Effect of reinforced recycled sawdust-fibers additive on the performance of ecological compressed earth bricks

This study assesses the potential of waste wood sawdust, as a construction material additive, on the mechanical, thermal and physicochemical properties of compressed earth bricks. Following X-Ray Diffraction and Fluorescence analysis, the used raw clay material, retrieved from Ifrane, Morocco, was found to be of type Illite, with a prominent SiO2 content, 59.60%, making it a suitable construction material. Multiple waste additive proportions were analyzed (0%, 1%, 3%, 7%, 15% and 20%), by weight, at different sizes: small size: (δ ≤ 0.5 mm), medium size: (0.5 mm < δ ≤ 1 mm), and large size: (1 mm < δ ≤ 3 mm). The incorporation of higher recycled sawdust waste additive content at larger sizes produced bricks with higher porosity levels. This resulted in manufacturing lightweight brick structures, below the 1.70 g/cm3 permissible limit, with higher water absorption rates. Improvements in compressive strength in prepared samples were observed with the incorporation of smaller additive sizes. In fact, 3% additive specimens recorded a 6.05 MPa at larger sizes, compared to 7.69 MPa with smaller additive sizes, reflecting a 22% mechanical compressive strength gain. Produced samples manifested enhanced thermal performances with the use of the sawdust waste additive in the 60% and 36% range for thermal conductivity and specific heat capacity, respectively; in addition to recording prominent energy savings in terms of thermal heating and cooling loads, with energy gains in the 50% interval. Theoretical models were developed to test the accuracy of the experimental findings. An obtained good correlation coefficient, very close to 1, corroborated the accuracy of the collected findings.