Gypsum and lime stabilised earth-rice husk composite

The use of environment friendly bio-based materials, with low environmental impact and low production costs could be the answer to improve the energy performance of buildings, leading to a reduction of the energy demand and cost for the building sector. This study presents the development of a novel bio-based material made with earth and reinforced with rice husk, stabilised with hemi-hydrated gypsum and air lime. The objective was to produce a high-performance composite that not only could be used as a masonry with good insulation performance but also as a regulator of the indoor air humidity. The implementation of an image analysis method enables to assess of the influence of the length and orientation of the rice husk fibres on the physical and thermal properties of the composite. In order to evaluate the influence of these factors on the performance of a bio-based material, a comparison was made with previously produced earth blocks with hemp shiv, with different natural fibre contents, different production methods and dimensions. The distribution curves obtained for the fibres length and orientation combined with fibres characterisation, highlight that the fibre length could have an influence on the thermal conductivity of the composites. Despite having a relatively low thermal conductivity, the results still do not allow the composite to be considered an insulation material but they could contribute to the indoor thermal comfort.