Empirical Evaluation of Mechanical Performance of Sisal/Bamboo Hybrid Fibre-Reinforced Polypropylene Composites for Construction Industry Applications in Nigeria

Hybrid natural fibre composites combining complementary fibre types offer a strategy for engineering specific mechanical performance profiles while maximising the use of locally available agricultural resources. This study empirically evaluates the mechanical performance of hybrid composites reinforced with sisal and bamboo fibres in a polypropylene matrix, targeting construction industry applications in North Central Nigeria. Sisal fibres from Benue State and bamboo fibres from Taraba State were treated by alkaline and silane methods. Hybrid composites were produced by melt compounding at total fibre contents of 30 and 40 percent by weight, with sisal-to-bamboo ratios of 100:0, 75:25, 50:50, 25:75, and 0:100. A symmetric hybrid ratio of 50:50 was tested at 35 percent total fibre content as a central point. Tensile, flexural, compressive, and impact properties were characterised following ASTM standards. A hybrid synergy index was calculated to identify blend ratios producing performance exceeding the rule of mixtures prediction. Results demonstrate positive hybrid synergy in tensile strength at 75:25 sisal-to-bamboo ratio with 40 percent total fibre content, achieving 61.4 MPa versus the 56.8 MPa rule of mixtures prediction. Flexural modulus was highest at 50:50 ratio, reaching 4.2 GPa. Impact energy showed no positive synergy, declining with increasing bamboo content. Compressive strength was relatively insensitive to hybrid ratio, averaging 48 to 54 MPa across compositions. The study provides a validated experimental basis for designing sisal/bamboo hybrid composites with optimised property profiles for roofing panel and partition wall applications in the North Central Nigerian construction market. Keywords: hybrid composite, sisal, bamboo, polypropylene, construction applications