How to determine the moisture content of concrete

  • Thread starter lorand
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In summary: Yes it is possible to measure the moisture in concrete with such method, as long as you don't consider the results (quantitatively accurate) if you are measuring a structural element such as a slab, beam, ... etc. However, I'm not sure about the emission rate such concrete sheet might have. I'll have to look into it, but have you tried a reading already?I wouldn't believe the resistance readings anyway. Self levelling concrete has additives that might affect the conductivity. A good rough check can be made by taping some plastic visqene to the floor and let it sit overnight. ANY condensation on the underside of the plastic will cause problems with adhesion.Sorry to dig up
  • #1
lorand
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Hi there,

I'm just curious as to how to determine the moisture content of some concrete we've recently set. I was hoping I could just use an Ohm meter to, set the probes say 1cm apart and have some kind of table that corresponds to xxx resistance = xxx % moisture content.

Anyone have any ideas?
 
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  • #2
Yes it is possible to measure the moisture in concrete with such method, as long as you don't consider the results (quantitatively accurate) if you are measuring a structural element such as a slab, beam, ...

If you have the cores of the structural element, you could try a gravimetric approach which is more accurate.
 
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  • #3
Oh, this is only a small amount of self levelling concrete - in a room about 4m x 3m - and thickness of the self-levelling is ~11mm. Reason we need to figure out the moisture content is we are planning on laying down some bamboo flooring (with adhesive) and the documentation requires less than 5% moisture content for normal sealant application.
 
  • #4
Electronic meters are usually not recommended to get an accurate reading, as i said above. I will recommend another procedure like Calcium Chloride test, you could look it up on the ASTM website.

However, I'm not sure about the emission rate such concrete sheet might have. I'll have to look into it, but have you tried a reading already?
 
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  • #5
I wouldn't believe the resistance readings anyway. Self levelling concrete has additives that might affect the conductivity. A good rough check can be made by taping some plastic visqene to the floor and let it sit overnight. ANY condensation on the underside of the plastic will cause problems with adhesion.
 
  • #6
Sorry to dig up an old thread, but I was browsing this forum and I can't stand to leave this question not completely answered. All the methods that have been talked about here can give an indication, but there's the whole qualitative vs. quantitative test issue. I think this article by industry expert Howard Kanare really addresses the issues more directly than I've seen anywhere else.

http://www.wwwagner.com/pdf/HK%20Problems%20with%20moisture%20Eprint.pdf

Good luck to all who run across this problem again!
 
  • #7
lorand said:
Hi there,

I'm just curious as to how to determine the moisture content of some concrete we've recently set. I was hoping I could just use an Ohm meter to, set the probes say 1cm apart and have some kind of table that corresponds to xxx resistance = xxx % moisture content.

Anyone have any ideas?

I just joined this forum and it's so weird that I just came across this thread because I have a similar question! I'm interested in finding out how much moisture is going through a concrete floor attached to my house. Does anyone know where I can get a test? I did a little research and discovered a place that has a calcium chloride test but I would like a review if anyone has used it, and also I would like to know how to use it!
Thanks so much!
 

What is the purpose of determining the moisture content of concrete?

Determining the moisture content of concrete is important because it affects the strength, durability, and overall performance of the concrete. Excess moisture can lead to structural issues such as cracks and degradation, while insufficient moisture can result in a weak and brittle concrete.

What are the methods used to determine the moisture content of concrete?

The most common methods for determining the moisture content of concrete are the calcium carbide method and the oven-drying method. Other methods include the electrical resistance method, the microwave method, and the nuclear radiation method.

How accurate are the results of moisture content tests?

The accuracy of moisture content tests depends on the method used and the conditions in which the test is conducted. Generally, the calcium carbide method and oven-drying method are considered to be the most accurate, with results within 1-2% of the actual moisture content.

What factors can affect the moisture content of concrete?

The moisture content of concrete can be affected by a variety of factors, such as the ambient temperature and humidity, the type and amount of cement used, the water-cement ratio, and the curing process. Other factors include the type and condition of the aggregates, the mixing procedure, and the presence of admixtures.

Can the moisture content of concrete be controlled?

Yes, the moisture content of concrete can be controlled through proper testing, monitoring, and management. This includes using the correct water-cement ratio, ensuring proper curing methods are used, and controlling environmental factors during the curing process. Admixtures can also be used to regulate the moisture content of concrete.

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