Effect of Fibre Reinforcing Index on Compressive and Bond Strengths of Steel Fibre Reinforced Concrete

Abstract

The paper reports the results of the experimental study carried out to investigate the effect of fibre reinforcing index (FRI) on the compressive strength and bond behaviour of steel fibre reinforced concrete (SFRC). For this, 150 × 300 mm cylinders of portland cement concrete (PCC) as well as of SFRC of nominal mix M20 were cast with 10 mm diameter bar embedded up to a depth of 100 mm. Also cubes of 100 mm size of PCC and SFRC were simultaneously cast to study the effect of FRI on compressive strength Fibre content and the aspect-ratio were so varied that FRI was between 30 and 150. Test results indicate an increase up to 32% in compressive and 78% in bond strength in case of SFRC over conventional concrete. Bond strength found to be more sensitive to matrix disturbances caused by higher FRI, than compressive strength. Therefore, in SFRC, the maximum increase in bond strength is obtained at lower FRI, while the maximum increase in compressive strength is found at higher FRI. It is further observed that the development length can be reduced by 45% in case of SFRC when compared with RCC. Relationships have also been developed to relate compressive and bond strengths with FRI.