Abstract
Results of length change measurement of early-age (8hr. to 14 days) concretes subjected to freezing and thawing cycles were examined for their relation to the freeze-thaw resistance of respective concrete. Water-cement ratio of concrete was fixed at either 45, 55 or 65%, while the air content was kept constant at 5.5%. The conventional method, in which a certain residual strain is employed as a reference value, was not necessarily adequate for the adequate evaluation of the freeze-thaw resistance of earlyage concrete. It was revealed that there existed a straight-line relation between the number of freeze-thaw cycles in a normal scale and the residual strain in a logarithmic scale in the region where the strain exceeded 100×10-6. A factor which was derived from the gradient of the linear relation was found to have a close correlation with the conventional durability factor, regardless of the difference in the mix proportions, ages and curing conditions concrete.
