人工砂中石粉含量对水泥砂浆性能的影响

Effects of stone powder of artificial sand on properties cement mortar

使用不同石粉含量(5%~28%)的人工砂制备了水泥砂浆,试验研究了石粉含量对水泥砂浆流动性、凝结时间、抗折、抗压强度、干缩及抗渗等性能的影响。结果表明:随着人工砂中石粉含量从5%增加至28%,砂浆流动度、抗折、抗压强度等性能均呈先增后降的规律,凝结时间总体上随其增加而缩短,砂浆120 d干缩率则是先增大后减小,而砂浆抗渗性受石粉含量的影响较小。其原因在于水泥砂浆中的石粉能够起到填充效应,完善骨料级配,增大(过量则减小)密实度,还能减小砂浆体系孔结构的平均半径,增大孔内液体收缩力。此外,石粉中的微颗粒(小于80μm)不仅能增大砂浆体系的需水量,还能充当辅助胶凝材料,降低砂浆体系水胶比,自身还能部分参与浆体水化反应。

Cement mortar is prepared by artificial sand with different contents of stone powder（5%-28%）.The effects of content of stone powder on fluidity,setting time,flexural strength,compressive strength,dry shrinkage and impermeability performance of cement mortar are studied.Results show that with the increase of the content of stone powder from 5% to 28%,mortar fluidity,compressive strength,flexural strength all are presented increase first and then decrease trend.The setting time decreases with the increase of content of stone powder,but 120 d mortar dry-shrinkage ratio increase first and then decrease with its incresase.Impermeability performanceare less affected by the content of stone powder.The reason is that the stone powder in the cement mortar have filling effect.It can improve aggregate gradation,increase（when excessive,reduced）density.It can also reduce the average radius of the pore structure of mortar system,and increase the liquid contractility in it.The specific surface area of stone powder can also increase the water demand of mortar system.In addition,the micro particles（less than 80 μm）in the stone powder can act as supplementary cementious materialto reduce the water-binder ratio of mortar system,and part of it can also participate in the hydration reaction.