Evaluation of First-Crack Strength of Waste Copper Wire Fiber Reinforced Concrete

Cracks in concrete are paths for external agents that result in corrosion of steel reinforcement. Corrosion of steel is one of the main and expensive deterioration mechanisms affecting reinforced concrete structures. Adding fibres to concretes arrests the propagation of cracks. Copper wire has a very slow corrosion process, better mechanical properties and ductility than most of the steel fibres. This research studied the first-crack strengths of waste copper wire fibre-reinforced concrete (WCWFRC). The first-crack strength parameters tested on beam specimens (100 x 100 x 500 mm) were the deflection, load-deflection relationship, flexural strength and toughness of samples containing 0, 0.5, 1.0 and 1.5% waste copper wire fibre (WCWF). Models for the relationship between the first-crack strength parameters and the WCWF contents were developed using regression analysis, and the models’ adequacy were determined using coefficient of determination (R2). The results revealed that the resistance to deformation, deflection, flexural strength and toughness increased with increase in WCWF contents at first-crack. The initial stiffness of the samples increased from 26.75 kN/mm at 0.5% WCWF content to 38.33 kN/mm at 1.5% WCWF content. The model equations for the relationships between the first crack properties and WCWF contents have R2 values greater than 93% which indicates good response predictive ability. The increments in the first-crack strengths with increase in WCWF contents proved that WCWF improves energy absorption capacity of the concrete.