Temperature control and energy-saving efficiency evaluation of low-energy warm-mix asphalt mixtures with composite additives

Traditional warm-mix asphalt (WMA) faces challenges in reducing mixing temperatures to achieve lower energy consumption. To address this challenge and meet global environmental goals, this study designs various composite warm-mix additives using commonly used additives and their optimal dosages. The viscosity reduction mechanisms of asphalt and asphalt mixtures are examined using viscosity-temperature and air voids-temperature curves. Regression equations for viscosity and voids as a function of temperature are developed to determine the optimal mixing temperature of WMA. The study integrates thermodynamic equilibrium equations with field data to quantify the energy consumption in producing composite WMA mixtures. The results reveal that WMA significantly reduces mixing temperatures, making it suitable for low-energy asphalt mixtures. The use of various composite additives enhances the mechanical properties of asphalt pavements. Optimal mixing temperatures are set as 60-100 degrees C for WMA in warm-paving applications, and 20-60 degrees C for WMA in cold-paving applications. Viscosity ranges from 0.17 to 0.28 Pa s, with air voids varying from 6% to 7% for WMA in warm-paving applications and 8%-9% for WMA in cold-paving applications. Controlling the mixing temperature improves energy-saving efficiency, achieving reductions from 47.1 % to 97.6 %. The study recommends the use of WMA (Sasobit/Evotherm/DAT) for warm-paving applications and WMA (Sasobit/Diesel oil) for cold-paving applications. This study provides valuable insights for developing energy-efficient and high-performance asphalt pavements.