Corrosion of Prestressed Steel Wire in Concrete

Abstract

The forms of corrosion produced on stressed cold-drawn prestressing steels in concrete with and without calcium chloride and in hot alkaline chloride solutions have been studied. In concrete, the degree of corrosion of the steel was found to depend on the quantity of chloride added and on the quality of the concrete. Tensile testing of the steel wire after removal from the concrete indicated the type and extent of corrosion on the wire, and this was confirmed by a scanning electron microscopy study of the fracture surfaces produced. Hot alkaline chloride solutions produced pitting, mainly above the liquid level, which led to ductile fracture. There was no evidence of stress-corrosion cracking of the steel in either concrete or alkaline chloride solution environments.

The pitting attack produced in the circumstances discussed may prove a serious hazard, and consequently the ‘quality’ of the concrete and grouting should be maintained and chloride contamination avoided.