再生复合微粉对混凝土力学性能及微观结构的影响

Effect of Recycled Composite Micro-powder on Mechanical Properties and Microstructure of Concrete

基于复合胶凝材料对硅酸盐水泥水化的影响规律,利用再生砖粉与再生混凝土粉混合而成的复合微粉作为辅助胶凝材料替代水泥,研究了复合微粉在取代率为0%、15%、30%、45%和再生砖粉与再生混凝土粉质量比为8∶2和6∶4条件下对混凝土工作性能、力学性能及微观结构的影响机理.结果表明:随着再生砖粉与再生混凝土粉质量比和复合微粉取代率的增加,混凝土拌和物的流动性降低,但复合微粉取代率在15%以内时的流动性变化幅度较小;水化初期,复合微粉主要发挥填充作用,复合微粉混凝土7 d抗压强度较普通混凝土略低;随着养护龄期的增长,复合微粉混凝土28 d抗压强度和劈裂抗拉强度在复合微粉取代率为15%、再生砖粉与再生混凝土粉质量比为6∶4时较普通混凝土分别提高了4.2%和10.1%.

Based on the influence of composite cementitious materials on the hydration of Portland cement,recycled brick/concrete composite micro-powder was used as supplementary cementitious material to replace cement,and mechanism of the effect of composite micro-powder on the workability,mechanical properties,and microstructure of concrete under the substitution rate of 0%,15%,30%,45%and the mass ratio of 8∶2 and 6∶4 was studied.The results show that the fluidity decreases as the increase of brick powder ratio and composite micro-powder substitution rate,but the fluidity changes less than 15%;at the beginning of hydration,the composite micro-powder mainly plays the roll of filling.The 7 d compressive strength of composite micro-powder concrete is slightly lower than that of ordinary concrete.With the prolongation of hydrating age,the 28 d compressive and splitting tensile strengths increased by 4.2%and 10.1%respectively at the substitution rate of 15%and the mass ratio of 6∶4 with composite micro-powder.