碱硅酸反应对水泥基材料力学性能的影响

Influence of Alkali-Silica Reaction on Mechanical Properties of Cementitious Materials

通过对比活性不同的两种砂制备的砂浆试样在碱硅酸反应中的膨胀率,结合三轴抗压测试研究了碱硅酸反应前后水泥基材料的力学性能变化,分析了碱硅酸反应后材料微观结构演变与力学性能间的关系。结果表明碱惰性砂制备的砂浆试样中骨料周围局部区域形成少量针状凝胶相,由于碱硅酸反应速率较慢且凝胶相较少,因而其膨胀率较小且对水泥基材料力学性能的影响较小。碱活性砂制备的砂浆试样中,骨料周围易生成大量针状凝胶层,且随着碱硅酸反应的进行凝胶相膨胀加剧,促进水泥基材料中骨料周围的水泥浆体中形成大量裂纹,进而明显影响水泥基材料的力学性能。研究表明,三轴抗压测试中,除膨胀率外,极限抗压强度和应变量也可以作为评价水泥基材料碱硅酸反应水平的参量。

The expansion rate of mortars ,prepared with active sand and non-active sand ,under alkali-silica reaction （ASR） was recorded .The effects of ASR on mechanical properties of cementitious materials were studied by triaxial compression test .The relation between the microstructure of cementitious materials and the mechanical properties was investigated as well .The results showed that there was a little blade crystals gel formed in a local region near the aggregate in materials prepared with non-active sand .For the quantity of formed gel is small ,the expansion effects of ASR are limited .Whereas ,thick blade crystals gel layers formed near the aggregate when the active sand prepared materials subjected to ASR .Moreover ,the reactive products would lead to cracks and then significantly affects the mechanical properties of mortars . Additionally ,the results showed that besides the expansion rate ,the ultimate compressive strength and the strain are also effective indexes to estimate the influence of ASR .