(@)C80^{\circ} \mathrm{C} curing ( R^(2)=0.82\mathrm{R}^{2}=0.82 ) shows that elevated temperature curing leads to a more defined and predictable relation between these properties, enhancing concrete’s durability. However, under ambient curing ( R^(2)=\mathrm{R}^{2}= 0.65 ), the relationship is still present but more influenced by variations in pore structure and moisture content. 图 8b 证实了抗压强度与吸水率之间众所周知的反比关系。在 80^(@)C80^{\circ} \mathrm{C} 养护条件下（ R^(2)=0.82\mathrm{R}^{2}=0.82 ），两者之间的相关性更强，这表明温度升高的养护使这些性能之间的关系更加明确和可预测，从而提高了混凝土的耐久性。然而，在常温养护条件下（ R^(2)=\mathrm{R}^{2}= 0.65），这种关系仍然存在，但受孔隙结构和含水量变化的影响更大。
3.6. Microstructure analysis after ambient and 80^(@)C80^{\circ} \mathrm{C} heat-curing 3.6.常温和 80^(@)C80^{\circ} \mathrm{C} 热固化后的微观结构分析
Fig. 9a shows a binder matrix dominated by amorphous phases. This phase consists of C-S-H (calcium-silicate-hydrate) or N-A-S-H (sodium-aluminum-silicate-hydrate) structures formed by the reaction of blast furnace slag (GBFS) and alkali activators. Amorphous structures indicate a lack of crystalline phases and represent binder phases formed due to rapid reactions in alkaline activation. This enabled the material to gain early strength. The matrix appears homogeneous and compact. The low density of microspores indicates that adhesion is efficient even under ambient curing conditions. The limited pore structure means that water absorption is low, and the propagation of micro cracks is inhibited. This contributed to the long-term durability of the mixture. Natural aggregates such as river sand are strongly integrated into the binder matrix. No segregation or weak adherence zones are observed in the image. The presence of natural aggregates provides a more reactive and robust 图 9a 显示了以无定形相为主的粘结剂基体。这种相由高炉矿渣（GBFS）和碱活化剂反应形成的 C-S-H（水合硅酸钙）或 N-A-S-H（水合硅酸铝钠）结构组成。无定形结构表明缺乏结晶相，代表在碱性活化过程中快速反应形成的粘结相。这使材料获得了早期强度。基质看起来均匀而紧密。微孢子的低密度表明，即使在常温固化条件下，粘附力也很有效。有限的孔隙结构意味着吸水率低，微裂缝的扩展受到抑制。这有助于提高混合物的长期耐久性。河沙等天然骨料与粘结剂基质紧密结合。图像中没有发现离析或弱粘附区。天然集料的存在提供了一种反应性更强、更坚固的材料。
microstructure compared to RAP aggregates. This contributes to a higher mechanical performance. The experimental study determined that the mixture showed good mechanical performance. In particular, high compressive strength was obtained despite curing in the ambient environment. These microstructural observations confirm that the compact structure and strong aggregate-matrix bonding directly contribute to the mechanical performance. The low porosity of this mixture indicates that water absorption rates are also low. The minimization of water absorption contributed to the high resistance to freeze-thaw cycles. Bituminous film residues were detected around RAP aggregates (Fig. 9b). This coating reduced the effectiveness of the reaction with the alkaline activator, resulting in a weak bond between the binder and the aggregates. The presence of bitumen layers indicates a weak adherence between the matrix and the aggregates. This can lead to bonding deficiencies and voids in the microstructure. Micro cracks and voids were observed in some areas. Softening of the bituminous layers during thermal curing caused displacement of the aggregates (expansion and contraction effects) and the formation of micro cracks. These voids’ presence increased the mixture’s porosity and limited its mechanical strength. An inhomogeneous structure is observed in the microstructure. Especially due to the coating of RAP aggregates, full harmonization with the matrix could not be achieved. Although thermal curing conditions favor the formation of the binder phase by accelerating alkaline activation, bituminous coatings seem to restrict chemical reactivity. The compressive strength of the mix containing 100%100 \% RAP decreased significantly compared to the reference mixes. Microstructural analysis shows that this decrease is due to the poor interaction of bitumen coated RAP aggregates with the binder. Despite thermal curing, the limited reactivity of these aggregates prevented the increase in strength. The micro cracks and voids observed may have increased the water absorption capacity of this mixture. The experimental results indicated that the water absorption of mixtures containing 100%100 \% RAP was higher. Although thermal curing increased the strength of the matrix by accelerating the alkali activation process, aggregate-matrix bonding was limited due to the RAP content. The presence of bituminous layers prevented full utilization of heat activation. 与 RAP 骨料相比，其微观结构更复杂。这有助于提高机械性能。实验研究表明，混合料具有良好的机械性能。特别是，尽管在环境中固化，但仍获得了较高的抗压强度。这些微观结构观察结果证实，紧凑的结构和集料与基质之间的牢固粘结直接促进了机械性能的提高。这种混合物的低孔隙率表明其吸水率也很低。吸水率的降低有助于提高抗冻融循环的能力。在 RAP 骨料周围检测到了沥青膜残留物（图 9b）。这种涂层降低了与碱性活化剂反应的效果，导致粘结剂与集料之间的粘结力减弱。沥青层的存在表明基质和集料之间的粘附力很弱。这会导致微观结构中出现粘结缺陷和空隙。在某些区域观察到了微裂缝和空隙。热固化过程中沥青层的软化导致集料位移（膨胀和收缩效应）并形成微裂缝。这些空隙的存在增加了混合物的孔隙率，限制了其机械强度。在微观结构中可以观察到不均匀结构。特别是由于 RAP 骨料的包裹，无法实现与基体的完全协调。虽然热固化条件通过加速碱性活化有利于粘结相的形成，但沥青涂层似乎限制了化学反应性。与参考混合料相比，含有 100%100 \% RAP 的混合料的抗压强度明显下降。 微观结构分析表明，强度降低的原因是涂有沥青的 RAP 骨料与粘结剂的相互作用不佳。尽管进行了热固化，但这些骨料有限的反应能力阻碍了强度的提高。观察到的微裂缝和空隙可能增加了这种混合物的吸水能力。实验结果表明，含有 100%100 \% RAP 的混合物吸水性更高。虽然热固化通过加速碱活化过程提高了基体强度，但由于 RAP 的含量，骨料与基体的粘结受到了限制。沥青层的存在阻碍了热活化的充分利用。
In Fig. 9c, a weak bond was formed with the binder matrix due to RAP aggregates, and it was determined that homogeneity decreased. The aggregate-matrix interface shows that binding problems were experienced; bitumen coatings prevented the chemical interaction of alkaline activators. GF can be considered to limit the propagation of micro cracks and reduce the material’s brittleness. However, the effect was limited due to the low ratio ( 在图 9c 中，由于 RAP 聚合体的存在，与粘结剂基质形成了薄弱的粘结，并确定均匀性有所下降。集料-基质界面显示出结合问题；沥青涂层阻碍了碱性活化剂的化学作用。可以认为 GF 限制了微裂缝的扩展，降低了材料的脆性。然而，由于 GF 的比例较低 (0.5%0.5 \% ). The microstructure exhibits a more porous and low-density structure due to ambient curing. Pores can ).由于常温固化，微观结构呈现出更多孔和低密度的结构。孔隙可以
Fig. 9. Microstructures of geopolymers subjected to ambient and heat curing. 图 9.经过常温固化和加热固化的土工聚合物的微观结构。
increase the water absorption rate and reduce the freeze-thaw resistance. The presence of micro cracks is one factor limiting the mixture’s mechanical strength. The compressive strength of this mix containing 100 % RAP and 0.5 % GF was lower than the reference mixes. Bitumen residues prevented bonding, and the low proportion of GF caused microstructural weaknesses. The presence of a porous structure increased the water absorption capacity of the mix, indicating that this mix has low resistance to water and a high capillary water absorption rate. Although the presence of GF increased the micro crack resistance, this effect was limited due to the low proportion ( 0.5%0.5 \% ). The fiber aggregates may have created weak spots and micro voids in some areas, adversely affecting the mix’s mechanical performance. GF tends to inhibit the propagation of micro cracks, but if too much fiber is used, the porosity of the mixture increases. Here, the micro voids caused by the fibers are also observed to intensify (Fig. 9d). Bituminous coatings around the RAP aggregates limited the connection between the binder phase and the aggregates. Despite heat curing, the softening of these bitumen layers adversely affected the aggregate-matrix interaction. In some areas, micro cracks and voids were formed in the matrix due to the presence of bitumen. This may have limited the density and strength of the material. Although the thermal curing process accelerated alkaline activation and increased the formation of binder phases, an inhomogeneous structure is observed in the microstructure. RAP-induced voids and micro voids formed by fibers prevented the densification of the matrix. Despite containing 1%1 \% GF, the compressive strength of this mixture was limited due to fiber aggregates and poor bonding of RAP aggregates. Although thermal curing promoted the formation of binder phases, the fiber and RAP content caused microstructural weaknesses. The presence of RAP aggregates increased water penetration, while micro voids formed due to GF further strengthened this effect. Heat curing accelerated the alkali-activation reactions and supported the binding of the matrix; however, the expected performance improvement could not be achieved due to the bituminous nature of RAP. Bitumen coatings softened at 80^(@)C80^{\circ} \mathrm{C} and limited the binding of aggregates, reducing the material’s strength. 微裂缝会增加吸水率，降低抗冻融性。微裂缝的存在是限制混合料机械强度的一个因素。含有 100 % RAP 和 0.5 % GF 的混合料的抗压强度低于参考混合料。沥青残留物阻碍了粘结，而 GF 的低比例则导致微观结构薄弱。多孔结构的存在提高了混合料的吸水能力，表明这种混合料的水阻力小，毛细吸水率高。虽然 GF 的存在提高了微裂缝的抗性，但由于其比例较低（ 0.5%0.5 \% ），这种影响是有限的。纤维集料可能会在某些区域产生薄弱点和微空隙，从而对混合料的机械性能产生不利影响。GF 往往会抑制微裂缝的扩展，但如果纤维用量过多，混合物的孔隙率就会增加。在这里，还可以观察到纤维造成的微小空隙加剧（图 9d）。RAP 集料周围的沥青涂层限制了粘合剂相与集料之间的连接。尽管进行了热固化，但这些沥青层的软化还是对集料与基质之间的相互作用产生了不利影响。在某些区域，由于沥青的存在，基质中形成了微裂缝和空隙。这可能限制了材料的密度和强度。虽然热固化过程加速了碱性活化并增加了粘结相的形成，但在微观结构中观察到了不均匀结构。RAP 引起的空隙和纤维形成的微空隙阻碍了基质的致密化。 尽管该混合物含有 1%1 \% GF，但由于纤维集料和 RAP 集料粘结不良，其抗压强度有限。虽然热固化促进了粘结相的形成，但纤维和 RAP 的含量造成了微观结构上的缺陷。RAP 骨料的存在增加了水的渗透，而 GF 形成的微空隙进一步加强了这种效应。热固化加速了碱活化反应，支持了基质的结合；然而，由于 RAP 的沥青性质，无法实现预期的性能改进。沥青涂层在 80^(@)C80^{\circ} \mathrm{C} 软化，限制了集料的结合，降低了材料的强度。
