Method for determining early-age frost damage of concrete by using air-permeability index and influence of early-age frost damage on concrete durability

In this study, a method for determining the early-age frost damage focused on the advantages of the Torrent air-permeability test, in which structures are measured nondestructively in their original locations was proposed, and the influence of early-age freezing on the durability of concrete is examined. In the experiment, series I for examining the influence of the freezing depth and series II for examining the influence of the beginning of the freezing age were carried out using by mortar specimen. And based on the results of the mortar test, a concrete experiment was performed to propose a method for determining the early-age frost damage and its influence on the durability. As a result, it is confirmed that the early-age frost damage to concrete could be determined by measuring the Torrent air permeability according to the freezing depth and beginning of the freezing age. In addition, by integrating the mortar and concrete test results, a criterion was proposed to determine the early-age frost damage by measuring the Torrent air permeability at 3 d. Furthermore, it indicate that even specimens with a compressive strength equal to or exceeding 5 N/mm(2) are subject to durability deterioration when damaged by early-age frost. The proposed Torrent air-permeability method also can be used to identify such changes in the integrity of concrete. (C) 2017 Elsevier Ltd. All rights reserved.