Measuring pH levels
Audio for slide 1 (mp3 |6|KB)
When the alkalinity in a concrete subfloor is too high, it can stop the floor covering adhesive from bonding properly to the concrete.
Although this problem has always existed, it hadn't been fully realised by flooring installers until quite recently.
This is partly due to the fact that the materials used by installers have changed over time.
It's also due to continuing research and a much better understanding of the importance of pH levels.
Although this problem has always existed, it hadn't been fully realised by flooring installers until quite recently.
This is partly due to the fact that the materials used by installers have changed over time.
It's also due to continuing research and a much better understanding of the importance of pH levels.
Audio for slide 2 (mp3 |6|KB)
The new Australian Standard for resilient flooring installation (AS 1884-2012) now says that a pH test must be carried out on a concrete subfloor as part of the pre-installation assessment.
The minimum number of tests required is the same as for moisture testing - three in the first 100 m2 of floor, plus one extra test for every additional 100 m2.
The minimum number of tests required is the same as for moisture testing - three in the first 100 m2 of floor, plus one extra test for every additional 100 m2.
Audio for slide 4 (mp3 |6|KB)
Materials with a low pH level are more acidic and have a lower attraction for hydrogen.
Materials with a higher pH are more alkaline and have a higher attraction for hydrogen.
The balancing point is 7. If the pH is lower than 7, it is more acidic; if it's higher, it's more alkaline.
When it's right on 7, it's called 'pH neutral'.
Materials with a higher pH are more alkaline and have a higher attraction for hydrogen.
The balancing point is 7. If the pH is lower than 7, it is more acidic; if it's higher, it's more alkaline.
When it's right on 7, it's called 'pH neutral'.
Audio for slide 5 (mp3 |6|KB)
Freshly mixed concrete is extremely alkaline - well above 10 - but the pH level drops as the concrete cures.
AS 1884 says that the pH level of the concrete surface should be between 9 and 10 before the flooring installation is commenced.
However, it also says that the final level should be determined by the adhesive manufacturer.
You should also check on the pH requirements of other manufacturers' products that you might be using on the subfloor, such as moisture barriers, epoxy coatings and leveling compounds.
AS 1884 says that the pH level of the concrete surface should be between 9 and 10 before the flooring installation is commenced.
However, it also says that the final level should be determined by the adhesive manufacturer.
You should also check on the pH requirements of other manufacturers' products that you might be using on the subfloor, such as moisture barriers, epoxy coatings and leveling compounds.
Audio for slide 8 (mp3 |6|KB)
Note that if the surface is still not porous after sanding - that is, if it doesn't pass the water drop test - you'll need to use a hand grinder to remove the non-porous material.
Remember, if the water is beading on the surface, you won't get an accurate pH reading because you'll only be testing the pH of the water drop itself.
If you do have to mechanically prepare the surface, it's best to wait until just before you install the floor covering so that your pH test is done on the actual floor surface you'll be installing over.
Remember, if the water is beading on the surface, you won't get an accurate pH reading because you'll only be testing the pH of the water drop itself.
If you do have to mechanically prepare the surface, it's best to wait until just before you install the floor covering so that your pH test is done on the actual floor surface you'll be installing over.
Learning activity
Audio 13 (mp3 |6|KB)Flooring Resources have produced a video clip called 'pH test for concrete' which describes how their pH test kit works. The link below will take you to the clip.
pH test for concrete
pH testing is still quite new for concrete floors, but there are other pH tests that people do all the time, including in their own homes. One example is testing pH levels in swimming pools.
Another is testing the soil in vegetable gardens, especially when certain types of vegetables aren't growing as well as they should.
Have you used a pH test kit before? What were you testing? How did the system work?
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