5. Conclusions and recommendations In this research, the mechanical properties of tire crumb and oil palm fruit fibre lightweight mortar with addition of 0%, 0.5%. 1x and 1.5% oPFF and tire-crumb replacement of 0-40% volume of aggregate were studied. The addition of oPFF to the matrix result in an increase in the water absorption value due to the high void content of the fibre causing more absorption of water during hydration. The best absorption recorded at 0.5% oPFF showing insignificant influence of fibres matrix. The 28 days compressive strength of samples with tire crumbs and more than 0.5% OPFF dropped drastically as compare to control specimen. However when 0.5% OPFF was added to 10% tire crumb, the improvement of 5% was recorded as compare to tire crumb sample without OPFF. This result proofed a bond strength improvement with addition of OPFF that interconnecting the matrix in the composites. The split tensile test shows an increase in the strength at 0.5% OPFF content for all tire crumb which due to good resistance of OPFF to early crack. The flexural performance of tire crumb-incorporated mor- tars was improved by the addition of OPFF at 0.5-1.5% by weight of cement content. Both the flexural peak load capacity and ductil ity of the mortars were increased significantly.