On-line measurement of simulated reinforcement corrosion in concrete under action of de-icers.

The primary cause of long term damage to steel reinforced concrete bridges and elevated highways in the UK is use of rock salt as a road de-icer. Alternatives based on acetate salts are now available. This paper describes adaptation of a novel technique, the Cormon Environmental Corrosion Monitor (ECM), for studying the corrosion rates of steel in concrete when treated with de-icing chemicals. ECMs have been used to provide a continuous reading of the mechanical expansion associated with the corrosion of steel embedded in concrete paste. The expansion is a consequence of the increased volume resulting from the formation of corrosion products. This generates internal stresses in the structure which enhance fracture and accelerate failure of steel reinforced concrete. In this respect, the use of ECMs provide a small scale, rapid and realistic simulation of rebar corrosion in concrete. The results show that changing from rock salt to an acetate de-icer decreases the corrosion rate of steel embedded in concrete by more than a factor of ten. Use of acetates from the outset shows no sign of corrosion damage. Possible mechanisms by which the acetate de-icers achieve this are discussed. (A)