4. High-temperature resistance 4.耐高温
4.1. Compressive strength 4.1.抗压强度
Fig. 10a shows the impact of GF content, curing temperature (ambient for 24 hours), and the replacement of RS with RAP on the average compressive strength of alkali-activated slag composite (AAC) 图 10a 显示了 GF 含量、固化温度（环境 24 小时）以及用 RAP 替代 RS 对碱活性矿渣复合材料 (AAC) 平均抗压强度的影响。
mixtures after exposure to high temperatures. Fig. 10b illustrates the changes in compressive strength of the AAC mixtures cured at ambient temperature following high-temperature exposure. The mixtures without GF experienced a strength loss ranging from 23%23 \% to 38%38 \% when exposed to 200^(@)C200^{\circ} \mathrm{C}, with the strength loss decreasing as the RAP content increased, reaching the lowest strength loss at 100 % RAP. On the other hand, the mixture without RAP exhibited the largest strength loss. RAP contains asphalt binder, which can act as a stabilizing agent at elevated temperatures. This material is relatively resistant to thermal degradation compared to conventional fine aggregates like river sand. As a result, the inclusion of RAP may help mitigate the effects of heat exposure, leading to less strength loss in the mixtures. At elevated temperatures like 200^(@)C200^{\circ} \mathrm{C}, the asphalt binder in RAP may undergo softening or reflowing, which could help heal or close micro cracks that form due to thermal expansion or shrinkage in the matrix. This could further reduce the extent of damage and contribute to the observed reduction in strength loss. River sand (RS) does not provide the same level of thermal stability as RAP. Unlike RAP, which contains asphalt binder that can resist thermal degradation, RS is more prone to thermal expansion and cracking when exposed to high temperatures. This increases the likelihood of micro cracks forming within the matrix, leading to greater strength loss. RS is a rigid and brittle aggregate compared to RAP, which has a certain degree of flexibility due to its asphalt content. When exposed to thermal stress, mixtures with RS may be more susceptible to sudden brittle failure and the development of thermal stresses, leading to more significant structural damage and strength loss.
The mixtures containing 0.5 % GF exhibited a strength loss ranging from 28.23%28.23 \% to 44.81%44.81 \% when exposed to 200^(@)C200^{\circ} \mathrm{C}, with the lowest strength loss occurring at 25%25 \% RAP content, and the highest strength loss observed in the absence of RAP. Similarly, the mixtures with 1 % GF experienced a strength loss between 31.24%31.24 \% and 53.74%53.74 \% when exposed to 200^(@)C200^{\circ} \mathrm{C}, with the least strength loss occurring at 25%25 \% RAP content and the greatest strength loss observed when RAP was not included. When the combinations without GF were heated to 400^(@)C400^{\circ} \mathrm{C}, the strength loss ranged from 63.77 % to 79.14%79.14 \%; the mixtures with 50%50 \% RAP content showed the lowest strength loss, while the mixtures without RAP showed the maximum strength loss. When subjected to 400^(@)C400^{\circ} \mathrm{C}, the mixes with 0.5%GF0.5 \% \mathrm{GF} showed strength losses ranging from 70.24 % to 80.73%80.73 \%; the lowest strength loss was seen at 25%25 \% RAP concentration, while the largest strength loss was shown in the absence of RAP. It seems that increasing GF content decreased the resistance to high temperature. RAP plays a crucial role in enhancing thermal resistance, with 50 % RAP content showing the best performance due to its
Fig. 10. The compressive strength at ambient and after high temperatures and b) strength loss. 图 10.常温和高温后的抗压强度以及 b) 强度损失。
flexibility and ability to mitigate cracking at high temperatures. The addition of 0.5%GF0.5 \% \mathrm{GF} provides reinforcement but is less effective at 400^(@)C400^{\circ} \mathrm{C}, leading to increased strength loss compared to RAP-only mixtures. The absence of RAP results in maximum strength loss, as the matrix becomes brittle and prone to cracking under thermal stress without the flexible nature of RAP to counteract this effect. The mixtures with1 % GF exhibited a strength loss ranging from 69.87%69.87 \% to 82.08%82.08 \% when exposed to 400^(@)C400^{\circ} \mathrm{C}, with the lowest strength loss occurring at 25%25 \% RAP content, and the highest strength loss observed at 50%50 \% RAP. It seems that increasing GF content decreased the resistance to high temperature. The increase in GF content ( 1%1 \% ) reduced the resistance to high temperatures due to several factors, including the thermal degradation of glass fibers, overcrowding of fibers leading to weaker matrix structure, and the disruption of the beneficial effects of RAP. The optimal performance at 25%25 \% RAP suggests that moderation in both RAP and GF content is key to maintaining thermal stability, as excessive GF content leads to internal stresses and reduced bonding, which contribute to greater strength loss at elevated temperatures.
When the ambient cured mixtures were exposed to 600^(@)C600^{\circ} \mathrm{C}, the strength loss ranged from 85%85 \% to 89%89 \%, showing minimal variation regardless of RAP content, or GF content. But, all RAP-incorporated mixtures exhibited less strength loss compared to those without RAP, with the exception of the mixture containing 50%50 \% RAP and 1%1 \% GF.
At high temperatures like 600^(@)C600^{\circ} \mathrm{C}, the AAC matrix undergoes significant microstructural degradation. The main phase of alkali-activated slag (calcium silicate hydrate, or C-S-H gel) can start to decompose at these temperatures, leading to a collapse in the structural integrity of the binder [65,66]. This is a primary factor in the substantial loss of compressive strength, which affects all mixtures similarly, regardless of the RAP or GF content. The high temperature may cause excessive drying, shrinkage, and the formation of micro cracks, which can propagate and weaken the matrix. Both RAP and GF may help slightly in reducing these effects at lower temperatures, but at 600^(@)C600^{\circ} \mathrm{C}, these improvements are overshadowed by the severe damage to the overall structure. RAP is made of bituminous materials and aggregates. While RAP can provide some initial thermal insulation and mitigate strength loss at moderate temperatures ( 200^(@)C200^{\circ} \mathrm{C} and 400^(@)C400^{\circ} \mathrm{C} ), at 600^(@)C600^{\circ} \mathrm{C}, the bituminous content of RAP undergoes thermal decomposition, contributing to the weakening of the matrix. Consequently, RAP’s ability to enhance strength retention diminishes at such high temperatures. Glass fibers have a softening point between 600^(@)C600^{\circ} \mathrm{C} and 800^(@)C800^{\circ} \mathrm{C}. When exposed to temperatures approaching 600^(@)C600^{\circ} \mathrm{C}, the fibers may lose their reinforcing capability as they start to soften or even melt. This diminishes their
effectiveness in bridging cracks and maintaining mechanical strength, leading to a strength loss similar to mixtures without GF [67]. 在弥合裂缝和保持机械强度方面的有效性，导致强度损失与不含 GF 的混合物相似[67]。
