Ready Mix Concrete, popularly known as RMX refers to a concrete mix in plastic or unhardened state, manufactured especially for construction site. It is freshly mixed concrete, a mixture of Portland cement, water and aggregates consisting of sand and gravel or crushed stone. In traditional construction works, each constituents of concrete mix is mixed in specified proportions at site. Ready mix concrete is becoming popular day by day in construction works. In India only 2 - 5 % of total cement is used in Ready Mix Concrete whereas in other countries like Japan 70% cement is used in Ready Mix Concrete. RMX is bought and sold by volume usually in cubic meters and can be used for various custom-made applications.
How to prepare ready mix concrete?
Ready mix cement concrete is prepared in a factory or batching plant according to required specification. The concrete is mixed under computer-controlled operations according to quality control norms. At mixing site or batching plant ready mix concrete is prepared by mixing Portland cement, water, coarse aggregate comprising gravel or crushed stone and fine aggregate consisting of coarse sand which are procured separately and be mixed in specified proportions.
How to utilize ready mix concrete?
After mixing cement concrete, the mix is carried through trucks mounted with transit mixer on working site and is placed at required component of building/work
with the help of sophisticated equipment and methods. Ready mix concrete is preferred to on-site concrete mixing due to non-availability of good raw materials at site, lack of facilities and non-availability of trained technical staff. However, ready mix concrete prepared at sites of longer distances can reduce the flexibility in supply chain and in actual components of the building.
How to prepare concrete mix?
Cement concrete has four primary constituents as raw materials such as water, cement, coarse aggregate (stone ballast or Basra) and fine aggregate (coarse sand).
At the time of mixing, the paste formed by water and cement binds fine aggregate and coarse aggregate through a chemical reaction, called hydration and form into a rock-like mass.
The coarse aggregate and fine aggregate is well graded; cement is according to specification and the water is free from alkaline and salty material. Add water to cement according to water cement ratio to get maximum strength of concrete mix.
Achieving strength of concrete mix
In construction work, “Cement Concrete” is main and a versatile building material. It can be molded into any shape to achieve great strength. It is ideal for construction work such as building project, roadwork or dam etc. It is perishable in plastic or unhardened state. Raw materials, mixing, transportation, placing and curing can influence its plastic and hardened properties according to advance concrete institute (ACI 121). The strength or quality of cement concrete in construction work depends on the quality and strength of raw materials, transportation, placing and curing.
It should be checked constantly during cement concrete work to get qualitative strength constantly. Any committed or omitted slackness in any process of cement concrete reduces the strength of cement concrete.
Benefits of ready mix concrete
- Can meet the demand of cement concrete mix for wide area.
- Offers better quality, and consistent mix than site mix concrete
- Doesn’t require storage space for raw materials at site
- Reduces noise and dust pollution at site
- No need to procure/ hire plant and machinery at site of work
- Time saving as the work is completed before time
- Does not require hiring labor to mix concrete at site
- Doesn’t need technical staff employed for production of concrete mix
Drawbacks of ready mix concrete
- More expensive than site mix concrete due to transportation cost and modern additives which are used to increase time span in traveling.
- Critical in case of sites at longer distance as the mix takes traveling time from central plant to the site.