Effects of incorporating hybrid fibres on rheological and mechanical properties of fibre reinforced concrete.

• HFRC is the simple combination of two different types of fibres in concrete. • The optimum increase in strength of HFRC was achieved at 2% hybrid fibre content. • A strong relation was found between hybrid fibre content and mechanical properties. • Experimental and predicted strengths of HFRC showed reasonably good agreement. Hybrid fibre reinforced concrete (HFRC) is one of the most promising construction techniques and repairing material in recent times for the construction industry. Generally, plain concrete has a very low tensile strength and limited resistance to cracking prior to the ultimate load. Fibre hybridization with different types of fibres helps in resisting these cracks in the concrete structures. This research aims to study the rheological and mechanical properties of HFRC made with steel and coconut (coir) fibre in comparison to control concrete. For this purpose, the experimentation was carried out in the laboratory on cylinders and prisms specimens made from conventional (control) concrete and HFRC with 2%, 4%, and 6% of fibre concentration by weight of cement. Besides, the concentration of waste steel fibre was kept at a constant rate of 1% for all of the HFRC mix in this study. The rheological properties of HFRC mixes were obtained by slump test, compacting factor test, ball penetration test, and density test. These properties were then compared to the corresponding properties of control concrete. On the other hand, compressive strength test, splitting tensile test and flexural tests were performed to attain the mechanical properties of HFRC. The test results indicate that the incorporation of hybrid fibres in the concrete decreases the concrete workability compared to the control concrete. The experimental results showed that the compressive strength is improved compared to the control mix whether the splitting and flexural strength shows an 18.36% and 24.87% improvement over the control mix. Finally, the inclusion of optimum content of hybrid fibres that is 2% by weight of cement showed enhancement in the mechanical properties of HFRC in terms of compressive, tensile and flexural strength with compared to control concrete. [ABSTRACT FROM AUTHOR]