When the alkalinity of concrete reduces to pH 9 to the depth of reinforcement, the steel will corrode and spalling will begin.
New concrete is highly alkaline with a pH of around 13. This provides passivation of steel reinforcement through development of a protective oxide layer; however, environmental or service conditions act to reduce the pH over time.
RemedyAP uses pH testing to determine the alkalinity of concrete.
The RemedyAP team uses two methods:
Qualitative: Applying phenolphthalein indicator solution to freshly exposed concrete in situ to measure the depth of low alkalinity (image above).
Quantitative: Extracting core samples and performing pH profiling in our laboratory to determine exact pH values at varying depths.
