New Practice for Measurement of Concrete Slab Surface pH using Electronic Meters
1. Scope
This practice will establish standardized procedures for the quantitative measurement of concrete subfloor surface alkalinity using electronic pH meters. The scope will includes specific protocols for pH electrode calibration, surface preparation, application of distilled or deionized water, and the required equilibration time to ensure stable readings. It is designed for use on concrete slabs, cementitious underlayments, and self-leveling materials to verify compatibility with moisture and alkalinity sensitive adhesives, resinous coatings (including mitigation systems), and resilient flooring systems.
Keywords
alkalinity; cementitious underlayment; concrete; concrete pH; concrete slab; concrete slab pH; digital pH meter; electronic pH meter; flat surface pH; flat surface pH meter; equilibrium pH; quality assurance; floor failure; floor failure investigation; adhesive failure; concrete alkalinity; concrete testing; efflorescence; high pH; pH testing; concrete surface chemistry
Rationale
Current industry reliance on colorimetric pH paper (litmus testing) is increasingly recognized as insufficient for high-stakes flooring and coating installations. Independent scientific research studies, including from the medical field, have demonstrated that pH paper is highly susceptible to gross inaccuracies. These inaccuracies stem from manufacturing variances, chemical degradation due to light and humidity exposure, and the shelf-life of the reagents, all of which can occur before the paper is used on-site.
Use of pH paper relies on the subjective interpretation of color scales, which is prone to significant user error and variation under different lighting conditions. Reliance on inaccurate pH data is the root cause of many floor failures.
This standard is necessary to provide a quantitative, data-driven alternative. By using electronic pH meters, stakeholders can eliminate the variables of color interpretation and reagent degradation.
This standard will be used by contractors, installers, inspectors, and manufacturers to provide a scientific and technically defensible measurement of slab alkalinity, reducing the incidence of alkalinity-related flooring failures.
The title and scope are in draft form and are under development within this ASTM Committee.
Work Item Status
Date Initiated: 10-30-2025
Technical Contact: Walter Bell
Item: 000
Ballot:
Status: