Cement is the most important ingredient for the preparation of concrete since it with the crystallization process mutually and firmly connects the particles of aggregate. Although it was known in Roman Empire its use has widely spread only after the discovery of Portland cement in England at the end of 19th century. Concrete is a product, made of cement, aggregate, water and additives. Fresh concrete is the concrete before crystallization that can still be cast or pumped. After the crystallization of the cement the concrete becomes solid and mechanically resistant and can only be removed with mechanical methods (breaking, milling, use of explosives). For this reason the timing of the concrete production is of greatest importance. It has to be matched with the moment of consumption. The concrete that is not used on time namely loses its properties and in the worst case destroys various equipment, tools and devices.
The concrete production is a process at which aggregate is mixed with a certain quantity of cement, water and various additives. It is performed in an industrial plant called concrete plant. Concrete plants can be divided on several criteria. Stationary concrete plants are erected at a certain fixed location and provide the fresh concrete to its surrounding in radius of some tenths of kilometers. Mobile concrete plants are constructed in such a way that they can be in a short time transferred from one location to another. This way they can satisfy the needs of customers approximately at the location of concrete consumption. Regarding the flow of concrete production the plants can run a continuous or charge process. At the continuous process the concrete is delivered all the time while charge process delivers the concrete in certain quantities, ordered by the customer and which can be transported by trucks for the concrete transport. The main part of a concrete plant is a mixing drum with system for delivery of aggregate, cement and water. Around the drum several transport systems are located (horizontal transport conveyers, vertical elevators), drying drums, vibration strainers, filters, silos, reservoirs and feeders. An important feature of a concrete plant is its production capacity, usually given in cubic meter of the product per hour.
