Shear capacity steel fibre reinforced concrete composite slab

Abstract

This thesis present the results of combined bending and shear test on composite slabs with steel fibres (SFs) in-situ concrete topping. Mechanical properties of steel fibre reinforced concrete (SFRC) were first determined by varying the fibres dosage from 0.50% to 1.25%. The test results show that there was not much improvement of the SFRC properties for steel fibres dosage of 1.0% and 1.25%. Apart from that, strong correlations were found between the concrete splitting tensile strength, compressive cube strength and flexural strength of SFRC. Following this, SFRC with 1.0% dosage was cast onto precast slab with different surface roughness. The SFRC replaced the conventional method using cast in-situ reinforced concrete topping. The experimental results on its ultimate shear capacity were further compared with previous research, and a parametric equation was proposed in predicting the interface shear strength using SFRC as concrete topping. The results shows that the ultimate shear capacity were 16.69% and 13.47% higher than the calculated value for the exposed aggregate and longitudinal roughened surface roughness, respectively. However, they were 15.23% and 17.56% lower than the smooth as-cast surface specimen with conventional reinforced concrete topping, respectively. As for the interface shear strength, the surface roughened in the longitudinal direction was the highest with 2.17 N/mm2. Further comparison was made with BS 8110 and Eurocode 2 and the results show that they were higher than the minimum value provided in both codes. The finding also suggested that surface roughened in the longitudinal direction was better than the other specimens with SFRC topping in terms of interface bonding.