Mixer trucks, specifically their drums, are primarily categorized by their design to optimize for various concrete mixes and operational requirements, although the core function of mixing remains. The most common type is the transit mix drum, which is the standard conical drum seen on most concrete agitator trucks. These drums are designed to keep the concrete thoroughly agitated while in transit, ensuring a consistent mix from the batch plant to the construction site. They are incredibly versatile and handle a wide range of standard concrete mixes. The helical blades inside ensure continuous mixing to prevent hardening and facilitate efficient discharge.

Another less common but specialized type is the volumetric mixer truck, which is fundamentally different. Instead of a pre-mixed batch, a volumetric mixer carries the raw ingredients (cement, aggregates, water, and admixtures) in separate compartments. The actual mixing of the concrete occurs on-site, in real-time, only as needed. This allows for precise control over the exact volume and type of concrete produced, eliminating waste from over-ordering or hardened concrete. It’s particularly useful for small, diverse jobs or in remote locations where a traditional ready-mix concrete truck might not be practical. While the transit mixer agitates pre-mixed concrete, the volumetric mixer produces it on demand, each serving distinct operational niches within concrete delivery.