Types of Ready Mix Concrete and Their Advantages

[Rony]

There are nine major types of concrete available for construction projects, including concrete pavers, precast concrete, ready mix concrete, concrete blocks, and more. However, in this post, we are looking at ready-mix concrete (RMC) as a major construction material and its advantages.

What is Ready Mix Concrete?​

a. Ready-mix concrete is custom-made concrete that has been manufactured in a factory or within a batch plant based on specific mix designs. RMC is known for its durability and sustainability and is generally delivered in one of two ways:

b. Volumetric concrete mixers: Ready-mix concrete will be delivered to the worksite, allowing you to mix the concrete on site.

c. Barrel truck or in-transit mixers: The prepared concrete is delivered to the work site within a transit mixer installed over a truck. This type of concrete is recommended as it guarantees higher durability and sustainability.

Types of Ready-made Concrete​

Ready-mix concrete can comes in three types depending upon the specific mixture of ingredients. They are:

1. Central mixed concrete​

Also known as central batching plant concrete, central mixed concrete is formed when concrete is mixed thoroughly before being loaded into a truck mixer. While the concrete in transit, the truck mixer functions as an agitator only.

Non-agitating units or dump trucks can also be employed when the workability requirement is low or the lead is less.

2. Shrink mixed concrete​

The concrete formed from shrink mixed concrete has been partially mixed in the truck-mounted drum mixer during transit.

The amount of mixing in transit is dependent on how much mixture is done in the central mixing plant. A best practice would be for tests to be carried to establish the requirement of mixing the drum mixer.

3. Transit mixed concrete​

Also called dry-batched concrete, transit mixed concrete is made when all the basic ingredients (water inclusive) are combined in the truck mixer. While loading the construction materials, the truck’s mixer drum rotates very fast at charging speed.

After which, it slowly rotates until it reaches a normal agitating speed. Transit mixed concrete comes in three variations. They are:

a. Concrete mixed at the job site​

While being transported to the construction site, the drum is revolved at a slow or agitating speed of 2 rotations per minute (RPM). On reaching the site, before discharging the material, it will get around 70 to 100 revolutions at a maximum speed of 12 to 15 rpm. This helps to ensure that a smooth mixture is formed.

b. Concrete mixed in transit​

Here, the drum speed is kept constant during transit. It rotates continually for roughly 8 rpm at 70 revolutions. After 70 revolutions, the rotation is slowed to an agitating speed of 2 rpm till discharging takes place at the site.

c. Concrete mixed in the yard​

In this case, the drum is mixed at an agitating speed of 2 rpm during the period of transit. Upon reaching the site, the mixing drum will be rotated at a high speed of 12 to 15 rpm for approximately 50 revolutions.

Advantages of Ready Mixed Concrete​

1. Ready-mix concrete is precise, of high quality, and fine quality because the mixing plant makes use of sophisticated equipment and consistent methods.
2. Since it uses sophisticated equipment, the chance of human errors is eliminated and this will also reduce the dependency on intensive labour. On a side note, less labour saves you money.
3. The ready-made concrete method solves the problem of batching and poor control on the input materials found in other mixing methods.
4. Petrol and diesel consumed in ready mixed concrete are low, and as a result, air and noise pollution are reduced.
5. The output in a premier concrete plant is around 9X more than what is obtained from a site mix concrete plant. For instance; using an 8/12 mixer, you get 30 to 60 metric cubes per hour from RMC as opposed to 4 to 5 metric cubes per hour from a site mix concrete plant.
6. Better handling, proper mixing practice, use of admixtures and other cementitious materials will help to reduce the amount of cement used by 10 – 12%.
7. During the manufacture, there is strict control over the testing of materials, continuous monitoring of key practices, and process parameters.
8. Ready-mixed cement makes use of bulk concrete instead of bags of cement, saving cement and reducing dust circulated in the process.
9. As a result of cement saving, energy and resources will be conserved.
10. Moreover, less consumption of cement reduces cement production hence less environmental pollution.
11. Concrete as per the specification is delivered timely at the site be it in small or large quantity. There is no delay due to site-based batching plant erection/dismantling or the absence of equipment to hire.
12. RMC requires little space for storing the raw construction materials at the site.
13. The concrete mix is used with high versatility.