Method
Carbo Detect™ reagent is a type of pH indicator which will indicate the change of pH on a freshly exposed concrete surface. The indicator is simply sprayed on the surface to be checked. The indicator will change to pink in uncarbonated concrete and remain colorless when sprayed on carbonated (low pH) concrete. If the concrete test area is very dry, a light misting with water will help show the color.

By spraying the indicator along a core drilled from the top surface down to the reinforcement bar it can be readily seen how far the carbonation has progressed and therefore the outlook for corrosion, which will only occur after carbonation reaches the reinforcement bar.

Care should be taken to prevent drilling and coring dust from contaminating the surface to be tested.