粉煤灰替代矿渣微粉作为胶凝材料的早期强度激发研究

Study on activation of early strength for slag powder adding fly ash as a new cementitious material

粉煤灰是热电厂排放的火山灰粉体废弃物,具有潜在活性,通常用于水泥掺合料。但掺加粉煤灰的胶凝材料会降低早期强度,导致粉煤灰掺加量受到很大限制。针对金川矿山充填采用棒磨砂充填料和水泥胶凝材料,开展了粉煤灰和矿渣微粉等复合胶凝材料早期强度激发剂试验。试验设计料浆浓度为78%,胶砂比为1∶4。首先,采用生石灰、脱硫灰渣、芒硝、亚硫酸钠等复合激发剂的正交设计,进行粉煤灰和矿渣微粉早期激发作用的材料配比试验;然后,采用DPS数据处理软件,建立充填体强度与激发剂材料掺量的回归方程,并通过优化决策确定激发剂最优配比。结果显示,由质量分数分别为5%的生石灰、17.5%的脱硫灰渣、3%的芒硝、1.5%的亚硫酸钠构成的复合激发剂,胶结充填体3d强度达到2.19 MPa,大于金川矿山设计的1.5 MPa强度要求。当采用20%的粉煤灰替代矿渣微粉时,胶结充填体3d强度达到1.504 MPa,也满足金川矿山对充填体强度的要求,且28d沉缩率仅为8.68%。由此可见,充分利用粉煤灰和矿渣微粉开发充填胶凝材料,不仅可以降低充填成本,提高采矿经济效益,而且还能够保护环境,实现绿色开采。

Fly ash is active potentially which is volcanic ash powder waste exhausted by thermal power plant.It is used as admixture in cement.But the cementitious material including fly ash decreased its early strength,so the fly ash mixing amount must be limited.A test is designed to activate the early strength for the new cementitious materials mixed by fly ash and slag,according to the rod milling sand aggregate and cement as cementitious material in Jinchuan mining.The density of slurry in the experiment is 78%,the cement-sand ratio is 1∶4.Firstly the test for the mixture ratio of materials is designed which activated the early strength of fly ash and slag powder using an orthogonal test including quicklime,desulfurization ash,mirabilite,sodium sulfite and other compound activators.Then regression equation between the strength of backfill body and activator materials mixing amount based on DPS software is established.The optimal proportion is established by optimization decision.The 3duniaxial compressive strength of filling body whose compound activator is composed by 5% quicklime,17.5% desulfurization ash,3%mirabilite,1.5% sodium sulfite is 2.19 MPa,which is bigger than the design strength（1.5 MPa）for Jinchuan mining.The 3dstrength of filling body is 1.504 MPa when slag powder is replaced by 20% fly ash,which meets the strength requirements of backfill body in Jinchuan mining.Therefore,development of cementitious material with making full use of fly ash and slag powder not only decreases filling cost and increases mining economic benefit,but also protects environment and achieves green mining.