BY:- AIYAPPA T.B, 5TH SEM CIVIL, KPT. READY MIX CONCRETE BY:- AIYAPPA T.B, 5TH SEM CIVIL, KPT. WEL COME

CONTENTS Introduction. Advantages. Disadvantages. Production of Ready Mixed Concrete. Transit Mixed Concrete. Shrink Mixed Concrete. Central Mixed Concrete. Delivery of Ready Mixed Concrete. Conclusion.

INTRODUCTION Ready mix 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. It is popularly called as RMC, specially manufactured for delivery to the customers construction site in a freshly mixed and plastic or unhardened state. It is sold by volume expressed in cubic meters.

ADVANTAGES:- A centralized concrete batching plant can serve a wide area. The plants are located in areas zoned for industrial use, and yet the delivery trucks can service residential districts or inner cities. Better quality concrete is produced. Elimination of storage space for basic materials at site. Elimination of hiring of plant and machinery. Wastage of basic materials is avoided. Labors associated with production of concrete is eliminated. Time required is greatly reduced. Noise and dust pollution at site is reduced.

DISADVANTAGES:- The materials are batched at a central plant, and the mixing begins at that plant, so the traveling time from the plant to site is critical over longer distances. Access roads, and site access have to be able to carry the weight of the truck and load concrete is approx 2.5tonne per cuM. concrete’s limited time span between mixing and going-off means that readymix should be placed within 2hours of batching at the plant

Production of Ready Mixed Concrete:-

A. Transit Mixed (or "truck-mixed") Concrete:- In transit-mixed concrete, also called truck mixed or dry-batched, all of the raw ingredients are charged directly in the truck mixer. Most or all water is usually batched at the plant. Concrete mixed at the job site:- While traveling to the job site the drum is turned at agitating speed (slow speed). After arriving at the job site, the concrete is completely mixed. Concrete mixed in the yard:- The drum is turned at high speed or 12-15 rpm for 50 revolutions. This allows a quick check of the batch. The concrete is then agitated slowly while driving to the job site. Concrete mixed in transit:- The drum is turned at medium speed or about 8 rpm for 70 revolutions while driving to the job site. The drum is then slowed to agitating speed.

B. Shrink Mixed Concrete

B. Shrink Mixed Concrete Concrete that is partially mixed in a plant mixer and then discharged into the drum of the truck mixer for completion of the mixing is called shrink mixed concrete. Central mixing plants that include a stationary, plant-mounted mixer are often actually used to shrink mix, or partially mix the concrete. The amount of mixing that is needed in the truck mixer varies in these applications and should be determined via mixer uniformity tests. Generally, about thirty turns in the truck drum, or about two minutes at mixing speed, is sufficient to completely mix shrink-mixed concrete.

C. Central Mixed Concrete :-

C. Central Mixed Concrete :- Central-mixing concrete batch plants include a stationary, plant-mounted mixer that mixes the concrete before it is discharged into a truck mixer. Central-mix plants are sometimes referred to as wet batch or pre-mix plants. The truck mixer is used primarily as an agitating haul unit at a central mix operation. Principal advantages include:- Faster production capability than a transit-mix plant. Improved concrete quality control and consistency and Reduced wear on the truck mixer drums. There are several types of plant mixers, including:- Tilt drum mixer Horizontal shaft paddle mixer Dual shaft paddle mixer Pan mixer Slurry mixer

Delivery of Ready Mixed Concrete:-

Delivery of Ready Mixed Concrete:- The Truck Mixer :- While ready mixed concrete can be delivered to the point of placement in a variety of ways, the overwhelming majority of it is brought to the construction site in truck-mounted, rotating drum mixers. Truck mixers have a revolving drum with the axis inclined to the horizontal. Inside the shell of the mixer drum are a pair of blades or fins that wrap in a helical (spiral) configuration from the head to the opening of the drum. This configuration enables the concrete to mix when the drum spins in one direction and causes it to discharge when the direction is reversed.

Conclusion:- The use of Ready Mix Concrete in construction industries drastically reduces the time of construction. Now a days RMC plants are grow very fast to cater the need of construction industry. The proportions should be properly and carefully selected while mixing. The quality of concrete is best because of perfect batching and mixing.

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