2017 Volume 71 Issue 1 Pages 386-393
There has not been sufficient knowledge on the effect of suppressing cracking of concrete containing fly ash（hereafter FA）. In this study, the restrained cracking test of mortar containing FA with less than 1.0％ of the loss on ignition using the embedded reinforcing bar test method developed by the authors was carried out under the drying condition of different relative humidity and the shrinkage cracking resistance of FA mortar was investigated in detail. As results of the experiment, the lower the relative humidity the earlier the occurrence of cracking and the larger the number of specimens cracked. Also, in the formulation mixed with FA, there were few specimens with the occurrence of cracking compared with reference mortar without FA, and the age of the occurrence of cracking was delayed. It was found that the addition of FA decreases the drying shrinkage strain and increases the rate of increase of the constraint stress generated in the mortar, and this is considered to be the contribution of the crack prevention effect.
