关键词: 混凝土, 铁尾矿, 粉煤灰, 二元掺合料, 抗压强度

Abstract: In order to improve the compressive performance of binary solid waste concrete，the effect of iron tailingsfly ash composite admixture on the compressive performance of binary solid waste concrete was investigated based on different mechanical activation methods.The hydration mechanism of compressive strength enhancement of iron tailingsfly ash composite admixture concrete was analyzed by using tests such as Xray diffraction (XRD)，scanning electron microscopy (SEM) and thermogravimetric (TGDSC) analysis.The compressive strength enhancement of concrete with iron tailingsfly ash composite admixture was most obvious when the mechanical activation method of blended before grinded was adopted，reaching 70.6 MPa at 28 d of age.Different mechanical activation methods lead to different structures of hydration products，while changed the degree of involvement of the admixture in the secondary hydration reaction.The mechanical activation method of blended before grinded can contribute to the further hydration of cement clinker，consume more Ca(OH)2 to participate in the secondary hydration reaction and generate more and denser reticular C—S—H gels.From the point of view of concrete compressive strength and the hydration and hardening mechanism of concrete cementing materials，the activation effect of mechanical activation by blended before grinded was better，which facilitated the strength development of binary solid waste concrete.

Key words: concrete, iron tailings, fly ash, binary admixture, compressive strength