In a civil construction environment, the temperature of concrete during the curing process needs to be measured and recorded to evaluate the process of curing and removal of framework thereafter.
Such measurement can be carried out by different methods:
In this process, the temperature can be continuously recorded. There are temperature data loggers with external thermocouple probes. The data logger will have a capacity of readings such as 8000 readings for a model being supplied by Cryopak, USA as seen in this image. If data is taken every 10 minutes this means a recording capacity of 55 days. However for concrete curing, 7-10 days’ readings only are required and hence a model with 8000 readings is more than sufficient.
A thermocouple can be inserted into the data logger. any type and length of thermocouple can be used. The thermocouple can be inserted into the concrete before curing start the recordings on the data logger. The current temperature will always be displayed on the LCD screen and the recording also will take place. When the recording is over, remove the thermocouple from the data logger. You will have to leave the thermocouple in the concrete since it cannot be removed now after the concrete is cured. The data logger can be reused using a new thermocouple. The data logger can be connected to a computer and the data can be downloaded.
2. Concrete temperature measuring using a thermocouple (No recording)
In this method, the recording will not happen. Thermocouple wires are cheap cables used to measure the temperature. Thermocouple wires come in different length such as 1 meter, 10 meters, 50 meters, 100 meters etc. During the concreting process, the thermocouple can be inserted into the concrete at various points. The thermocouple has two ends viz. one end which measures the temperature and the other end consisting of a pin to insert into a measuring device. The end with the pins should be kept outside the concrete works. Whenever readings need to be checked, the meter can be inserted and the readings can be taken.
In the example shown in this image, thermocouple probes are inserted at 1 meter, 10 meters & 20 meters. The connecting pins are kept outside the concrete. You can take a measurement using a meter at different times. The thermocouple cannot be taken back after curing because it has gone deep inside the concrete. However, this will not be a major concern, since the wire is very thin and very cheap.
The meter for taking measurement also is shown over here. There is a small plug at the bottom to which the pin can be inserted. The selector switch at the front has to be switched to °C upon which the temperature of the concrete will be automatically shown.
3. Temperature recording using Multi-channel Data Loggers/ Recorders
If you need to record the temperature at different points of a concrete block or beam simultaneously and compare the temperature at various points simultaneously, you may have to use a Multi-channel data logger. These are capable of taking up to 200 temperature sensors or thermocouple from various points of a concrete block. This is especially useful when large concrete beams are made and the curing process has to be uniform across the entire length, failing which the strength will be affected. The multi-channel data loggers are capable of storing millions of data in the data logger and also can be connected to a computer. The multi-channel data logger has a graphic display screen in which graph of all the sensors are shown simultaneously and the operator can check whether there is any wide deviation between various points
We have various instruments for measuring concrete temperature data of concrete core and skin.
Also please see our separate article on temperature measuring of concrete with the handheld printer.
Summary of this Article on Methods for temperature measurement of concrete during the curing process:
It is important to measure and record the temperature inside the concrete during the curing process. For this purpose, we have to insert thermocouples into the concrete and take the measurements using different types of instruments. This article gives a brief of different methods for measuring the temperature inside concrete at various points.
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