CORROSION OF MILD STEEL IN CONCRETE (SUPPLEMENT)
NAVAL CIVIL ENGINEERING LAB PORT HUENEME CA
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In a research effort to determine the fundamental cause of deterioration of certain concrete buildings in a marine environment. It was shown that sea salts can accumulate in a building wall exposed to airborne sea spray in quantities sufficient not only to deteriorate the concrete but also to cause the reinforcing steel to rust and thereby expand with enough force to crack the concrete. In small reinforced concrete walls sprayed with sea water once each morning, the same destructive phenomena has occurred at the Laboratory within a period of 2 years that occurred in about the same length of time to concrete buildings on the Pacific Ocean atolls. The concrete has cracked severely along the lines of the reinforcing steel. In order to reduce the adverse effects of salt and increase the life of a reinforced concrete building in a marine environment, no salt water should be added to the concrete at the time of mixing the concrete. Corrosion of the reinforcing steel will be delayed if the initially salt-free concrete is of high quality, with low permeability and a low water-cement ratio. The greater the depth of embedment of the reinforcing steel taking practical considerations and economy into account, the greater will be the delay of salt penetration to it and the increased depth of cover will provide greater resistance to rupture by the pressure induced by the building of corrosion products on the steel.
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