Preparation of High Strength Concrete from Vanadium Titanomagnetite Tailings

To comprehensively utilize the vanadium titanomagnetite tailings from Chengde area,the high strength concrete products were prepared using the tailings,cement clinker,blast furnace slag and gypsum as raw materials.The effects of fineness of tailings,dosage of tailings and water reducer on the compressive strength and fluidity of the samples were studied.The composition and structure of the samples were analyzed.The sulfate corrosion resistance and permeability resistance of the samples were tested.The results show that the compressive strength of cement mortar increases first and then decreases with the increase in tailings and water reducer dosage as well as decrease of tailings particle size.The fluidity of cement mortar increases with increasing the tailings fineness and water reducer dosage,and the early compressive strength of cement mortar decreases with the tailings addition.When the dosage of tailings,cement,blast furnace slag,gypsum and water reducer is respectively 60%,24%,12%,4% and 1%,and the tailings with-0.074 mm particle size account for 80.44% in amount,the 28-day compressive strength of concrete products reaches 90.2 MPa,which meets the requirements of C50~C80 grade in Technical Regulations for High Strength Concrete Structures.The results of XRD and SEM analysis show that after curing for 28 d,plate-like tobermorite,needle like ettringite and amorphous hydrated calcium silicate can be formed.Hydrated calcium silicate gel tightly cemented coarse aggregate,giving the sample high compressive strength,excellent sulfate resistance and permeability resistance.