Modeling the Time-to-Corrosion Cracking in Chloride Contaminated Reinforced Concrete Structures

The time-to-cracking, from corrosion initiation to cracking of the reinforcing steel cover concrete, is one of the critical time periods for modeling the time to repair, rehabilitate, and replace reinforced concrete structures in corrosive environments. The time to corrosion cracking was experimentally determined from simulated bridge deck slabs. The experimental design considered corrosion rate, concrete cover depth, reinforcing steel bar spacing, and size. Three of the 14 slab series cracked during the 5-year study. Metal loss was determined for the cracked specimens that had cover depths of 1, 2, and 3 in. (25, 51, and 76 mm). A time to corrosion cracking model was developed that considered the critical amount of corrosion products that consists of the amount of corrosion products needed to fill the interconnected void space around the reinforcing bar plus the amount of corrosion products needed to generate sufficient tensile stresses to crack the cover concrete. The experimentally observed time to cracking is in good agreement with the model predicted time to cracking.