The simple Heat-Box:

The Heat-Box is just a cube of an insulating material. The cube has a void for the concrete sample.

The insulation material has the density 13-15 kg/m3 and the thermal conductivity = 0.04 W/mK approximately.

Expanded polystyrene (EPS) is appropriate to use.

If you find a material with slightly other density and thermal conductivity it may not be a problem, because an initial calibration procedure should be done before the first test.

If you are using these molds:Cylindar Molds (USA) or Cylindar Molds (Europe) (height 308 mm) the external dimensions of insulation should be:

length x width = 600 x 600 mm, height = 610 mm

The box can be built up by the following layers:

  1. 150 mm (EPS without void, lid)
  2. 310 mm (EPS with void)
  3. 150 mm (EPS without void, bottom plate)

In the layer in the middle a void (cylinder) is made for the mold.

The individual layer can be built by several thinner layers, if it is appropriate.

If you are using EPS blocks, you can use a hot wire for cutting the void.

Instead of using blocks you can make a box and fill it with beads around the mold. In that case you must consider the supporting of the mold. The supports should be very slender having a low heat capacity and a low thermal conductivity.

If you are using a thin sheet metal container as a mold the software can also handle standard cylinders with the height 300 mm. In that case the central layer should be only 300 mm.

In order to get minimum 20 mm air gap below the box, it should be placed on 4 spacers.

The Heat-Box software can handle 3 boxes.

The datalogger:

To measure the progress of sample temperature and ambient temperature, a datalogger with 2 channels is needed.

The Heat-Box software accepts a format like:

    id Date/time Channel 1[°C] Channel 2[°C]

    1 07/11/2006 10:24:37 15.30 23.30

    2 07/11/2006 10:29:37 15.50 22.50

    3 07/11/2006 10:34:37 15.60 22.50

    4 07/11/2006 10:39:37 15.70 22.60

    5 .. ..

However, the date and time format could be different, and you can also use Fahrenheit, [°F].

The Testo 175-T3 datalogger delivers the mentioned format. If you use other dataloggers you must transform the measured data into the required format, before using the Heat-Box software.

How to try it out:

The procedure for calibration of the box and determination of the Heat of Hydration is found here. (Regarding the datalogger, the introduction will of course differ if you are using another datalogger than Testo 175-T3).

If you want to check that you get the correct results, before purchasing the software, you are welcome to do the following:

  1. Build the simple Heat-Box.
  2. Complete the calibration and determination of Heat of Hydration.
  3. Send the obtained 2 text files to us.
  4. Inform us about weight of water when calibrating and the height of the mold.
  5. Inform us about weight of concrete sample, powder content, density and heat capacity (or provide us with the concrete mix recipe).

Then we will use the Heat-Box software and calculate the Heat of Hydration for you.

Heat-Box