粗骨料对膏体泌水性及力学性能的影响

The effect of coarse aggregate on the bleeding and mechanical properties of cemented paste backfill

本文研究了骨料类型、粗骨料含量、质量浓度和灰砂比对膏体泌水率和力学性能的影响。用全尾砂代替河砂可以显著降低泌水率。尾矿的掺入使膏体的保水性提高了10%~20%,28 d后的无侧限抗压强度(UCS)提高了10%~30%。当粗骨料含量为60%时,泌水率对质量浓度的敏感性降低。可以看出,增加粗骨料含量是提高膏体流动性的一种方式。膏体的力学性能随粗骨料含量呈先增加后减小的趋势,当粗骨料含量为50%时,CPB强度最大可达6.5 MPa。膏体的力学性能随着质量浓度的增加而成比例增强,79%质量浓度的样品养护28 d后的UCS可达到7.9 MPa。灰砂比对力学性能影响较大,当灰砂比由1:6增加到1:4时,28 d后的UCS增加了54.4%,泌水率下降至1.4%。

An experimental study is conducted to investigate the effect of different aggregate types,coarse aggregate content,mass concentration,and cement-sand ratio on the bleeding rate and mechanical properties of cemented paste backfill(CPB).Replacing river sand with unclassified tailing can significantly reduce the bleeding rate.The addition of fine-grained tailing increased the water retention of the mixture by 10%−20% and the 28 d unconfined compressive strength(UCS)by 10%−30%.The sensitivity of the bleeding rate to mass concentration is reduced at 60% coarse aggregate content.Increasing the coarse aggregate content is a way to improve the high-concentration CPB fluidity.There is a coarse aggregate optimal content to maximize the sample strength.Test results show that when the coarse aggregate content is 50%,the maximum CPB strength can reach 6.5 MPa.As the mass concentration increases,the mechanical properties increase proportionally.After curing 28 d,the UCS of the 79%mass concentration sample reached 7.9 MPa.The cement-sand ratio had a greater effect on the mechanical properties,and when the cement-sand ratio increased from 1:6 to 1:4,the UCS at 28 d increased by 54.4%,and the bleeding rate decreased to 1.4%.