Fresh and mechanical characteristics of roselle fibre reinforced self-compacting concrete incorporating fly ash and metakaolin

This study covered the fresh and mechanical characteristics of self-compacting concrete incorporating various fractions of (natural) roselle fibre (1 to 4% with 1% increment by weight of powder content). The fresh state behaviour of the composite was assessed by measuring the slump flow diameter, V funnel flow time, L-box blocking ratio and J-ring step height. Meanwhile, the mechanical characteristics of the composite were determined by measuring the compressive strength, splitting tensile strength, modulus of rupture, modulus of elasticity and impact strength. Data collected from the experiments of the fresh and mechanical characteristics of the roselle fibre reinforced self-compacting concrete mix were correlated and subjected to regression analysis. The findings indicated that the incorporation of the roselle fibre reduced the workability behaviour of the self-compacting concrete. By contrast, the mechanical characteristics, such as compressive strength, splitting tensile strength, modulus of rupture and modulus of elasticity were enhanced with increasing fibre content. However, 4% fibre addition resulted in a marginally decreased compressive strength and modulus of elasticity of the self-compacting concrete. Empirical equations were developed to correlate the splitting tensile strength, flexural strength and modulus of elasticity to the compressive strength with high values of coefficient of determination. Experimental findings were found to be in good agreement with existing correlations reported in standards and literature. (c) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The incorporation of roselle fibre reduced the workability of self-compacting concrete but improved mechanical characteristics. Higher fibre content resulted in increased compressive strength, splitting tensile strength, modulus of rupture, and modulus of elasticity. However, a 4% fibre addition may lead to a slight decrease in compressive strength and modulus of elasticity of the self-compacting concrete.