A comparison between semi-isothermal and semi-adiabatic calorimetry of retarded cement mixes

Synopsis A comparative study has been made of the effect of three retarding admixtures, representing the main commercially available materials, on the rate of heat evolution from hydrating cement. Two methods of calorimetry have been used, semi-isothermal and semi-adiabatic, to enable a preliminary assessment to be made of any major differences between the methods. Because of experimental differences, the results from the two test methods are not directly comparable, but significant differences are seen between the two sets of data. This emphasizes the need to take into account the effect of temperature rise during cement hydration and the differing effects of various admixtures.