Question

Discuss the three different types of ready-mixed concrete

Please i want the answer written here not on paper

Answer 1

Ready mixed concrete: Now a days ready mixed concrete (RMC) is the most common form of concrete while constructing the structure. Weather it maybe buildings, bridges and dams etc. Generally it is prepared at concrete plant instead of mixed one the construction site. In this ready mixed concrete method, concrete is transported from the plant to site. Which guarantees the quality of the concrete. Types of RMC: 1.Rapid setting concrete: There are three types of ready mixed concrete (RMC) depending upon the mixing of the various ingredients as given below. a. Transit mixed concrete b. Shrink mixed concrete c. Central mixed concrete a. Transit mixed concrete: It is also called dry batched concrete because all the basic ingredients including water are charged directly into the truck mixer. Again this concrete mixer classified into 3 types. 1. Concrete mixed at job site 2. Concrete mixed in transit 3. Concrete mixed in yard 1.Concrete mixed at job site: The drum is revolved at a slow speed of 2 rpm but after reaching the site justice before discharging the material it is revolved at maximum speed of 12 to 15rpm for nearly 70 to 100 for ensuring homogenous mixing. 2. Concrete mixed in transit: The drum speed is kept medium during the transit time that is approximately 8 rpm for about 70 revolutions. After 70 revolutions, it is slowed down to agitating speed of 2 rpm till Discharging the concrete. 3. Concrete mixed in the yard: They drum is turned at high speed of 12 to15rpm for about 50 revolutions in the yard itself. The concrete is then agitated slow during transit time. b. 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.

c. Central mixed concrete:

It is also called central batching plant where the concrete is thoroughly mixed before loading into the truck mixer. Sometimes the plant is also referred as wet batch or pre mix plants. While transporting the concrete, the truck mixer acts as agitator only. Sometimes, when workability requirement is low or the lead is less, non agitating units or dump trucks can also be used.