Effect of the coconut fibers and cement on the physico-mechanical and thermal properties of adobe blocks

This work aimed to investigate the effect of cement and coconut fibers on the thermal and physico-mechanical characteristics of adobe blocks. Thus, a clayey raw material consisting of kaolinite (62 wt%), quartz (31 wt%), goethite (2 wt%) with a plasticity index of 21.5 % was used to manufacture adobe blocks amended with cement and coconut fibers. First the adobe blocks were formulated with an optimal cement content of 4 wt% before adding coconut fibers up to 1 wt%. The physico-mechanical and thermal characteristics of manufactured composites were then studied. According to the results obtained, the incorporation of coconut fibers into the clay-cement matrix decreases the apparent density and volume shrinkage and increases the porosity of the adobe blocks. The presence of coconut fibers in adobe blocks promotes the phenomenon of water absorption. The combined effect of the formation of calcium silicate hydrate (CSH) and hydrogen bonds between fibers molecules and those of clayey minerals leads to an improvement in the mechanical properties of adobe blocks. The thermal conductivity of adobe blocks decreases with the fiber content due to the presence of pores and cellulose molecules in the fibers which have an insulating nature. Taking into account their physico-mechanical and thermal properties, adobe blocks containing 0.6 wt% coconut fibers and 4 wt% cement are suitable for building sustainable habitats and thermally comfortable.