How Cement Mixers Work



When it comes to cement mixers, there is so much to learn. It is safe to say that there is a large variety of construction tools that perform a multitude of tasks. From cranes that move impossibly heavy loads to previously unreachable areas to construction vehicles that carry necessary materials from point A to point B. Then there are specialised construction vehicles like bulldozers that help clear out construction sites of unwanted debris. All of these tools play a critical role in helping construction teams do their job effectively.


These mixers are one of the most essential tools in the arsenal of any construction team. While concrete was present in some shape or form before the Romans built the Appian Way, working with cement has always been arduous. But with the invention and implementation of concrete mixers, builders have been able to perfect cement mixtures well, producing larger quantities quicker.


When we mention mixers, generally, this is in reference to what is known in the construction industry as concrete mixers. They can be found in many sizes, configurations, and types to handle multiple tasks as required by builders. The need to fill various roles implies that mixers are dynamic, changing form and shape as the needs arise.


In this article, we will explore how mixers work and function by investigating their captivating combination of new and old technology. We will also look to review some of the essential types of mixers, from standard traditional drum-shaped mixers to ready-mix transit mixer trucks to the somewhat less known but growing in popularity – volumetric mixers. This is a concrete plant on wheels.


After reading this article, you will never see cement mixers in the same light. But before we dive right into it, let’s explain the differences between concrete and cement: In terms of baking, the main difference between cement and concrete applies to the difference between a loaf of bread and flour. Concrete can be seen as a generic word for a mix of aggregate – typically consisting of gravel or stone, cement, and water.


The cement we see in recent times is an intricate blend of finely ground up minerals and goes by its generic name, “Portland”. Concrete is created by mixing all these three ingredients in a cement mixer, depending on whether the mixer is driving down the road or stationary. The water is absorbed into the cement, which binds all the aggregates together, creating concrete.




The Mechanics Behind Mixers


Cement mixers are critical components of machinery utilised in construction in various sectors worldwide. They have been designed for a singular purpose: repeatedly mixing concrete with the correct consistency. Although this may sound like this would make a mixer less versatile, that is untrue. This is because it does its job so well that it can mix cement in various consistencies, which allows them to do a lot when mixing cement.


Standing mixers work on similar principles as cement mixing trucks. Both have a rather sizeable oval-shaped bucket or drum that must be turned constantly. The drum is tilted sideways to ensure that all the concrete will is mixed well. When it applies to standing cement mixers, the most commonly utilised on building sites, there are a few basic steps on how they acquire the best cement mix.


Get The Right Recipe


It is so important that your concrete mixture is entirely correct so that you can get the best concrete made, similar to baking a cake. Concrete is composed of types of cement, sand, stone, and with the following:


  • 1 x 50kg cement bag
  • 90L of stone/gravel
  • 90L of medium-building sand
  • 36L of water


The Best Way To Mix Concrete:


  1. Firstly, add the gravel or stone while the mixer runs.
  2. Add half of the water and mix for roughly a minute.
  3. Then begin incorporating the cement mix and mix it for another minute.
  4. Next, add the sand and the remaining water to the mix.
  5. Lastly, let the whole mixture mix for three more minutes.


Always Tilt The Drum


Cement mixer drums must always be utilised in a tilted position to make sure that all the concrete is mixed correctly. The ideal situation is for the drum to sit at a 60-degree angle in the tilting wheel; this is just enough not to spill the mixture.


Give The Mixture Enough Time


When you are under pressure, you may be tempted to hurry up the concrete mixing process. Nevertheless, it is crucial to follow the recipe and always make sure to give it enough time for your concrete to mix correctly.




What To Avoid When Using A Mixer


Here are a few key points on what you should not do when working with cement mixers:


Do not overload cement mixers. Make sure you stick to its weight limit to ensure you get the correct consistency. If you happen to overload your machine, your mixture may not mix properly and may even break the machine arm.


Do not forget to maintain your machine. You need to grease the bearings and points of the mixer every week.


Do not forget to check the ring gear for adjustment and running if required.


Make sure that you never leave the mix to dry. It would be best to spray the drum down daily using a high-pressure washer to remove any leftover concrete. If this is not done, then the concrete will dry and harden inside of the drum, and this could cause severe damage in the long term.


