Effect of aggregate/binder ratio on mechanical and energy absorption properties of a straw-lime composite material

This study investigates the mechanical and energy absorption properties of an eco-friendly straw-lime composite. Compression tests were performed to explore the effect of the straw-to-binder ratio (S/B = 0.2, 0.3, and 0.4), as well as the influence of compression speed, and test direction, on the mechanical properties and capabilities to dissipate energy. The Digital Image Correlation (DIC) technique was applied to analyze strain field homogeneity during the deformation process and to evaluate Young's modulus and Poisson's ratio. Results show decreasing strength and energy absorption with higher straw to binder ratios. Samples tested orthogonal to straw fiber orientation exhibited an increase of over 100% in absorbed energy per unit volume compared to parallel samples. Physical properties are sensitive to strain rate, with values up to 0.72 MPa for the plateau stress and 300.40 kJ/ m3 for the absorbed energy, for a 0.2 S/B ratio at a loading speed of 100 mm/min. The material has shown greater energy absorption than lightweight foam concrete of equivalent density. These results are promising for the development and new use of straw-lime biocomposites as energy absorbing protective materials.