矿物掺合料对全再生骨料混凝土性能的影响

Effect of mineral admixtures on properties of plain recycled aggregate concrete

为制备性能良好的全再生骨料混凝土,研究了粉煤灰和矿粉对全再生骨料混凝土早期工作性、抗压强度和抗氯离子渗透性等的影响。结果表明,掺入粉煤灰、矿粉可以提高全再生骨料混凝土的流动性,但降低了混凝土的早期强度,特别是当掺量超过40%后,强度下降较为明显,养护龄期达90 d后,掺有粉煤灰和矿粉的混凝土强度超过基准全再生骨料混凝土;粉煤灰和矿粉均可明显改善全再生骨料混凝土的抗氯离子渗透性能;矿粉对混凝土抗压强度和抗氯离子渗透性的影响比粉煤灰更加显著。综合考虑全再生骨料混凝土的工作性、抗压强度和抗氯离子渗透性能,粉煤灰和矿粉最佳掺量均以20%为宜。

For the preparation of plain recycled aggregate concrete with good performance, the effect of slag, fly ash on the early workability, compressive strength and resistance to chloride ion penetra-tion of plain recycled aggregate concrete were investigated. The results show that mixing with slag and fly ash can improve the liquidity of plain recycled aggregate concrete, but the early strength of concrete is reduced, especially when the content is more than 40% , the strength is decreased obvi-ously. After the age of 90 day, the strength of concrete with admixture exceeds the benchmark of plain recycled aggregate concrete. Fly ash and slag can significantly improve the chloride ion pene-tration resistance of the recycled aggregate concrete. The effect of slag on the compressive strength and resistance to chloride ion penetration is more significant than that of fly ash. Considering the workability, compressive strength and anti-chloride ion permeability, the dosages of fly ash and slag were set at 20% for both, and this can achieve the highest performance of plain recycled aggregate concrete.