Effect of Ageing on Pore Structure and Permeability of Cementitious Materials

Abstract

The durability of cementitious materials is influenced by their pore structure and by the transport properties in the near-surface zones. The permeability is controlled by the continuity of the capillary pores, which decreases with increasing hydration. Reactive additions such as ground granulated blast furnace slag (ggbfs), fly ash, or natural pozzolana may cause a hydration behaviour different from the hydration of ordinary Portland cement. Their reaction rate is slow compared to that of the Portland clinker, however, these hydration products may exhibit a denser structure. Therefore, cements blended with large amounts of hydraulic or pozzolanic additions may require longer hydration periods to achieve their favourable properties [1,2].

Carbonation of the near-surface zones also causes a significant change in the microstructure of concrete due to the deposition of the carbonation products within the pore system [3,4], thus, carbonation may also affect the transport properties in the near-surface zones.

In mortars and concretes, the paste/aggregate interface exhibits characteristics which are different from the bulk paste. The properties of this weak contact zone may be improved by reactive additions [5, 6].