Thermal conductivity of insulation material based on straw aggregates and a bio-binder extracted from wheat straw and sunflower pith
Résumé
Among the sectors influencing the environment, the building sector is known to be very energy consuming and to use large granular materials. Face to these problems, the development of materials based on renewable and biodegradable resources represents a major scientific challenge to produce both high-performance materials and materials that can be used as an alternative to synthetic materials. Several materials have been studied and proposed in particular for the thermal insulation of buildings [1]. However, these materials based on vegetable aggregates remain in most cases cement or lime-based [2] which are energy consumers and emit carbon dioxide [3, 4]. The objective of this work is to propose a bio-composite with both vegetable aggregates and binders with thermal performances that are competitive with materials based on mineral binders. Vegetable glues were extracted using wheat straw fines that cannot be used as aggregates. The straw fines were soaked in a solution containing 6% NaOH at 90 °C for 2 hours. Then, the extracted liquid was concentrated by adding the sunflower pith powder and/or gelatin. The bio-binder obtained was mixed with the straw aggregates to prepare biocomposite samples using the protocol developed in the framework of the PEPITE research program funded by the "Région Centre". Experimental results in terms of thermal conductivity allowed to examine the influence of each bio-binder, and to compare the performance of straw aggregate based bio-composites developed [5-6].