The effect of permeable formwork on durability and corrosion performance of concrete

Abstract

The longevity of any reinforced concrete element is determined by the quality of the cover concrete. The only way for aggressive chemicals to get into the structural components and cause rebar corrosion and other types of damage is through the cover concrete. The controlled permeable formwork (CPF) liner is a unique approach for enhancing the quality of cover concrete. This liner permits surplus water and trapped air to escape while keeping the cement and fine particles in place on the concrete surface. Due to the modification, the water-cement (w/c) ratio is reduced, cement content is increased and surface porosity in the concrete cover zone is reduced. The influence of CPF liner on durability property and corrosion resistance of reinforced concrete was investigated in this study. Concrete samples were cast against a CPF liner and impermeable formwork (IMF) at three different water-cement ratios (0.47, 0.40, and 0.33). The rapid penetration of chloride, ingress of chloride, migration of chloride and accelerated corrosion were all examined at various ages. The results showed that CPF concretes exhibited good resistance to chloride ion intrusion of 46–56%. Furthermore, when casting of concrete is done with CPF liner, the time it takes for crack is 1.5 times longer than when concrete is cast against IMF.

Keywords

• Accelerated rebar corrosion
• Controlled permeable formwork
• Rapid chloride penetration
• Chloride migration
• Chloride ingress