高性能混凝土早期抗裂试验研究

TESTING RESEARCH ON RESIST-CRACKING OF HIGH PERFORMANCE CONCRETE AT EARLY AGE

为减少高性能混凝土早期收缩开裂,利用非接触测量技术,通过测量高性能混凝土早期自生及单面干燥条件下的收缩,研究减缩剂、聚丙烯纤维及不同减水剂对高性能混凝土早期自生及干燥收缩的影响。在此基础上,利用板式混凝土早期收缩开裂试验架,对高性能混凝土进行约束试验,研究减缩剂、减缩剂+聚丙烯纤维等对高性能混凝土早期抗裂的作用。结果表明:减缩剂、聚丙烯纤维、减缩剂+聚丙烯纤维及聚羧酸高效减水剂均有减缩抗裂效果。其作用大小为:减缩剂+聚羧酸高效减水剂>减缩剂+FDN高效减水剂>减缩剂+聚丙烯纤维>聚丙烯纤维。

In order to induce cracking of high performance concrete （HPC） at early age, a non-contacting measurement technology was adopted in this article. Autogenous shrinkage and shrinkage with single side in dry environment of HPC were tested by using the measure technology. The effects of shrinkage reducing agent （SRA）, polypropylene fiber（PPF）and different water reducing agents on autogenous shrinkage and shrinkage of HPC with single side in dry environment were discussed. Based on the results of shrinkage test, the slab specimens of HPC were restrained by utilizing the steel frame and the effects of SRA, SRA ＋ PPF etc. on resist-cracking of HPC in dry environment were discussed. The whole anti- cracking effects of these ways, which can both reduce autogenous shrinkage and cracking of HPC, are obtained from high to low： SRA＋ polycarboxylate high performance water reducing agent, SRA＋ FDN high performance water reducing agent, SRA ＋PPF, and PPF.