外加剂对机制砂清水混凝土性能的影响

Influence of admixtures on manufactured sand fair-faced concrete properties

根据遂广遂西高速公路中清水混凝土的设计与施工要求,优化配合比设计,通过正交试验和极差分析,研究了引气剂、增黏剂和减缩剂对机制砂清水混凝土性能的影响,确定其最佳掺量,并对混凝土的体积稳定性、耐久性和微观机理进行分析。结果表明:掺入0.2‰引气剂、1.0%减缩剂和2.0‰增黏剂,制备的混凝土黏聚性、匀质性好,色泽均匀、表观质量优异,微结构致密,28 d干燥收缩率<250×10^(-6),早期抗裂等级达IV,耐久性好,并在依托工程中成功应用。

According to the design and construction requirements of bridge fair-faced concrete in Suiguang Suixi highway,the mix proportion was optimized,and the influence of air-entraining agent,viscosity increaser and shrinkage-reducing agent on concrete performance was studied by orthogonal experiment and range analysis,determining their optimal dosage,while volume stability,durability and microscopic mechanism were analyzed. The results showconcrete prepared by adding 0.2‰ air-entraining agent,1.0%shrinkage-reducing agent and 2.0‰ viscosity increaser,has good cohesiveness and uniformity,and uniform colour and excellent apparent quality,and dense microstructure,and its 28 d dry shrinkage rate is below250 × 10^-6,while early crack resistance grade is IVand durability is good. The concrete prepared has been successfully applicated in practical project.