纳米偏高岭土对铁尾矿砂-再生混凝土抗压性能影响及微观结构分析OA北大核心CSTPCD

In order to comprehensively utilize solid waste,recycled coarse aggregate is partially replaced by natural aggregate,and iron tailings sand is partially substituted for natural sand as coarse and fine aggregate,respectively.Additionally,nano-metakaolin(NMK)is used as a partial replacement for cement as the binding material,resulting in the production of iron tailings sand-recycled concrete(IRC).A cube compressive strength test was conducted to investigate the impact of NMK on the compressive strength of Iron tailings sand-recycled concrete(IRC).The changes in the microstructure of recycled concrete were examined using scanning electron microscopy(SEM)and the nitrogen adsorption method(BJH).The results indicate that the strength of recycled concrete exhibits an increasing rate of change with higher iron tailings replacement rates.The greater the replacement rate,the higher the change rate of compressive strength.The addition of an appropriate amount of NMK proves beneficial in enhancing the compressive strength of recycled concrete,reaching its maximum when the NMK content is 5%.The introduction of an optimal amount of NMK promotes a significant increase in C-S-H gel through secondary hydration reactions.This,in turn,improves the compactness within the mortar and between the mortar and the aggregate.Furthermore,it enhances the strength of the interfacial transition zone,optimizes the internal structure of the pores,and ultimately enhances the compressive strength of IRC.