Fig. 11a shows the impact of GF content, curing temperature (80^(@)C:}\left(80^{\circ} \mathrm{C}\right. for 24 hours), and the replacement of RS with RAP on the average compressive strength of alkali-activated slag composite (AAC) mixtures after exposure to high temperatures. Fig. 11b illustrates the changes in compressive strength of the AAC mixtures cured at 80^(@)C80^{\circ} \mathrm{C} following hightemperature exposure. 图 11a 显示了 GF 含量、固化温度 (80^(@)C:}\left(80^{\circ} \mathrm{C}\right. 24 小时）以及用 RAP 替代 RS 对高温暴露后碱活性矿渣复合材料 (AAC) 混合物平均抗压强度的影响。图 11b 显示了在 80^(@)C80^{\circ} \mathrm{C} 下固化的 AAC 混合物在高温暴露后抗压强度的变化。
The blends without GF exhibited a strength loss ranging from 26.03%26.03 \% to 31.74%31.74 \% after exposure to 200^(@)C200^{\circ} \mathrm{C}, with the least strength loss observed at 0%0 \% RAP content and the greatest strength loss at 50%50 \% RAP. This trend contrasts with the behavior of ambient-cured mixtures, where RAP content generally had a more positive influence on strength retention. The higher strength loss observed in the 80^(@)C80^{\circ} \mathrm{C}-cured mixtures with 50%50 \% RAP content after exposure to 200^(@)C200^{\circ} \mathrm{C}, compared to the ambient-cured mixtures, can be attributed to the more rigid and brittle matrix formed at elevated curing temperatures. This matrix is less capable of accommodating the thermal expansion of RAP and the softening of its bitumen at 200^(@)C200^{\circ} \mathrm{C}, leading to more micro cracking and greater strength degradation, especially in mixtures with higher RAP content. 不含 GF 的混合物在暴露于 200^(@)C200^{\circ} \mathrm{C} 之后，强度损失从 26.03%26.03 \% 到 31.74%31.74 \% 不等，在 RAP 含量为 0%0 \% 时强度损失最小，而在 RAP 含量为 50%50 \% 时强度损失最大。这一趋势与常温固化混合物的行为形成鲜明对比，在常温固化混合物中，RAP 含量通常对强度保持有更积极的影响。与常温固化混合物相比，RAP 含量为 50%50 \% 的 80^(@)C80^{\circ} \mathrm{C} 固化混合物在暴露于 200^(@)C200^{\circ} \mathrm{C} 温度后强度损失更大，这可归因于在固化温度升高时形成的基质更硬、更脆。在 200^(@)C200^{\circ} \mathrm{C} 温度下，这种基质较难承受 RAP 的热膨胀和沥青的软化，从而导致更多的微裂纹和更大的强度下降，尤其是在 RAP 含量较高的混合物中。
The mixtures cured at 80^(@)C80^{\circ} \mathrm{C} and containing 0.5%GF0.5 \% \mathrm{GF} showed a strength loss between 36.00%36.00 \% and 42.33%42.33 \% which was higher than the mixtures without GF following exposure to 200^(@)C200^{\circ} \mathrm{C}. The smallest strength loss was noted with 50%50 \% reclaimed asphalt pavement (RAP) content, while the largest strength loss occurred at 100%100 \% RAP content. The presence of GF may alter the interactions within the geopolymer matrix. At elevated temperatures, the bond between the GF and the geopolymer may weaken, resulting in reduced load transfer efficiency and increased susceptibility to failure. Curing at 80^(@)C80^{\circ} \mathrm{C} may have introduced internal stresses or microstructural changes that become more pronounced when the material is subjected to further thermal exposure. This can lead to greater strength loss in GF-containing mixtures. The observation that the smallest strength loss occurred with 50%50 \% RAP content while the largest loss was at 100%100 \% RAP content suggests that the moderate RAP content may provide some beneficial effects on the microstructure, helping to maintain integrity under heat. In contrast, 100%100 \% RAP may lead to a more brittle mix that is less capable of withstanding thermal stress, resulting in higher strength loss. 在 80^(@)C80^{\circ} \mathrm{C} 条件下固化并含有 0.5%GF0.5 \% \mathrm{GF} 的混合料在 36.00%36.00 \% 和 42.33%42.33 \% 之间的强度损失高于暴露于 200^(@)C200^{\circ} \mathrm{C} 条件下的不含 GF 的混合料。 50%50 \% 再生沥青路面 (RAP) 含量的强度损失最小，而 100%100 \% RAP 含量的强度损失最大。GF 的存在可能会改变土工聚合物基体内的相互作用。在温度升高的情况下，GF 与土工聚合物之间的粘结力可能会减弱，从而导致荷载传递效率降低，更容易发生破坏。在 80^(@)C80^{\circ} \mathrm{C} 温度下固化可能会产生内应力或微观结构变化，这些变化在材料进一步受热时会变得更加明显。这可能导致含 GF 混合物的强度损失更大。 50%50 \% RAP 含量的强度损失最小，而 100%100 \% RAP 含量的强度损失最大，这一观察结果表明，适度的 RAP 含量可能会对微观结构产生一些有益的影响，有助于在热作用下保持完整性。相比之下， 100%100 \% RAP 可能会导致混合料更脆，承受热应力的能力更弱，从而导致更高的强度损失。
The mixtures cured at 80^(@)C80^{\circ} \mathrm{C} that contained 1%1 \% glass fibers (GF) experienced a strength loss ranging from 29.07%29.07 \% to 40.28%40.28 \%, which was greater than the strength loss observed in mixtures without GF after exposure to 200^(@)C200^{\circ} \mathrm{C}. The least strength loss was recorded with 50%50 \% 在 80^(@)C80^{\circ} \mathrm{C} 下固化的含有 1%1 \% 玻璃纤维 (GF) 的混合物的强度损失在 29.07%29.07 \% 到 40.28%40.28 \% 之间，大于不含 GF 的混合物在暴露于 200^(@)C200^{\circ} \mathrm{C} 下观察到的强度损失。 50%50 \% 的强度损失最小。
Fig. 11. The compressive strength after 80^(@)C80^{\circ} \mathrm{C} and under high temperature b) strength loss after high temperature.
reclaimed asphalt pavement (RAP) content, while the highest strength loss was noted at 100%100 \% RAP content. The presence of GF likely leads to greater strength loss due to their thermal degradation and the mismatch in thermal expansion between fibers and the matrix. RAP content, particularly at 50%50 \%, provides a softening effect that helps counterbalance some of the thermal damage, while higher RAP levels compromise the structural integrity further. 而 100%100 \% RAP 含量时强度损失最大。由于 GF 的热降解以及纤维与基体之间热膨胀的不匹配，GF 的存在可能会导致更大的强度损失。RAP 含量（尤其是 50%50 \% 时）可提供软化效果，有助于抵消部分热损伤，而较高的 RAP 含量则会进一步损害结构完整性。
The mixtures cured at 80^(@)C80^{\circ} \mathrm{C} experienced a strength loss ranging from 69.86%69.86 \% to 81.16%81.16 \% after exposure to 400^(@)C400^{\circ} \mathrm{C}, irrespective of the GF and RAP content. The combined effects of thermal degradation of the geopolymer matrix, loss of bound water, breakdown of glass fibers, and the thermal instability of RAP lead to significant strength loss in the mixtures, regardless of the specific GF and RAP content. 在 80^(@)C80^{\circ} \mathrm{C} 条件下固化的混合物在暴露于 400^(@)C400^{\circ} \mathrm{C} 条件下后，无论玻璃纤维和 RAP 含量如何，都会出现 69.86%69.86 \% 到 81.16%81.16 \% 不等的强度损失。土工聚合物基体的热降解、结合水的损失、玻璃纤维的分解以及 RAP 的热不稳定性的综合影响导致了混合物强度的显著下降，而与具体的 GF 和 RAP 含量无关。
The mixtures cured at 80^(@)C80^{\circ} \mathrm{C} exhibited a strength loss between 79.31%79.31 \% and 84.70%84.70 \% after exposure to 600^(@)C600^{\circ} \mathrm{C}, regardless of the GF and RAP content. The extreme temperature of 600^(@)C600^{\circ} \mathrm{C} causes significant damage to the geopolymer matrix through decomposition, dehydration, and micro cracking, while the degradation of GF and RAP reduces their ability to mitigate strength loss. These combined factors lead to the high strength loss, regardless of the GF and RAP content. 在 80^(@)C80^{\circ} \mathrm{C} 温度下固化的混合物在暴露于 600^(@)C600^{\circ} \mathrm{C} 温度后，强度损失介于 79.31%79.31 \% 和 84.70%84.70 \% 之间，与 GF 和 RAP 含量无关。 600^(@)C600^{\circ} \mathrm{C} 的极端温度会通过分解、脱水和微裂缝对土工聚合物基体造成严重破坏，而 GF 和 RAP 的降解则会降低它们减缓强度损失的能力。这些综合因素导致了高强度损失，而与 GF 和 RAP 的含量无关。
4.2. Weight loss
Fig. 12 illustrates the effects of GF content, curing temperatures (ambient and 80^(@)C80^{\circ} \mathrm{C} for 24 hours), and the substitution of RAP for RS on the average weight loss of AAC mixtures after exposure to high temperatures. Fig. 12a illustrates the weight loss of the mixtures cured at ambient temperature, while Fig. 12b depicts the weight loss of the mixtures cured at 80^(@)C80^{\circ} \mathrm{C}. The mixtures cured at ambient temperature experienced a weight loss ranging from 3.54%3.54 \% to 5.47%5.47 \%, with RAPincorporated mixtures generally showing a lower rate of weight loss. However, the addition of GF resulted in a slightly higher rate of weight loss at 200^(@)C200^{\circ} \mathrm{C}. 图 12 说明了 GF 含量、固化温度（常温和 80^(@)C80^{\circ} \mathrm{C} 24 小时）以及用 RAP 代替 RS 对 AAC 混合物暴露于高温后的平均重量损失的影响。图 12a 显示了在环境温度下固化的混合物的重量损失，而图 12b 显示了在 80^(@)C80^{\circ} \mathrm{C} 温度下固化的混合物的重量损失。在环境温度下固化的混合物的重量损失从 3.54%3.54 \% 到 5.47%5.47 \% 不等，加入 RAP 的混合物的重量损失率通常较低。然而，添加 GF 后， 200^(@)C200^{\circ} \mathrm{C} 的重量损失率略高。
The lower weight loss of RAP-incorporated mixtures cured at ambient temperature and exposed to 200^(@)C200^{\circ} \mathrm{C} is primarily due to the characteristics of RAP. RAP contains bitumen, a hydrophobic binder that can enhance the thermal stability of the mixtures by reducing the evaporation of moisture and other volatile components at elevated temperatures. The bitumen acts as a sealant, which limits the loss of mass during heating. The slightly higher rate of weight loss in GF-added mixtures at 200^(@)C200^{\circ} \mathrm{C}, despite the presence of RAP, could be due to the interaction between GF and the matrix at elevated temperatures. While RAP, with its bitumen content, reduces weight loss by enhancing 在环境温度下固化并暴露于 200^(@)C200^{\circ} \mathrm{C} 的掺入 RAP 的混合物失重较少，这主要是由于 RAP 的特性。RAP 含有沥青，这是一种疏水性粘结剂，可通过减少水分和其他挥发性成分在高温下的蒸发来提高混合物的热稳定性。沥青可作为密封剂，限制加热过程中的质量损失。尽管存在 RAP，但在 200^(@)C200^{\circ} \mathrm{C} 时添加 GF 的混合物的重量损失率略高，这可能是由于 GF 与基质在高温下的相互作用。沥青含量较高的 RAP 可通过增强 GF 和基质之间的相互作用来减少重量损失。
