Experimental Investigation of the Relationship between the Compressive and Flexural Strengths of Concrete made with Sisal Fibre and <i></i>

Abstract

This paper is an experimental investigation of the effects of combining sisal fibre reinforcement with Bacillus coagulans bacteria on the compressive and  tensile strengths of concrete. It was aimed at determining the relationship between the compressive strength and flexural tensile strength of such  concrete. A normal concrete mix of 1:1.5:2 with water cement ratio of 0.5 was reinforced with Sisal fibres in the range of 0.5-1.25% in step 0.25% by  weight of the dry constituent of the mix and then mixed with the bacteria solution at 12x108 cell/m density. Concrete cubes and beam specimens were  tested at 28days and the result indicated that up to the amount of fibre reinforcement tested, both the compressive and tensile strengths were higher  than that of the control mix for all mixes. Highest strengths were obtained at 1.25% fibre addition with medium workability without admixture. Mixes with  fibre reinforcement combined with bacteria were stronger in compression compared with corresponding mixes with only fibre reinforcement.  However, mixes with fibre reinforcement combined with bacteria were weaker in tension compared with corresponding mixes with only fibre  reinforcement. The relationship between flexural strength and compressive strengths of the mixes remained fairly constant across the level of fibre  reinforcement tested; for only sisal reinforcement this was about 14%. However, for fibre reinforcement combined with bacteria treatment this was about  12%.