Construction Material Knowledge Base RMC

What is ready-mix concrete or RMC and what are the types?

Cement is the foundation of any establishment however, it’s never used alone. Most cement is amalgamated with different materials to make it more usable and sturdy. Ready-mix concrete or RMC is specifically manufactured or batched for customers’ construction process. It is premixed in the cement factory and the whole mix is delivered to the construction site. The mixture contains cement, water, and aggregates, sand, gravel, or crushed stones. Generally, these mixes are prepared on the construction site however there are few sites where you don’t have the provision, in those cases companies premix and send it across. There are a few different kinds of concrete mixes mentioned below, read through and understand the available options.

1. Transit mixed concrete

It is also called dry-batched concrete because all the basic ingredients including water are charged directly into the truck mixer. The mixer drum revolved fast at charging speed during the loading of the material and after that, it continued rotating at a normal agitating speed. In this type of ready mix concrete, also three types of variations are possible as given below:

Concrete mixed at job site:

While being transported towards the destination, the drum is revolved at a slow or agitating speed of 2 rpm, but after reaching the site just before discharging the material, it is revolved at a maximum speed of 12 to 15 rpm for nearly 70 to 100 revolution for ensuring homogeneous mixing.

Concrete mixed in transit:
The drum speed is kept medium during the transit time, i.e. approximately 8 rpm for about 70 revolutions. After 70 revolutions, it is slowed down to an agitating speed of 2 rpm till discharging the concrete.

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.

2. Shrink mixed concrete

The concrete is partially mixed in the plant mixer and then balance mixing is done in the truck-mounted drum mixer during transit time. The amount of mixing in transit mixer depends upon the extent of mixing done in the central mixing plant. Tests should be conducted to establish the requirement of mixing the drum mixer . The concrete is partially mixed in the plant mixer and then balance mixing is done in the truck-mounted drum mixer during transit time. The amount of mixing in transit mixer depends upon the extent of mixing done in the central mixing plant. Tests should be conducted to establish the requirement of mixing the drum mixer.

3. 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 premix plants. The truck mixer is used primarily as an agitating haul unit at a central mix operation. Dump trucks or other non-agitating unit’s are sometimes be used for low slump and mass concrete pours supplied by central mix plants. About 20% of the concrete plantains the use of a central mixer.

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

The tilting drum mixer is the most common American central mixing unit. Many central-mix drums can accommodate up to 12 yd3 and can mix more than 200 yd3 per hour. They are fast and efficient but can be maintenance-intensive since they include several moving parts that are subjected to a heavy load. Horizontal shaft mixers have a stationary shell and rotating central shaft with blades or paddles. They have either one or two mixing shafts that impart significantly higher horsepower in mixing than the typical drum mixer. The intensity of the mixing action is somewhat greater than that of the tilt drum mixer. This high energy is reported to produce higher strength concrete vi-ato thoroughly blending the ingredients and more uniformly coating the aggregate particles with cement paste. Because of the horsepower required to mix and the short mixing cycle required to complete mixing, many of these mixers are 4 or 5yd3 units and two batches may be needed to load a standard truck or agitator. Pan mixers are generally lower capacity mixers at about 4 to 5yd3 and are used at precast concrete plants. 

 RMC is mostly available at dedicated dealers. These dealers source the cement and other material from various sources. Cement, out of all the other material, needs a quality check, as it’s the most expensive of all. Source good quality cement can be confusing, price points are another target point. For clear sourcing, alternatives are available. One of the digital alternatives is tradologie.com. It is the world’s only digital procurement system. here the interested dealers can choose from numerous buyers to buy the cement. You can deal with them live, all at once. Discuss payment terms, quality, delivery terms, etc. all in real-time. All the available buyers are online, at once and help you choose the best available option out of so many. Mixing can be an elongated process but cement procurement is just a few clicks away, only at Tradologie.com.

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