Experimental observations of early-age drying of Portland cement paste under low-pressure conditions

Shrinkage properties of plain and recycled steel–fibre-reinforced rapid hardening mortars for repairs

“…Moisture movement during drying of concrete is characterised by two stages; a constant drying rate stage which is succeeded by a falling drying rate [12,15,23], depending on the degree of continuity between liquid and vapour phases and on driving force variations [16]. At the beginning of drying, the evaporation rate is constant and is approximately equal to the rate of evaporation of water exposed to the same conditions [24][25].…”

“…The moisture content continues to decrease until vapour pressure reaches ambient level. Figure 1 shows a typical cumulative moisture loss and evaporation rate during stage one and stage two for a cement paste sample [15]. It is shown that during stage one, the drying behaviour is independent of capillary microstructure [26].…”

“…It is shown that during stage one, the drying behaviour is independent of capillary microstructure [26]. In a study performed by Bakhashi & Mobasher [15] to investigate the effect of curing time on the diffusion characteristics of cement paste, it was found that the moisture loss was substantially reduced by curing the cement paste for 24 hours and the transition from stage one to stage two took place quicker compared to non-cured samples. This can be attributed to microstructural and pore distribution changes with additional hydration.…”

“…Since crack width is one of the main parameters that governs the durability of repairs [8], a thorough understanding of the effect of moisture movement and restraint from the substrate is needed to predict crack development in concrete, a material which has widely varied and dynamic porosity systems [9]. The moisture transport mechanism of cementitious mixes is complex and is the subject of extensive research [9][10][11][12][13][14][15][16][17]. FRC mixes, however, have been studied to a lesser extent [15,18].…”

“…The moisture transport mechanism of cementitious mixes is complex and is the subject of extensive research [9][10][11][12][13][14][15][16][17]. FRC mixes, however, have been studied to a lesser extent [15,18]. It is known that w/c ratio, cement content and cement type, directly affect moisture diffusion.…”