READY MIX CONCRETE
PROF. SACHIN JAIN
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 worksite, 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 worksite confusion. However, using a pre-determined concrete mixture reduces flexibility, both in the supply chain and in the actual components of the concrete. 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.
Concrete’s natural color is gray. Its favored uses are utilitarian. Its very ubiquity causes it to blend into the background. But ready-mix concrete does have one remarkable characteristic: other than manufactured ice, perhaps no other manufacturing industry faces greater transport barriers. The transportation problem arises because ready-mix concrete both has a low value-to-weight ratio and is highly perishable—it absolutely must be discharged from the truck before it hardens. These transportation barriers mean ready-mixed concrete must be produced near its customers. For the same reason, foreign trade in ready-mixed concrete is essentially nonexistent. This article is an introduction to the basics of the market for ready-mix concrete, focusing mainly on its consumers and its producers in the United States, but with occasional comparisons to other countries when contrasts are useful.
INDUSTRY HISTORY AND BACKGROUND:
Ready-mixed concrete’s ubiquitous use as a building material is largely because of two advantages. It is cheap. It also allows great diversity in design and function, because in its fluid form, it can be poured into molds of any shape. Concrete’s weakness, quite literally, is that while it is reasonably strong when bearing compressive (pushing) loads, it is an order of magnitude weaker in its ability to bear tensile (pulling) forces. Concrete was regularly used as a building material throughout the twentieth century, but when the National Ready Mixed Concrete Association was founded in 1930, only a handful of ready-mixed plants operated in the United States. The standard practice at the time was for construction firms to mix their own concrete at the job site using bagged cement and aggregates the contractors purchased themselves. (This practice remains common in developing countries.) However, with the wartime industrial and government building during the 1940s and the housing and highways building boom that followed, demand for ready-mixed rose sufficiently to take advantage of the scale economies of specialized offsite concrete mixers. By 1958, the first year in which the...
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