SHRINKAGE STRAIN DISTRIBUTION IN HIGH STRENGTH CONCRETE WITH ONE SURFACE EXPOSED TO DIFFERENT RELATIVE HUMIDITY

Shrinkage strains of high strength concretes wit and without silica fume were measured at various depths from the drying surface by using linear variable differential transformer (LVDT) displacement sensors, and only one surface of the prism specimen was exposed to drying conditions (RH=75%, 54% and 33%) during the experiment. The results show that the internal shrinkage strain becomes lower with the increasing depth from drying surface. Such shrinkage difference gets severer with the longer drying time and the lower relative humidity of drying condition. There is a linear relationship between the reduction of internal relative humidity and shrinkage strain at every depth of specimen. However, the increased shrinkage at inner position is higher than that at outer position of each specimen when the same reduction of relative humidity happens.