Influence of carbon steel fibers on the flexural crack width of RC beam

Abstract Reinforced concrete beams are the significant structural elements in the structure. They improve resistivity against flexural loads. The concrete portion in the reinforced concrete beam is good in compression but at the time of bending reinforcement will take about the structural element. When the flexural stresses exceed the flexural capacity of the reinforced concrete beam cracks will occur at the flexural portion. In this investigation for avoiding and delaying flexural cracks, carbon steel fibres are incorporated into the concrete mix. The carbon steel fibres are added in concrete concerning the total volume of concrete. Different percentages like 0.5%, 1%, 1.5% and 2% of carbon steel fibres are added to the conventional concrete. Another side large amount of CO2 emission occurs while manufacturing the cement in the industry. Because of that the cement content is replaced 30% with GGBS (Ground Granulated Blast Furnace Slag). The mix design used in this investigation is M30 with a water-cement ratio of 0.4. Cubes, cylinders and RC beams of 1.5 m X 0.23 m X 0.23 m are cast and placed in curing for 7 days and 28 days respectively. In this investigation single crack and multiple crack behaviour is analysed. The compression and split tensile strength of concrete are enhanced by incorporating carbon steel fibres in the conventional concrete. The RC beams with 28 days effective curing were tested under the loading frame of 2000T capacity. The result shows the initial crack propagation time is increased by increasing fibres content because at the time of crack propagation fibers present in the concrete mix will resist the entry of crack in the concrete and crack width is reduced by increasing fibres content compared with conventional concrete.