机制砂比表面积对混凝土性能的影响

Effect of specific surface area of manufactured sand on concrete behaviors

测定原河砂和原机制砂及其每个筛分区间砂的比表面积,验证砂比表面积测试仪器和计算方法的可靠性。配制了同批而不同比表面积的河砂和机制砂,设计了河砂混凝土和机制砂混凝土各3组,分别测试其坍落度和28d抗压强度。研究表明:对于相同级配河砂和机制砂,机制砂具有较大的比表面积;机制砂比表面积对混凝土拌合物的坍落度有显著影响,随着机制砂比表面积的增大,混凝土拌合物的坍落度减小;但机制砂比表面积对混凝土抗压强度的影响较小。建议给出机制砂比表面积控制指标,以体现机制砂的粒形和表面特征。

The specific surface areas of primary river sand and primary manufactured sand,and their sieve-sized region sands were measured,and the validity of the testing device and calculation method of sand specific surface area has been verified.Meanwhile,three groups of river sand concretes with the prepared river sands and three groups of manufactured sand concretes with the prepared manufactured sands were designed and mixed.Also,their slump and 28 day compressive strength were tested.The study results reveal that,for the river sand and manufactured sand with the same grading,the manufactured sand has larger specific surface area;that the specific surface area of manufactured sand has significant influ-ence on the slump of fresh concrete,which decreases with the increase of the specific surface area of manufactured sand;that the effect of the spe-cific surface area of manufactured sand on concrete compressive strength can be ignored.A control index of the specific surface area of manufac-tured sand should be advised in order to reflect the sand grain shape and surface characteristics.