Study On The Preparation Of Iron Tailings Powder Composite Admixture And Concrete Properties

Levigating iron tailings as concrete admixture has become a new way of iron tailings utilization. Consider that the low chemical activity, the impact on the physical properties and durability performance of concrete is not clear, the research on preparation of iron tailings powder composite admixture(TPCA) by iron tailings as the base material,the phosphorus slag,limestone as the supplementary materials and its concrete properties was carried out.The relationship between the iron tailings powder under the different grinding time and 28 d compressive activity index has been studied by least square method. Based on the introduction of effective grinding time Q(min),to improve the technology and reduce the energy consumption of technology activity of TPCA was studied through the fineness,ratio of raw materials,the combination of grinding process and grinding agent four aspects.Through different test means such as laser granularity analyzer,RRB(Rosin-Rammler-Bennett) equation fitting,the influences of grinding order and grinding time on the preparation and properties of TPCA with cascade-grinding were studied.The results shows that the activity of iron tailings with the increase of grinding time,has the characteristics of the growth is not obvious.The physical and mechanical properties of TPCA made in cascade grinding is superior to the mixed grinding and separate grinding;grinding phosphorus slag which is hard but high activity first step should improve the fineness of TPCA and its overall activity index; Reasonable combination of grinding time is better for improving the uniformity of TPCA particle and the mortar liquidity;Amount of grinding aid agent triethanolamine is helpful to improve the fineness of TPCA and the energy consumption reduced.Cascade utilization of grinding process of TPCA flow ratio is 100%,the 28 d compressive activity index was 82% while Q=42.5min,the ratio of raw material of iron tailings,phosphorus slag,limestone is 6:3:1,triethanolamine content is 0.04%.C20~C55 high performance concrete was designed and made by using TPCA. The strength and durability of concrete with TPCA was also compared with concrete with ?grade fly ash and S95 slag powder as composite admixture. The results show that high performance concrete of C20~C55 strength grade can be prepared by using 30% TPCA and the influence of TPCA on concrete strength is equivalent with ?grade fly ash, while lower than S95 slag powder.The carbonization resistance,chloride ion penetration resistance and frost resistance of concrete with 20%~40% TPCA is slightly lower than concrete with admixture consisted of ?grade fly ash and S95 slag powder,however,the influence isn't significant.The hydration mechanism of iron tail and TPCA in the hydration and hardening process of composite binder was comparative studied through the hydration heat,the strength of paste,X-ray diffraction(XRD) and scanning electron microscopy(SEM).The results show that iron tailings powder itself has a weak pozzolanic activity, while the TPCA pozzolanic activity was improved significantly compared with iron tailings powder, and the pozzolanic activity was mainly reflected at the later stage of hydration.