透水模板浇筑混凝土拌合物水胶比试验分析

Water-binder ratio of concrete mixture formed by controlled permeability formwork

为研究透水模板降低混凝土拌合物水胶比的程度,对试验浇筑的混凝土拌合物试件采用微波法测定排水过程结束时由表及里的水胶比变化。试验结果表明:透水模板浇筑混凝土拌合物表层水胶比可降低40%～50%,水胶比减少最明显的区域位于试件浅表层15mm范围内;由于浅层形成滤饼,阻碍了更深部位混凝土渗透排水,故随距离表层深度的增加,水胶比变化变小。研究发现不同透水模板布对混凝土拌合物水胶比的改善效果存在差异;粉煤灰与减水剂掺量对透水模板使用效果也有一定影响。

To study the degree of water-binder ratio of concrete mixture reduced by the controlled permeability formwork,the variation of the water-binder ratio of the specimens of poured concrete mixture at the completion of drainage process from outside to inside was determined by means of the microwave oven method.The results indicate that the water-binder ratio of fresh concrete surface is reduced by 40%-50% by use of the controlled permeability formwork.The zone obviously reduced is within the range of 15 mm from the surface of the specimens.The filter cakes formed in the surface layer stops the concrete at deep part from draining.With the increase of the depth from the surface,the variation of water-binder ratio has small decrease.Different controlled permeability formwork liners have different improvement effects on the water-binder ratio of concrete mixture.Moreover,the fly-ash and water reducer have certain influences on the utilization effects of the controlled permeability formwork.