原状尾矿砂粗颗粒较多且颗粒级配差,但以适当比例与细砂混合后可使级配得以改善,适合配制混凝土.试验表明,尾矿混合砂作为混凝土细集料使用,会增加新拌混凝土的需水量,但通过掺加高效减水剂,在保持用水量不变的情况下,使混凝土拌合料坍落度达到(180+20) mm,取得与天然中砂混凝土相同的施工性能.用7∶3尾矿细砂混合砂配置C30混凝土,28 d强度比天然中砂混凝土提高8.7％.尾矿混合砂配制的混凝土收缩值较天然中砂混凝土大.然而随着混合砂的级配和细度模数的改善,尾矿混合砂对混凝土的收缩性能影响逐渐减小.%In raw tailing sand it can be seen more coarse particles and poor particle size distribution, but it properly mixed with fine sand can make gradation improved and may be suitable for preparation of concrete. Test showed that tailing mixed sand, as concrete fine aggregate, may increase water demand of fresh concrete. But through introducing superplasticizer to maintain water demand consistent, slump of concrete mixing materials can reach (180+20) mm, which may obtain the same workability as concrete with natural medium sand. For C30 concrete prepared with tailing mixed sand that the mass ratio of tailing sand and fine sand was 7:3, the strength at 28 d can increase by 8.7% than that in natural medium sand concrete. The shrinkage of concrete prepared with tailing mixed sand may be more than that of natural medium sand concrete. However, with the improvement of gradation and fineness modulus of mixed sand, the effect of tailing mixed sand on contract properties of concrete may decrease gradually.
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