Pang Haotian, Qi Wenyue, Huang Yanli, Zhao Qingxin, Zhang Jinghui, Zhao Dezhi, Yu Junchao, Song Hongqi
Hebei Province Engineering Research Center for Harmless Synergistic Treatment and Recycling of Municipal Solid Waste, Yanshan University, Qinhuangdao 066004, China.
State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, China; Hebei Province Engineering Research Center for Harmless Synergistic Treatment and Recycling of Municipal Solid Waste, Yanshan University, Qinhuangdao 066004, China.
Sci Total Environ. 2024 Oct 15;947:174459. doi: 10.1016/j.scitotenv.2024.174459. Epub 2024 Jul 2.
In this study, coal-based solid waste geopolymer mortar (SWCB) was prepared by using granulated ground blast-furnace slag (GGBS) and coal gasification coarse slag (CGCS) as precursors, and soda residue (SR) and phosphogypsum (PG) as activators, with gangue sand (GS) utilized as an inert filler. The corresponding compressive strength, fluidity, ion leaching, and microstructure of the developed SWCB were systematically investigated under varying solid contents, binder-to-sand ratios, and activator ratios. The findings suggest that the incorporation of activators promoted the dissolution of the silicon-aluminum phase in GGBS and CGCS into Al(OH), [SiO(OH)], and [SiO(OH)], which could subsequently react with the Ca and SO released by PG, forming AFt and C-(A)-S-H, thereby playing a crucial role in enhancing matrix strength. AFt was the predominant hydration product in the early reaction stage. The morphology of the AFt phase evolved from needle-like or filamentous to fine and coarse rods as hydration progressed. Initially, the formation of C-(A)-S-H gel increased with rising activator content before decreasing. The optimal synergy between AFt and C-(A)-S-H was observed at an activator content of 30 %. However, the growth of gypsum crystals was hindered when the activator content surpassed 30 %, resulting in a plate-like or columnar morphology. C-(A)-S-H gel exhibited remarkable adsorption capability towards P atoms attributed to intermolecular Van der Waal's forces, enabling simultaneous physical encapsulation of P atoms, while Cl element immobilization was primarily attributed to the contribution of SiOH sites to Cl adsorption.
在本研究中，以粒化高炉矿渣（GGBS）和煤气化粗渣（CGCS）为前驱体，以碱渣（SR）和磷石膏（PG）为活化剂，利用煤矸石砂（GS）作为惰性填料，制备了煤基固体废弃物地质聚合物砂浆（SWCB）。在不同的固体含量、粘结剂与砂的比例以及活化剂比例下，系统研究了所制备的SWCB相应的抗压强度、流动性、离子浸出和微观结构。研究结果表明，活化剂的加入促进了GGBS和CGCS中硅铝相溶解为Al(OH)₃、[SiO(OH)]₄和[SiO(OH)]₆，随后它们可与PG释放的Ca²⁺和SO₄²⁻反应，形成钙矾石（AFt）和C-(A)-S-H，从而在增强基体强度方面发挥关键作用。AFt是早期反应阶段的主要水化产物。随着水化的进行，AFt相的形态从针状或丝状演变为粗细不同的棒状。起初，C-(A)-S-H凝胶的形成随着活化剂含量的增加而增加，之后减少。在活化剂含量为30%时，观察到AFt与C-(A)-S-H之间的最佳协同作用。然而，当活化剂含量超过30%时，石膏晶体的生长受到阻碍，导致其形态为板状或柱状。由于分子间范德华力，C-(A)-S-H凝胶对P原子具有显著的吸附能力，能够同时对P原子进行物理包裹，而Cl元素的固定主要归因于SiOH位点对Cl吸附的贡献。
