Which element is specific to batch plants and not listed as a basic element of drum plants?

• A. Pug mill mixer
• B. Burner
• C. Parallel Flow Dryer
• D. RAP Entry Point

Answer: (A)

The key idea is understanding how mixing happens in batch versus drum asphalt plants. In a batch plant, the aggregates are dried and screened, then prepared in separate weighed portions, and the final blending with asphalt cement happens in a dedicated mixing device called a pug mill mixer. This device blends the materials in discrete batches, which is why it’s unique to batch plants. Drum plants, on the other hand, use a continuously rotating drum that dries and mixes everything inside it in one ongoing process, so there isn’t a separate pug mill as part of the basic drum-plant setup.

The other items are elements you commonly find in drum plants: a burner provides the heat for drying, and the parallel flow dryer describes how the drum and gas flow are arranged in many drum plants. Introducing reclaimed asphalt pavement is also a standard feature in drum plants through a RAP entry point. So the pug mill mixer stands out as the component specific to batch plants.