Hardening Peculiarities of Blended Cements with Silicate Admixtures of Different Origin

The influence of silicate-containing materials of different origin on cement properties was investigated. Selected mineral silicate-containing admixtures have significant differences in the chemical and mineralogical composition.It was found that the cement hardening rate is affected by the condition of silicate and aluminate admixture component. The presence of amorphous silica or glass in the admixture leads to a slow strength gain of cements in early hardening periods, and the introduction of heat-treated materials with high thermoactivated aluminate content into cements allows to significantly accelerate the process.Using natural silicate-containing materials (flask, tripoli, zeolite) in the production of blended cements is limited by high values of normal cement density that indirectly affects the ultimate cement strength.The study of the processes taking place in early hydration stages allows to evaluate the admixture effectiveness and predict cement properties. Kinetics of changes in pH of an aqueous solution of cements can be used as a criterion.Thus, introducing several admixtures that would have a positive impact on the sample strength in early hardening periods and grade cement strength is advisable in selecting compositions of blended cements. It was proposed to use rock dump processing waste of coal mining as a mineral admixture in cement production