Performance of hybrid sugarcane and polypropylene fibres in concrete

This study investigates the effects of sugarcane fibre (SCF), an agricultural waste fibre, and polypropylene fibre (PPF), a synthetic fibre, on concrete’s mechanical and durability properties. Experimental tests were conducted on concrete incorporating SCF and PPF in different proportions (0.5%, 1%, and 1.5% by weight of binder), along with a hybrid combination (SCPP-FRC) containing a maximum of 1.5% fibres. Results indicate that both fibres, used individually or in hybrid form, significantly improve the concrete’s performance. Individually, SCF and PPF increased compressive strength by 7–17% at 1% fibre content, beyond which strength declined due to fibre clumping. The optimal hybrid mix (SCF 0.75% + PPF 0.75%) achieved the highest strength. Tensile and flexural strengths improved by 23% and 28%, respectively. SCF-based concrete exhibited higher water absorption (5.58%) compared to control and PP-FRC due to SCF’s hydrophilic nature, while hybrid SCPP-FRC showed moderate absorption. Acid resistance tests revealed that SCPP-FRC had lower strength loss (18%) than control concrete after 56 days of acid exposure. Scanning electron microscopy analysis confirmed fibre bridging effects, enhancing the interfacial transition zone, resulting in denser concrete. The study concludes that a 1% fibre content or (0.75% SCF + 0.75% PPF hybrid) optimally improves concrete’s mechanical and durability properties.