Hydrothermal properties of sandcrete blocks produced with raw and hydrothermally-treated sawdust as partial substitution materials for sand

Sandcrete blocks are used predominantly as walling elements for shelter construction in developing countries like Nigeria. Though several researches have revealed that the effect of an incessant rise in the cost of sand suitable for the production of sandcrete blocks could be mitigated by partial substitution of sand with waste materials, information on performance determinants like moisture effect and heat flow processes in relation to such developed blocks are scarce and in most cases, completely lacking in the literature. Also, sawdust is continuously generated in vast amounts but majorly under-utilised and improperly discarded as waste, thereby causing serious environmental problems. This study focussed on the production and appraisal of hydrothermal properties of solid core sandcrete blocks in which sand is partially substituted with sawdust at 0, 10, 20, 30, and 40% loading levels by volume. Water absorption, sorptivity, bulk density, specific heat capacity, thermal conductivity, thermal diffusivity, heat penetration time, thermal lag, and solar radiation absorptivity were determined for the blocks. The results revealed that blocks with raw sawdust (RSD) content are more capable of decreasing wall heat transmission load and improving the energy efficiency of building envelopes compared to their counterparts containing hydrothermally-treated sawdust (TSD). Partial sand substitution with 20% of RSD or 10% of TSD was observed to be optimum in order to meet both the water absorption and bulk density requirements outlined in standard protocols. By utilising sawdust as described in this work, problems associated with its disposal could be minimised while the development of affordable, safe, and sustainable housing is enhanced.