基于材料组成及约束的砂浆减裂方法

Mortar Cracking Reduction Method Based on Material Composition and Constraints

摘要:

本文依据砂浆开裂的预测方程，基于材料组成及约束确定了砂浆“减裂新方法”，并从理论与试验层面验证了减裂新方法在不同环境下的有效性；为提高减裂新方法的实用价值，研究了在木模四周及底板抹黄油润滑脂，在木模底板铺塑料膜以及在木模底板塑料膜间铺设3 mm厚缓凝型净浆等减小砂浆构件约束的方式及其减裂效果。结果表明：减小水胶比、减小约束度、增大砂灰比的减裂新方法可明显提升砂浆的抗裂性能；在木模底板塑料膜间铺设3 mm缓凝型净浆的方式，可使砂浆构件的约束度降低66%，减裂效果明显。

Abstract:

Based on the prediction equation for mortar cracking， a new crack-reduction method for mortar by considering material composition and constraints was proposed. The effectiveness of this new method under different environmental conditions was validated both theoretically and experimentally. To enhance the practical value of the crack-reduction method， various constraint-reducing techniques were investigated， including applying grease lubricant on the sides and base of wooden molds， laying plastic film on the base of wooden molds， and placing a 3 mm-thick layer of retarding-type neat paste between the plastic films on the mold base. The effects of these methods on crack reduction were also evaluated. The results demonstrate that the new crack-reduction method by reducing the water-to-binder ratio， decreasing constraint intensity， and increasing the sand-to-cement ratio significantly improves the crack resistance of mortar. Among the constraint-reducing techniques， placing a 3 mm-thick layer of retarding-type neat paste between the plastic films on the mold base reduced the constraint intensity of mortar specimens by 66%， showing a notable crack-reduction effect.