Effect of Expanded Perlite in the Brick Mixture on the Physicochemical and Thermal Properties of the Final Products

Abstract

Thermal insulation is an efficient solution to reduce energy consumption. A great way to reduce the energy consumption of a building is the use of thermal insulation bricks which provide fire resistance and a remarkable thermal capacity, which make them a unique building material for energy efficient buildings. In this study, a fine grain size of expanded perlite was used as additive in a ceramic mass. Brick solid samples were produced from three different mixtures with different ratios of expanded perlite in the mass. From every mixture, three different vacuum values were used. The constructed brick samples were dried and fired in the same conditions and their properties such as bending strength, density and thermal insulation were gathered for six different peak temperatures. The thermal insulation coefficient of every constructed mixture was calculated according to EN1745. It was found that the addition of perlite when keeping the other parameters constant led to decreases in products’ density by 2.9% up to 7.1% and in the thermal conductivity coefficient by 5.4% up to 9.5%, confirming that expanded perlite is a very good porogen material. The bending strength also decreased by 18% up to 28%, but in all cases, it remained well above the minimum accepted value of 100 kp/cm2. The vacuum employed during extrusion proved an important parameter affecting the results; however, its effect proved less significant as the perlite percentage in the mixture increased.