UHPC浆体的工作性和流变性与颗粒膜层厚度的关系

建立超高性能混凝土(UHPC)浆体的工作性和流变性之间的关系可从理论上研究其工作性变化规律。本文以颗粒膜层厚度为UHPC浆体的工作性的综合衡量指标,设计了正交试验,研究水胶比、超细粉煤灰替代率和硅灰掺量对UHPC浆体的工作性与流变性的影响。根据流动度和流变性测试结果,分析了水胶比和超细粉煤灰替代率的共同作用对UHPC浆体的工作性与流变性的影响,探究了UHPC的净浆与砂浆的工作性关系,基于浆膜层厚度给出了UHPC砂浆的工作性与流变性的关系式。研究结果表明:水胶比是UHPC浆体的工作性与流变性的最主要影响因素,水胶比、超细粉煤灰替代率和硅灰掺量提高均造成UHPC浆体的颗粒表面膜层厚度增大;水胶比和超细粉煤灰替代率的共同作用下,UHPC浆体的流动度和黏度系数具有相关性。

Relationship of Workability and Rheological Properties of UHPC Slurry and Film Thickness of Particles

The varying principle of workability of ultra-high performance concrete (UHPC) slurry can be theoretically studied with the relationship of its workability and rheological properties. An orthogonal test was designed to study the effects of water-binder ratio (W/B), substituted rate of cement by superfine fly ash and silica fume content on the workability and rheological properties of UHPC slurry. The film thickness on particles was taken as the index to evaluate workability and rheological properties of UHPC slurry. According to the test results of workability and rheological properties, the combined effect of W/B and substituted rate of cement by superfine fly ash on the workability and rheological properties of UHPC slurry were analyzed, and the relationship of workability between paste and mortar was investigated. Based on the film thickness on particles, the relationship between the workability and rheological properties of UHPC mortar was established. The results show that W/B is the most important factor, and as W/B, substituted rate of cement by superfine fly ash and silica fume content substituted increase, the film thickness on particles increases. Flow spread and consistency coefficient of UHPC slurry are correlated due to the combined effect of W/B and substituted rate of cement by superfine fly ash.