Concrete additives, along with the natural hydration process of the concrete, introduce some level of acid or baseto the existing moisture content of a concrete slab. Acids form hydrogen (positive ions) when added to water; bases form hydroxide (negative ions). Neither one is inherently good or bad, but they both have different atomic reactions when added to water. Those differences create an overall pH level which is neutral, acidic or basic. Moisture content and pH are inextricably linked by the chemical reactions that additives create in water.
The pH reading measures acidity vs. basicity. The pH scale ranges from 0 (battery acid) to 14 (liquid drain cleaner). How does this apply to concrete? When a finished floor product is to be installed onto the slab, many adhesive manufacturers will require pH levels of 10 or below. Unfortunately, freshly poured concrete has a pH of 12-13. This pH is due to the formation of calcium hydroxide during the hydration process. The calcium hydroxide then in turn reacts with carbon dioxide in the air , forming calcium carbonate, which reduces pH at the surface. This being said, if high levels of moisture are not present in the slab, there will be no vehicle to transport soluble hydroxides to the surface, thus adhesives and flooring are safe.
If one wants a slab to endure, pH is extremely important at the installation stage. However, it also can affect the performance of any adhesives, finishes or flooring materials applied to the concrete slab. So not only is a slab’s relative humidity (RH) significant but the pH can be as well.
Wagner Meters’ pH Meter
Wagner Meters produces its own Rapid RH® Digital pH Meter for installers who must meet appropriate pH levels in the slab. The digital pH meter is a valuable accessory to the Wagner Meters Rapid RH® moisture measurement system. Slab moisture content and pH are interrelated but, measured separately. Stakeholders need a conclusive assessment of both factors in order to give the “okay” for the finished flooring installation for installations where both measurements are required. So, Wagner Meters produces a self-contained pH meter kit so installers can conveniently build pH measurement into overall slab assessment.
The pH meter from Wagner Meters is designed for precision and convenience, and Wagner Meters recommends utilizing its pH test kit as an integral part of Rapid RH® moisture content assessment.
The Rapid RH® portable pH meter includes:
- automatic calibration with manual temperature adjustment
- electrode slope percentage display after calibration
- Liquid Crystal Display (LCD) of both the pH and temperature of the solution
- dual sets of buffer solution pH data (Chinese & Europeans standards) with manual selection
- automatic shutdown after 15 idle minutes
- Celsius (°C) or Fahrenheit (°F) display selection
- a portable case with room for all contents
Fundamental knowledge is crucial in understanding how pH may affect floor coverings as well as moisture content fluctuations during the concrete hydration process. The Wagner Meters Rapid RH® Digital pH Meter is valuable to obtaining data regarding pH prior to floor covering.
RH and pH are a tandem team during concrete installation, and maintaining an appropriate RH level can do much to mitigate potential pH problems. During hydration, concrete moisture content rises from the bottom of a slab to its surface. Many concrete assessment tools measure surface MC conditions, but the Wagner Meters Rapid RH® system verifies the entire slab’s moisture content for more precise RH levels, and for stable pH conditions as well. Researchers have proven the relative humidity assessment method to be most accurate method in determining slab MC; the Rapid RH® system from Wagner Meters is a cost-effective and expedient way of doing so. Appropriate RH levels lend themselves to helping maintain appropriate pH levels.
It’s nice to know that a potential flooring installation nightmare can be identified with a couple of easily-obtained test results with the Wagner Meters Rapid RH® and Digital pH Meter.