thermal stability, the addition of GF may introduce more voids or microcracks in the matrix. These voids could lead to higher moisture retention during curing and, subsequently, more moisture evaporation when exposed to heat. When exposed to 400^(@)C400^{\circ} \mathrm{C} after ambient curing, weight loss increased with the inclusion of GF but lower weight loss was observed for the mixtures with RAP regardless of GF content. The weight loss ranges from 12.82%12.82 \% to 17.94%,16.54-18.38%17.94 \%, 16.54-18.38 \%, and 17.47-22.73 % for mixtures with 0%,0.5%0 \%, 0.5 \%, and 1%1 \% GF content, respectively. At 400^(@)C400^{\circ} \mathrm{C}, the increase in weight loss with the inclusion of GF is likely due to the thermal behavior of the fibers and their interaction with the matrix at elevated temperatures. GF may introduce additional voids or micro-cracks in the mixture, which can increase moisture retention and result in greater evaporation during heating. As the GF content increases, this effect becomes more pronounced, leading to higher weight loss. However, mixtures containing RAP generally exhibit lower weight loss, regardless of GF content. This is primarily because RAP contains bitumen, which enhances thermal stability by reducing moisture evaporation and acting as a sealant. The bitumen helps to limit mass loss at high temperatures, making RAP-incorporated mixtures more resistant to thermal degradation compared to those without RAP, even when GF is present. Thus, while GF increases weight loss, the presence of RAP mitigates this effect to some extent. When exposed to 600^(@)C600^{\circ} \mathrm{C} after ambient curing, weight loss increased slightly with the addition of GF, but replacing RS with RAP showed no significant difference in weight loss. At this elevated temperature, both RS and RAP may exhibit similar thermal behavior, as the moisture and volatile content of the mixtures become the primary factors influencing weight loss, and the stabilizing effects of RAP’s bitumen are no longer as effective. As a result, the influence of RAP on weight loss becomes less pronounced compared to lower temperatures. The mixtures cured at 80^(@)C80^{\circ} \mathrm{C} exhibited weight loss results similar to those cured at ambient temperature, but with slightly lower values. 在热稳定性方面，添加 GF 可能会在基质中产生更多空隙或微裂缝。这些空隙可能会在固化过程中导致更高的水分保持率，随后在受热时导致更多的水分蒸发。在常温固化后暴露于 400^(@)C400^{\circ} \mathrm{C} 时，重量损失随着 GF 的加入而增加，但无论 GF 含量如何，含有 RAP 的混合物的重量损失都较低。含有 0%,0.5%0 \%, 0.5 \% 和 1%1 \% GF 的混合物的失重范围分别为 12.82%12.82 \% 到 17.94%,16.54-18.38%17.94 \%, 16.54-18.38 \% 和 17.47-22.73%。在 400^(@)C400^{\circ} \mathrm{C} 条件下，加入 GF 后重量损失增加可能是由于纤维的热行为及其在高温下与基体的相互作用。GF 可能会在混合物中引入额外的空隙或微裂缝，这可能会增加水分保留，并导致加热过程中更多的水分蒸发。随着 GF 含量的增加，这种影响会变得更加明显，导致重量损失增加。不过，无论 GF 含量如何，含有 RAP 的混合物通常失重较少。这主要是因为 RAP 中含有沥青，沥青可减少水分蒸发并起到密封作用，从而提高热稳定性。沥青有助于限制高温下的质量损失，使含有 RAP 的混合物与不含 RAP 的混合物相比更耐热降解，即使含有 GF 也是如此。因此，虽然 GF 会增加重量损失，但 RAP 的存在会在一定程度上减轻这种影响。在常温固化后暴露于 600^(@)C600^{\circ} \mathrm{C} 中时，加入 GF 后重量损失略有增加，但用 RAP 替代 RS 后，重量损失没有显著差异。 在这种高温下，RS 和 RAP 可能会表现出类似的热行为，因为混合物中的水分和挥发物含量成为影响失重的主要因素，而 RAP 沥青的稳定作用不再那么有效。因此，与较低温度相比，RAP 对失重的影响变得不那么明显。在 80^(@)C80^{\circ} \mathrm{C} 温度下固化的混合物的失重结果与在环境温度下固化的混合物相似，但失重值略低。
The mixtures cured at 80^(@)C80^{\circ} \mathrm{C} exhibited slightly lower weight loss compared to those cured at ambient temperature due to the accelerated curing process. Elevated curing temperatures promote more rapid evaporation of moisture and improve the development of the internal matrix, reducing the amount of free water and volatiles remaining in the mixture. This leads to greater densification and reduced porosity, making the mixtures less prone to moisture loss when exposed to high temperatures. As a result, mixtures cured at 80^(@)C80^{\circ} \mathrm{C} have less residual moisture and therefore exhibit slightly lower weight loss compared to those cured at ambient conditions. 与在环境温度下固化的混合物相比，在 80^(@)C80^{\circ} \mathrm{C} 下固化的混合物由于固化过程加快，重量损失略低。固化温度升高可促进水分更快地蒸发，改善内部基质的形成，减少混合物中残留的自由水和挥发物。这将导致更高的致密性和更低的孔隙率，使混合物在高温下不易流失水分。因此，在 80^(@)C80^{\circ} \mathrm{C} 条件下固化的混合物残留水分较少，因此与在环境条件下固化的混合物相比，重量损失略低。
Fig. 12. The weight loss after high temperature (a, b).
4.3. Microstructure analysis after elevated temperatures
The structural integrity of the C-S-H and N-A-S-H phases weakened due to high temperature (Fig. 13a). Micro cracks were formed in the matrix, and disintegration of the binder phase was observed. The temperature of 600^(@)C600^{\circ} \mathrm{C} caused the drying of the gel phases formed by alkali activation and deterioration of the chemical structure. Water loss accelerated the propagation of cracks by creating tensile stresses in the microstructure. Micro cracks are common in the specimen exposed to high temperature, especially at the aggregate-matrix interfaces. This weakened the adherence of the binder phase with the aggregate and limited the structural integrity. Porosity increased significantly, which decreased the specimen’s density and resulted in poor mechanical performance. The effect of high temperature weakened the bond between the aggregate and the binder matrix. This weak bonding led to the propagation of micro cracks through the interfaces and the formation of more extensive damage. According to the experimental findings, the compressive strength decreased significantly after 600^(@)C600^{\circ} \mathrm{C} exposure. This SEM image confirms that one of the main causes of mechanical losses is the degradation of the binder phase and the formation of micro cracks. Due to the high temperature, the porosity of the matrix increased and the density decreased. Since RAP and GF were not present in this mixture, no contribution could be made to strengthen the microstructure after exposure to 600^(@)C600^{\circ} \mathrm{C}. The resilient effect of glass fibers or RAP was missing here. As a result, the sample became more brittle. The bituminous coatings remaining on the surface of the RAP aggregates appear to have undergone significant thermal degradation (Fig. 13b). The softening and disintegration of bitumen at 600^(@)C600^{\circ} \mathrm{C} further weakened the bond between the aggregates and the binder matrix. In some areas, it can be observed that the bitumen has become fluidized by thermal effects, helping to partially close micro cracks. However, this effect is only observed in limited areas. It is noteworthy that micro cracks became widespread due to thermal expansion of RAP and softening of the bitumen layer. The increase in porosity decreased the density of the material and weakened the mechanical strength. It is observed that the matrix structure is not homogeneous and cracks are concentrated at the aggregate-matrix interfaces. This accelerated the propagation of damage by creating weak points under thermal stress. Although thermal curing initially favored the formation of binder phases, the expected strength could not be increased due to the bituminous nature of RAP aggregates. At high temperature, these bituminous layers dissolved and affected the bonding even more negatively. Experimental findings show that the mixtures containing 100%100 \% RAP experienced significant losses in strength after 600^(@)C600^{\circ} \mathrm{C} exposure. This SEM image confirms the prevalence of cracks and pores due to the poor bonding of the binder phase and RAP aggregates. The softening of the bitumen may have helped to close some micro cracks; however, this effect was insufficient to maintain structural integrity. Cracks due to thermal expansion increased the strength loss. 高温导致 C-S-H 和 N-A-S-H 相的结构完整性减弱（图 13a）。基体中出现了微裂纹，并观察到粘合剂相的解体。 600^(@)C600^{\circ} \mathrm{C} 的温度导致碱活化形成的凝胶相干燥，化学结构恶化。失水在微观结构中产生拉应力，加速了裂纹的扩展。暴露在高温下的试样普遍存在微裂缝，尤其是在骨料-基质界面处。这削弱了粘结相与骨料的粘附性，限制了结构的完整性。孔隙率明显增加，降低了试样的密度，导致机械性能变差。高温的影响削弱了骨料与粘结剂基体之间的粘结力。这种薄弱的粘合力导致微裂缝在界面上扩展，并形成更大范围的损坏。根据实验结果， 600^(@)C600^{\circ} \mathrm{C} 暴露后，抗压强度显著下降。这张扫描电子显微镜图像证实，造成机械损失的主要原因之一是粘合剂相的降解和微裂纹的形成。由于温度较高，基体的孔隙率增加，密度降低。由于 RAP 和 GF 不存在于这种混合物中，因此在暴露于 600^(@)C600^{\circ} \mathrm{C} 之后对微观结构的强化没有任何作用。玻璃纤维或 RAP 的弹性作用在这里消失了。因此，样品变得更脆。残留在 RAP 骨料表面的沥青涂层似乎经历了严重的热降解（图 13b）。 600^(@)C600^{\circ} \mathrm{C} 处沥青的软化和分解进一步削弱了集料与粘结剂基体之间的粘结力。在某些区域，可以观察到沥青在热效应下变得流动，有助于部分封闭微裂缝。不过，这种效果只在有限的区域内观察到。值得注意的是，由于 RAP 的热膨胀和沥青层的软化，微裂缝变得越来越普遍。孔隙率的增加降低了材料的密度，削弱了机械强度。据观察，基质结构并不均匀，裂缝集中在集料-基质界面处。这在热应力作用下产生了薄弱点，从而加速了破坏的扩展。虽然热固化最初有利于粘结相的形成，但由于 RAP 骨料的沥青性质，预期强度无法提高。在高温条件下，这些沥青层会溶解，对粘结产生更不利的影响。实验结果表明，含有 100%100 \% RAP 的混合物在经过 600^(@)C600^{\circ} \mathrm{C} 暴露后，强度损失显著。这张扫描电子显微镜图像证实，由于粘结剂相与 RAP 骨料的粘结不良，裂缝和气孔普遍存在。沥青的软化可能有助于封闭一些微裂缝，但这种效果不足以保持结构的完整性。热膨胀导致的裂缝增加了强度损失。
