Experimental evaluation of the frost resistance durability of RCC layer subjected to early-age freezing

Abstract

Freeze–thaw cycle, shear and nuclear magnetic resonance tests were conducted to investigate the effect of early-age freezing on the frost resistance durability of roller compacted concrete (RCC) layers during their service period. The effects of interval time and pre-curing time on the frost durability of early-age frozen RCCs were discussed. The appearance damage, shear failure mode, shear strength and pore structure of the early-age frozen RCC layers after freeze–thaw cycles were evaluated. Results showed that the appearance damage of the early-age frozen RCC layers after the freeze–thaw cycles began with microcracks at the layer joints, which then extended to the upper and lower layers. The shear failure mode was dominated by slip failure. Early-age freezing caused initial damage to the layer and increased the rate of loss of peak shear strength and the volume of harmful pores during the freeze–thaw cycles. The degree of shear strength loss due to interval time was in a descending order as follows: 24, 12, 4 and 0 h. The loss in shear strength was the largest in the specimens pre-cured for 12 and 24 h, followed by those pre-cured for 48 and 72 h. The loss in shear strength was the smallest for the specimens pre-cured for 7 days, similar to the result for the unfrozen control group. In addition, the corresponding relationship between shear strength and pore structure at the layer of the early-age frozen RCCs during the freeze–thaw cycles was quantitatively described based on fractal dimension theory. A freeze–thaw damage model was developed to consider the effects of early-age freezing on the surface of RCC, and the calculated results of the model were in good agreement with the test results.