Correlation of microwave and conduction calorimeter measurements on the hydration of cement

摘要

Ordinary Portland eenienl (OPC) is one of the most widely used construction materials. The hydration of cement involves very complicated chemical and physical processes. A better understanding of the mechanisms of hydration and microstruclural development in the cement paste is important for improving its mechanical strength. There are two methods to study cement hydration in situ. One is conduction calorimetry 111 which is a well-established method, and the other is electrical measurement [2- 71 which is not yet well established because of the difficulty in directly relating the results of the electric measurement to the chemical and physical changes which occur during cement hydration. We have successfully developed a microwave technique to study the early hydration of OPC [H], slag cement [8,9], mortar [10] and OPC high-alumina cement (MAC) blend [II] by measuring the change in dielectric constant during cement hydration. The heat evolution rale of OPC in the first 30 h of hydration measured using conduction calorimetry is shown in Fig. 1.