As seen in Fig. 13c, melting and evaporation of bitumen at high temperatures caused the formation of micro voids and cracks at the interface. Thermal expansion of RAP and melting of bitumen residues led to a weakening of the aggregate-matrix bond, resulting in a loss of structural integrity. Despite containing 0.5%0.5 \% GF, it could not wholly prevent the propagation of micro cracks. Although the GF limited some cracks, they formed weak bonding zones in the matrix at 600^(@)C600^{\circ} \mathrm{C}. Micro voids formed around the GF due to the heat, and fibers were observed to separate from the matrix in some places. This adversely affected the density and strength of the material. Exposure to temperatures up to 600^(@)C600^{\circ} \mathrm{C} intensified the micro cracks and increased the porous structure. The cracks are generally concentrated at the aggregate-matrix interface, indicating that the binder phase deteriorates under temperature. As noted in the experimental results, the compressive strength of this mixture decreased significantly after exposure to 600^(@)C600^{\circ} \mathrm{C}. The SEM image confirms that the degradation of the binder phase, the propagation of micro cracks and poor interfaces are the leading causes of these losses. The melting of bitumen at high temperatures and micro-void formation 如图 13c 所示，高温下沥青的融化和蒸发导致界面处形成微小空隙和裂缝。RAP 的热膨胀和沥青残渣的熔化导致骨料与基质的粘结力减弱，从而失去了结构的完整性。尽管含有 0.5%0.5 \% GF，但它并不能完全阻止微裂缝的扩展。虽然 GF 限制了一些裂缝，但它们在 600^(@)C600^{\circ} \mathrm{C} 处的基体中形成了弱结合区。由于受热，GF 周围形成了微小空隙，在某些地方还观察到纤维与基体分离。这对材料的密度和强度产生了不利影响。暴露在高达 600^(@)C600^{\circ} \mathrm{C} 的温度下会加剧微裂缝并增加多孔结构。裂缝一般集中在骨料-基质界面，表明粘合剂相在温度作用下发生了退化。如实验结果所示，该混合物的抗压强度在暴露于 600^(@)C600^{\circ} \mathrm{C} 之后显著下降。扫描电子显微镜图像证实，粘结相退化、微裂纹扩展和界面不良是造成这些损失的主要原因。高温下沥青的熔化和微空洞的形成
can increase the water absorption rate. Although 0.5%0.5 \% GF partially prevented the micro crack propagation, the expected improvement was not achieved due to the voids formed around the fibers at high temperatures. Using 1%1 \% GF shows that the fibers are densely integrated into the matrix (Fig. 13d). However, thermal degradation of the GF was observed at 600^(@)C600^{\circ} \mathrm{C} : voids and weak spots formed around the fibers, which may have adversely affected the mechanical performance. The softening or melting of the GF at this temperature weakened the integrity within the material rather than closing micro cracks. The bituminous coatings on RAP aggregates were completely degraded and became fluid at 600^(@)C600^{\circ} \mathrm{C}, preventing interaction with the binder phase. This led to the formation of voids and cracks at the aggregate-matrix interface. The melting of bitumen at high temperature may have closed some micro cracks; however, these effects were limited in inhomogeneous areas. In general, poor bonding of aggregates to the binder matrix was evident. The high temperature exposure caused intense porosity and micro crack formation in the material. Pores were particularly prevalent at the aggregate-matrix interfaces, leading to a severe reduction in strength. According to the experimental findings, significant losses in the compressive strength of this mixture were experienced after 600^(@)C600^{\circ} \mathrm{C} exposure. The effect of GF and RAP in maintaining the structural integrity was limited due to the temperature, which resulted in a weakening of the mechanical performance. Although thermal curing initially promoted bonding, the degradation of the bituminous structure of RAP and the loss of thermal resistance of the GF resulted in severe weakening at 600^(@)C600^{\circ} \mathrm{C}. The microstructure of Fig. 16 d is characterized by dense micro cracks, porous structure and poor interface bonding. Although the use of 1%1 \% GF partially limited the propagation of micro cracks, fiber degradation under high temperature reduced the mechanical performance-the bitumen content of RAP aggregates both limited bonding and increased porosity due to thermal expansion. As a result, the strength of this mixture was significantly reduced. 可提高吸水率。虽然 0.5%0.5 \% GF 部分阻止了微裂纹的扩展，但由于高温下纤维周围形成的空隙，并没有达到预期的改善效果。使用 1%1 \% GF 表明纤维与基体紧密结合（图 13d）。然而，在 600^(@)C600^{\circ} \mathrm{C} 条件下观察到了 GF 的热降解：纤维周围形成了空隙和薄弱点，这可能会对机械性能产生不利影响。在此温度下，GF 的软化或熔化削弱了材料内部的完整性，而不是闭合微裂缝。RAP 集料上的沥青涂层已完全降解，在 600^(@)C600^{\circ} \mathrm{C} 温度下成为流体，阻碍了与粘结剂相的相互作用。这导致在集料-基质界面形成空隙和裂缝。沥青在高温下熔化可能会封闭一些微裂缝，但这些作用仅限于不均匀区域。总的来说，骨料与粘结剂基质的粘结效果很差。高温暴露导致材料产生大量孔隙和微裂缝。孔隙在骨料与基质界面处尤为普遍，导致强度严重下降。根据实验结果，这种混合物的抗压强度在 600^(@)C600^{\circ} \mathrm{C} 暴露后出现了显著下降。由于温度的影响，GF 和 RAP 在保持结构完整性方面的作用有限，导致机械性能减弱。虽然热固化最初促进了粘结，但 RAP 沥青结构的降解和 GF 热阻的丧失导致了 600^(@)C600^{\circ} \mathrm{C} 时的严重削弱。图中的微观结构 16 d 以密集的微裂缝、多孔结构和界面粘结不良为特征。虽然 1%1 \% GF 的使用部分限制了微裂缝的扩展，但高温下的纤维降解降低了机械性能--RAP 集料中的沥青含量既限制了粘结，又因热膨胀而增加了孔隙率。因此，这种混合物的强度大大降低。
5. Freeze-thaw exposure
5.1. Compressive strength
Fig. 14a displays the effect of GF content, curing temperature (ambient for 24 hours), and the substitution of RS with RAP on the average compressive strength of AAC mixtures on exposure to 60 F -T cycles. Fig. 14b presents the variations in compressive strength of the ambient-cured AAC mixtures after 60 F-T cycles. All mixtures experienced strength loss ranging from 8.98%8.98 \% to 56.46%56.46 \%, with the smallest loss observed in the mixture containing 25%25 \% RAP and 0.5%GF0.5 \% \mathrm{GF}, and the largest loss in the mixture containing 100%100 \% RAP and 1%1 \% GF after 60 FT cycles. The mixture with 25%25 \% RAP and 0.5%0.5 \% GF exhibited the smallest strength loss likely due to an optimal balance between the binder properties provided by RAP and the reinforcing effects of glass fibers. This combination enhances the overall integrity and durability of the mixture, making it less susceptible to damage from freeze-thaw cycles. In contrast, the mixture containing 100%100 \% RAP and 1%1 \% GF showed the largest strength loss. The high proportion of RAP may introduce more voids or weaknesses in the matrix, reducing cohesion and overall strength. Additionally, RAP can vary in quality, and a higher percentage may lead to a less effective binding matrix. The microstructure of the mixtures, including factors like porosity, crack propagation, and interfacial bonding, significantly affects freeze-thaw resistance. Higher RAP content might lead to increased porosity or weaker interfacial bonds, making the mixture more vulnerable to damage during freeze-thaw cycles. During freeze-thaw cycles, moisture can infiltrate the microstructure. The mixture with 100%100 \% RAP may be more prone to water absorption, leading to greater expansion and contraction during freezing and thawing, which can exacerbate strength loss. 图 14a 显示了 GF 含量、固化温度（环境 24 小时）以及用 RAP 替代 RS 对 AAC 混合物在 60 F -T 循环下的平均抗压强度的影响。图 14b 显示了常温固化的 AAC 混合物在 60 次 F-T 循环后抗压强度的变化。所有混合物在 60 FT 循环后都出现了从 8.98%8.98 \% 到 56.46%56.46 \% 的强度损失，其中含有 25%25 \% RAP 和 0.5%GF0.5 \% \mathrm{GF} 的混合物的强度损失最小，而含有 100%100 \% RAP 和 1%1 \% GF 的混合物的强度损失最大。含有 25%25 \% RAP 和 0.5%0.5 \% GF 的混合物强度损失最小，这可能是由于 RAP 提供的粘结性能和玻璃纤维的增强效果达到了最佳平衡。这种组合增强了混合物的整体完整性和耐久性，使其不易受到冻融循环的破坏。相比之下，含有 100%100 \% RAP 和 1%1 \% GF 的混合物强度损失最大。高比例的 RAP 可能会在基质中引入更多空隙或薄弱环节，从而降低内聚力和整体强度。此外，RAP 的质量可能会有差异，比例越高，结合基质的效果越差。混合物的微观结构，包括孔隙率、裂缝扩展和界面结合等因素，都会对抗冻融性产生重大影响。较高的 RAP 含量可能会导致孔隙率增加或界面结合力减弱，从而使混合物在冻融循环期间更容易受到破坏。在冻融循环过程中，水分会渗入微观结构。 含有 100%100 \% RAP 的混合物可能更容易吸水，导致在冻结和解冻过程中产生更大的膨胀和收缩，从而加剧强度损失。
At 0%0 \% GF content, the reference mixture ( 0%0 \% RAP) experienced the highest strength loss, while all mixtures incorporating RAP showed lower strength loss. Notably, the mixture with 25 % RAP demonstrated
Fig. 14. The compressive strength of the ambient cured and on exposure to 60F-T60 \mathrm{~F}-\mathrm{T} cycles b ) strength loss after 60F-T60 \mathrm{~F}-\mathrm{T} cycles.
