Ready mixed concrete (RMC) is a specialized material in which cement, aggregate and other ingredients are weight batched at a plant in a central or track mixer before delivery to the construction site in a condition ready for placing by the customer.
IS: 4926-2003 defines ready mixed concrete as ‘Concrete mixed in a stationary mixer in a central batching and mixing plant or in a track mixer and supplied in a fresh condition to the purchaser either at site or into purchaser’s vehicle’.
The short ‘life’ of fresh concrete, with only 2-3 hours before it must be placed, results in ready mix concrete being a very much local delivery service, with rarely more than 30-60 min journey to the construction site.
Experience shows that the specifying authority or engineer will be satisfied with ready mix concrete if
- The supply complies with the specification for fresh and hardened concrete.
- He is assured of continuity of supplies from experienced and reliable ready mix concrete companies.
In turn, the contractor or builder will be satisfied if
- The deliveries are always on time and concrete is supplied at the required rate.
- The workability is correct appropriate for the placing method used.
- The quantities are correct.
- On those occasions when concrete proves to be defective, the suppliers bears his fair share of the cost of removal and replacement of the defective material.
- The total cost of concrete, including supply, handling and placing is economic. From this, it is seen that the specifying authority (engineer) is concerned primarily with the quality of the product, whereas the user, i.e., builder or contractor, is mainly concerned with the service and its cost, i.e., value for his money.