Comparing properties of foamed concrete and lightweight expanded clay aggregate concrete at the same densities

Abstract

In recent years the use of lightweight concrete has been considered due to reducing the weight of structures and offering excellent acoustic and thermal insulation. Foamed concrete (FC) and Lightweight Aggregate Concrete (LAC) are classified in the lightweight concrete category. The present experimental study aimed to compare the characteristics of LAC made with Lightweight Expanded Clay Aggregate (LECA) and foamed concrete at the same densities. Accordingly, eight concrete mixes were designed and made with LECA and foamed concrete at densities of 1400, 1600, 1800 and 2000 kg/m3. Different tests were performed on specimens of each mix to study their compressive strength, flexural strength, water absorption, microstructure, and thermal conductivity. Experimental results showed that at higher densities (1800 and 2000 kg/m3), the 28-day compressive strength of FC specimens is 7.3 % higher than that of LAC, but the contrary happens at lower densities (1400 and 1600 kg/m3), so that the 28-day compressive strength of LAC is up to 36.9 % higher. Also, the results showed that the 28-day flexural strength of FC is between 11.8 % and 55.4 % higher than LAC. A microstructural investigation verified the compressive strength test results. Furthermore, it was shown that FC due to its higher content of entrained air, has 4.8–11.9 % higher water absorption than LAC at all densities. The results also showed that foamed and LECA concretes have similar thermal conductivity at all densities with a maximum difference of less than 5 %.