灰渣基地聚合物力学强度与组成结构受养护时间的影响

Influence of Curing Time on the Mechanical Strength and Composition Structure of Fly Ash-Based Polymers

摘要: 本研究通过设置不同Si/Al、W/B和Na/Al配比，系统考察了养护时间对灰渣基地聚合物力学性能、微观结构和热行为的影响。结果表明，强度主要在前3 d快速增长，3 d抗压强度已达28 d的70%以上，7~28 d增幅不足10%。合理配比可使材料由含百纳米孔隙和球形颗粒的初始结构逐步转变为连续致密的无定形凝胶；碱剂过量或W/B不当则易产生棒状碱晶体和连通孔洞，抑制后期强度提升。热分析进一步表明，地聚合物的主要放热缩聚集中在30℃~480℃区间，28 d的焓变仅为3 d的约7.7%~19.7%。总体说明灰渣基地聚合物具有“早期快速聚合、后期缓慢致密”的特征，可为优化配比参数提供依据。

Abstract: This study investigates the effects of curing time on the mechanical properties, microstructural evolution, and thermal behavior of slag-ash-based geopolymers by designing mixtures with different Si/Al, W/B, and Na/Al ratios. The results show that strength development occurs mainly within the first 3 days, during which the compressive strength reaches more than 70% of the 28-day value, while the increase from 7 to 28 days is less than 10%. With an appropriate mix design, the material gradually evolves from an initial structure containing hundred-nanoscale pores and spherical particles into a continuous and dense amorphous gel; however, excessive alkali or an improper W/B ratio leads to the formation of needle- or rod-like alkali crystals and interconnected pores, which hinder later strength development. Thermal analysis further indicates that the main exothermic polycondensation occurs within the 30˚C~480˚C range, with the 28-day enthalpy release being only about 7.7%~19.7% of that at 3 days. Overall, the results demonstrate that slag-ash-based geopolymers exhibit a characteristic “rapid early polymerization followed by slow densification”, providing guidance for optimizing key mixture parameters.