Fully automatic concrete mixing plant well reduces labor amount in construction project, and more humanized designs are added in terms of using this kind of concrete mixing plant. Then, how do we rightly operate fully automatic concrete mixing plant? Which requirements should be met for operators? The so-called full automation of concrete mixing plant means that all devices such as transporting system, batching system, mixing system and discharging system can be controlled by a computer. First of all, aggregate concrete batching is transported by belt conveyor. The pump and fly ash are transmitted by screw conveyor to be weighed. Then, in the operation process of fully automatic concrete mixing plant, water and additives are weighed by electric scale. All needed concrete materials are weighed by electric scale and made a ratio according to design process. The main concrete mixer is adjusted according the materials. When production combination starts and the materials are mixed evenly,

Currently, the strength of common used concrete is 20一40 n/mm. It is not difficult to produce the concrete of 80一100 N／mm if necessary. In order to lighten self-weight, concrete with light weight but high strength gets big development. Due to the continuous improvement of material strength, the application scope reinforced concrete and prestressed concrete is expanding. In recent 30 years, reinforced concrete and prestressed concrete have achieved remarkable development in long-span structure and high-rise building structure. For instance, Germany builds a roof beam of hangar with scope of 90m by adopting prestressed lightweight concrete; the scope of bridge in Japan reaches 239 m. During this period, design theory also has new development. Since the 1970s, structural reliability theory has gradually stepped into the stage of engineering practical on the basis of mathematical statistics, which makes the limit design method more improved and scientific. In the meantime, structure