Characterization of rubber-clay composites as recycled waste lightweight construction materials

The aim of this research is to assess the impact of using recycled rubber plastic waste as additives to clay bricks in various proportions (0%, 1%, 3%, 5%, 7%, and 15%) by weight, with different grain-sizes (δ < 1 mm and 1 mm < δ < 3 mm) to evaluate their thermophysical and mechanical properties. Following the X-ray diffraction and fluorescence tests, the clay used in this study is of Illite type with non-swelling properties with a presence of Aluminum oxide (Al₂O₃) and Silica (SiO₂), making it a suitable construction material. Collected findings revealed that the higher the recycled rubber waste additive content, the higher the percentage of porosity, and the lower the bulk density, consequently, the production of lightweight bricks following the ASTM C20-00 standards in accordance with Moroccan testing standards NM EN 772 − 12. Water absorption recorded an increase from 41(g/(cm².min^0.5)) to 60(g/( cm².min^0.5)) in specimens with the highest recycled rubber additive content. Furthermore, produced samples with 1%, 3%, and 7% recycled rubber waste additive content are classified as Earth Blocks Class 4 (EB4), while specimens with 15% recycled rubber waste additive content are classified as Earth Blocks 3 (EB3). Finally, the addition of recycled rubber waste additives improved the thermal conductivity of the specimens from 0.44 (W/m.K) to 0.24 (W/m.K) with the highest recycled rubber waste additive content of 15%.