Coupled effects of sustained compressive loading and freeze-thaw cycles on water penetration into concrete

The combined action of sustained loading and freeze-thaw cycles (FTCs) plays an important role in the durability and service life of concrete exposed to the cold coastal area. Water transport is a primary factor closely pertaining to freeze-thaw damage in concrete, and the microcracks induced by sustained loading could provide a flow path to facilitate water penetration into concrete. This paper presents the results of an experimental investigation on water penetration behavior of ordinary and air-entrained concrete (OC and AC) subjected to sustained compressive loading and FTCs. Aiming at the combined effects of low compressive stress ratio and FTCs on water transport, a series of water absorption and permeability experiments with the stress ratio of 0, 0.3, and 0.5 after various FTCs were conducted. The relative dynamic elastic modulus and mass loss were afterwards measured to characterize the frost damage within concrete. The experimental results indicated that the sustained compressive loading and frost action have significant influences on capillary water absorption and permeability for the OC and AC specimens. Both the initial coefficient of capillary absorption and water permeability coefficient increase with the increase of FTCs, while they initially decrease and later increase with the increase of compressive stress ratio.