Experimental investigation on shrinkage and water desorption of the paste in high performance concrete

• The shrinkage behavior of the paste in high performance concrete is studied.
• Two regression lines were established in each shrinkage vs water desorption plots.
• The cement-fly ash paste has highest shrinkage among the composite pastes.
• Increasing curing time and reducing w/c ratio reduces the shrinkage of cement paste.

The shrinkage and water desorption of the cement paste with various mineral admixtures, water/binder (w/b) ratios and curing times were measured in different environmental humidity, and the shrinkage behavior of those pastes were analyzed by studying their pore structure. The results indicated that, the paste contains fly ash has highest shrinkage and rapidest water desorption among the pastes of cement, silica fume cement and ground granulated blast slag (GGBS) cement; the shrinkage increases with the w/b ratio and reduces with the curing time. The porosity and pore diameter in the early age paste control the water loss and water desorption rate and the shrinkage of the paste. The curves of shrinkage versus water desorption of different pastes were very similar, two regression straight lines were established in each plots, one was in relative humidity (RH) of 45% and 60%, the other one was in RH 15%.