矿渣-粉煤灰地聚物固化淤泥力学性能和路用性能研究

Mechanical Properties and Road Performance of Slag-Fly Ash Geopolymer Stabilized Sludge

为实现河底淤泥的资源化处置,常采用水泥等胶凝材料固化淤泥提高承载力作为路基材料。传统固化材料能耗大、碳排放量高。为开发可持续性固化材料,本研究采用矿渣-粉煤灰二元地聚物固化淤泥,研究其力学性能及路用性能。通过研究Si/Al摩尔比、Na/Al摩尔比对地聚物凝结时间和抗压强度的影响规律,确定地聚物配合比设计。依据优化配合比固化淤泥,研究地聚物掺量、养护龄期对固化淤泥力学性能的影响,并对固化淤泥进行水稳性、加州承载比、干缩和温缩试验,以评估其路用性能;采用扫描电镜和X射线衍射等试验方法对固化淤泥进行微观分析,揭示其固化机制。试验结果表明,矿渣-粉煤灰基地聚物地质聚合产物为无定形地聚物凝胶、水化硅酸钙、水化铝酸钙等,增强了土颗粒之间的胶结并且填充了孔隙,提高了固化淤泥的力学性能和路用性能。研究结果为地聚物固化淤泥土工程应用提供了实验基础。

River sludge is usually stabilized with cementitious binder and applied in pavement construction as sub-ground soil for sustainable treatment. However, the application of Ca-based binder, such as Portland cement and lime, is increasingly limited by the high energy consumption and CO;emission. To solve this problem, granulated blast furnace slag(GBFS) and fly ash were used to synthesize binary-phases based geopolymer to stabilize sludge. Firstly, the mix proportion of geopolymer stabilizer was determined based on the influence of Si/Al and Na/Al molar ratio on the setting time and compressive strength of geopolymer. Subsequently, the effects of geopolymer content and curing age on the mechanical properties of stabilized sludge are studied, and the practical performance of stabilized sludge was evaluated with water stability, CBR, dry shrinkage and temperature shrinkage tests. Furthermore, the stabilization mechanism was revealed by the microstructure characterization with scanning electron microscopy and X-ray diffractometry. The experimental results show that the geopolymerization products include amorphous geopolymer gel, calcium silicate hydrate and calcium aluminate hydrate, which enhance the binding of soil particles and filled the voids, and thus improve the mechanical properties and road performance of stabilized sludge. It provides experimental foundation for the practical application of geopolymer stabilized sludge in pavement construction.