Concrete mixers are used to mix cement, sand and aggregate into a homogenous slurry state. Based on the method of mixing, they are classified into three types – tilting type (T) , Non-Tilting type (NT) and Reverse type (R). If the name of the concrete Mixer is 200T then the number “200” denotes the volume of the mixer in terms of liters and the letter “T” denotes the method of mixing.
Rotating drum Mixer – Tilting type (T)
Tilting type concrete mixers are available in the volumes of 85T, 100T, 140T and 200T. They are very popular in India because of their mobility, compactness and low cost. They are used to produce concrete in smaller batches.
Rotating drum Mixer – Non-Tilting type (NT)
Non-tilting type concrete mixers are available in the volumes of 200NT, 280NT, 375NT, 500NT and 1000NT. Like the name indicates, they cannot be tilted. Ingredients are fed on one side, usually on the top, and the the mixed concrete is taken on the other side. They are used to produce concrete in larger batches.
Rotating drum Mixer – Reverse type (R)
Reverse type concrete mixers are available in the volumes of 200R, 280R, 375R, 500R and 1000R. They are just like NT mixers, but their drum can rotate in opposite direction during discharge hence segregation of concrete is avoided.
Volume of concrete mixer needed for concrete if you want to use one bag of cement
- The volume of concrete mixer should be 10% excess then 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, volume of concrete mixer should be at least 200 liter if you want to use one whole bag of cement.
Mixing Time of concrete mixers
Approximately thirty rotation is sufficient to mix concrete ingredients into a homogenous slurry state. Since concrete mixers rotate at a minimum rate of 15 rpm, mixing time required to produce 1 batch of concrete is 2 minutes.
Other Concrete Mixers
Pan mixers can be rotated in both horizontal and verticle axis in a very high speed. They are used to produce high strength concrete or special concrete.
Continous mixers can produce concrete continuously for larger construction works, like a dam. Ingredients will be fed in one direction and concrete will be received on the other end.