针对镁渣利用率低以及对现代混凝土尺寸稳定性要求高的问题,以镁渣掺量、粉煤灰取代率为因素,设计正交试验方案,试验研究镁渣粉煤灰复合混凝土的干燥收缩特性。结果表明:镁渣粉煤灰复合混凝土的干缩变形与时间呈双曲线关系,且有很好的相关性;镁渣和粉煤灰对混凝土的干缩变形均有抑制效应,镁渣的作用效应明显的强于粉煤灰的作用效应,镁渣和粉煤灰复掺较镁渣单掺对混凝土干缩变形的抑制效应增强;镁渣对混凝土干缩的作用效应随时间逐渐增大,90d基本趋于稳定,测定龄期内混凝土仅有收缩,无膨胀变形和膨胀性危害,掺入适量的镁渣来补偿混凝土的收缩变形是可行的。
Aiming at the low utilization rate of magnesium slag and high requirement of modem concrete for dimension stability, we have designed an orthogonal test scheme to experimentally study the drying shrinkage characteristics of composite concrete mixed with magnesium slag and fly ash. Results show that the shrinkage increases with time following a trend of hyperbolic curve with a high correlation. Either magnesium slag or fly ash has inhibitory effect on shrinkage deformation and the former's effect is stronger. This inhibitory effect is enhanced when fly ash is added into magnesium slag composite. The effect of magnesium slag on drying shrinkage builds up gradually with time and tends to be stable at roughly 90 d. Only shrinkage occurred and neither expansion nor expandable harm in concrete has been observed during the testing period. Thus, it is feasible to add a certain amount of magnesium slag to compensate the shrinkage of concrete.