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为了解纤维对水泥砂浆塑性收缩开裂的影响机理,采用改进过的滤纸法探究了不同聚丙烯纤维掺量(0.2%、0.4%、0.6%、0.8%、1%,质量分数)、不同纤维长度(3mm、6mm、9mm、12mm)对水泥净浆失水率的影响。研究结果表明,在纤维长度3mm、6mm、9mm时,随着掺量的增加,水泥浆有着基本的失水规律即先增大再减小再稍增大,并总是存在着失水率最大的纤维掺量(0.6%～0.8%),且最大失水掺量随着纤维长度的不同而不同。而在长度12mm时却出现了反常,在0.6%处有着最小失水率。3mm、12mm纤维的保水性较6mm、9mm强,3mm、12mm的失水率低于空白样,6mm、9mm部分掺量有保水性,这与纤维的表面效应、堵孔效应、界面效应相关。
In order to understand the influence mechanism of fiber on the plastic shrinkage and cracking of cement mortar, the influences of different polypropylene fiber content (0.2%, 0.4%, 0.6%, 0.8%, 1%, mass fraction) (3mm, 6mm, 9mm, 12mm) on the water loss of cement paste. The results show that at the fiber length of 3mm, 6mm, 9mm, with the increase of the dosage, the basic law of water loss of cement slurry increases first, then decreases then increases slightly, and there is always the largest water loss rate Of the fiber content (0.6% ~ 0.8%), and the maximum amount of water loss varies with the fiber length. In the length of 12mm, however, there was an anomaly, with a minimum rate of water loss at 0.6%. The water retention of 3mm and 12mm fibers is 6mm, 9mm, 3mm and 12mm, respectively. The water loss of 6mm and 9mm is water retention, which is related to the surface effect, plugging effect and interface effect.