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}