高强轻集料混凝土的早期自收缩研究

Study on early autogenous shrinkage of High Strength Lightweight Aggregate Concrete(HSLWAC)

研究了高强轻集料混凝土的自收缩特性和影响因素。结果表明:高强混凝土的收缩主要是自收缩;水泥用量在一定范围内显著影响混凝土的自收缩;轻集料混凝土的自收缩有明显不同于普通混凝土之处,其早期自收缩比普通混凝土低,而后期自收缩高于普通混凝土,高强普通混凝土的自收缩在28d以后逐渐趋于稳定,而高强轻集料混凝土的自收缩在28d以后仍有比较明显地增加。研究发现,通过调整轻集料体积率,掺加适量粉煤灰,提高轻集料的预饱水程度能有效减小高强轻集料混凝土的自收缩。

Autogenous shrinkage(AS) characteristic and its effect on AS of High Strength Lightweight Aggregate Concrete(HSLWAC)were studied.Test results show that the main shrinkage of high strength concrete is AS.The amount of cement can affect the AS of concrete remarkably.The AS characteristic of HSLWAC is different from normal concrete in some aspects.At the early stage it is lower than that of normal concrete,while it is much higher than that of normal concrete at the late stage.The AS of high strength normal concrete becomes stable after 28 days,but the HSLWAC still has great AS rate.It is found that adapting the volume rate of lightweight aggregate,mixing with proper dosage of fly ash and raising the water saturation degree of lightweight aggregate can markedly reduce the AS rate of HSLWAC.