I. Methods and Principles of Warm Mix Agent Addition
Warm mix agent (WMA) is an additive used to lower the construction temperature of asphalt mixtures. Its core function is to reduce the viscosity of asphalt through physical or chemical means, allowing mixing and paving at lower temperatures (typically 20-30°C lower than hot mix asphalt). Depending on the method of addition, it can be divided into two categories:
1. Direct addition to asphalt: The warm mix agent is added before or during asphalt heating and then mixed into the asphalt. For example, organic viscosity-reducing warm mix agents (such as Fischer-Tropsch wax) must be mixed with asphalt at 160-170°C (see “Technical Specifications for Highway Asphalt Pavement Construction” JTG F40-2004).
2. Even mixing: The warm mix agent is added simultaneously with the asphalt mixing stage. This is commonly used in foaming warm mix technologies (such as water-based Asphalt-Min) and requires specialized equipment to achieve uniform dispersion within the mixing silo. II. Comparison of the Two Methods and Recommended Selection
