Concrete mixers are used to mix cement, sand and aggregate into a homogenous slurry state. Based on the mixing method they are classified into three types – tilting type (T), Non-Tilting type (NT) and Reverse type (R).
One can find out the type and volume capacity of concrete mix from their name. The starting number indicates the volume and the ending letter indicates the type of mixing. For example, if the name of the concrete mixer is 200T, the number “200” indicates the volume capacity of the mixer in liters and the letter “T” indicates that the concrete mixer is regular tilting type.
Rotating drum Mixer – Tilting type (T)
Tilting type concrete mixers are available in volumes 85T, 100T, 140T and 200T. They are very popular in India due to their mobility, compactness and low cost. They are used to produce concrete in smaller quantities.
Rotating drum Mixer – Non-Tilting type (NT)
Non-tilting type concrete mixers are available in the volumes 200NT, 280NT, 375NT, 500NT and 1000NT. As the name implies, they cannot be tilted. The materials are fed on one side, usually on the top hopper, and the mixed concrete is taken on the other. They are used to make large quantities of concrete.
Rotating drum Mixer – Reverse type (R)
Reverse type concrete mixers are available in volumes 200R, 280R, 375R, 500R and 1000R. They are similar to NT mixers, but their drum rotates in opposite directions to discharge the concrete.
Volume of concrete mixer needed for concrete for one bag of cement
The volume of concrete mixer should be 10% in excess to the volume of concrete to be mixed.
Lets assume Concrete Grade = M15 (1 :2 : 4)
- 1 Cement bag = 35 liters
- Sand = 35×2 = 70 liters
- Aggregate = 35×4 = 140 liters
- Concrete yield in slurry state = 2/3 (cement+Sand+Aggregate) = 2/3 ( 35+70+140) = 170 liters
- 10% excess = 170 + (170x(10/100) = 187 liters
Therefore, if you want to use a full bag of cement, the volume of the concrete mixer should be at least 200 liters.
Mixing Time of concrete mixers
About thirty cycles are sufficient to mix the concrete material in a homogeneous state. Since the concrete mixers rotate at a speed of at least 15 rpm, the mixing time required to prepare 1 batch of concrete is 2 minutes.
Other Types of Concrete Mixers
Pan mixes can rotate at very high speeds on the horizontal and vertical axes. They are used to make high-strength concrete and other special concrete.
Continuous mixers can produce concrete continuously for larger construction works, like a dam, roads and flyovers. The materials are fed in one direction and concrete is obtained at the other end.
Leave a Reply