There are many classification standards for concrete plants. Concrete plant can be divided into dry mix plant and wet mixing plant depending on whether a central mixer is used.
Dry Mix Concrete Plant
A dry mix concrete plant, also known as Transit Mix Plant, weighs sand, gravel and cement in weigh batchers via digital or manual scales. All the ingredients then are discharged into a chute which discharges into a truck. Meanwhile, water is either being weighed or volumetrically metered and discharged through the same charging chute into the mixer truck. These ingredients are then mixed for a minimum of 70 to 100 revolutions during transportation to the jobsite.
Wet Mix Concrete Plant
A wet mix concrete plant, combines some or all of the above ingredients including water at a central location into a concrete mixer. The concrete is mixed at a single point, and then simply agitated on the way to the jobsite to prevent setting (using agitors or ready mix trucks) or hauled to the jobsite in an open-bodied dump truck. Dry mix differ from Wet mix plants in that Wet Mix contain a central mixer whereas dry, which can offer a more consistent mixture in a shorter time (generally 5 minutes or less). Dry mix plants typically see more break strength standard deviation and variation from load to load because of inconsistencies in mix times, truck blade and drum conditions, traffic conditions, etc. With a Central Mix plant, all loads see the same mixing action and there is an initial quality control point when discharging from the central mixer. Certain plants combine both dry and wet characteristics for increased production or for seasonality.