Resistance to corrosion induced cracking in self consolidating hybrid fiber reinforced concrete

Abstract

Corrosion of reinforcing steel is a familiar form of environmental attack on reinforced concrete structures. Common design methodology attempts to combat this threat by means of a specified cover thickness which increases the diffusion length over which chlorides must travel and subsequently the time before corrosion can initiate. However, once active corrosion begins and expansion stresses at the rebar surface crack the cover concrete, this does little to prolong the life expectancy of the structure with respect to corrosion resistance. In an effort to enhance structural durability, we have developed a self-consolidating hybrid fiber reinforced concrete (SC-HyFRC) which improves the cover concrete's crack propagation resistance to expansion forces caused by rust formation at the rebar surface. By exposing reinforced concrete samples in an aqueous environment to a constant amplified current we are able to accelerate the rate of corrosion at the rebar surface and quickly develop an equivalent amount of rust formation to that which would be expected from multi-year exposure under marine environmental conditions. Electrochemical measurements taken post-acceleration provide us with corrosion rates which exhibit the improved performance of the self-consolidated hybrid fiber reinforced concrete relative to a standard self-consolidated concrete mix without fibers. In contrast to the non-fiber reinforced samples, hybrid fiber reinforced specimens did not exhibit any cracking after accelerated corrosion. © RILEM 2012.