What is Ready Mix Concrete, Types, Advantages and Disadvantages in Construction

What is ready mix concrete (RMC)

The word ready mixed itself implies that the various materials are mixed in correct proportion except maybe the liquid part to give the end-user the desired specified results. The whole entire concept has come about because the end-user doesn’t just have to bother about the quality of various ingredients, wastage, and storage of materials and still gets the desired results. 

Therefore, a concrete whose constituents are weigh-batched at a central batching plant and are mixed either at the plant itself or in truck mixers and are transported to the construction site and delivered in a batter condition ready to use is termed as ready mixed concrete (RMC). 

In the majority of almost all countries, where RMC exists, it had always made a slow start at the beginning but afterward, it had developed at a faster rate and later all over once again showed very steady growth. Architect Jurgen Heinrich Magens from experience knew that concrete doesn’t harden at frosty temperatures. He first patented the concept of cooling concrete so that it can be transported over a longer distance. Thus RMC was patented in Germany in the year 1903. In 1907, be discovered that the available time for transportation could be prolonged not only by cooling fresh concrete but also by Vibrating it during transportation. He, therefore, obtained his second patent.

Types of ready mix concrete (RMC)

Ready-mixed concrete can be divided into three main types are the following given below.

1. Plant mixed concrete.
2. Transit mixed concrete (mixed on the way).
3. Shrink mixed concrete.

1. Plant Mixed concrete

The concrete is mixed in a central batching plant and is transported through special agitator trucks. The agitator truck keeps the concrete moving in a circular path rotation at the rate of 2 - 6 r.p.m. (rotations per minute). These rotations prevent segregation and the setting of concrete mix.

2. Transit mixed concrete (mixed on the way)

Transit mixer is one of the most popular types of equipment for use transporting concrete over a long distance particularly within the ready mixed concrete plant. The concrete is batched at the central batching plant and mixing is done in the truck mixer either in transit (on the way) or immediately prior to discharging the concrete at site. Transit mixing permits longer haul and is less vulnerable in case of delay. The truck mixer has the speed of rotating the drum is at the speed of 4 – 16 r.p.m. Sometimes a small concrete pump is also additionally mounted on the truck carrying transit mixer. This pump helps in pumping the concrete discharged from the transit mixer.

3. Shrink mixed concrete

The concrete in which the ingredients of concrete are mixed partly within the plant and partially during transit is known as shrink mixed concrete. This type of concrete gives the best utilization of the agitator truck. 

Types of equipment required for ready mix concrete (RMC) are the following given below.

• Central batching plant
• Agitator truck
• Concrete pumps
• Pipelines for delivery
• Couplings etc.

The agitator truck consists of an ordinary normal chassis over which there is mounted along a horizontal or inclined drum called the canister. The concrete is filled within the canister. A small diesel engine 15 placed between the drum and also the driver's cabin. This engine rotates the drum or the paddles inside the drum. There is a water tank over the engine, which provides a sufficient quantity of water 10 mixing the concrete as well as for washing the canister after discharge. The capacity of us canister ranges from 7 m2 - 8 mo. The approximate cost of the RMC is Rs. 3200/m3.

Advantages of ready mix concrete (RMC)

1. Consistency in quality - Properly graded aggregates are mixed in accurate ratios which help in maintaining consistent quality in every batch produced. 

2. Better durability - Due to a high level of quality control, there is an increase in the service of structure and reduction in life cycle costs. It can have a major impact on the national economy and ca facilitate optimized utilization of resources like limestone, energy, and industrial by-products. 

3. Cost Savings - Through reduced wastage of raw materials, it helps lower administrative and manpower costs. 

4. Time-Saving - Rate of concrete pouring can be 12 - 15 times faster as compared to traditional site concrete mix. 

5. Minimization of environmental pollution - Usually transportation of aggregates concrete is done in open trucks, which causes a lot of air pollution, whereas for ready-mix it is carried in closed transit mixers. 

6. Minimum wastage of materials - There is considerable wastage of materials on-site due to poor storage conditions and repeated shifting of mixer location. This can be prevented if RMC IS used. 

7. Concreting in congested areas - Areas that are congested and have difficulty in storing aggregates and placing of concrete mixer. The concrete can be placed in such site conditions by using RMC. 

8. Non-availability of labour gangs - The problems due to the non-availability of labour gangs and concrete mixers can be minimized by the use of RMC. 

9. Control of temperature - Temperature control of concrete in extreme weather conditions can be exercised in a much better manner than done at the site. 

10. Less nuisance - Publicly places, it creates less nuisance. Congested roads and footpaths - are often blocked by carelessly stored concrete materials. RMC allows a much better way of the flow of road traffic as well as pedestrian movement.

Disadvantages of ready mix concrete (RMC)

During transportation, it may be more effects on the workability of concrete due to traffics and transportation. A site, engineer is supposed to check the workability through a slump test before using it for construction. Before placing the concrete the formwork is properly to check it should be more capable of bearing the load advance in a large area as the concrete can be bought in larger amounts the failure chance is high due to transfer the more weight in a small time. During concreting, the ready mix concrete is more harmful because the pressure is very high and it is also used many types of chemical admixtures it also more effects on the worker's body skin. Required professional technical workers some types of ready mix concrete workers are lack of knowledge and it does not properly mix the concrete according to the concrete design.