膨润土和玄武岩纤维改性水泥砂浆的防渗抗裂性能

Impermeability and Crack Resistance of Bentonite and Basalt Fiber Modified Cement Mortar

为解决当前水泥砂浆防渗抗裂能力较差的问题,本文研制了一种新型水泥砂浆材料。通过制备不同掺量下的膨润土和玄武岩纤维改性水泥砂浆,测试其抗渗性能和抗裂性能,并对水泥砂浆的微观机理进行分析。结果表明,在水泥砂浆中加入膨润土、玄武岩纤维后,可增强其抗渗性能和抗裂性能。当混掺4%(质量分数)膨润土和0.4%(质量分数)玄武岩纤维时,水泥砂浆抗渗压力值最大,较未掺膨润土和玄武岩纤维时可提高61.11%,抗渗等级为P8级;同时,掺入膨润土和玄武岩纤维后的水泥砂浆裂缝降低系数可以达80%以上,抗裂等级属于Ⅰ级,裂缝的特征表现为“少、细、短”。混掺膨润土和玄武岩纤维使水泥砂浆的密实度增加,裂缝和孔洞减少。膨润土和玄武岩纤维的掺入未改变水泥砂浆的水化产物种类,但使氢氧化钙的结晶度降低,促使水化硅酸钙凝胶生成。

In order to improve the impermeability and crack resistance ability of cement mortar, a new type of cement mortar material was developed in this paper. Through the preparation of bentonite and basalt fiber modified cement mortar with different content, the impermeability and crack resistance were tested, and the micro mechanism of cement mortar was analyzed. The results show that the addition of bentonite and basalt fiber enhances the impermeability and crack resistance of cement mortar. When 4%(mass fraction) bentonite and 0.4%(mass fraction) basalt fiber are mixed, the impermeability pressure of cement mortar is the highest, which increases by 61.11% compared with the group without bentonite and basalt fiber, and the impermeability grade is P8. At the same time, the crack reduction factor of cement mortar mixed with bentonite and basalt fiber reaches more than 80%, the crack resistance grade belongs to grade I, and the characteristics of cracks are "few, fine and short". Mixing bentonite and basalt fiber improves the compactness of cement mortar and reduces cracks and holes. The addition of bentonite and basalt fiber does not change the type of hydration products of cement mortar, but reduces the crystallinity of calcium hydroxide and promotes the formation of calcium silicate hydrate gel.