Ready-made concrete is a concrete produced in a batch plant, in accordance with a technically designed mix design. Ready-made concrete is usually shipped in two ways.
The first is a barrel truck or a transit mixer. This type of truck delivers the concrete in a plastic state to the site.
Second is a volumetric concrete mixer. This gives the mixture ready in a dry state and then mixing the concrete on the site.
The batch plant combines the right amount of rock, sand, water and cement simultaneously by weight, enabling specific concrete mixtures to be developed and implemented at construction sites. The first ready-to-use factory was built in the 1930s, but the industry did not begin to grow significantly until the 1960s, and has continued to grow ever since.
Ready-to-use concrete is often preferred over other materials due to cost and wide use, ranging from bird baths to buildings and high bridges. It has a long life span when compared to other products of the same usage, such as roads. It has an average life span of 30 years under high traffic area compared to 10 to 12 years old of asphalt concrete with the same traffic.
Ready-made concrete, or RMC as it is also known, refers to concrete that is specifically collected or produced for a customer's construction project. It is a mixture of Portland cement, water and aggregates: sand, gravel, or crushed stone. All aggregates should be of type material washed with a finite amount of fine or dirt and clay. Ready-made concrete is bought and sold by volume - usually expressed in cubic meters (cubic yards in the US).
Ready-made concrete is dug up or produced under controlled conditions. These can be transported and placed on the site using a number of methods. In 2011, there were 2,223 companies employing 72,924 workers who produced RMC in the United States.
Video Ready-mix concrete
The advantages and disadvantages of ready-mix concrete
- The materials are incorporated in the batch plant, and the hydration process begins when the water fills Portland cement, so the travel time from the factory to the location is critical over a longer distance. Some sites are too far away; however, the use of admixtures, retarders, and fly ash can be added to slow the hydration process, allowing longer transit time.
- Crack and shrink. Concrete shrinks while healing. It can shrink 1/16 inch (1.59 mm) over an area of ​​10 feet (3.05 meters). This causes stress internally on the concrete and must be accounted for by engineers and coatings that place the concrete.
- Furthermore, road access and site access should be able to carry a larger load-weighted loader load. (Green concrete is around £ 3924 per cubic yard.) This problem can be solved by utilizing so-called "mini mix" trucks that use 4mÃ, mix smaller mixer capacity can reach more weight-restricted sites.
- Concrete has a limited lifespan between batching/mixing and curing. This means that ready-to-use mixtures should be placed within 30 to 45 minutes of clustering process to withstand deterioration and mixed design specifications. Modern admixtures and plasticizers and water reducers can change that time span. However, the scope is limited. The amount and type of mixture added to the mixture is very important.
Maps Ready-mix concrete
Concrete meter
As an alternative, the centralized batch plant system is a volumetric mobile mixer. These are often referred to as concrete in place, mixed concrete field or mobile mixed concrete. This is a miniature version of the phone from a large stationary batch factory. They are used to provide ready-made concrete using a continuous batching process or a concrete meter system. The volumetric mobile mixer is a truck that holds sand, rock, cement, water, fiber, and some add a mixture and color depending on how the batch plant is equipped. These mixed trucks or mixed batches are ready in the workplace itself. This type of truck can mix as many or as few concrete as needed. Stirring on-site eliminates the hydration of travel times that can cause transit concrete to become unusable, These trucks are identical to a centralized batch mill system, because the truck is scaled and tested using the same ASTM (standard American test method). ) like all other ready mixed manufactures. It is a hybrid approach between batches of centralized batches and traditional mixing in place. Each type of system has advantages and disadvantages, depending on the location, size of the work, and the design of the mix defined by the engineer.
Mixed mixed mixture vs mixture ready volumetric mix.
- Concentrated concrete batching plants can serve large areas. The mix-site truck can serve larger areas including remote locations that can not be reached by standard trucks.
- The batch plant is located in an area categorized for industrial use, while the delivery truck can serve residential districts or inner cities. The mix-site truck has the same capabilities.
- Volumetric trucks often have lower water demand during the batching process. This will produce concrete that can be significantly stronger in compressive strength compared to a centralized batch batch for the same mixture design using the ASTM C109 test method.
- The centralized batch system is limited by the size of the fleet. It takes up to 10 minutes to haul and load one truck from 9 to 12 yards depending on the size and type of plant. They can not change mixed designs during the batch process.
- The volumetric mixer can smoothly change all aspects of the mix design while still producing the concrete. They can continue mixing quality concrete for an unlimited time while continuing to be filled with fresh ingredients. They can produce 1 yard of concrete in just 40 seconds depending on the mixed design and the size of the completed batch plant.
- For short payloads, (orders under 10 yards) Transit Mixers usually return to their batch factory after each delivery. Volumetric trucks can go straight from one job to another until the truck is emptied, reducing traffic and fuel consumption.
See also
- Concrete types
References
- Notes
- References Panarese, William C.; Kosmatka, Steven H.; Kerkhoff, Beatrix (2002). "10". Concrete Mixed Design and Control . Skokie, Illinois: Portland Cement Association. ISBN 0-89312-217-3.
- National Ready Mixed Concrete Association
- The Ready Concrete Producers Association
- European Ready Mixed Concrete Organization
- French Ready Mixed Concrete Association
- Manufacturers of Concrete Batching - European Technology
External links
Source of the article : Wikipedia
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