Cement Mixers

There are various types of cement mixer but they all do the same job of mixing up sand, cement and aggregates to make concrete.

Cement is produced in factories called cement works. Crushed limestone is mixed with clay and water then burned in a kiln before being crushed into a fine dry powder ready for use.

Compared to many other building materials, concrete is easy, quick and cheap. Blocks and bricks require careful laying and cutting; concrete just needs to be mixed and poured. Concrete, a strong material in its own right, can be strengthened or 'reinforced' by adding steel rods to the moulds. Reinforced concrete is widely used in the construction industry.

Of course you can 'knock up some muck' in the time-honoured fashion on a board with a shovel but a mixer saves an awful lot of time and effort.

Which Cement Mixer?

The cheapest mixer, though not a substitute for a cement mixer and only useful for smaller jobs, is the paddle mixer of which there are several types. Small batches of sand and cement can be mixed with a mixer drill which is a slow speed high torque drill with rotating paddles. Easy to use indoors in confined spaces they are also used to mix plaster, mortar, floor screed and paint. Mixing capacity will depend on the size of the paddle and the power of the mixer.

The electric cement mixer is very widely used and is portable and cheap to hire or buy. If using an electric cement mixer its vital to take all due precautions with the power supply and keep the cables well clear of the work.

Petrol cement mixers and diesel cement mixers are generally a little more expensive but have the obvious advantage of being able to work on site without electricity. Many builders favour the diesel cement mixer for its low running cost and durability, though petrol models are slightly cheaper. On the other hand, the electric cement mixer is cheap, light, portable and quiet.

For advice and guidance on how to use a portable cement mixer visit the Mixing Concrete page.

Cement Mixers by Volume

The type and size of cement mixer obviously depends on the job it is required to do. For example, small portable cement mixers are great for bricklaying but too small for pouring concrete foundations. Which type of cement mixer to use will depend on the volume of concrete required. For larger jobs a cement mixer truck will be required.

• Mixers with a limited output of say 200 litres per batch, sometimes referred to as mini, manual, portable or hand cement mixers could achieve an hourly placing rate of 2 to 3 cubic metres assuming transportation with a wheelbarrow. Cheap portable mixers are loaded by hand so that good uniformity between successive mixes is not that easy to achieve. Note that the volume output of all concrete cement mixers is around 30% less than the dry input volume; this is due to the consolidation that takes place during mixing. Cheap, versatile and strong, the mini mixer can be used for mixing mortars and plasters as well as concrete.



• Diesel, petrol or electric 'medium batch' mixers with outputs ranging from say 200 to 750 litres would have a reversing drum or chute discharge at the higher end of the scale. These mixers usually incorporate water tanks and loading shovels so that more uniform output is achievable. Due to their greater output, the larger types of portable mixer may be better used on site in conjunction with dumpers rather than wheelbarrows.



• Increasingly,industrial cement mixers are being used where the rapid on site production of high-quality consistent concrete is required. The industrial cement mixer typically has twin shaft batch mixers enabling a 30 second mixing time with reliably good consistency. The industrial cement mixer is relatively portable, very powerful and increasingly favoured for its ability to produce large quantities of very consistent concrete.



• Ready mixed concrete trucks typically have a capacity of 4 to 6 cubic metres. An average diesel engined mixer truck could have a maximum laden weight of 20 tonnes. Cement trucks transport the mixed concrete direct from the mixing plant to the site. Cement mixer trucks discharge their loads via a chute straight onto the required area or into a dumper, crane skip or concrete pump.