Evaporation Mechanisms and Variability Prediction of Concrete in Dynamic Urban Road Environments

During long-term service, concrete on urban roads is exposed to dynamic coupled environments, including diurnal temperature fluctuations, wind disturbance from traffic, and cyclic vibration from vehicle loads. Its early moisture evaporation behavior differs essentially from that in static atmospheric conditions. Clarifying the evaporation mechanism and evolution rules is a core scientific issue for improving the service durability of pavement concrete. In this study, C30 and C50 concrete mixes widely used in urban road engineering were taken as research objects. A self-developed dynamic environment simulation test bench was adopted, combined with macroscopic evaporation monitoring and microscopic methods including scanning electron microscopy (SEM), mercury intrusion porosimetry (MIP) and thermogravimetric analysis (TGA). The moisture evaporation characteristics of concrete under temperature/wind vibration coupling were systematically studied. The microscopic mechanism of dynamic evaporation was revealed, and a multi-factor coupled evaporation prediction model was established. The results show that a 5 °C temperature rise and 2 m/s wind speed increase raise the early evaporation rate by 32.5% and 28.7% respectively. Vibration at 30 Hz improves surface pore connectivity by 15.3–21.5%. Under dynamic coupled conditions, the 14-day cumulative evaporation of C30 and C50 concrete increases by 41.2% and 35.8% compared with static conditions, accompanied by reduced hydration degree and coarsened pore structure. The proposed model has an average relative error of 6.5% and a coefficient of variation of 7.8%, with significantly higher accuracy than classical static evaporation models. This work can provide a theoretical basis and technical support for mix optimization, early moisture curing improvement and durability enhancement of urban road concrete.