Concrete mixer trucks transport concrete from the batch plant—where they load aggregate, cement, and water—to the jobsite. Concrete mixer trucks are often erroneously called cement mixers or cement trucks, but the final product is concrete. The concrete can either be ready mixed at the plant, or the materials can be loaded into the truck, which then mixes the concrete as it travels to the jobsite.
The concrete is mixed in a rotating barrel mounted on the truck chassis. This barrel keeps the concrete liquid and ready to pour when it reaches the site after trucking. Inside the barrel are blades that mix the materials, called charging. These trucks are also called ready mix trucks for this reason.
On site, the concrete is poured from the truck through chutes, with the blades reversed to help push, or discharge, the concrete from the barrel. Concrete mixer trucks come in rear- and front-discharge configurations. Rear-discharge concrete mixers require a worker at the back of the truck to manage the chute and place the concrete appropriately. A front-discharge truck allows the driver to see the jobsite and place the concrete by controlling the chute from within the cab. In cases where the concrete mixer truck cannot access the jobsite, the concrete might be placed in a concrete pump, which pumps the concrete to the project.
The truck chassis have many axles in order to spread the weight of the loaded concrete to comply with various load regulations. The trucks travel over the road as well as off-road. They operate locally, as the concrete must be delivered and placed before it hardens inside the barrel. Hardened concrete is difficult to remove from inside the barrel.