The term "concrete mixer" can refer to two types of plant: either a small mixing machine used in the building industry, or ready-mix concrete lorries which take the concrete onto the sites. In the public works sector, the second definition is intended.
The role of ready-mix concrete lorries is to bring the prepared concrete from a concrete mixing plant, if this is not already on site.
The main element is a mixing drum with a horizontal axis, in the shape of a cylinder-type cone. The size of these machines means that large quantities of concrete can be produced. The batches obtained vary from 7,000 to 14,000 litres (a batch is the unit of production corresponding to the capacity of the tank).
According to specific requirements, ready-mix concrete lorries can take ready-prepared concrete, or just the components (cement, aggregates, water etc), which will be mixed during transportation. These are firstly introduced into the drum via feed hoppers, then the mix is obtained with the help of mixing spirals. The concrete mixer is also equipped with a water reservoir, in order to ensure the batch has the correct water content.
Once it has arrived at its destination, it is unloaded via conduits called "chutes" by reversing the tank’s operating direction.
Some ready-mix concrete lorries also incorporate an insulation panel in the mixing drum, enabling the transportation of concrete in difficult climatic conditions (heat, etc).