the least strength loss after 60 freeze-thaw cycles. All mixtures incorporating RAP showed lower strength loss because RAP contains bitumen and other components that can enhance the overall performance of the mixture. The bitumen helps reduce moisture penetration and improve the material’s ability to withstand freeze-thaw cycles, leading to greater durability. The mixture with 25 % RAP demonstrated the least strength loss after 60 freeze-thaw cycles. This is likely due to the balanced interaction between the RAP and the cementitious materials, which can enhance the mechanical properties and resistance to damage. The 25 % RAP content may provide sufficient binding and stability while maintaining effective moisture resistance. Incorporating RAP can contribute to improved microstructural integrity by reducing porosity and enhancing the interfacial bond between aggregates and the matrix. The presence of RAP can create a more cohesive mixture that is better equipped to resist the stresses imposed by freeze-thaw cycling. 在 60 次冻融循环后，沥青混合料的强度损失最小。所有含有 RAP 的混合物都显示出较低的强度损失，这是因为 RAP 含有沥青和其他成分，可以提高混合物的整体性能。沥青有助于减少水分渗透，提高材料承受冻融循环的能力，从而提高耐久性。含有 25% RAP 的混合物在 60 次冻融循环后强度损失最小。这可能是由于 RAP 与胶凝材料之间的平衡相互作用，可增强材料的机械性能和抗破坏能力。25% 的 RAP 含量可提供足够的结合力和稳定性，同时保持有效的防潮性能。掺入 RAP 可降低孔隙率并增强集料与基体之间的界面结合力，从而有助于改善微观结构的完整性。RAP 的存在可以使混合物更有内聚力，从而更好地抵抗冻融循环带来的应力。
All mixes had a higher strength loss at 0.5%0.5 \% GF content than those without GF, with the exception of the mixture with 25%25 \% RAP, which showed the least amount of strength loss. Strength loss increased as the RAP concentration increased, especially at 50%50 \% and 100%100 \% RAP, in comparison to the combinations with 0%0 \% GF. Higher RAP content may 除含有 25%25 \% RAP 的混合料强度损失最小外，所有混合料在 0.5%0.5 \% GF 含量下的强度损失均高于不含 GF 的混合料。与含有 0%0 \% GF 的混合物相比，强度损失随着 RAP 浓度的增加而增加，特别是在 50%50 \% 和 100%100 \% RAP 的情况下。较高的 RAP 含量可能会
lead to increased moisture absorption, making the mixture more vulnerable to damage during freeze-thaw cycles. This can exacerbate the expansion and contraction effects associated with temperature changes. The combination of GF content and RAP proportions significantly influences the performance of the mixtures, with 25%25 \% RAP offering a favorable balance that minimizes strength loss, while higher RAP content leads to increased vulnerability due to reduced cohesion and potential moisture-related issues. 导致吸湿性增加，使混合物在冻融循环中更容易受损。这会加剧与温度变化相关的膨胀和收缩效应。GF 含量和 RAP 比例的组合会显著影响混合物的性能， 25%25 \% RAP 提供了一个有利的平衡，可将强度损失降至最低，而较高的 RAP 含量则会因内聚力降低和潜在的湿气相关问题而导致脆弱性增加。
All of the mixes generally lost more strength at 1%1 \% GF level than at 0%0 \% and 0.5%0.5 \% GF content. Once more, the mixture with 25%25 \% RAP showed the least amount of strength loss, and the blend with 50 % RAP showed the second-best resilience to exposure to freeze-thaw cycles. Because the binding qualities of RAP and the reinforcement from GF were effectively balanced, the mixture containing 25 % RAP continued to exhibit the least amount of strength loss. This specific ratio likely enhances the durability and moisture resistance of the mixture, making it less vulnerable to freeze-thaw damage. The microstructure of the mixtures with 25%25 \% and 50%50 \% RAP likely features improved interfacial bonding and lower porosity compared to higher RAP contents. This helps to mitigate the effects of moisture infiltration and stress during 与 0%0 \% 和 0.5%0.5 \% GF 含量相比， 1%1 \% GF 含量下所有混合料的强度损失都更大。此外，含有 25%25 \% RAP 的混合料强度损失最小，而含有 50 % RAP 的混合料在冻融循环下的抗压性次之。由于 RAP 的粘结性和 GF 的增强性得到了有效平衡，因此含有 25 % RAP 的混合物的强度损失仍然最小。这一特定比例可能会增强混合物的耐久性和防潮性，使其不易受到冻融破坏。与较高的 RAP 含量相比，含有 25%25 \% 和 50%50 \% RAP 的混合物的微观结构可能具有更好的界面粘结性和更低的孔隙率。这有助于减轻湿气渗入的影响和冻融过程中的应力。
Fig. 15. The compressive strength of heat cured and on exposure to 60F-T60 \mathrm{~F}-\mathrm{T} cycles b) strength variations after 60F-T60 \mathrm{~F}-\mathrm{T} cycles.
freeze-thaw cycles.
Fig. 15a illustrates the effect of GF content, curing temperature (80^(@)C:}\left(80^{\circ} \mathrm{C}\right. for 24 hours), and the replacement of RS with RAP on the average compressive strength of AAC mixtures after exposure to 60 F-T cycles. Fig. 15b shows the changes in compressive strength of the AAC mixtures cured at ambient temperature following 60F-T60 \mathrm{~F}-\mathrm{T} cycles. 图 15a 显示了 GF 含量、固化温度 (80^(@)C:}\left(80^{\circ} \mathrm{C}\right. 24 小时）以及用 RAP 替代 RS 对 AAC 混合物经受 60 次 F-T 循环后的平均抗压强度的影响。图 15b 显示了在环境温度下固化的 AAC 混合物在 60F-T60 \mathrm{~F}-\mathrm{T} 循环后抗压强度的变化。
The blends cured at 80^(@)C80^{\circ} \mathrm{C} with 0%GF0 \% \mathrm{GF} showed similar strength losses, ranging from 24%24 \% to 25%25 \% for those containing 0%0 \%, 25%25 \%, and 50%50 \% RAP. The mixture with 100 % RAP exhibited a slightly higher strength loss, with a value of 26.24%26.24 \%. Curing at 80^(@)C80^{\circ} \mathrm{C} accelerates the geopolymerization process, leading to a more homogeneous and wellstructured matrix. This enhanced the overall strength of the mixtures, resulting in comparable strength loss across different RAP contents after exposure to 60 freeze-thaw (F-T) cycles. The inclusion of RAP in moderate amounts ( 25%25 \% and 50%50 \% ) may not significantly disrupt the matrix integrity due to the strong bonding provided by the alkali-activated slag composite. Thus, the strength loss remains consistent with that of the reference mixture ( 0%0 \% RAP). RAP tends to improve the ductility and reduce the brittleness of the composite to some extent, which helps maintain structural integrity under freeze-thaw cycling. However, at very high RAP content ( 100 %), the material may exhibit slight weaknesses, explaining the slightly higher strength loss (26.24 %). 在 80^(@)C80^{\circ} \mathrm{C} 下固化的含 0%GF0 \% \mathrm{GF} 的混合物显示出相似的强度损失，含 0%0 \% 、 25%25 \% 和 50%50 \% RAP 的混合物的强度损失从 24%24 \% 到 25%25 \% 不等。含有 100 % RAP 的混合物强度损失略高，值为 26.24%26.24 \% 。在 80^(@)C80^{\circ} \mathrm{C} 条件下固化可加速土工聚合过程，使基质更均匀、结构更合理。这增强了混合物的整体强度，使不同 RAP 含量的混合物在经受 60 次冻融 (F-T) 循环后的强度损失相当。由于碱活化矿渣复合材料提供了强大的粘结力，适量（ 25%25 \% 和 50%50 \% ）的 RAP 可能不会显著破坏基体的完整性。因此，强度损失与参考混合物（ 0%0 \% RAP）保持一致。RAP 往往会在一定程度上改善复合材料的延展性并降低脆性，这有助于在冻融循环下保持结构的完整性。不过，当 RAP 含量非常高（100%）时，材料可能会表现出轻微的弱点，这也是强度损失（26.24%）略高的原因。
The blends cured at 80^(@)C80^{\circ} \mathrm{C} with 0.5%0.5 \% GF exhibited greater strength loss compared to those without GF. Among these, the mixture without RAP had the lowest strength loss, while the mixture with 100 % RAP experienced the highest strength loss. The addition of both GF and RAP can increase the mixture’s porosity. RAP introduces voids, while GF, when not properly integrated, can cause weak spots. The combination of both materials might have exacerbated the effects of freeze-thaw cycles, leading to greater strength degradation. At 100 % RAP, the inclusion of large amounts of reclaimed asphalt pavement reduces the matrix’s cohesion and overall bonding. RAP particles have different properties than natural aggregates (RS), such as lower stiffness and weaker bonding with the binder, leading to higher porosity and reduced freezethaw resistance. This can explain the higher strength loss in the 100%100 \% RAP mixture. 在 80^(@)C80^{\circ} \mathrm{C} 条件下固化的含有 0.5%0.5 \% GF 的混合物与不含 GF 的混合物相比，强度损失更大。其中，不含 RAP 的混合物强度损失最小，而含有 100 % RAP 的混合物强度损失最大。添加 GF 和 RAP 都会增加混合物的孔隙率。RAP 会产生空隙，而 GF 如果结合不当，则会产生薄弱点。这两种材料的结合可能会加剧冻融循环的影响，导致强度下降。在 100% RAP 的情况下，大量再生沥青路面的加入会降低基质的内聚力和整体粘结力。再生沥青路面颗粒与天然集料（RS）具有不同的特性，例如刚度较低，与粘结剂的粘结力较弱，从而导致孔隙率较高，抗冻融性降低。这可以解释 100%100 \% RAP 混合物强度损失较大的原因。
