Monitoring pozzolanic activity by direct activation with calcium hydroxide

In this paper the change in conductivity of pozzolan/CH mixtures, at ambient temperatures, is monitored for periods extending over two days. Such a method allows the chemical activity within the mixture to be followed and it is shown that a number of features/parameters can be identified which are related to the pozzolanic reactivity of the material. In particular, a pozzolanicity index is developed and is based on data obtained from conductivity measurements. The index reflects both the rate of pozzolanic reaction and time to setting. Work is presented on a range of cement replacement materials.