机制砂及其砂浆最小空隙率的试验研究

Experimental study on minimum void ratio of machine-made sand and mortar

通过对外购机制砂、自制机制砂以及预拌砂浆三种体系孔隙率的研究,发现细骨料级配符合fuller曲线比符合国标Ⅱ区中砂更能获得较低的孔隙率;在机制砂外观形貌不同时,相同的颗粒分布测得的填充率不同,表面粗糙的机制砂可以获得较高的填充率;在使用粗砂的砂浆混凝土中,粗颗粒的存在可以提高填充率,过多的细颗粒则会降低填充率,在不使用粗砂时,也有相似的结论;预拌砂浆中的细物料会改变体系的填充率,整体上讲,砂浆的孔隙率比机制砂的孔隙率高约3%,而干混砂浆的物料级配符合fuller曲线更具有优势。

By researching on porosity of three systems of foreign purchase mechanism sand, self-control mechanism sand and ready-mixed mortar, it is found that fine aggregate gradation in fuller curve than that conforms to the national standard Ⅱ area of medi- um sand can get lower porosity; and with difference mechanism sand morphology appearance, the filling rate of same partical size distri- bution is different, and the machine-made sand with coarse surface can obtain a higher filling rate; In the concrete mortar used coarse sand, the existence of coarse grain can increase the filling rate, and overdose of fine grain has counter-effect, and it has similar conclu- sion when not use coarse sand. The fine material in ready-mixed mortar system can change the filling rate, and overall, the void ratio of mortar is 3% higher than that of mechanism sand porosity, and the material grading that in line with fuller curve has more advantage.