Field indicator of chloride penetration depth

Chloride-induced corrosion of steel reinforcement is causing serious damage to many concrete structures. A number of methods to evaluate the chloride penetration into concrete have been developed. The most common practice in measuring the chloride profile is very time consuming. A simple colourimetric method of measuring the depth of chloride penetration into concrete by spraying a 0.1-N AgNO3 solution is very attractive. But some questions have been raised about its sensitivity. In this article, the results from colourimetric tests and the corresponding quantity of chloride detected at the colour-change boundary, determined for more than 70 concrete samples, are given. The magnitude and variation of chloride concentrations are compared with those reported in the literature and evaluated in relation to typical chloride threshold values. In addition, a relationship between the colourimetric penetration depth and the charge passed during testing to ASTM C1202 is shown. Crown Copyright (C) 2003 Published by Elsevier Science Ltd. All rights reserved.