In cold mountainous regions of China, the construction of highways is challenging, owing to frost damage of weak subgrade soils and the difficulties posed from dealing with waste materials derived from tunnel excavation. In order to address these issues, Wu et al. proposed a new approach of using coarse gravel reclaimed from tunnel excavation as an antifrost structural fill replacing the top layer of frost-susceptible subgrade soils. This approach was validated against the results of field investigations on the highway between Tanchang county and Diebu county (the TDH) in south Gansu Province, northwest China, but only studied the results of the first year. As an environmentally friendly and sustainable ground-treatment method, this strategy merits extensive research and widespread implementation. In this study, the frost-heave deformation of a two-year monitoring period is investigated through a field trial, and a frost-heave model is applied to explore the growth of the ice lens and accomplish the quantitative prediction of frost heave based on experimental measurements. The fine particles of reclaimed gravel sediments from the Lazikou tunnel are found to be resistant to frost. The measured values of the maximum frost heave are significantly lower than the permissible limit of 50 mm specified in the Chinese standards. The reclaimed gravel could significantly reduce frost heave. With a 2 m thick gravel fill, frost heave could be reduced by more than 70% when the groundwater table is located at a depth greater than 3 m. An empirical relationship to predict the frost heave in terms of the gravel fill thickness is proposed. This study presents a safe and sustainable approach focusing on the construction of highways in cold mountainous regions.