It was found that binary and ternary blended cement mortar containing FA and BA had lower drying shrinkage than that of PC control while drying shrinkage of ternary and quaternary containing SF replacement were higher than PC control and tend to increase with increasing SF replacement.
The drying shrinkage of blended cement mortar containing FA and BA was lower than that of PC control due to the lower of reaction (both of hydration and pozzolanic reaction) of blended cement and the dilution effect which contained finer pore lower than PC control and result to the lower autogenous shrinkage.
However, the drying shrinkage of blended cement mortar containing SF tend to increase due to high reactivity and fineness of SF which fill the capillary pore of cement pastes and greater pozzolanic reaction.
Drying shrinkage is not only caused by pore structure refinement by C–S–H gel formed and fineness of pozzolanic materials but also water removal from surface area of C–S–H and pozzolanic materials all of which have an effect on drying shrinkage of multi-blended cement [14].
Fig. 8a shows the drying shrinkage of multi-blended cement mortars cured in water at 25 C.
It was found that the drying shrinkage of binary and ternary blended cement mortars containing FA, BA and incorporating SF at 5% by weight (50FA, 30FA20BA, 45FA5SF and 30FA15BA5SF mixtures) were lower than PC control.
This is due to the lower of reaction of blended cement than PC control, especially blended cement mortars containing FA and BA which results to lower autogenous shrinkage and lower pore refinement.