Ready-mix concrete

Ready-mix concrete is 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 in–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 often preferred over on-site concrete mixing because of the precision of the mixture and reduced work site confusion.

Ready-mix 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. Ready-mix concrete is bought and sold by volume - usually expressed in cubic meters (cubic yards in the US).

Ready-mix concrete is manufactured under controlled operations and transported and placed at site using sophisticated equipment and methods. In 2011, there were 2,223 companies employing 72,924 workers that produced RMC in the United States.

As an alternative to ready-mix concrete, volumetric mobile mixers may be used to provide metered concrete services. The volumetric mobile mixer is a truck that contains concrete ingredient materials and water to be mixed on the truck at the job site to make and deliver concrete according to the amount needed. The on-truck mixing at the job site eliminates the travel delays that can cause the pre-mixed concrete to become unusable, however not as precise as weighed batches. This is a hybrid approach between ready-mix concrete and traditional on-site mixing.

Since site mixed concrete is volumetrically metered, the quality of the concrete is not on par with standard ready mixed concrete which is weighed.

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