Preventative measures to limit stress corrosion cracking in prestressed concrete

In the past decade, the most significant advances in the area of protection of prestressing steel from stress corrosion cracking have come in the fields of metallurgy and concrete materials. These efforts have developed from a more precise understanding of the mechanisms that cause stress corrosion cracking in prestressing steel, and development of concreting materials that provide greater protection for these steels. This report deals with two aspects of steel protection. First, with respect to the steel itself, new insights into the structure of the prestressing steels have shown metallurgists the conditions under which stress cracks form and advance, as well as ways in which to modify the physical properties of the steel to minimize the possibility of crack formation and advancement. Secondly, in the field of concrete materials, the emphasis on prevention of corrosion to steel has been in the area of durability of the concrete that protects the steel. Lower water-cement ratios and concretes with lower permeability exclude deleterious materials from the surface of the steel. New materials and procedures are discussed that have been designed to limit the penetration of corrosive elements that may attack the steel at the grain boundaries and initiate brittle failure.