The effect of rate of drying on the drying/wetting behaviour of hardened cement paste

Miniature hcp specimens were dried at various rates from saturation to equilibrium at 53% rh, and were then rewet. Strain and weight changes were measured. The results show: a) recoverable and irrecoverable shrinkage was not affected appreciably by rate of drying; b) after the first 15% of the pores had emptied, rate of drying did not influence shrinkage vs. moisture loss; and c) the rate at which specimens were dried had no effect on the subsequent swelling vs. time or swelling vs. moisture gain relationships. It is concluded that spurious effects caused by internal moisture gradients were not significant; for a wide range of drying rates, miniature specimens can be used to measure the unrestrained response of the material.