FEATURES OF STRUCTURE FORMATION OF COMPOSITE GYPSUM BINDERS WITH A COMPLEX OF MINERAL AND ORGANIC ADDITIVES

Abstract

For the dynamically developing low-rise construction industry, there is a growing need to expand the range of building materials, including fast-hardening types of binders. Composite gypsum binders are effective, including a carefully selected mixture of gypsum binder, Portland cement and active mineral additives. Materials based on them harden quickly and gain the required strength. An increase in the performance characteristics of this type of binders is achieved when mineral and chemical additives are used in a complex. This helps to regulate the processes of their structure formation and hardening, depending on the activity of the components, changes in water demand, as well as the peptizing, adsorption and air-entrapping effects of chemical additives. The article presents the results of a study of the effect of chemical additives – superplasticizers MARF SU 84, MELFLUX 5581 F and the retarder of the setting time of PlastRetard PE – on the physico-mechanical properties of a hardened composite gypsum binder, including gypsum binder, Portland cement and a complex of mineral components (fine quartz sand, metacaolin VMK-45, limestone dust). The issues of management of its structuring processes are considered. It has been established that finely dispersed mineral additives from quartz sand, VMK-45 metacaolin and limestone dust are effective components for the production of composite gypsum binders. The developed complex chemical additives MARFSU 84 (0.1%)+PlastRetard PE (0.08%) and MELFLUX 5581 F (0.1%)+ PlastRetard PE (0.08%) can significantly slow down the beginning and end of setting of gypsum cement mixtures up to 45...48 min and increase the compressive strength of the hardened KGV after 28 days by 1.5 ...1.6 times (up to 18.3...20.4 MPa), respectively.