The mixtures cured at 80^(@)C80^{\circ} \mathrm{C} with 1%GF1 \% \mathrm{GF} showed strength losses ranging from 27.96 % to 40.10%40.10 \%. Of these, the mixture containing 25%25 \% RAP had the lowest strength loss, whereas the mixture with 50 % RAP exhibited the highest strength loss. The mixture with 25 % RAP likely achieved a balance between the properties of RAP and the alkaliactivated slag matrix. At this level, the RAP content provides some flexibility and ductility, which helps the matrix withstand F-T cycles, resulting in the lowest strength loss. The addition of 1%GF1 \% \mathrm{GF} might not 在 80^(@)C80^{\circ} \mathrm{C} 条件下固化的含有 1%GF1 \% \mathrm{GF} 的混合物的强度损失在 27.96 % 到 40.10%40.10 \% 之间。其中，含有 25%25 \% RAP 的混合物强度损失最小，而含有 50 % RAP 的混合物强度损失最大。含有 25% RAP 的混合物可能在 RAP 和碱激活矿渣基质的特性之间达到了平衡。在这个水平上，RAP 的含量提供了一定的柔韧性和延展性，有助于基体承受 F-T 循环，从而使强度损失最小。添加 1%GF1 \% \mathrm{GF} 可能不会
have been as effective in improving freeze-thaw resistance, as the high RAP content creates a less uniform matrix. Glass fibers are typically intended to enhance tensile strength and crack resistance, but when the matrix already has significant weaknesses due to high RAP content, the fibers may not provide sufficient structural support, leading to greater deterioration under freeze-thaw conditions. 由于高 RAP 含量会造成基质不够均匀，因此玻璃纤维在提高抗冻融性方面同样有效。玻璃纤维的作用通常是提高抗拉强度和抗裂性能，但当 RAP 含量过高导致基体已经存在明显的薄弱环节时，玻璃纤维可能无法提供足够的结构支撑，从而导致在冻融条件下出现更严重的老化。
5.2. Weight loss on exposure to F-T cycles
Fig. 16a depicts the impact of GF content, curing temperatures (ambient and 80^(@)C80^{\circ} \mathrm{C} for 24 hours), and the replacement of RS with RAP on the average weight loss of AAC mixtures after 50 F-T cycles. All mixtures cured at 80^(@)C80^{\circ} \mathrm{C} exhibited lower weight loss compared to those cured at ambient temperature. Additionally, the inclusion of GF generally led to an increase in weight loss. Notably, mixtures containing 25%25 \% RAP showed the highest weight loss, regardless of GF content after 60 F T cycles. Curing at 80^(@)C80^{\circ} \mathrm{C} accelerates the geopolymerization process, leading to a more fully developed, denser matrix. This improved microstructure may enhance the material’s resistance to F-T cycles, resulting in lower weight loss compared to mixtures cured at ambient temperatures, which may not achieve the same degree of geopolymerization. The faster reaction rates at higher curing temperatures can result in a matrix with lower porosity. Less porous materials are less prone to absorbing water, which minimizes the effects of freeze-thaw damage, as water trapped within pores is the primary cause of expansion and degradation during freezing. While GF can improve tensile strength, its inclusion may create stress concentration points and microvoids within the matrix. These micro-defects can act as pathways for moisture ingress, increasing the susceptibility to freeze-thaw damage and leading to higher weight loss. The interface between the GF and the matrix might weaken under the mechanical stress of freeze-thaw cycles. This weakening could result in increased micro cracking, further contributing to weight loss. RAP contains a higher proportion of bituminous materials and may retain more moisture compared to natural river sand (RS). The presence of RAP in the mixtures can thus increase water absorption, leading to greater expansion during freeze-thaw cycles, especially after 60 cycles. This explains why mixtures with 25%25 \% RAP exhibited the highest weight loss, as the moisture retention could be higher in this specific composition. Curing at 80^(@)C80^{\circ} \mathrm{C} likely enhanced the bond between the binder and aggregates (both RAP and RS), making the overall structure more resistant to water ingress and freeze-thaw damage. This stronger bonding could explain the lower weight loss compared to mixtures cured at ambient temperature, where the bond is not as well-developed. 图 16a 描述了 GF 含量、固化温度（环境和 80^(@)C80^{\circ} \mathrm{C} 24 小时）以及用 RAP 替代 RS 对 50 次 F-T 循环后 AAC 混合物平均失重的影响。与在环境温度下固化的混合物相比，在 80^(@)C80^{\circ} \mathrm{C} 条件下固化的所有混合物的失重率都较低。此外，加入 GF 通常会导致失重增加。值得注意的是，含有 25%25 \% RAP 的混合物在 60 F T 循环后，无论 GF 含量如何，都表现出最高的失重率。在 80^(@)C80^{\circ} \mathrm{C} 条件下固化可加速土工聚合过程，使基质发育更充分、更致密。与在环境温度下固化的混合物相比，这种微观结构的改善可能会增强材料对 F-T 循环的耐受性，从而降低重量损失，因为在环境温度下固化的混合物可能无法达到相同的土工聚合度。固化温度越高，反应速度越快，基质的孔隙率就越低。孔隙率较低的材料不易吸水，从而将冻融破坏的影响降到最低，因为孔隙中的积水是造成冻胀和降解的主要原因。虽然 GF 可以提高拉伸强度，但加入 GF 可能会在基体中产生应力集中点和微孔。这些微缺陷会成为水分渗入的通道，增加冻融破坏的可能性，并导致更高的失重。在冻融循环的机械应力作用下，GF 与基体之间的界面可能会减弱。这种削弱可能会导致微裂纹增加，进一步加剧重量损失。与天然河沙（RS）相比，RAP 含有较高比例的沥青材料，可保留更多水分。 因此，混合物中 RAP 的存在会增加吸水率，导致在冻融循环过程中，特别是在 60 次循环后膨胀更大。这就解释了为什么含有 25%25 \% RAP 的混合物表现出最高的重量损失，因为这种特定成分的保湿性可能更高。在 80^(@)C80^{\circ} \mathrm{C} 条件下固化可能会增强粘结剂与集料（RAP 和 RS）之间的粘结力，从而使整体结构更能抵抗水的渗入和冻融破坏。与在环境温度下固化的混合物相比，这种粘结力更强的混合物失重更少，因为在环境温度下固化的混合物粘结力没有那么强。
Fig. 16. a) The weight loss and b) relation between the compressive strength and weight loss after 60 F-T cycles.
At 0%0 \% GF content, the highest weight loss occurred in the ambientcured reference mixture and the mixture cured at 80^(@)C80^{\circ} \mathrm{C} with 100%100 \% RAP. Conversely, at 0.5 % and 1 % GF content, the mixtures with 100 % RAP showed the greatest weight loss after 60 freeze-thaw cycles. The high weight loss in 100%100 \% RAP mixtures at both 0%0 \% and higher GF content is driven by RAP’s moisture retention capacity and increased porosity, which outweigh the reinforcing benefits of glass fibers, particularly during freeze-thaw cycles. Additionally, ambient-cured mixtures without GF lack the structural reinforcement to resist moisture penetration and freeze-thaw damage. 在 0%0 \% GF 含量条件下，重量损失最大的是常温固化参考混合物和在 80^(@)C80^{\circ} \mathrm{C} 条件下固化并添加 100%100 \% RAP 的混合物。相反，当 GF 含量为 0.5 % 和 1 % 时，含有 100 % RAP 的混合物在 60 次冻融循环后重量损失最大。 100%100 \% RAP 混合物在 0%0 \% 和更高 GF 含量下的高失重率是由 RAP 的保湿能力和增加的孔隙率造成的，这超过了玻璃纤维的增强效果，尤其是在冻融循环期间。此外，不含 GF 的常温固化混合物缺乏结构加固，无法抵御湿气渗透和冻融破坏。
After 60 F-T cycles, Fig. 16b shows a definite inverse connection between compressive strength and weight loss. Weight loss rises with decreasing compressive strength, suggesting that weaker combinations are more prone to deterioration under F-T exposure. The data also highlight that ambient curing exhibits a stronger correlation (R^(2)=0.95)\left(R^{2}=0.95\right) compared to 80^(@)C80^{\circ} \mathrm{C} curing ( R^(2)=0.89\mathrm{R}^{2}=0.89 ), suggesting that curing conditions significantly influence the durability of the mixtures under F-T cycles. 在 60 次 F-T 循环后，图 16b 显示抗压强度与重量损失之间存在明确的反比关系。重量损失随着抗压强度的降低而增加，这表明抗压强度较弱的组合在 F-T 暴露下更容易发生劣化。数据还显示，与 80^(@)C80^{\circ} \mathrm{C} 固化（ R^(2)=0.89\mathrm{R}^{2}=0.89 ）相比，常温固化（ (R^(2)=0.95)\left(R^{2}=0.95\right) ）显示出更强的相关性，表明固化条件对 F-T 循环下混合物的耐久性有显著影响。
Conclusion
This study explored the mechanical, durability, and microstructural properties of glass fiber-reinforced alkali-activated composites (AAC) cured at ambient and 80^(@)C80^{\circ} \mathrm{C} for 24 h incorporating varying amounts of reclaimed asphalt pavement (RAP) and glass fibers (GF). The primary binder used was ground blast furnace slag (GBFS), and the replacement of river sand (RS) with RAP was studied at 25%,50%25 \%, 50 \%, and 100%100 \%, with glass fibers added at 0%,0.5%0 \%, 0.5 \%, and 1%1 \%. The following key findings emerged from the study: 本研究探讨了玻璃纤维增强碱活性复合材料（AAC）在常温和 80^(@)C80^{\circ} \mathrm{C} 条件下固化 24 小时后的机械性能、耐久性能和微观结构性能，其中掺入了不同数量的再生沥青路面（RAP）和玻璃纤维（GF）。使用的主要粘合剂是磨碎的高炉矿渣 (GBFS)，研究了在 25%,50%25 \%, 50 \% 和 100%100 \% 时用 RAP 替代河砂 (RS)，在 0%,0.5%0 \%, 0.5 \% 和 1%1 \% 时添加玻璃纤维的情况。研究得出以下主要结论：
