Outline of the Standard NDIS 3437: Test Method for Penetration Depth of Chloride Ions into Hardened Concrete by Spraying AgNO₃ Solution

Abstract

When a silver nitrate（AgNO₃）solution is sprayed on a section of concrete in which chloride ions have penetrated from the outside, the areas containing more than a certain amount of chloride ions turn white, while the other areas turn brown. Based on this phenomenon, a test method to quickly visually check the penetration depth of chloride ions was established as the NDIS 3437 standard by the Japanese Society for Non-Destructive Inspection. This report introduces the background of the creation of this standard, an outline of the test method, the principle of the AgNO₃ solution spraying method, and the points to be noted regarding its implementation.