Investigation of wood biomass ash on the thermal behaviour of compressed earth bricks

Abstract

The aim of this work is to study the effect of the incorporation of wood ash from the combustion of biomass waste on the thermal properties of compressed earth bricks (BWA). These bricks were obtained as a partial substitution of the soil with different contents (0, 5, 10, 15 and 20% wt). The specimens manufactured were compacted with a compaction stress at 10 MPa, conserved in the laboratory at a temperature of 20 ± 2 °C, then allowed to harden for 7 and 28 days. The results showed that the partial substitution of the soil leads to a decrease in thermal properties.Thermal conductivity values were decreased to different soil substitution proportions and with curing time. Minimum values were achieved for specimens containing 20% by weight of WA, with better thermal insulation, at thermal conductivity values ranging from 0.78 W/mK in BWA at 28 days and 1 W/mK in BWA at 7 days. This decrease was attributed firstly to the quantity of water consumed during the pozzolanic reaction that occurs between the soil components and the lime of the WA, secondly to the microstructure of this soil used.