硅灰对LC15级全轻混凝土工作性影响研究

The Effecting Study of Silica Fume on Workability of LC15 Grade All Lightweight Concrete

采用广安地区生产的轻质骨料配制了LC15级全轻骨料混凝土,分析了硅灰对轻骨料混凝土工作性、干表观密度、抗压强度的影响。并通过研究硅灰对轻骨料混凝土浆体流变性能的影响解释了其宏观性能的变化。试验结果表明:在10%掺量范围内,硅灰降低了轻骨料混凝土的工作性,提高了其干表观密度及抗压强度。掺入硅灰的轻骨料混凝土浆体可以用修正的宾汉姆模型进行拟合。拟合结果表明:轻骨料混凝土的工作性下降是由于其浆体屈服应力及塑性黏度的提高,同时塑性黏度提高亦增加了浆体与骨料的黏结能力,从而提高了轻骨料混凝土的力学性能。

LC15 lightweight aggregate concrete was prepared by using the lightweight aggregates produced in Guang’an area,and the effect of silica fume on the workability,drying density and compressive strength of the lightweight concrete was studied.Furthermore,the explanations for macro properties changes from the rheological properties of pastes were put forward.The experimental results show that the addition of silica fume within the range of 10% decreases the workability of lightweight concrete but increases the drying density and compressive strength of that.The rheological parameters of pastes with silica fume can be obtained from modified Bingham model.The results from rheological parameters show that the decreasing workability is attributed to the increasing yield stress and plastic viscosity of pastes.Meanwhile,the adhesive properties is also improved due to the increasing plastic viscosity of pastes,which is also responsible for the increasing mechanical properties of lightweight concrete.