镁渣复合掺合料混凝土的干燥收缩特性

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、掺合料取代率和矿粉复合率为因素，设计正交试验方案，试验研究镁渣复合掺合料混凝土的干燥收缩特性，分析作用规律，建立关系模型，微观结构分析掺合料的作用机理。结果表明：镁渣复合掺合料混凝土的干缩变形与时间呈相关性很好的双曲线关系，其拟合参数的关系模型显著性水平高，与各因数的相关性好；混凝土的干缩变形随镁渣掺量和掺合料取代率的增大而减小，随矿粉复合率的增大而增大，作用的重要性次序为镁渣掺量、掺合料取代率和矿粉复合率；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，掺入适量的镁渣来补偿混凝土的收缩变形是可行的。

Drying Shrinkage Characteristics of Magnesium Slag Composite Admixture Concrete

Aiming at the problem of the low utilization rate of magnesium slag and high requirement of dimension stability for modern concrete, orthogonal test scheme was designed to study the drying shrinkage characteristics of magnesium slag composite admixture concrete by experiment. The shrinkage model of concrete was established through analysis of the role of law, analyzed the mechanism of admixture by micro structure. Results show that the drying shrinkage of magnesium slag composite admixture concrete increases with time in a trend of hyperbolic curve, which has significant correlation. The significant level of fitting parameters model is high, good correlation with each factor. The drying shrinkage of concrete decreases with magnesium slag dosage and admixture replacement rate, increases with powder composite rate. The order of importance is magnesium slag dosage, admixture replacement rate and powder composite rate. The effect of magnesium slag on drying shrinkage of concrete increases gradually with time, tends to be stable at 90d. In this period, there is only shrinkage, no expansion and expandable harm in concrete. So it is feasible to add proper amount of magnesium slag to compensate the shrinkage of concrete.