Thermal conductivity of autoclaved aerated concrete under different temperature and humidity conditions

Abstract

The paper is aimed at measuring the thermal conductivity coefficients of autoclaved aerated concrete of average density (D450, D500 and D600) in a dry, water-saturated and frozen state. Thermal conductivity coefficients were determined using 100-mm cubes using standard methodology and measuring instrument ITP-MG “Zond” (Russia). It was found that the thermal conductivity of samples of the studied aerated concrete grades in the dry state is approximately 3.3–4 times lower than the thermal conductivity of samples in the water-saturated state and 3.5–4.2 times lower as compared to frozen water-saturated samples. The decrease in the average density of autoclaved aerated concrete from 618 kg/m3 to 434 kg/m3 led to a decrease in the thermal conductivity coefficient by 24.4%. The difference in the values of thermal conductivity coefficients of water-saturated samples and frozen watersaturated samples comprises 3.5–21.1% for the studied grades of autoclaved aerated concrete. Discrepancies between the values of thermal conductivity coefficients obtained by calculation and by experiment equal 7.6–36.5% for dry samples, 32.6–61.7% for water-saturated samples, and 38.6–88.6% for frozen water-saturated samples. Following the results of research into autoclaved aerated concrete grades of average density D450, D500 and D600, mathematical relations of thermal conductivity coefficients on their average density and temperature and humidity state were obtained.