Determining the chloride resistance of ECC shotcrete

Abstract

Engineered cementitious composite (ECC) shotcrete is a sprayable cement composite reinforced with synthetic fibres that exhibits a strain-hardening characteristic when subjected to load. The ductile behaviour of ECC makes it an ideal repair material for concrete structures as the strains from expansion of the original concrete structure can be accommodated. Three tests were conducted to assess ECC’s performance in resisting chloride ions and thereby determining its suitability as a repair material for concrete structures exposed to marine environments. The three tests conducted determined the total accessible voids, capillary suction rate and chloride diffusion coefficient of the material. Six variations of ECC mix designs (including a standard ECC mix with specified compression strength of 40 MPa) were tested as well as a 40 MPa concrete. The results showed that a standard ECC shotcrete had a significant improvement in chloride resistance when compared to the 40 MPa concrete. The chloride resistance further improved when a metallic soap additive was added to the ECC mix. It was concluded that ECC is a suitable repair material for concrete structures exposed to marine environments.