Pages: 5 Published: Jan 1983
The basic problem associated with the deterioration of conventional reinforced concrete due to corrosion of embedded reinforcement is generally not that the reinforcing itself is reduced in mechanical strength, but rather that the products of corrosion exert stresses within the concrete which cannot be supported by the limited plastic deformation of the concrete, and the concrete therefore cracks. This process is thus somewhat akin to the protectiveness or nonprotectiveness of oxide films on materials formed during high-temperature treatment, where the Pilling-Bedworth Ratio determines stresses in the oxide which are dependent on the relative volume of oxide to the volume of metal from which it came.1 Presumably, had the corrosion product from the steel (still in some doubt at this juncture in the actual concrete environment but ultimately a hydrated ferrous ferric oxide) occupied less volume than the metal from which it was formed, then the problem of reinforced concrete cracking and spalling would not have occurred. As a corollary, however, should this volume change have been significant in the reverse direction, it is possible that bond-strength problems between the reinforcement and the concrete may have occurred during the corrosion process.
Paper ID: STP31832S