细骨料对SCC等效砂浆工作性能的影响

Effect of fine aggregate on workability of SCC equivalent mortar

为研究细骨料对自密实混凝土(self-compacting concrete,SCC)工作性能的影响,基于等效砂浆原理,研究河砂的细度、级配、0.60 mm以下粒径颗粒质量分数和砂率对SCC等效砂浆经时扩展度、含气量和表面质量的影响。研究结果表明:在砂率相同时,随河砂细度模数减小,SCC等效砂浆扩展度降低,扩展度经时下降值增加,含气量增大,且含气量的经时下降值变小;河砂中(0, 0.15] mm和(0.15, 0.30] mm粒径颗粒质量分数对等效砂浆的流动性有重要影响;随(0, 0.3] mm的粒径颗粒质量分数增加,等效砂浆黏聚性增强,流动性下降,扩展度经时下降值增加,含气量增加,模拟灌板上表面气泡平均直径和最大直径均减小;通过适当增加(降低)砂率可在一定程度克服河砂细度模数偏大(偏小)对流动性能的影响,但仅改变砂率不能有效提高等效砂浆稳定性。

In order to study the effect of fine aggregate on the workability of self-compacting concrete(SCC), the effects of fineness, gradation, particle content below 0.60 mm and sand ratio of river sand on the slump flow, air content and surface quality of SCC equivalent mortar were studied according to the principle of equivalent mortar(CEM). The results show that when the sand ratio is the same, with the decrease of river sand fineness modulus,the slump flow of CEM decreases, slump flow decreases obvionsly with the increase of time, the air content of mortar increases, and air content decreases with the increase of time. The mass fraction of(0, 0.15] mm and(0.15,0.30] mm particles in river sand has an important effect on the fluidity of CEM. With the increase of(0, 0.30] mm particle size fine particle content, the fluidity of CEM decreases, slump flow decreases obvionsly with the increase of time, the air content increases, and the average and the maximum diameters of bubbles on the surface of simulated irrigation plate decrease. The influence of river sand fineness modulus rather large or small on workability can be compensated for by increasing(decreasing) the sand rate appropriately, but the stability cannot be improved effectively.