铁尾矿砂对混凝土强度及抗硫酸盐冻融的影响

Effects of Iron Tailings on Concrete Strength and Sulfate Freezing-Thawing Resistance

为了达到清洁生产的目的,铁尾矿砂作为细骨料被用于制备混凝土。通过宏观和微观两个层面探讨了不同铁尾矿砂取代率对混凝土强度及抗硫酸盐冻融性能的影响,并分析其影响机理,制备了铁尾矿砂取代率依次为0、20%、40%、60%、80%、100%的6种混凝土。结果表明,随着铁尾矿砂取代率的增加,混凝土试样的抗压强度和劈裂抗拉强度均呈现先增加后减小的趋势,当铁尾矿砂取代率小于40%时,混凝土内部微观结构致密,对其强度和抗硫酸盐冻融性能有积极影响,但取代率过大时会产生相反的影响;据此建立了铁尾矿砂混凝土抗压强度与劈裂抗拉强度之间的关系,以及冻融条件下Weibull损伤模型,得出铁尾矿砂取代率为40%时混凝土强度和抗冻性能最优的结论。

In order to achieve the purpose of cleaner production, iron ore tailings are used as fine aggregate to prepare concrete. The effects of different iron tailings substitution rates on concrete strength and sulfate freezing-thawing resistance were discussed at the macro and micro levels, and the effects mechanism was analyzed. Six kinds of concrete samples with iron tailings substitution rates of 0, 20%, 40%, 60%, 80% and 100% were prepared. The results show that with the increase of the iron tailings substitution rate, the compressive strength and splitting tensile strength of concrete samples increase first and then decrease. When the substitution rate is less than 40%, the internal microstructure of concrete is dense, which has a positive effect on strength and sulfate freezing-thawing resistance, but when the substitution rate is too large, it will have the opposite effect. On this basis, the relationship between compressive strength and splitting tensile strength of iron tailings concrete and Weibull damage model under freezing-thawing conditions were established. It is concluded that the strength and frost resistance of concrete are the optimal when the iron tailings substitution rate is 40%.