Do not under any circumstance attempt to hit the drum with an object or a spade to remove old hardened concrete because it can cause severe damage to the mixer.


To keep your cement mixers in excellent working condition, you should do daily checks on the engine, for example, the air cleaner, to ensure that it is clear of dirt or dust and make sure that you check the oil level. Additionally, you should check the drive belt daily for the correct tension and alignment.




Unique Mixers: Mixer Trucks


All cement mixers leverage weight, power, and torque distribution to get the concrete on the site. There are even some larger mixers that are unique as they sit on the back of large trucks. The mixer trucks offer significant advantages as they help move cement from central mixing plants to construction sites. This means that the cement is of excellent quality as the cement manufacturers specialise in mixing batches. But also means that construction teams can avoid the hassle of mixing the cement themselves. In this section, let us review these unique truck mixers in greater detail.


The majority of the mixer fleet, particularly the older batch model trucks, uses a primary tip-and-pour method so that the concrete is removed from the mixer. A chute connects to a port, and the concrete pours out, depending on the consistency, out of the mixer to the project. Typically, the truck driver works the machinery and aims using the chute. If necessary, many transit cement mixers are coupled to a hydraulic lift bed that can tip up the drum, comparable to a dump truck.


Numerous other trucks are volumetric, and the newer trucks utilise a pump to transport the concrete from the mixer to the construction site. The pumps, typically reciprocating piston pumps, can be fixed on the truck’s rear or front. Placing the pump in front will allow the truck driver to manoeuvre to a section of the work site and direct the concrete from inside the cab.


Challenges to Maintaining Your Mixer


The truth is that once the last concrete comes out of the drums or the pump, the truck still needs to be emptied. Did you know that a small amount of concrete always stays inside the truck, especially within drum mixers? You can wash the truck with running water through the rotating drum. You can even pressure wash the drum if you wish. However, some concrete is always left behind. And it ends up drying. The next time you use it, it will go a little more inside. And over time, this can be a severe problem, decreasing the volume of the mixer and its capacity.


Several companies offer pre-treatments, acid baths, chemicals, and high-pressure washes for the interiors and drums. Nevertheless, eventually, the concrete will cumulate to a point where the only logical alternative is to be mechanically removed. Many smaller companies can handle this by sending in one of their workers with a jackhammer to remove the hardened concrete.


Jobs like this are largely unknown outside of the world of the construction field. It got its 5 minutes of fame during an episode of the Discovery Channel’s “Dirty Jobs” show, which sent one of the hosts to work with Jim’s chipping service. This is one of the few companies that specialise in cleaning hardened concrete.


These immensely specialised vehicles are essential to the construction business and will be around for a while. The question remains what cement mixers look like in the future?


The Future of Mixers


To answer the above question, what the future holds for all mixers needs to be clarified. Similar to many industries, concrete is going “green”. The manufacturers of volumetric cement mixers say that their products are even environmentally friendly as they save fuel by mixing materials at the physical construction site – the trucks do not have to run their engines so that they keep the concrete from setting.


Further, truck operators can only produce the amount of concrete required to finish the job. Not only does it help you save materials, but this method also assists in preventing the dumping of excess concrete.


One case study for implementing this strategy can be found with the manufacturer Peterbilt which is currently experimenting with compressed air systems. The truck will start using compressed air, and when it eventually reaches a certain speed, the diesel engine should kick in. Because an engine needs a more significant amount of fuel to overcome inertia, you can get it up to speed with relatively inexpensive compressed air would show fuel savings over a period.


The recent technology which has been developing is now geared towards inner-city delivery trucks instead of larger trucks that have mixers.


About BS Power


There is so much more that can be said on this topic. Fortunately, BS Power is a knowledgeable import and manufacturing company that can provide you with so much information that can ease your mind of any questions you have about anything related to not only concrete mixers but construction, forestry, agriculture, and a wide variety of other applications.


We provide products from Honda, Briggs and Stratton, Stihl, Baumax, and Husqvarna. We are based in Cape Town, Western Cape, but have made clients from all over South Africa and even the rest of Southern Africa, like Zimbabwe, Swaziland, Zambia, Botswana etc., extremely happy. We deliver the best solutions and top-quality equipment like cement mixers to all our customers.