Mechanical and thermal characterization of bio-sourced mortars made from agricultural and industrial by-products

Abstract

In the last decades, the environmental sector has occupied an essential place in the world. The main objective of this concern is to preserve the environment and to reduce the use of non-renewable raw materials as much as possible. Thus, the construction sector can contribute to environmental conservation by the use of bio-based materials. Bio-building materials are composed, at least in part, of components made from biomass derived from plants or animals. Today, these materials are used in a variety of produces and for a variety of purposes, including insulation, mortar and concrete, panels, plastic composites, and construction chemistry. In the first step of this study, the Physico-chemical (bulk density, absolute density, water absorption, relative humidity) and thermal (thermal conductivity and thermal resistivity) properties of wood ash, and vegetable aggregates (sunflower plant bark and pith) have been studied and compared with results from the literature review. Afterward, different mixes were prepared based on ashes and adding a certain percentage of cement used as a binding material (0%, 10%, and 20%) to improve their mechanical behavior. Then, concrete with wood ash and vegetable aggregates (pith or sunflower bark) was prepared in order to optimize the mixture that has the best thermal and mechanical performance. The growth of the compressive and flexural strength was evaluated at 7, 14, 28, and 90 days. Because of the excellent ability of wood ash to maintain cohesion, the obtained results demonstrated the possibility of producing mortar with less cement. In terms of thermal performance, increasing fiber content while decreasing the volume density can reduce thermal conductivity of mortars.