Performance of earth based products reinforced with rice husk for indoor refurbishment

• Autor(a) principal: Antunes, Ana Rita Novais Duarte
• Data de Publicação: 2017
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10362/30812
• topic: Bio-based insulation panel; Rice husk; Earth; Gypsum; Air lime; Hygrothermal; Domínio/Área Científica::Engenharia e Tecnologia::Engenharia Civil

The use of environment friendly materials, with low environmental impact and low production costs is becoming an issue of great interest in the building sector. It is known that there is a need to reduce the energy requirement in buildings, once they account for 40% of total energy consumption in European Union (EU). The adoption of sustainable and efficient solutions 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. From a global point of view the use of bio-based materials provides low-cost and short-term opportunities to contribute to the EU objective to have nearly zero-energy buildings and reducing the greenhouse gas emissions. Bio-based materials are known for their environmental benefits but specially for being materials with high hygroscopic behaviour. The use of natural fibres in earth composites reinforcement has become an interest matter in the construction world, not only due to the availability, embodied energy and hygroscopic behaviour of the earth but also due to the properties and advantages of the use of reinforcement fibres. Earth is a construction material with high advantages but the negative aspects are also relevant, whereas the use of binders to reduce the negative aspects is very common. Based on these fundaments, the present thesis studies the production of a novel bio-based insulation material with earth, stabilised with gypsum and lime and reinforced with rice husk. The objective was to produce a high-performance material that not only could be used as an insulation material 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 natural 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 different natural fibre contents, different production methods and dimensions. The experimental tests showed promising results, especially on the hygrothermal properties of the earth panels. Despite having a relatively low thermal conductivity, the results still do not allow the panels to be considered an insulation material but they could contribute to the indoor thermal comfort. As a regulator of the humidity the panels show great ability to adsorb and desorb the air moisture with relative humidity changes, proving the effectiveness of earth and natural fibres on the hygrothermal comfort.