The increase of heat-insulating properties of foam concrete by introducing mineral additives

Abstract

Foam concrete is used as an effective heat-insulating material. This material becomes hard in the natural conditions and has a significant shrinkage that leads to deterioration of the porous structure and as a result of it, increases the thermal conductivity of the material. One of the actual solutions to this problem is the use of mineral modifying additives that regulate the porous structure of foam concrete. A number of such additives were used in this work: wollastonite and diopside (industrial wastes) with natural dispersion and with specific surface of 300 and 600 m2/kg. Besides that, instead of fly ash in foamed concrete the use of perlite microspheres was researched in this work. The proposed new compositions for the production of foam concrete products with mineral additives provide the reduction of the thermal conductivity coefficient to 41-43% in comparison with the control. When the fly ash aggregate is completely replaced by perlite microspheres, the coefficient of thermal conductivity is reduced to the level of 0.062 W/(m°C), but the advanced price of this filler does not allow to recommend it for the mass use yet. Thus, with the introduction of modifying mineral additives, a significant improvement in the stability of the foam concrete structure is achieved, which contributes to the thermal conductivity reduction of the material and to the achievement of the technical and economic effect.