无收缩自密实混凝土的制备及应用研究

针对某钢箱梁采用自密实混凝土工程的设计和施工特点,通过优化配合比设计,掺加聚羧酸高效减水剂、粉煤灰和矿粉获得高流态拌合物,引入内部复合膨胀源以补偿混凝土的自收缩和干燥收缩,制备出各项技术指标均达到工程设计要求的C40无收缩自密实混凝土。研究表明:复合膨胀剂掺量为12%的自密实混凝土其坍落扩展度可达715 mm,离析率仅为3.5%,密封条件下养护24 h以后仍有部分残余膨胀。通过采取合理的浇筑方法和控温措施,保证了工程的施工质量。

PREPARATION AND APPLICATION OF NON SHRINKAGE SELF COMPACTING CONCRETE

Aiming at the design and construction characteristics of self compacting concrete for a steel box girder engineering by optimizing the mix design,mixing with the polycarboxylate superplasticizer,fly ash and slag powder for high fluid mixture,adding internal composite expansion source to compensate for the autogenous and drying shrinkage,a C40 non shrinkage self compacting concrete was prepared,and its technical indexes could meet design requirements. Test research shows that self compacting concrete with compound expansion agent dosage being 12%,the slump expansion can be up to 715 mm,segregation rate is only 3. 5%; and there exist residual expansion until24 h later by the sealing condition curing. By taking reasonable pouring method and temperature control measures,the construction quality was ensured.