Liu Xiaoming, Liu Erping
School of Civil Engineering, Central South University, Changsha 410075, China.
Polymers (Basel). 2023 Jun 15;15(12):2696. doi: 10.3390/polym15122696.
Geopolymer prepared from solid waste is a high value-added means. However, when used alone, the geopolymer produced by phosphogypsum has the risk of expansion cracking, while the geopolymer of recycled fine powder has high strength and good density, but its volume shrinkage and deformation are large. If the two are combined, the synergistic effect of the phosphogypsum geopolymer and recycled fine powder geopolymer can realize the complementarity of advantages and disadvantages, which provides a possibility for the preparation of stable geopolymers. In this study, the volume stability, water stability and mechanical stability of geopolymers were tested, and the stability synergy mechanism between phosphogypsum, recycled fine powder and slag was analyzed by micro experiments. The results show that the synergistic effect of phosphogypsum, recycled fine powder and slag can not only control the production of ettringite (AFt) but also control the capillary stress in the hydration product, thus improving the volume stability of the geopolymer. The synergistic effect can not only improve the pore structure of the hydration product but also reduce the negative impact of calcium sulfate dihydrate (CaSO∙2HO), thus improving the water stability of geopolymers. The softening coefficient of P15R45 with a 45 wt.% recycled fine powder content can reach 1.06, which is 26.2% higher than P35R25 with a 25 wt.% recycled fine powder content. The synergistic work reduces the negative impact of delayed AFt and improves the mechanical stability of the geopolymer.
利用固体废弃物制备地质聚合物是一种高附加值的方法。然而，单独使用时，磷石膏制备的地质聚合物存在膨胀开裂的风险，而再生细粉地质聚合物强度高、密实性好，但体积收缩变形大。若将二者结合，磷石膏地质聚合物与再生细粉地质聚合物的协同效应可实现优势互补，为制备稳定的地质聚合物提供了可能。本研究测试了地质聚合物的体积稳定性、水稳定性和力学稳定性，并通过微观试验分析了磷石膏、再生细粉与矿渣之间的稳定性协同机理。结果表明，磷石膏、再生细粉与矿渣的协同效应不仅能控制钙矾石（AFt）的生成，还能控制水化产物中的毛细应力，从而提高地质聚合物的体积稳定性。该协同效应不仅能改善水化产物的孔隙结构，还能降低二水硫酸钙（CaSO∙2HO）的负面影响，从而提高地质聚合物的水稳定性。再生细粉含量为45 wt.%的P15R45的软化系数可达1.06，比再生细粉含量为25 wt.%的P35R25高26.2%。协同作用降低了延迟生成的AFt的负面影响，提高了地质聚合物的力学稳定性。
