Technology and Physico-Mechanical Properties of Claydite Foam Concrete for Monolithic and Prefabricated Construction

Abstract

Theoretical and experimental investigations have resulted in obtaining an effective insulating and structural material (claydite foam concrete) that is not subjected to slump and shrinkage in the range of main grades used in construction in terms of average density D300–D700, characterized by 5–31 % greater strength and 8–27 % elasticity modulus, as well as a higher (£30.7 %) level of vapor permeability and moisture return (by 17.4–46.7 %) with lower values (by 10.0–83.2 %) of water absorption, sorption moisture and thermal conductivity in comparison with aerated concrete of autoclave hardening and foam concrete of equal density. A three-stage technology has been developed for preparing claydite foam concrete. At the first stage cement dough is prepared and if it is necessary an optimum amount of hardening accelerator (1 % CaCl2 from cement mass) and additives condensing cement stone structure (1 % Al2SO4 from cement mass ) are introduced into it, they prevent slump of a binder (foam concrete) during the subsequent hardening, and in combination with 0.5 % from cement mass “Hydroxypropylmethylcellulose УСК-200 TT” – and shrinkage of foam and claydite foam concrete during the subsequent drying. At the second stage, the binder is aerated while introducing protein-based foam agent (Laston) into the cement dough in an optimal amount (depending on the given density) 0.5–1.3 % from the cement mass; and at the third stage, expanded clay gravel is introduced into prepared foam concrete mixture (in rational amount of approximately 0.7–0.8 m3 per 1 m3 of claydite foam concrete) with continuous mixing for 60–90 seconds. Methodologies for calculation of foamand claydite foam concrete compositions have been developed; molding modes of expanded clay foam concrete with high degree of homogeneity (variation coefficient of density and strength uk £ 6.2 % in the process of manufacturing molding with layer height up to 1500 mm) have been justified that confirms efficiency of the proposed technology.