small batching plant for local small deliveries
The inside of a transit mixer uses a simple Archimedes' screw
to mix and to lift the concrete to the delivery chute.
Ready-mix concrete is a type of concrete that is manufactured in a factory or batching plant, according to a set recipe, and then delivered to a work site, by truck mounted transit mixers . This results in a precise mixture, allowing specialty concrete mixtures to be developed and implemented on construction sites. The first ready-mix factory was built in the 1930s, but the industry did not begin to expand significantly until the 1960s, and it has continued to grow since then.
Ready-mix concrete is sometimes preferred over on-site concrete mixing because of the precision of the mixture and reduced work site confusion. However, using a pre-determined concrete mixture reduces flexibility, both in the supply chain and in the actual components of the concrete.
The leading ready-mix concrete supplier worldwide is the Mexican concrete company Cemex; its main competitor is France-based Lafarge and the leading ready-mix concrete supplier in Middle East is the Unibeton Ready Mix.
Ready Mixed Concrete is also referred as the customized concrete products for commercial purpose. the Ready-mix Concrete Company offer different concrete according to user's mix design or industrial standard.
The ready mixed concrete company is required to equip themselves with up-to-date equipments, such as transit mixer, concrete pump, and Concrete Batching Plant, which needs visualized production management software and also PLC controller.
Ready Mixed Concrete, or RMC as it is popularly called, refers to concrete that is specifically manufactured for delivery to the customer's construction site in a freshly mixed and plastic or unhardened state. Concrete itself is a mixture of Portland cement, water and aggregates comprising sand and gravel or crushed stone. In traditional work sites, each of these materials is procured separately and mixed in specified proportions at site to make concrete. Ready Mixed Concrete is bought and sold by volume - usually expressed in cubic meters. RMC can be custom-made to suit different applications.
Ready Mixed Concrete is manufactured under computer-controlled operations and transported and placed at site using sophisticated equipment and methods. RMC assures its customers numerous benefits.
Standard ready-mix concrete -VS- site-mix concrete
- A centralized concrete batching plant can serve a wide area. Site-mix trucks can serve a larger area including remote locations that standard trucks can not.
- The plants are located in areas zoned for industrial use, and yet the delivery trucks can service residential districts or inner cities. Site-mix trucks have the same capabilities.
- Better quality concrete is produced. Site mix can produce higher compression strength with less water then standard batching methods.
- Elimination of storage space for basic materials at site. Standard batch plant needs more room for its operation than site-mix trucks.
- Elimination of procurement / hiring of plant and machinery.
- Wastage of basic materials is avoided. With a site-mix truck, there is less waste and wash out. This is better for the environment.
- Labor associated with production of concrete is eliminated. It takes more people to operate a standard batch plant than a mobile-mix truck.
- Time required is greatly reduced. One mobile-mix truck can produce 8 yards of concrete in 8 minutes. It can also operate continuously without needing to be moved away from the pump truck. One mobile-mix truck can produce 460 yards of concrete in an 8-hour shift, whereas standard trucks must stop and move off the pump to bring in the next, thus taking nearly 3 hours longer to deliver the same amount of concrete. This increases the labor cost.
Disadvantages of ready-mix concrete
- The materials are batched at a central plant, and the mixing begins at that plant, so the traveling time from the plant to the site is critical over longer distances. Some sites are just too far away, though this is usually a commercial rather than a technical issue.
- Generation of additional road traffic. Furthermore, access roads and site access have to be able to carry the greater weight of the ready-mix truck plus load. ([Wet?] concrete is approx. 2.5 tonne per m³.) This problem can be overcome by utilizing so-called 'minimix' companies which use smaller 4m³ capacity mixers able to access more-restricted sites.
- Concrete's limited timespan between mixing and going-off means that ready-mix should be placed within 90 minutes of batching at the plant. Modern admixtures can modify that timespan precisely, however, so the amount and type of admixture added to the mix is very important.
- It can also lead to unemployment of men on site i.e hand job method
- ^ ASTM C 94 and AASHTO M 157
- Panarese, William C.; Kosmatka, Steven H.; Kerkhoff, Beatrix (2002). "10". Design and Control of Concrete Mixtures. Skokie, Illinios: Portland Cement Association. ISBN 0-89312-217-3.