尾矿微粉-粉煤灰复合掺合料试验研究与机理分析

Experimental study and mechanism analysis of tailings micropowder-fly ash composite admixture

为使尾矿资源化利用更加高效、合理,本研究考察了尾矿微粉微粉掺量和细度对水泥胶砂强度的影响。在此基础上,引入粉煤灰与尾矿微粉形成复合掺合料,探究复合掺合料掺量,复合掺合料中尾矿微粉与粉煤灰的比例对水泥胶砂强度的影响。结果显示:在微粉单掺10%以内时,对胶砂强度影响不大,强度基本保持在对比胶砂的90%以上。当掺量大于10%后,强度明显降低,掺量达到30%以上时,试验胶砂各龄期强度降至对比胶砂的70%以下。将粉磨20min的尾矿微粉与粉煤灰按比例混合制成复合掺合料。经试验与微观分析发现,尾矿微粉与粉煤灰比例从1:0变为2:1过程中,强度出现了明显上升,28d龄期胶砂试块C-S-H和钙矾石含量明显增多,Ca(OH)2含量减少。因此,尾矿微粉与粉煤灰的比例应保持在2:1或以下为宜。

In order to make the resource utilization of tailings more reasonable and efficient,this study investigated the influence of the content and fineness of tailings micropowder on the strength of cement mortar.On this basis,fly ash is introduced and combined with tailings powder to form a composite admixture.The effects of the content of compound admixture and the ratio of tailings micropowder to fly ash in compound admixture on the strength of cement mortar were investigated.The results show that when the micro-powder is mixed within 10%,it has little effect on the strength of mortar.At this time,the strength of cement mortar is basically maintained at more than 90%of the contrast cement sand.When the content is more than 10%,the strength begins to decrease obviously.When the content reaches more than 30%,the strength of the test mortar at each age decreases to less than 70%of that of the control mortar.Grinding tailings micropowder for 20 min,and mixing it with fly ash in proportion to prepare composite admixture.Through experiments and microscopic analysis,it was found that the strength increased obviously when the ratio of tailings powder to fly ash changed from 1:0 to 2:1.At the age of 28 d,the contents of C-S-H and ettringite in mortar samples increased obviously,while the content of Ca(OH)2 decreased.Therefore,the ratio of tailings micro-powder to fly ash should be kept at 2:1 or below.