Ready-mix concrete is concrete that is manufactured in a batch plant, according to a set engineered mix design. Batch plants combine a precise amount of gravel, sand, water, and cement together by weight, allowing specialty concrete mixtures to be developed and implemented on construction sites.
Ready-mix concrete is often used over other materials due to the cost and wide range of uses in building, particularly in large projects like high rise buildings and bridges. It has a long life span when compared to other products of similar use, like roadways. It has an average life span of 30 years under high traffic areas compared to the 10 to 12-year life of asphalt concrete with the same traffic.
Ready-mix concrete, or RMC as it’s also known, refers to concrete that is specifically batched or manufactured for customers’ construction projects and supplied to the customer on-site as a single product. It is a mixture of Portland or other cement, water and aggregates: sand, gravel, or crushed stone. All aggregates should be of a washed type material with limited amounts of fines or dirt and clay.
Advantages and disadvantages of ready-mix concrete
- Materials are combined in a batch plant, and the hydration process begins at the moment water meets the cement, so the travel time from the plant to the site, and the time before the concrete is placed on-site, is critical over longer distances. Some sites are just too far away; however, the use of admixtures, retarders and cements like pulverised fly ash or ground granulated blast furnace slag (GGBS) can be used to slow the hydration process, allowing for longer transit and waiting time.
- Concrete is formable and pourable, but a steady supply is needed for large forms. If there is a supply interruption, and the concrete cannot be poured all at once, a cold joint may appear in the finished form.
- Cracking and shrinkage. Concrete shrinks as it cures. It can shrink 1⁄16 inch (1.59mm) over a 10-foot-long area (3.05 meters). This causes stress internally on the concrete and must be accounted for by the engineers and finishers placing the concrete, and may require the use of steel reinforcement or pre-stressed concrete elements where this is critical.
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- RMC is ready to use the material for
concrete which is a mixture of cement, sand, aggregates, and water.
- The idea of RMC was first introduced
in the year 1903 by an Architect Jurgen Heinrich Magens from Germany.
- In 1907 they discovered that RMC
available time can be prolonged by cooling and vibrating it during the
- In INDIA RMC was used in 1950 in the
construction of Dams like Bhakra Nangal and koyna.
- High-quality concrete is produced.
- Elimination of storage space for
materials like cement, Sand, and aggregate.
- Eliminate the hiring of plant and
labors for making concrete.
- Wastage of basic material is avoided.
- The time required is greatly reduced.
- Noise and Dust pollution is reduced
at the site.
Required for Manufacturing RMC:
- Aggregate is an important material in the
manufacture of concrete. This gives the body to the concrete mixture 70 – 80 %
of the concrete.
Based on the size the aggregate is divided into two categories.
- Coarse aggregate. (Size more than
4.75mm are coarse aggregate)
- Fine aggregate. (Size less than
4.75mm are fine aggregate)
- Cement is a binder material which setsand
hardens independently and binds other material together.
- Sand some amount of sand and Water
is also added to the mixture and concrete is produced.
- Transit Mixed or Truck mixed
- Shrink Mixed concrete.
- Central-mixed concrete.
Mix or Truck Mixed
- In this, all the materials along with
water are added in the tuck mixture.
- While traveling to the job site the
drum rotates slowly and while arriving at the job site the concrete is
completely mixed and ready to use.
- Concrete mixed in the yard the drum
is turned at high speed at 12 – 50 RPM for 50 Revolution. The concrete is
slowly aggregated while traveling to the job site.
- Concrete mixed in transmit the drum
is turned at medium speed or above 8 rpm for 70 revolutions while driving to
the job site.
- In general, the Truck should deliver
the concrete in two hours of time.
- However, this period can be prolonged
by using admixtures or in the cool.
and Testing for Ready-mix Concrete:
per IS 4926 – 2003 the point and time of sampling shall be at the distance from
the discharge from the producers delivery vehicle or from the mixture to the
Tavara Mines and Mineral are manufacturing and supplying
high-quality M Sand and RMC.