Effect of Surface-Treated Date Palm Rachis and Geogrid Reinforcement on High-Strength Self-Compacting Concrete Slabs

Abstract

The growing environmental concerns and increasing cost of conventional construction materials have intensified the need for sustainable and economical alternatives in concrete construction. This study investigates the flexural behavior of high-strength self-compacting concrete (HSSCC) slabs reinforced with alternative reinforcement systems, namely date palm rachis and geogrids. To enhance the bond characteristics between the reinforcements and the concrete matrix, surface treatments were applied using polyester resin mixed with fine sand, coarse sand, or fine glass powder.A series of slab specimens was cast and tested under flexural loading to evaluate load–deflection behavior and ultimate load capacity. The results were compared with those of an unreinforced control slab. The control specimen exhibited brittle behavior, failing at an ultimate load of approximately 9.9 kN with a limited deflection of about 4.3 mm. Slabs reinforced with untreated palm rachis showed only marginal improvement, reaching an ultimate load of approximately 10.2 kN. Surface treatment significantly enhanced the flexural performance of palm-rachis-reinforced slabs. Fine sand coating resulted in the highest ductility, with a maximum deflection of about 15.2 mm, while coarse sand coating provided the best overall performance, combining stable crack propagation with the highest ultimate load of approximately 13.1 kN. Palm rachis coated with fine glass powder exhibited increased stiffness accompanied by reduced deflection capacity. Geogrid reinforcement mainly contributed to improving flexural strength. Fine sand–coated geogrids achieved the highest ultimate load among geogrid specimens (≈11.4 kN), whereas coarse sand coating led to minor strength enhancement. Conversely, fine glass–coated geogrids showed excessive deflection (≈15.9 mm) and a considerable reduction in ultimate load (≈6.5 kN).