Influence of phosphorus tailings fineness on the hydration process and physical properties of ordinary Portland cement
Lilong Jiang, Jianqiu Li, Qinggang Zhang, Lin Yang, Jianxin Cao
Abstract
In order to promote the resource utilization of phosphorus tailings and reduce carbon emissions of building materials industry, the effects of four kinds of phosphorus tailings with different fineness on the water requirement of cement standard consistency, setting time, cement mortar consistency, mechanical strength and shrinkage properties were discussed in this paper. The concentration of some ions in the leach solution of phosphorus tailings with different fineness was determined. The effects of phosphorus tailings fineness on the hydration process and hydration products of cement were analyzed by heat of hydration, IMP, XRD and SEM. The results show that with the average particle size of phosphorus tailings increasing from 15 µm to 30 µm, the initial setting time of phosphorus tailings cement composite slurry is shortened by 120 min, the consistency of phosphorus tailings cement composite mortar is reduced by 4 mm, and the 28-day compressive strength is reduced by about 8 MPa. The ion concentrations of Ca 2+ , Mg 2+ and F - in the leaching solution increased with the decrease of the fineness of the phosphorus tailings, but the concentration of PO 4 3- ions changed little. Fine phosphorus tailings increase the total amount of heat release from hydration of cement slurry , and promote the emergence of new phase hydration products hydrotalcite minerals.