FEATURES OF THE PROCESSES OF HYDRATION OF BINDING COMPOSITIONS USING WASTE OF EXPANDED PERLITE SAND

Abstract

The results of studying the processes of hydration of binder compositions obtained at different ratios of cement and waste of expanded perlite sand (from 5 to 10%), in a vortex jet mill, under different modes of mechanical and chemical activation - from one to three passes are presented. Comprehensive studies of hydration products by X-ray phase analysis and electron microscopy indicate that the use of highly dispersed wastes from the production of expanded perlite sand in binding compositions allows an increase in the content of hydrated neoplasms due to an increase in the degree of hydration of the main clinker phases, as well as due to the pozzolanic activity of these wastes. The contact zone between the hydrated compounds and the remnants of the grains of the original cements has a special effect on the formation of a high-strength structure of the cement stone. The structure formation of a cement stone depends on a number of factors, which can be influenced by various technological methods. When designing compositions of cement composites, it is necessary to ensure that hydration products in the created system are present along with low-basic calcium hydrosilicates and high-basic ones. Their ratio should be such that carbonization does not reduce the volume of the formed crystalline phase of the cement stone. The composition of the hydration products determines the level of supersaturation of the solution, the type and number of impurities soluble in water, the duration of the hydration process, etc. The chemistry of the reactions of the hydrated system changes accordingly. It is found that the intensity of the diffraction maxima, indicating the presence of highly basic calcium hydrosilicates in the compositions that underwent mechanical activation, increases by 18% in comparison with the ordinary PC. The strength characteristics of Portland cements, which have undergone mechanical activation, increase up to 15% compared to the original PC. The most rational binder composition is established in terms of composition (No. 6), mechanical activation and maximum compressive strength at 28 days of age – 69.1 MPa.