水灰比对混凝土毛细吸力的影响

Impact of Water-cement Ratio on the Capillary Suction in Concrete

毛细吸力为非饱和混凝土中驱动孔隙水-气流动、控制材料收缩开裂的重要作用力,其大小取决于混凝土细观孔隙结构,与混凝土的主要指标—水灰比密切相关。因此,基于相对湿度法,研发了一套非饱和混凝土毛细吸力的间接测试装置及方法,分析不同水灰比条件下毛细吸力的演化特征,并从孔隙尺度探析了毛细吸力演变的内在机制。结果表明,毛细吸力随水饱和度的减小呈非线性增长趋势,饱和度越低增长速率越大;水灰比减小会导致混凝土孔隙更加细密,从而使毛细吸力增大。

Capillary suction is an important force in unsaturated concrete, and it plays an important role in driving pore water-air flow and controlling the shrinkage and cracking characteristics of materials. The capillary suction depends on the microscopic pore structure of concrete, and it is related to the main indicator of concrete(water-cement ratio). Based on the relative humidity method, this paper developed a set of indirect measurement devices and methods for the capillary suction of unsaturated concrete, studied the evolution characteristics of capillary suction under different water-cement ratio conditions, and analyzed the internal mechanism of the evolution of capillary suction from the pore scale. The results show that the capillary suction increases nonlinearly with the decrease of water saturation. The lower the saturation, the greater the growth rate is;The decrease of the water-cement ratio will result in more dense concrete pores so as to increase the capillary suction.