Danish Aamar, Torres Anthony S
Department of Engineering Technology, Texas State University, San Marcos, TX 78666, USA.
Department of Engineering Technology, Texas State University, San Marcos, TX 78666, USA.
Waste Manag. 2025 Aug 1;204:114899. doi: 10.1016/j.wasman.2025.114899. Epub 2025 Jun 2.
The growing disparity between the supply and demand for fly ash (FA), which is increasingly used in sustainable building materials, contrasts with the large quantities of FA already in landfills, contributing to environmental pollution and disasters. Meanwhile, geopolymer technology offers significant environmental and financial benefits for managing waste. Therefore, this research examines the potential for producing high-performance geopolymers using reclaimed FA (RFA) (from landfilled FA recycling) and ground granulated blast furnace slag (GGBFS) through hot water curing. The characteristics and performance of these geopolymers were evaluated based on strength, transport properties, durability, and microstructural analysis. The results revealed that the strength of geopolymers is approximately unaffected by replacing up to 60 % of GGBFS with RFA, and increasing the RFA dosage to 80 % still yielded material suitable for at least medium-grade applications. Specifically, inclusion of 20-80 % RFA resulted in a 28-day compressive strength ranging from 81.1 to 38 MPa. While RFA slightly increased water absorption and decreased surface electrical resistivity of geopolymers, indicating vulnerability to environmental agents, excessive GGBFS reduced resistance to acid attack, suggesting that 40-60 % RFA is needed for adequate chemical resistance. Similarly, adding RFA led to lower drying shrinkage and improved resistance to elevated temperatures. Also, RFA posed no leaching problem, and neither raw RFA nor RFA-based geopolymers exceeded solid inert or hazardous waste thresholds, with the latter more effective at immobilizing heavy metals. The findings support high-performance geopolymer production containing RFA to manage landfilled FA, reduce environmental burden, and encourage the circular economy in construction.
粉煤灰（FA）在可持续建筑材料中的使用日益增加，其供需差距不断扩大，这与大量已填埋的粉煤灰形成鲜明对比，这些填埋的粉煤灰造成了环境污染和灾害。与此同时，地质聚合物技术在废物管理方面具有显著的环境和经济效益。因此，本研究探讨了通过热水养护，利用再生粉煤灰（RFA）（来自填埋粉煤灰回收）和磨细粒化高炉矿渣（GGBFS）生产高性能地质聚合物的潜力。基于强度、传输性能、耐久性和微观结构分析，对这些地质聚合物的特性和性能进行了评估。结果表明，用RFA替代高达60%的GGBFS时，地质聚合物的强度基本不受影响，将RFA用量增加到80%仍能得到至少适用于中等等级应用的材料。具体而言，掺入20%-80%的RFA可使28天抗压强度在81.1至38MPa之间。虽然RFA略微增加了地质聚合物的吸水率并降低了其表面电阻率，表明其易受环境因素影响，但过量的GGBFS会降低耐酸侵蚀性，这表明需要40%-60%的RFA才能具有足够的耐化学性。同样，添加RFA可降低干燥收缩率并提高耐高温性。此外，RFA不存在浸出问题，原始RFA和基于RFA的地质聚合物均未超过固体惰性或危险废物阈值，后者在固定重金属方面更有效。这些研究结果支持了含RFA的高性能地质聚合物的生产，以管理填埋的粉煤灰，减轻环境负担，并促进建筑行业的循环经济。
