Compressed Earth Blocks with Sewage Sludge Ash

There is a growing interest in finding more sustainable building materials to mitigate carbon emissions from materials and the depletion of natural resources. Currently, sewage sludge ash (SSA) and large amounts of excavated soil are deposited without utilization. This study investigated whether SSA can be utilized with clay loam to improve the mechanical and physical performance of unstabilized and lime (CaO) stabilized compressed earth blocks (CEB). To examine the potential of the SSA, clay loam was mixed with the following: 5% SSA, 5%SSA + 5% CaO, 5% CaO, 5% CaO + 5% inert quartz. Small cylindrical specimens were cured at two different temperatures for 14 days, with 7 days of drying afterwards. The mechanical and hygrothermal performance of the unstabilized and stabilized CEBs was tested. The use of SSA in CEB reduced the shrinkage of the samples, while compressive strength or hygrothermal properties were not impaired compared to the reference. Stabilization with CaO did not improve CEB properties under the tested conditions. The results thus showed potential for using SSA in unstabilized CEB.