The Increase of Hydration Activity of Portland Cement by Additives of Crystalline Hydrates

Abstract

The article presents the results of a study of the effect of synthesized microdisperse additives of crystalline hydrates based on calcium sulfoaluminates on the properties of cement stone. The effectiveness of the use of a rotary pulsation apparatus (RPA) to obtain microdispersed additives is identified. The possibility of accelerating the hardening of cement stone by entering microdispersed additives into its composition is shown. It has been established that in the presence of microdispersed additives of crystalline hydrates in the cement stone, the phase composition of hydrate tumors changes, the amount of calcium hydrosilicates and ettringite increases, the porosity decreases and the strength of the cement stone increases. This provision is confirmed by the increase in the degree of cement hydration, the amount of bound water in all periods of hardening of the stone. It is proposed to use microdisperse additives, which play the role of primers for the crystallization of ettringite and calcium hydrosilicates, to increase the strength of cement stone in the early stages of hardening.

Morphology of ettringite crystal of sulfoferrite clinker

“…The samples were analysed by various physicochemical methods. Amount of ferruginous ettringite formed was determined by the chemical method [6].…”

“…Ettringite is the main crystalline hydrate involved in expansion of the cement stone [4][5]. However, as shown in [6], ettringite crystal hydrates have different morphologies, and, therefore, not all crystals cause the effect of system expansion. The study of ettringite morphology is important for describing the hardening of expanding cements [7][8][9][10][11][12][13].…”

Behavior of Basalt Fibers in an Alkaline Environment

“…Researchers have established during hydration the effect of the cement clinker of the basicity of calcium sulfoferrites on the concentration of CaO [21].…”