a) Increasing the curing temperature from ambient to 80^(@)C80^{\circ} \mathrm{C} led to a significant improvement in the compressive strength of AAC mixtures, with gains ranging from 26%26 \% to 60%60 \%, independent of GF and RAP content. The mixture with 100 % RAP and 0 % GF showed the smallest strength increase, while the mixture with 0%0 \% RAP and 1%1 \% GF demonstrated the greatest strength enhancement a) 将固化温度从常温提高到 80^(@)C80^{\circ} \mathrm{C} 可显著提高 AAC 混合物的抗压强度，提高幅度从 26%26 \% 到 60%60 \% 不等，与 GF 和 RAP 含量无关。RAP 含量为 100 %、GF 含量为 0 % 的混合物强度提高幅度最小，而 RAP 含量为 0%0 \% 、GF 含量为 1%1 \% 的混合物强度提高幅度最大。
b) Replacing RS with 25 % RAP resulted in the highest compressive strength. A substitution of RS with 50%50 \% RAP also led to an increase in compressive strength compared to the mixture containing 100%100 \% RS. However, when RS was entirely replaced with 100 % RAP, a slight reduction in compressive strength was observed, independent of curing conditions or the addition of GF. b) 用 25% 的 RAP 替代 RS 可获得最高的抗压强度。与含有 100%100 \% RS 的混合物相比，用 50%50 \% RAP 替代 RS 也能提高抗压强度。然而，当用 100 % RAP 完全替代 RS 时，观察到抗压强度略有下降，这与固化条件或添加 GF 无关。
c) The mixture containing 25%25 \% RAP and 0%0 \% GF demonstrated the highest compressive strength, whereas the mixture with 100 % RAP and 1%1 \% GF showed the lowest compressive strength under both ambient and 80^(@)C80^{\circ} \mathrm{C} heat curing conditions. c) 含有 25%25 \% RAP 和 0%0 \% GF 的混合物显示出最高的抗压强度，而含有 100 % RAP 和 1%1 \% GF 的混合物在环境和 80^(@)C80^{\circ} \mathrm{C} 热固化条件下显示出最低的抗压强度。
d) The addition of 0.5%0.5 \% and 1%1 \% GF reduced the compressive strength of the AAC mixtures cured at ambient and 80^(@)C80^{\circ} \mathrm{C} for 24 h , irrespective of RAP content, when compared to the mixtures without GF
e) Glass fibers significantly enhanced the flexural strength of the AAC mixtures, with the mixture containing 1%1 \% GF and 25%25 \% RAP achieving a 24.27%24.27 \% increase in flexural strength compared to the reference mix without RAP. However, at 100 % RAP, even the inclusion of 1%1 \% GF did not prevent the reduction in flexural strength, which decreased by 9.56%9.56 \% under ambient curing conditions. e) 玻璃纤维显著提高了 AAC 混合物的抗折强度，与不含 RAP 的参考混合物相比，含有 1%1 \% GF 和 25%25 \% RAP 的混合物的抗折强度提高了 24.27%24.27 \% 。然而，当 RAP 为 100 % 时，即使加入 1%1 \% GF 也无法阻止抗折强度的降低，在环境固化条件下，抗折强度降低了 9.56%9.56 \% 。
f) Irrespective of the glass fiber (GF) content and curing temperature, the mixtures with 25 % RAP consistently exhibited the lowest sorptivity under both curing conditions and the mixtures with 100 %RAP had the largest sorptivity values. f) 无论玻璃纤维 (GF) 含量和固化温度如何，含有 25% RAP 的混合物在两种固化条件下的吸水率都最低，而含有 100% RAP 的混合物的吸水率值最大。
g) Ambient-cured mixtures experienced lower strength loss at all hightemperature exposures with the addition of RAP, particularly when GF content was 0%0 \% and 0.5%0.5 \%. However, at 600^(@)C600^{\circ} \mathrm{C}, significant strength loss was observed, ranging between 84%84 \% and 89%89 \%, regardless of RAP or GF content. g) 添加 RAP 后，常温固化混合物在所有高温暴露条件下的强度损失都较低，特别是当 GF 含量为 0%0 \% 和 0.5%0.5 \% 时。 然而，在 600^(@)C600^{\circ} \mathrm{C} 时，无论 RAP 或 GF 含量如何，都会观察到明显的强度损失，范围在 84%84 \% 和 89%89 \% 之间。
h) 80^(@)C80^{\circ} \mathrm{C}-cured mixtures experienced higher strength loss at 200^(@)C200^{\circ} \mathrm{C} with the addition of RAP, particularly when GF content was 0%0 \%. When GF content was 0.5%0.5 \% and 1%1 \%, RAP-incorporated mixtures exhibited
lower strength loss at 400^(@)C400^{\circ} \mathrm{C}. However, at 600^(@)C600^{\circ} \mathrm{C}, significant strength loss was observed, ranging between 81%81 \% and 85%85 \%, regardless of RAP or GF content.
i) All ambient-cured mixtures experienced strength loss ranging from 8.98%8.98 \% to 56.46%56.46 \%, with the smallest loss observed in the mixture containing 25%25 \% RAP and 0.5%GF0.5 \% \mathrm{GF}, and the largest loss in the mixture containing 100%100 \% RAP and 1%1 \% GF after 60 F-T cycles. The high proportion of RAP may introduce more voids or weaknesses in the matrix, reducing cohesion and overall strength. i) 在 60 个 F-T 循环后，所有常温固化的混合物都出现了从 8.98%8.98 \% 到 56.46%56.46 \% 的强度损失，其中含有 25%25 \% RAP 和 0.5%GF0.5 \% \mathrm{GF} 的混合物的强度损失最小，而含有 100%100 \% RAP 和 1%1 \% GF 的混合物的强度损失最大。高比例的 RAP 可能会在基体中引入更多空隙或薄弱环节，从而降低内聚力和整体强度。
j) All 80^(@)C80^{\circ} \mathrm{C}-cured mixtures experienced strength loss between 24.49%24.49 \% and 45.89%45.89 \% after 60 freeze-thaw (F-T) cycles. The mixture with 50%50 \% RAP and 0%0 \% GF exhibited the least strength loss, while the mixture with 100%100 \% RAP and 0.5%0.5 \% GF showed the greatest loss after 60F-T60 \mathrm{~F}-\mathrm{T} cycles. j) 在 60 次冻融 (F-T) 循环后，所有 80^(@)C80^{\circ} \mathrm{C} 固化混合物的强度损失都在 24.49%24.49 \% 和 45.89%45.89 \% 之间。含有 50%50 \% RAP 和 0%0 \% GF 的混合物在 60F-T60 \mathrm{~F}-\mathrm{T} 循环后强度损失最小，而含有 100%100 \% RAP 和 0.5%0.5 \% GF 的混合物在 60F-T60 \mathrm{~F}-\mathrm{T} 循环后强度损失最大。
k) Elevated curing at 80^(@)C80^{\circ} \mathrm{C} significantly improved the strength and durability of the mixtures, particularly for those with lower RAP content ( 25%25 \% and 50%50 \% ). For example, the mixture with 25%25 \% RAP and 1%1 \% GF cured at 80^(@)C80^{\circ} \mathrm{C} showed a 26.75%26.75 \% improvement in compressive strength compared to the same mixture cured at ambient conditions. However, at high RAP content (100 %), elevated curing led to greater micro cracking due to the thermal softening of RAP’s bituminous material, limiting the potential for strength gains. k) 在 80^(@)C80^{\circ} \mathrm{C} 升温条件下固化可显著提高混合物的强度和耐久性，尤其是 RAP 含量较低的混合物（ 25%25 \% 和 50%50 \% ）。例如，在 80^(@)C80^{\circ} \mathrm{C} 条件下固化的含有 25%25 \% RAP 和 1%1 \% GF 的混合物与在环境条件下固化的相同混合物相比，抗压强度提高了 26.75%26.75 \% 。然而，在 RAP 含量较高（100%）的情况下，由于 RAP 沥青材料的热软化，升温固化会导致更大的微裂纹，从而限制了强度增加的潜力。
CRediT authorship contribution statement
Abdulkadir Cüneyt Aydın: Methodology, Investigation, Formal analysis, Data curation, Conceptualization. Gökhan Kaplan: Writing review & editing, Writing - original draft, Visualization, Methodology, Investigation, Formal analysis, Data curation, Conceptualization. Ahmet Tortum: Methodology, Investigation, Formal analysis, Data curation, Conceptualization. Ahmet Benli: Writing - review & editing, Writing - original draft, Visualization, Methodology, Investigation, Formal analysis, Data curation, Conceptualization. Ali Öz: Writing original draft, Supervision, Methodology, Investigation, Formal analysis, Data curation, Conceptualization. Dilan Kılıç: Methodology, Investigation, Formal analysis, Data curation, Conceptualization. Abdulkadir Cüneyt Aydın：方法论、调查、形式分析、数据整理、概念化。戈汗-卡普兰写作审核与编辑、写作-原稿、可视化、方法论、调查、形式分析、数据整理、概念化。Ahmet Tortum：方法论、调查、形式分析、数据整理、概念化。Ahmet Benli：写作--审阅和编辑、写作--原稿、可视化、方法论、调查、形式分析、数据整理、概念化。阿里-厄兹撰写原稿、监督、方法论、调查、正式分析、数据整理、概念化。Dilan Kılıç：方法论、调查、形式分析、数据整理、概念化。
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper
Data Availability
No data was used for the research described in the article.
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