CALORIMETRY

The heat evolution of reacting cement and extenders has been measured using a variety of methods. The methods are defined by three different groups of calorimetry: isothermal, semi-adiabatic and adiabatic.

 

A definition of each method of calorimetry is as follows:

 

• Isothermal methods attempt to measure the heat generated during a reaction where the sample is kept at a constant temperature

• Semi-adiabatic methods monitor the heat liberation of a reaction while attempting to limit the heat exchange between the sample and the environment but not entirely preventing it

• Adiabatic methods aim to eliminate the heat exchange between the sample and the environment as far as possible during the reaction

 

Isothermal and semi-adiabatic calorimetry pose a problem as the rate of heat liberation is influenced by temperature; therefore the heat lost to the environment is not able to contribute to the temperature of the sample and ultimately the rate of heat evolution is affected. For this reason 'fully' adiabatic calorimetry is favoured by researchers attempting to limit this heat exchange between the environment and test sample.

 

Apart from largely eliminating the heat exchange between a test sample and the environment, adiabatic calorimetry is also convenient, easily reproducible and a practical procedure, given that the equipment is of sufficient quality.