Pore Size Distribution of Cement Based Materials Determined by Dynamic Water Vapor Sorption and Low Temperature Calorimetry

In this work, both dynamic water vapor sorption (DVS) and low temperature calorimetry (LTC) methods were adopted to study the pore size distribution of cement pastes prepared by two types of cements CEM I and CEM III. A model porous material, MCM-41, was also included in order to investigate important aspects of the measurement and the data evaluation approaches. As indirect methods for pore structure characterization, important assumptions involved in the data analysis of both methods were highlighted and discussed. In addition, a special attention was paid to the comparison of the results obtained from the two methods. A careful examination of the bases for the two methods for pore structure characterization revealed that a number of matters could affect the obtained results, including sample preparation, possible influencing factors on the measured results, unsolved factors for data analysis, etc. Consequently, the results obtained from one method might differ significantly from the other. Nevertheless, a certain degree of agreement was still found for the pore size distributions determined by the DVS and the LTC methods, despite of the uncertainties involved in each method. Meanwhile, it was concluded that probably none of the two studied methods could deliver the “true” (actual) pore size distribution information at this stage. To further improve the accuracy of the results obtained from the methods, it was highlighted that emphases should be laid on clarifying relevant assumptions made in both measurement and data analysis.