There was a time that mixing cement and concrete was always done by hand. Mixing concrete with trowels and spades is physically demanding work. Hand-mixed concrete is almost always an exercise in trial-and-error; it’s very difficult to find the right consistency and viscosity of concrete, and the right ratio of water to solid materials. Thanks to cement mixers, the guesswork and hard work of mixing concrete by hand is now a thing of the past.
What Are Cement Mixers?
In the old days, a worker has to keep stirring and mixing concrete to keep it from setting and hardening. Hand-mixing concrete is very a very difficult and backbreaking task. Once concrete absorbs the water and sets with other solid particles, it cannot be dissolved and remixed into new concrete. Concrete must be constantly mixed in a place with a constant temperature, which is very tricky when you’re mixing concrete outdoors. Mixing it is also very messy, and there’s no way to store the liquid concrete once it’s already wet and mixed.
Cement mixers are automated machines that mix and store liquid concrete. A construction crew member simply has to pour in the cement, gravel, sand, and water into the machine, and the mixer does all the work. A cement mixer is essentially a large moving drum that mixes concrete ingredients, and keeps the mixture fluid until it is ready to be poured. Most mixers are pieces of heavy equipment that you usually see on construction sites or road and highway repairs, although there are some portable mixers that can be used for smaller jobs at home.
How Cement Mixers Work
Most cement mixers have giant rotating mixers that are coupled to an engine, the main line of a power outlet, or a suitable power plant. The drum has a giant screw installed inside it, which allows it to thoroughly mix the concrete and keep the mixture fluid in consistency. The revolving motion of the cement mixer’s drum keeps the concrete mix fluid, and it also prevents the mixed concrete from settling and sticking to the sides of the drum.
When the concrete is ready to be poured, the mixture is either scooped out of the drum with a bucket or a pail. Larger mixers have chutes where the mixture is allowed to flow down to a container or to the pavement. Some sophisticated mixers have pump mechanisms and hoses that are very useful for paving roads, or for transporting concrete for skyscrapers, towers, and other high structures.
Types of Cement Mixers
Cement mixers come in many different sizes and types to suit just about every job:
Mixer trucks. Most of us are familiar with these big machines that mix and transport big loads of concrete through long distances. While a mixer truck can mix wet and dry ingredients in the mixing drum itself, most construction companies prefer to load premixed concrete into the mixer truck. Premixed concrete is easy to load and unload from the truck, and construction companies save a lot of effort and money by using the mixer to transport the concrete and keep it fluid, instead of using the machine to actually mix the concrete ingredients.
Industrial mixers. An industrial mixer is a fixed machine that can mix great amounts of concrete, which is loaded into mixer trucks for transport. Batch mixers use giant mixing shafts that resemble the mixing paddles and rods used in a mixer or a blender. An industrial mixer can completely mix a batch of concrete in less than 30 seconds.
Portable mixers. Many homes which are still under construction use smaller mixers that can be dismantled and moved to different locations. A portable mixer is a smaller version of a mixer truck, only that it is propped up on a frame or a tripod and mixes smaller batches of concrete. It is usually powered by electricity. A portable mixer can also be made from a frame, a used metal drum, and a motor.
There will still be times that mixing concrete by hand work best for the task at hand, like repairing a hole in a concrete wall or building concrete flower boxes. For those big and heavy jobs that require more power and volume, a concrete mixer may just be what you need to get the work done.