等扩展度条件下骨料包裹砂浆层的影响因素

Influencing factors of aggregate mortar coating under the condition of equal slump-flow

水泥(砂)浆在混凝土中起胶凝和润滑的双重作用,其用量随着混凝土流动性要求的提高而增大,已有研究发现浆体过多会导致混凝土的体积稳定性问题,环保绿色程度低,但骨料级配等因素对混凝土中浆体合理用量的影响研究尚不多见。在粗骨料低空隙率前提下固定粗骨料用量不变,调整砂浆用量来控制混凝土扩展度,研究骨料级配和砂浆流变特性对粗骨料包裹砂浆层厚度及用量的影响。试验结果表明:粗骨料的几何平均粒径增大,包裹砂浆层厚度单调增加,包裹砂浆用量会呈现先减小后增大的趋势,存在最优几何平均粒径;扩展度要求越高,包裹砂浆层厚度及包裹砂浆用量越大,最优几何粒径越小;当粗骨料级配不变时,包裹砂浆层厚度和包裹砂浆用量均随砂浆屈服应力和塑性黏度的增大而增大。

Cement(sand)slurry in the concrete plays a dual role of gelation and lubrication,its dosage with concrete increase with the increase of fluidity requirements,the existing research shows that slurry can lead to volume stability of concrete problems and low degree of green environmental protection,but the aggregate gradation on the effect of reasonable dosage of slurry in the concrete research is still rare.The influence of coarse aggregate grading and mortar rheological features on the mortar coating thickness and mortar coating content of coarse aggregate is studied by adjusting the mortar content under the condition of equal slump-flow of concrete,which coarse aggregate has a fixed amount and relative less bulk voids.The mortar coating thickness increases monotonically with the increase of the geometric average particle size of coarse aggregate,mortar coating content shows a trend of first decreasing and then increasing,while a minimum mortar coating content occurs around the optimal geometric average particle size.It has also been proved that larger mortar coating thickness and mortar coating content are required with higher fluidity,but the smaller the optimal geometric mean particle size.The mortar coating thickness and mortar coating content increase with the increase of mortar yield stress and plastic viscosity under fixed particle size grading of coarse aggregate.