Effect of microcracking and type of cementitious materials on the chloride ion permeability of ECC

Concrete in real structures is always cracked. Durability is of increasing concern in the concrete industry, and it is significantly affected by the presence of cracks. The corrosion of reinforcing steel due to chloride ions in deicing salts or sea water is a major cause of premature deterioration of reinforced concrete structure, The increase in permeability as a result of the cracks allows more chloride ions to penetrate into the cementitious composites, facilitating or speeding the deterioration. The present work studies the relationship among the microcracking and chloride ion permeability of concrete mixtures that contain different supplementary cementitious materials (SCMs) along with the effects of different SCM types on some of the mechanical properties. Four SCMs, representing a wide range of compositions, are used in the study. The splitting tensile deformations are introduced to generate microcracks in specimens, where cylindrical specimens are pre-loaded up to 80% of their splitting deformation capacities. Rapid chloride permeability test (RCPT) is used to assess the effect of microcracking and SCM type on the chloride ion permeability of concrete. Test results indicate that the SCM type is rather decisive on mechanical properties and the presence of microcracking greatly affects the chloride ion penetration of the concrete.