Enhancement of early-age frost resistance of roller-compacted concrete pavements with antifreeze admixtures: Field investigations in cold regions

Ensuring adequate early-age frost resistance remains a critical challenge for the field performance of roller-compacted concrete (RCC) pavements constructed in cold weather conditions. To address this challenge, this study investigates the effectiveness of antifreeze admixtures in mitigating early-age frost damage in RCC pavements. In the first stage, the effects of calcium nitrate and sodium thiocyanate on the mechanical performance of RCC under simulated cold conditions were examined in the laboratory, and the optimum dosage was identified as 3% calcium nitrate and 2% sodium thiocyanate. In the second stage, two RCC pavement sections—one without antifreeze and the other incorporating the optimum antifreeze dosage—were constructed under winter conditions. Core samples taken from the pavement at 7, 28, and 90 days were used to assess compressive strength, density, water absorption, and sorption properties. In addition, the mineralogical and microstructural characteristics of the concretes were analyzed using X-ray diffraction, scanning electron microscopy, and micro-computed tomography. These analyses revealed that cold exposure significantly limited hydration in the antifreeze-free RCC, leading to freeze-induced microcracking, a more porous microstructure, and a low 7-day compressive strength of 21.60 MPa. In contrast, the antifreeze-modified RCC exhibited hydration behavior comparable to that under standard curing conditions, with no evidence of early-age frost damage. As a result, the antifreeze-modified RCC achieved a 7-day compressive strength of 57.15 MPa, exceeding even the 90-day compressive strength of the reference mixture.