Patent ID: 6646427
Filing Date: 2003-11-11
Classification: G01N

Abstract:
A method for determining the chloride corrosion threshold of metal embedded in a cementitious material, said method comprising:(a) encasing a sample of said metal in a set mass of said cementitious material in which are embedded components comprising an anode, a counter electrode and electrical leads capable of individually joining said metallic sample, said anode and said counter electrode to electrical circuitry external to said mass, (b) placing a liquid solution of chloride ions in contact with said set cementitious material, with a cathode immersed in said liquid solution; (c) applying in time increments an electric potential between said cathode and said anode to induce migration of chloride ions from said liquid solution through said set cementitious material to said metallic sample, without directly polarizing said sample; (d) between time increments of step (c), determining the half-cell potential of said metallic sample or applying an electric potential between said metallic sample and said counter electrode while detecting the value of a parameter indicative of the presence or absence of corrosion activity of said metal at an interface between said metallic sample and said set cementitious material; and (e) analyzing said set cementitious material for chloride content at a location adjacent to said metallic sample at a time corresponding to the point at which the half-cell potential or corrosion activity indicated by said detected value exceeds a selected critical level, said chloride content thus detected representing said critical chloride threshold.