骨料粒径对自密实混凝土离析的影响研究

Study of Impacts by Aggregate Size on Segregation of Self-compaction Concrete

影响自密实混凝土离析的因素很多,其中骨料粒径大小是主要因素之一。文章在运用斯托克斯理论分析骨料离析的基础上,采用落球测浆体黏性系数的方法研究不同骨料颗粒粒径在同稠度浆体下的离析程度,以及混凝土拌和物达到同流动性时骨料粒径与浆体黏性的关系。结果表明,随着骨料颗粒粒径的增大,骨料离析程度呈迅速加大趋势;在满足相同流动性的条件下,随着骨料粒径的增大,为减小骨料离析,浆体的黏度应相应增大;当骨料粒径增大到一定程度后,浆体黏度的增长明显加快,为保证相同的流动性,浆体用量也需明显增加;浆体黏度随骨料粒径增大的增长过程线存在一个突变段,从骨料离析的角度分析,确定在该突变段前为骨料的合理粒径范围。

Segregation of self-compaction concrete involves couples of factors.The aggregate size is one of the major factors impacting the segregation.Based on the analysis on the aggregate segregation by application of Stokes theory, in the paper, the segregation of aggregate at different sizes under the same viscosity of the grout is studied by applying the falling ball to measure the viscosity coefficient of the grout.Meanwhile, relation between the aggregate size and the grout viscosity is analyzed while the concrete mixture reaches the same flu-idity.The study represents that the aggregate segregation rapidly increases with the aggregate size increment.In condition of satisfying the same fluidity, the viscosity of the grout shall be increased, with the aggregate size increment, to reduce the aggregate segregation.When the aggregate size increases at certain degree, the grout viscosity obviously grows fast.To assure the same fluidity, the grout consumption shall be increased inevitably.One prompt transition section is available in the increment histograph of the grout viscosity growth with the aggregate size increment.In view of the aggregate segregation, the aggregate sizes shall be reasonable ones before the prompt change on the histograph .