When using warm-mix asphalt in hot weather, process parameters must be adjusted based on the temperature characteristics to ensure the full performance benefits of warm-mix asphalt (such as reduced energy consumption, reduced emissions, and improved workability) are fully realized, while also preventing the adverse effects of high temperatures on material stability. The following are instructions and precautions for using warm-mix asphalt in hot weather:
I. Selecting Warm-Mix Asphalt Types
1. Selecting Based on High-Temperature Properties
Organic warm-mix agents (such as waxes and esters):
Features: They enable low-temperature application by reducing asphalt viscosity. However, their compatibility with asphalt at high temperatures requires attention.
Applicable Applications: For ordinary asphalt pavement in hot weather, the addition amount should be controlled (typically 3%-5% of the asphalt mass) to avoid excessive softening at high temperatures.
Surface-active warm-mix agents (such as water-dispersible types):
Features: They reduce the temperature of the asphalt mixture through a foaming mechanism. However, water evaporates rapidly at high temperatures, requiring adjustment of the water addition ratio. Applicable Applications: Thin-layer overlays and modified asphalt pavements in high-temperature environments. The addition rate is generally 2%-4% of the asphalt mass. Ensure even water distribution.
Compound Warm Mix Admixture:
Features: Combining organic and surfactant ingredients, it offers enhanced high-temperature stability and is suitable for complex climates.

2. Prioritize High-Temperature-Resistant Products
In high-temperature regions, it is recommended to use warm mix admixtures clearly labeled "high-temperature resistant" or "suitable for summer construction." For example, certain compound warm mix admixtures containing silane coupling agents can enhance asphalt-aggregate adhesion and reduce the risk of high-temperature runoff.
II. Construction Temperature Control
1. Asphalt Heating Temperature
Conventional warm mix process: Asphalt heating temperature is generally 130-150°C (20-30°C lower than hot mix). However, in hot weather, overheating of the asphalt should be avoided.
High-Temperature Correction: If the ambient temperature exceeds 35°C, the asphalt heating temperature can be lowered to 120-140°C. This allows the ambient heat to compensate for the mixture's cooling rate and prevent asphalt aging. 2. Aggregate Heating Temperature
General Control: Aggregate heating temperature should be 10-20°C higher than asphalt, ensuring the discharge temperature of the mixed mixture is between 120-140°C after mixing.
High Temperature Adjustment: In hot weather, the aggregate heating time can be appropriately reduced to avoid excessively high aggregate temperatures (e.g., controlled at 140-150°C). This prevents the active ingredients in the warm mix from becoming ineffective due to high temperatures.
3. Mixing and Paving Temperature
Mixing Temperature: The recommended mixing temperature for the mixture is between 125-145°C, approximately 30°C lower than hot mix, but ensuring uniform dispersion of the warm mix.
Paving Temperature: The paving temperature should not be lower than 110°C. In hot environments, it can be increased to above 100°C to maintain the plasticity of the mixture and reduce rolling resistance.