Correlation between pore structure and low-temperature dilatation of hydrated cement pastes and mortars

Abstract

The pore structure and low-temperature dilatation behavior of traditional hydrated Portland cement paste compacted by different methods were investigated. The aim of the investigation was to demonstrate the influence of the water-cement ratio and the compacting conditions on the developing pore structure and the frost dilatation during the early stage of the hydration process. A low water-cement ratio and a high compacting pressure resulted in initially low porosity, but in coarser pore sizes. Vibration resulted in lower pore volumes as compared with those of cast cement pastes, but the pore size distributions were similar. In accordance with the pore size distribution, two frost dilatation effects were measured when macro-and mesopores also occurred in the hydrated cement pastes. In the samples compacted by high pressure, a single frost dilatation effect occurred in connection with the macropores present in the sample. The magnitude of the frost dilatation effect decreased with increasing curing time. The decrease is caused by a decrease in the volume of the pores and also by an increase in matrix strength.