减缩剂外涂对水泥基材料性能的影响

EFFECT OF COATING WITH SHRINKAGE REDUCING AGENTS ON THE PROPERTIES OF CEMENT-BASED MATERIALS

对比研究了减缩剂内掺和外涂对砂浆收缩、抗裂及力学性能的影响。结果表明:减缩剂外涂对砂浆试件有比较明显的减缩效果;减缩剂外涂的溶液浓度越高,减缩效果越好,适宜浓度为50%;相比内掺,减缩剂外涂可提高砂浆的抗折强度和抗压强度,提高砂浆抗裂性能,开裂面积下降了35%;减缩剂外涂增加水泥石中C–S–H凝胶及钙矾石的生成量,减少了水泥石中20～50nm毛细孔的数量。

The effect of mixing and coating with shrinkage reducing agents （SRA） on shrinkage, crack resistance and mechanical properties of mortar were comparatively investigated. The results show that coating with SRA can obviously reduce the shrinkage of the mortar. Coating with higher concentration solutions of SRA results in a greater shrinkage reducing ratio; the optimal concentration is 50%. Compared with mixing with SRA, coating with SRA enhances the flexural strength and compressive strength of the mortar. Coating with SRA reinforces the crack resistance of mortar, and the crack area is reduced by 35%.Coating with SRA can produce more C-S-H gel and ettringite;it also can reduce the number of capillaries between 20 and 50 nm.