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本文研究了纤维增强水泥基复合材料(FRCCs)和超高性能混凝土(UHPCs),通过掺加氧化钙类膨胀剂降低干燥收缩开裂风险。测试了三种不同的金属纤维:平直钢纤维、镀铜弯钩纤维、镀铜直纤维。测试了容重、抗压强度、抗弯强度以及干燥收缩变形。通过压汞试验和电镜扫描测试了FRCC的微观结构。试件成型后24h进行80℃预处理。结果证明,氧化钙类膨胀剂会减小干燥收缩;并且与镀铜纤维复合使用可以增加抗弯强度。这种协同效应可以归因于在纤维和水泥浆的表面生成了锌酸钙,明显增加了纤维与水泥基体间的结合力。
In this paper, fiber reinforced cementitious composites (FRCCs) and ultrahigh performance concrete (UHPCs) were studied, and the risk of shrinkage cracking was reduced by adding calcium oxide expansive agent. Three different metal fibers were tested: flat steel fibers, copper plated hook fibers, copper plated straight fibers. Bulk density, compressive strength, flexural strength and dry shrinkage were tested. The microstructure of FRCC was tested by mercury intrusion and electron microscopy. The samples were pretreated at 80 ℃ 24h after forming. The results show that calcium oxide expansive agent will reduce the drying shrinkage; and with the copper fiber composite can increase the bending strength. This synergistic effect can be attributed to the formation of calcium zincate on the surface of the fibers and grout, which significantly increases the bond between the fibers and the cementitious substrate.