CCM – measuring instrument
The carbide measuring method
Determination of the water content with a CCM device
CM measurement, measurement of residual moisture with a CCM device
Laying out ceramic tiles or other materials on surfaces containing too much moisture may subsequently lead to considerable constructional defects or structural damages. You better make sure in advance before tasking any risk. In the end it’s unfortunately YOU who layed the floor and who will be held accountable. So you better play it safe!
The carbide measuring method is particularly suitable for evaluating the readiness for covering of substrates before installing tiles.
A so-called Hydromette is used for rough estimations of the residual moisture in the substrate. However, a Hydromette can not measure an exact value but only reference values.
Reference values serve as a guide to determine the state of drying of the screed. A Hydromette is especially well suited for determining the highest moisture content location of the screed. This is the only area where it is worthwhile to carry out a carbide measurement in order to avoid later risks.
Carbide method – calcium carbide measurement
But now to the principles of the actual carbide method. CCM stands for CalciumCarbideMeasurement, short CCM. As already mentionned the carbide method is particularly suitable for determinating the residual moisture in screed and with this, for evaluating the readiness for covering of screeds. By means of a practical example we shot a film about the detailed procedure. Please find the video clip right here!
Steps of the carbide method (CCM):
The work steps of the carbide measuring method can be explained in short. It is a tool – a tool that eases the daily routine on the job site and protects you from possible problems. See for yourself how simple the individual work steps respectively the use of this CCM device are:
1. Identify the most humid spot
First of all you need to detect the most humid spot of the screed. In this work step a Hydromette for example can be a most helpful tool. It can measure the residual moisture up to 2cm down in the substrate and show approximative values. Please bear in mind the subconstruction of the floor. If there is a floor heating please mind the check points given by the composition floor layer. This prevents you from destroying the floor and the subconstruction. As soon as you have detected the most humid spot you can proceed to step 2:
2. Average value of the residual moisture
Hit a hole into the screed with a hammer. A 2x2cm wide hole is absolutely sufficient. This prevents the screed from bigger damages. For the calcium carbide measurement it is important to take samples of the complete cross section of the screed. To get representative and valid results you have to measure through all layers of the screed. The result is actually a mean value of the residual moisture in the screed, from the top layer,which is most of the time the dryest, to the lowest layer which dries slowlier since there is no air contact.
3. Break the material
Use a glove when you take the material sample out of the screed as the humidity of your skin might in the worst case change the value. Then grind the sample in the bowl by using the enclosed hammer. Both tools, hammer and bowl, are part of the CCM device set. Grind the average sample in the bowl to the extent that complete grinding is possible in the CM device with the steel balls. We recommend that the maximum diameter of the pieces should not exceed 1-2cm!
4. Determinating the necessary quantity
After grinding the sample you can weigh out the necessary quantity with the available balance. Use the enclosed spoon to fill the grinded material sample from the bowl into the small PE bag, preliminarily fixed to the precision spring scale. The necessary quantity in grammes varies as it depends on the used screed material. Weigh out a material sample from the prepared test material according to the following list: - Calcium sulphate screed: 100g / - Magnesia screed “young”: 20g – and when ready for covering: 50g - Cement screed “young”: 20g – and when ready for covering: 50g
5. Place the glass ampoule containing calcium carbide inside – measuring result
Place the test material (the crushed screed) and the steel balls in the opened CM device. Hold the CM device at an angle and place the glass ampoule containing calcium carbide inside. Please do not touch the glass ampoule with your bare hand as the humidity of your skin might influence the test result. We ask you to consider the following instructions in order to achieve a representative result:
6. Shaking the CM device - measuring the residual moisture
Shake vigorously after closing the CM device! Please shake back and forth and in circular movements. If you shake the CM device too strongly from top to bottom there is a risk of damaging the manometer. With the aid of the steel balls the test material will be fully ground and the glass ampoule with the calcium carbide will break. It’s only after the release of calcium carbide that a chemical reaction with the test material can take place so that the residual moisture content can be measured. Please shake at least for 2 minutes at the beginning.
7. Determination of the final value/final residual moisture
Wait at least 10-15 minutes before determining the final value / final residual moisture content while shaking every 5 minutes for 1 minute as described above. Before reading the final value of the CM measurement you should again shake the CM device for about 10 seconds. The final result (moisture content) can be read off directly from the manometer or taken from the calibration table (see operating instructions). Enter the value read in the log.
8. Don’t let yourself feel insecure by increasing values
Please note: A further increase in pressure is possible with calcium sulphate-bound screeds; this is to be disregarded, since chemically (i.e. firmly) bound water is present.
9. Cleaning the CM devise and checking the test material
Please clean the CM device thoroughly after use and put all accessories into the metal case. Please check the consistency of the test material after each measurement. If the test material is not completely ground , discard the test result and repeat the meaurement. It might be of avail to shred the material more finely in preparation of the measurement.
10. Disposal of waste
Please note: Dispose the test material containing also glass particles amongst other things in accordance to the instructions of the supplier. In case of further questions please do not hesitate to contact our expert advisers by email: firstname.lastname@example.org or phone +49 8667 878 0
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