Utilization of recycled almond wastes as additives in unfired clay bricks

With the aim of innovating in building materials and recycling waste materials, this work studies the feasibility of utilization of almond’s internal and external husks–hull and shell, respectively—as additives in unfired clay bricks. The used materials are provided from local resources of Ifrane, Morocco. Sixteen types of bricks and one control specimen are prepared by variation of type, proportion, and size of the additive. Their properties including bulk density, porosity, water absorption, heat conductivity, compressive, and flexural strengths are determined. Two grain sizes of almond wastes are considered. The considered proportions of almond wastes are 2%, 5%, 10%, and 20% by weight. The results show promising potentiality, especially using hull. Important losses are obtained in thermal conductivity up to 21.95% which offers economic and environmental benefits. Thermal conductivity decreased with the incorporation of both types of wastes with 0.3594 W/m.K as a minimal obtained value. Bulk density is improved as well and recorded 25.15% gain using the hull and 29.14% gain using the shell. Despite the general tendency of decrease in the compressive strength in bricks incorporating additives, exceptionally, considerable improvement (6.4%) is shown in bricks incorporating 2% of hull compared with the control specimen, with a final result of 19.40 MPa. All the engineering properties are depending highly on the porosity level in bricks which occurs because of the creation of flocculants. These later involve hydrogen bonding, electrostatic interaction, and hydrophobic effects. This study concludes that the incorporation of the almond hull up to 20%, in non-load-bearing clay bricks, is achievable and fusible, according to BS 3921 specification; bricks incorporating 2% of almond hull are considered load-bearing clay bricks according to the ASTM C62 standard.