Factors that influence deformation properties of heavy concretes containing alkali-activated cements

Abstract

Introduction. In the process of structurization, development of properties, and operation concrete structural elements undergo various linear and volumetric changes, triggered by material deformations. Therefore, it is the deformation properties that are taken into account when design documentation is drafted at the stage of making design solutions with regard for the influence of this factor on physical and mechanical characteristics of a final reinforced concrete product or a monolithic structure as a whole. Of particular interest are causes of deformations that emerge during the curing of concrete composites. Materials and methods. Deformation properties of heavy concretes, having binders that contain alkaline mixes, were studied in accordance with GOST 24452–80 Concrete. Methods for determining prism strength, modulus of elasticity and Poisson’s ratio, and GOST 17624–87 Concrete. Ultrasonic method for determining strength. Results. The paper presents studies focused on deformation-triggered changes. The results showed that the development of deformations was observed during the hardening of concrete prisms, and shrinkage deformations were characteristic of concrete compositions that contained the micro-filler made of opoka malmstone, while compositions, having a dune powder additive, demonstrated slight expansion. Conclusions. Deformations of concrete, containing such binders as mineral powders of aluminosilicate origin and activated by an alkaline solution, were studied to identify the nature of ongoing deformations. Hence, in case of the surface contact between concrete and the environment, shrinkage deformations are caused by moisture, carbonization and some contraction processes that manifest their characteristic features. In the absence of contact with the gas-air medium, deformations caused by contraction processes are clearly manifested. It is noteworthy that numerical values of shrinkage deformations are below the standard values for Portland cement heavy concrete.