Research on the early age mechanical properties of alkali-activated fly ash-slag geopolymer

Chen Yuhang; Zhang Shujuan; Sheng Zhijie; Zhu Yiting

doi:10.19896/j.cnki.mtkj.2025.06.023

Abstract：Geopolymer is a low-carbon and low-cost aluminosilicate cementitious material,and its early-age mechanical properties de-termine the effectiveness and feasibility of its engineering applications.Through uniaxial compression tests,the effects of different alkali activator content,alkali activator modulus,and water-binder ratio on the early-age uniaxial compressive strength of fly ash-slag geopolymer paste specimens were investigated.The experimental results indicate that when the dosage of alkali activator increases from 10％to 20％,the compressive strength at various ages continues to increase,with the order being J20>J15>J10.The increase in dosage promotes gel densification by enhancing alkalinity,thereby improving the mechanical properties of the material.When the modulus of the alkali activator increases from 1.0 to 1.4,the compressive strength at various ages decreases,with the order being M1.0>M1.2>M1.4.A low modulus promotes gel formation,while a high modulus inhibits reaction activity.When the water-to-binder ratio increases from 0.43 to 0.45,the compressive strength at various ages decreases,with the WB0.43 group having the highest strength.A lower water-to-binder ratio helps improve densification and gel formation efficiency.The research results can provide theoretical basis and experimen-tal reference for the early-age mechanical property regulation and engineering application of fly ash-slag geopolymers.