细观尺度下混凝土的工作性能研究

Study on Working Performance of Concrete under Mesoscale

混凝土的工作性能是影响混凝土结构力学性能和耐久性的关键因素,研究了粗骨料体积率、粗骨料最大粒径、粗骨料级配分形维数对混凝土工作性能和水泥净浆包裹层厚度的影响,并探讨了混凝土的密实性、流动性。实验结果表明:不同粗骨料体积率、粗骨料最大粒径对水泥净浆包裹层厚度影响变化较大,不同粗骨料级配分形维数水泥净浆包裹层厚度相差不足1μm;控制新拌混凝土坍落度(180±20)mm时,粗骨料体积率、粗骨料级配分形维数与减水剂用量符合二次函数关系;粗骨料最大粒径与减水剂用量符合负相关关系;混凝土的密实性受粗骨料体积率的影响变化较明显,而受粗骨料最大粒径、粗骨料级配分形维数的影响变化不大。

The working performance of concrete is a major factor to affect the mechanical properties and durability of concrete structure.The effect of volume rate,maximum particle size and gradation fractal dimension of coarse aggregate on concrete working performance and cement paste wrap thickness were presented and the compactness and fluidity of concrete were discussed.The experimental results show that the influences of volume rate and maximum particle of coarse aggregate on cement paste wrap thickness are obvious.The changing value of cement paste wrap thickness is less than 1μm with the gradation fractal dimension of coarse aggregate.The coarse aggregate volume rate,coarse aggregate gradation fractal dimension and the amount of water reducing agent are in quadratic function relationship,and the volume rate and gradation fractal dimension of coarse aggregate are negative correlation with the amount of water reducing agent when the slump of fresh concrete is controlled to(180±20)mm.The influence of volume rate of coarse aggregate on compactness of concrete is obvious,and the influence of maximum particle and gradation fractal dimension of coarse aggregate are rarely.