Durability Studies of Steel Fibre Reinforced Concrete

Abstract

In the present investigation, the effect of different dosage of steel fibres on bond strength between steel and concrete in reinforced concrete was investigated. As a part of durability study, the combined effect of marine environment and varying levels of pH on the ultimate bond strength retention and compressive strength retention of steel fibre reinforced concrete was also investigated. Durability studies were carried out by exposing the 28 days cured cubical specimens into marine environment having different pH levels (1, 4, 7, 10 and 13). The marine environment was simulated in the laboratory by adding 3.5% NaCl to the tap water. Designed quantity of sulphuric acid was added to salt solution to maintain pH of 1 and 4 in marine environment. Similarly, designed quantity of sodium hydroxide was added to the salt solution to maintain pH of 10 and 13 in marine environment. The specimens were exposed for the durations of 60 and 90 days. The resistance of concrete to marine environment with varying pH was measured through compressive strength retention and ultimate bond strength retention in steel fibre reinforced concrete. The addition steel fibres reduced workability of concrete, especially 1.5% of steel fibres yielded considerably low slump value. The ultimate bond strength and compressive strength values increased due to the addition of steel fibres. The pH of the marine environment has a significant influence on the compressive strength retention and bond strength retention. Exposure to marine environment with pH 1 underwent severe loss in compressive strength and ultimate bond strength with very low strength retention values. However, exposure to marine environment with pH 10 and 13 had minimal strength losses with higher values of compressive strength and ultimate bond strength retention. The alkaline nature of marine environment was not susceptible to strength reduction when compared to neutral (pH 7) and acidic (pH 1) marine environment. The steel fibre reinforced concrete performed better in acidic marine environment compared to control concrete without steel fibres.