Thermophysical and Mechanical Assessment of Unfired Clay Bricks with Dry Grass Fibrous Filler

Abstract

Dry grass is a widespread residue of agricultural activities in Morocco. This paper investigates the effect of incorporating this organic waste on the Physicochemical and Thermomechanical performance of unfired clay bricks. The used raw clay material used is of illite type, extracted from Bensmim in the Ifrane region. Various grass filler proportions (0 %, 1 %, 3 %, 7 %, 15 %, and 20 %) were used. Collected findings showed an increase in the porosity level reaching 14.75 % at 20 % additive content compared to 1.75 % of reference samples. In addition, brick samples with 20 % dry grass content reflected a bulk density of 1.52 g·cm⁻³ and water absorption coefficient of 52.25 g·cm⁻²·min^0.5), compared to reference samples of 1.77 g·cm⁻³ and 26.15 g·cm⁻²·min^−0.5), respectively. This reflects prominent lightweight properties. Mechanical and thermal conducted tests reflect a decrease in both compressive strength and thermal conductivity with grass reinforcement incorporation compared to reference values. In fact, a 48 % gain in thermal conductivity is observed with a decrease from 0.53 W·m⁻¹·K⁻¹ for reference samples, to 0.27 W·m⁻¹·K⁻¹ at the 20 % mark. Bricks with dry grass filler reflected an acceptable compressive strength as well as a significant improvement in insulation properties, enabling great energy saving and contributing to sustainable buildings with good mechanical functioning.