The Effect of Mussel Shell Additions on the Mechanical and Thermal Properties of Compressed Earth Blocks

Abstract

Since their appearance in the 1950s, compressed earth blocks, a modern form of adobe brick have increasingly been studied for their many advantages compared to earlier forms of earthen materials. Their mechanical and thermal improvement is one of the main interests of many researchers. This study investigates the mechanical and thermal behavior of compressed earth blocks (CEB) loaded with crushed mussel shells (CMS) and stabilized with Portland cement. Two series of mixtures were prepared for CEB manufacturing using various CMS contents (0%, 5%, 10% and 15%), then compacted with a static load. Series 1 CEB without cement; Series 2 CEB with cement. Using X-ray diffraction, the mineralogical composition of soil and CMS was established. A scanning electron microscopy (SEM) examination of the mussel shell's morphology was performed too. The compressive and tensile strengths for both series were assessed after two different curing times (14, 28 days). The thermal conductivity of manufactured blocks was evaluated using the hot-disk method. The findings revealed that the increase in CMS content (from 0% to 15%) led to a reduction of the compressive strength by 35% for non-stabilized CEB and by 53% for stabilized CEB. However, the obtained compressive strengths remain above the minimum required compressive strength (Ϭc > 1 MPa). In contrast, the thermal performances of both series were significantly enhanced. When increasing the CMS content (from 0% to 15%), the thermal conductivity decreases by 13% for non-stabilized CEB and decreases by 17% for stabilized blocks. The findings presented in this paper suggest that mussel shell aggregates are a feasible option to improve thermal behavior of compressed earth blocks.