Concrete is produced by combining basic materials like cement, aggregate and water into a homogenous, suitably designed, plastic mix that solidifies into structural and non-structural building members. The process of production of concrete involves batching, mixing, transportation, placing, consolidating and curing.

Concrete batching and mixing equipment



Concrete Weight Batching Equipment


concrete mixer with attached  weight batching

Batching is the process of proportioning cement, aggregate, water and admixture (where added), by weight (commonly used method) or volume, prior to mixing. The equipment used for batching and mixing can be divided into three categories, viz. mobile concrete mixers, commonly called concrete mixers; centralized batching and mixing plant; and mobile truck-mixers which are covered under concrete transportation.

Mobile concrete mixers

Tilting Concrete Mixer


These mixers have a conical or circular rotating drum with baffle fittings inside. These are mounted on pedestals with facilities for batching of various concreting materials. These are there types of concrete mixers, viz. tilting drum mixers, non-tilting drum mixers and reverse drum mixers. Tilting drum mixers discharge the concrete by tilting the drum. Tilting drum mixers are used for producing very small quantities of concrete or mortar mixes.


Non-Tilting Concrete Mixer

Non-tilting drums are suitable for requirements say up to 10 m3/h. these have ah hopper-fitted outlet on the top for loading and another chute-fitted outlet on the bottom for discharge. The reverse-drum mixers mix on one direction and discharge in the opposite direction.


Mobile Concrete Mixer

The mobile concrete mixers vary in size from as slow as 100 litres to 400 litres or more per cycle. The size of the concrete mixers denotes the volume of concrete that can be mixed in a single cycle, and usually it is expressed in cubic feet or cubic meters, or the ratio of the concreting materials volume to the wet concrete volume, for example 21/14 means a concrete mixer having maximum capacity to hold dry concreting materials up to 21 cubic feet capable of producing wet concrete of 14 cubic feet.

Concrete mixers are available as static units and trailer-mounted units.

The hourly output of a concrete mixer can be calculated by multiplying production in m3 per batch or cycle into the number of batches per hour. In the absence of actual data, for planning purposes, the hourly output for various sizes of concrete mixers can be taken as:

Hourly Output for various sizes of compact mixers output of concrete mixers.

Mixer size
Batches/hour
Output (M3/hour)
7/3.5
(100)
17
1.7
7/5
(140 litres)
16
2.3
10/7
(200 litres)
15
3.0
14/10
(280 litres)
14
3.9
21/14
(400 litres)
12
4.8
32/21
(600 litres)
10
6.0


Central batching plant

A central batching plant includes all types of equipment and materials necessary to provide input to the mixers and to deliver output to the concrete transporting system. Batching plants can be divide into two categories, viz. medium size or low profile batching plants, and large volume or high profile batching plants. Generally, medium size batching plants have a rated capacity of 25 m3/h to 60 m3/h and are used for producing concrete for building construction projects where as batching plants having higher capacity, say 120 m3/h, are employed for heavy construction or are used in the ready-mix concrete supply business.


Concrete Batching Plant



Experience dictates that for planning purposes, the average output of the central concrete batching plants be taken as 60% to 70% of hourly rated capacity for each working hour so as to cater for various correction factors specially idle-time on account of non-utilization period and repairs.