Jin Jiaxu, Qin Zhifa, Zuo Shenghao, Feng Jiaju, Sun Qi
School of Civil Engineering, Liaoning Technical University, Fuxin 123000, China.
Liaoning Key Laboratory of Mine Subsidence Disaster Prevention and Control, Liaoning Technical University, Fuxin 123000, China.
Materials (Basel). 2022 Apr 21;15(9):3006. doi: 10.3390/ma15093006.
Cemented paste backfill (CPB) has become a significant structural material in most mines across the world. In this study, the effects of chemical rheological additives including viscosity modifying agent (i.e., polyacrylamide) and polycarboxylate superplasticizer (PCE) on fresh and hardened properties of CPB with different water-to-solid (W/S) ratios and water-to-cement (W/C) ratios were investigated. The microstructure of CPB specimens was also characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and backscattered electron image (SEM-BSE). The obtained results indicate that PAM (polyacrylamide) dosage and W/S are the most significant parameters influencing the workability of fresh CPB mixtures. For the hardened CPB specimens, the decreasing W/S ratio leads to higher flexural and compressive strength values and lower dry shrinkage strains. The interfacial transition zone (ITZ) between the cement matrix and the tailings sand was also observed to be narrower, with fewer micro cracks and capillary pores. Meanwhile, the existence of PAM decreased the number of hydration products and retarded the hydration reaction. Overall, the CPBs with high W/C ratios (i.e., 1.0 and 1.2), low W/S ratios (i.e., 0.3), and moderate amounts of rheological additives (i.e., 0.05% PAM and 1.0% PCE) have excellent fresh and hardened properties. The findings of this study contribute to better optimization of CPB mixtures in backfill construction, bringing benefits of low costs and low environmental impacts.
胶结膏体充填材料（CPB）已成为全球大多数矿山的一种重要结构材料。在本研究中，研究了包括粘度调节剂（即聚丙烯酰胺）和聚羧酸高效减水剂（PCE）在内的化学流变添加剂对不同水固比（W/S）和水灰比（W/C）的CPB新拌及硬化性能的影响。还通过X射线衍射（XRD）、热重分析（TGA）、扫描电子显微镜（SEM）和背散射电子图像（SEM-BSE）对CPB试件的微观结构进行了表征。所得结果表明，聚丙烯酰胺（PAM）用量和W/S是影响新鲜CPB混合物工作性能的最重要参数。对于硬化后的CPB试件，W/S比降低会导致更高的抗折和抗压强度值以及更低的干缩应变。还观察到水泥基体与尾矿砂之间的界面过渡区（ITZ）更窄，微裂纹和毛细孔更少。同时，PAM的存在减少了水化产物的数量并延缓了水化反应。总体而言，具有高W/C比（即1.0和1.2）、低W/S比（即0.3）和适量流变添加剂（即0.05% PAM和1.0% PCE）的CPB具有优异的新拌及硬化性能。本研究结果有助于更好地优化充填施工中的CPB混合物，带来低成本和低环境影响的好处。
