A concrete mixer is a machine that mixes the concrete powder, sand, water and gravel to form a slurry that hardens into concrete.
In these mixers, the mixing of concrete component is blended to form a mixture of specified consistency.
The concrete mixer is composed of twin horizontal shafts and is coupled to the engine, it can be powered by electric, diesel or fuel depending on model-type and size.
The mixers are portable or mobile, some can be pushed manually while others are required to be driven by the vehicle.
Types of concrete mixer:
Drum type concrete mixer:
In drum type mixers, the drum plays an important role, which means that different drum type mixers are reclassified according to its size as follows:
1. Tilting Type Mixer:
After proper mixing in a tilting type mixer, the drum can be tilted to one side and the effective mixing of concrete can be performed simultaneously.
They have capacities between 0.1 m3 to 0.2 m3.
In tilt type drum mixers, the drum is made of cast iron and steel plates, its body rotates on its axis inside the drum for continuous movement while the blades are fixed.
When charging the drum, all materials in the required specification are inserted into the hopper with help of winding and unwinding of the wire rope, the material is charged into the drum through the hopper.
The hopper is made of steel plate, the clutch and brake control the speed of the hopper.
Water is poured as per requirement, the drum is rotated at specially required rpm and then it is tilted to the other side and the mixed concrete is taken out through the drum and used for site work.
Due to their portability and easy operation, they are preferred on-site and can handle a total site of 15 cm to 20 cm.
2. Non-Tilting Type of Mixers:
In a non-tilt concrete mixer a drum rotates about the horizontal axis and it is opened on either side for discharging and one for charging.
Loading skips and chutes are used for charging and discharging.
In non-tilt mixers, mixing should be done with proper care.
First all the mixtures are charged with water and when all the materials are charged in the loading skip.
It is then picked up and put into a rotary drum, then uniform and the whole mixing of concrete is done at some moving velocity.
The second gate is opened and the uniform mixture is allowed to fall from it to be transported to the required position.
While charging, care must be taken that the mixer should not be charged more than its capacity.
These concrete mixer are mainly used for mixing and placing concrete for pavements of highways and roads, airways etc.
These are mounted on crawler tracks so that they can move along with the placing of the concrete at 0.75 and 1 m3 size mixer is used.
It is a popular truck-mounted device or machine used to transport concrete over long distances.
Mixing of concrete into a truck-connected mixers, which rotates at 2–6 revolutions per minute, the capability of the transit mixers is 4 m3 to 7 m3.
In some of the transit mixers, concrete is batched at central batching plant and blended in a truck mixer either in transit or instant before discharging.
Sometimes concrete pumps are also mounted on trucks carrying transit mixers that pump concrete from the transit mixers.
Concrete mixer are in various sizes and range from large cement trucks with a rotating drum to small mixers used for small domestic projects or craft projects.