There are a variety of ways to mix concrete. Some people use manual hand-powered mixing; others prefer a concrete mixer. Concrete is a composite material of sand, coarse aggregates, cement, water, and other chemical admixtures (if needed). Concrete is also the primary construction material for most projects. The method of combining concrete can be fundamental to the structure’s durability and serviceability. In concrete mixing, several processes occur, like batching, compacting, transporting, and finishing. All these steps are crucial in making the perfect mixture. Even though making concrete is relatively easy, the correct concreting process can be complicated and needs extra care. At BS Power, we want to help you make the perfect batch, so let’s discuss the different mixing methods and how you can tell whether your mixture is just right.

 

Importance Of Mixing Concrete

 

To produce excellent quality concrete, it is of utmost importance that you mix your concrete ingredients properly. The most effective way to do this is with a concrete mixer. While combining the aggregate particles, the surface must be coated with cement paste. Expertly mixed concrete will give you the desired performance and workability in construction projects. If your concrete is not mixed well, this may lead to segregation and bleeding. But how do you know if your mixture was done right? Well, some of the essential characteristics of a well-mixed concrete batch include:

 

• The concrete should have uniformity in its colour.
• All concrete materials like fine aggregates, coarse aggregates, cement, and water must be mixed homogeneously.
• Cement paste needs to cover the whole surface of the aggregate.
• Bleeding and segregation should not occur if you use the machine correctly.

 

Three methods are used to produce robust and effective concrete:

 

• Hand mixing of concrete (This is done manually without using a mixer).
• The concrete mixer method
• Ready mix concrete (Mixing in either a semi-automatic or automatic batching plant)

 

Different construction projects may require different types of concrete mixing. If you want the best results, you should know the appropriate method for mixing concrete depending on your needs. Various factors can affect the process of concrete mixing, such as,

 

• The construction site’s location with enough land for construction activities, e.g., highly congested urban areas.
• Available space for concrete mixing, batching, and storage of aggregates.
• The volume of concrete is required.
• The construction schedule, like how much concrete will be required per hour daily.
• Height of which the concrete is being placed.
• Cost

 

 

Hand Mixing Concrete – Without A Mixer

 

Mixing concrete by hand is manually mixing all the concrete ingredients without a concrete mixer machine. Mixing concrete without a machine is usually used for small projects where the quantity needed is less and quality control is slightly less critical. Hand-mixing concrete makes mixing concrete uniformly more challenging and requires special care and effort. That is why the effort needed to mix concrete by hand should be carefully weighed against the cost of a mixer, as it may be more labour efficient and therefore cost less to hire a machine even for smaller projects. Hand mixing is a method that should generally only be used for smaller projects around the home.

 

According to the author of Construction Handbook for Civil Engineers and Architects, concrete should be mixed by hand only as an exception when the required volume does not allow for a concrete mixer machine to work effectively. That is to say that the device could not adequately mix the ingredients due to the low volume added. The handbook states that when mixing by hand, one should add 10% more cement to the mixture to compensate for the lack of a machine.

 

Process Of Hand Mixing Concrete

 

• Hand mixing concrete should always be done on a hard, non-porous, clean base. To provide stability well mixing.
• The measured quantity of sand is spread on a platform, and then cement is placed over the sand.
• The cement and sand are mixed thoroughly many times with the help of tools like shovels in the dry state until there is an even colour throughout the mixture, and it is free from any streaks.
• Next, the coarse aggregates, which have been measured, are spread out in a uniform layer on top of the mixture and mixed correctly. Remember, it is essential to use measurement boxes for batching aggregates, i.e., to determine how much aggregate is needed. Under no circumstance should you use or allow ‘Ghamelas’ for batching.
• Later, the mixture is appropriately blended by turning over and twisting from the centre of the mixture to the side, then back to the centre again. This process is repeated several times.
• After performing the above process several times, you must make a depression in the centre of the mixed materials.
• 75% of the total water needed is then added to the depression and mixed with the assistance of shovels.
• Finally, the left water is added, and the mixing process is continued until a uniform colour is achieved and the correct concrete consistency is achieved. The total time it takes to mix concrete should not exceed 3 minutes.

 

Precautions While Hand Mixing Concrete:

 

• The base platform must be clean, dirt-free, and permanently watertight.
• Use a good quality and clean shovel for the mixing procedure.
• If you find any debris or dirt in the aggregates, wash them before you use them.
• Personal protective gear and equipment like hand gloves, masks etc., must be worn by the mixers while handling the concrete.
• The platform you use for mixing needs to be cleaned at the end of a day’s work.

 

Machine Mixing Concrete – Using A Concrete Mixer

 

Machine mixing is the industry standard. It is the most widely used method because it is highly effective in fulfilling construction project demands compared to the other techniques discussed in this article. If you only have a short time to mix and want a homogeneous quality for your concrete, well maintain an optimum consistency, then machine mixing will be your chosen method.

 

As stated by the author of ‘Properties of Concrete, A.M. Neville, a concrete mixer not only ensures the uniformity of the mix but also discharges the mix without disturbing the uniformity. A concrete mixer is appropriate in larger projects where vast amounts of concrete are needed because it ensures consistency is always homogeneous.

 

The Process Of Mixing With A Machine

 

• First, wet the inner walls of the concrete mixer’s drum.
• Coarse aggregates are placed in the mixer, then sand and cement.
• Mix all the dry materials in the concrete mixer. Usually, it should only take up to 3 minutes.
• After all the ingredients have been adequately mixed, slowly add the water whilst the machine is in motion. Be careful to check the amount of water needed constantly, as over-pouring water into the mixture may result in a weaker batch that may not be usable in your project.
• After adding the water, you should allow the initial mixture of all the elements to occur. This process is not very long and should generally be completed within two minutes.
• If there is any concrete segregation after you dispense the first batch. Replacing the materials and starting with a new batch is suggested. Due to the machine’s efficiency over manual mixing, remixing is the most effective means to ensure an excellent first batch. Reusing the old mixture may cause clotting and affect future batches, so it is better to scrap it.

 

Precautions While Mixing With A Concrete Mixer

 

• The concrete mixer is required to be wet before your usage.
• Take care of mixing speed, time, and the number of revolutions of the drum. Be sure to follow the manufacturer’s recommendations, which can generally be found in the manual.
• To maintain consistency, use the machine mixture within 30 minutes after the mixer has discharged it.
• If you are mixing batch types, after you have discharged one concrete batch, clean the interior surface thoroughly before the next. If not, lumps of hardened concrete from the previous batch can fall into the next batch you make and worsen the quality of the concrete.
• If you are mixing continuously, cleaning the concrete mixer after fixed intervals is essential.
• You must inspect the inner drum of the concrete mixer regularly to check for corrosion, cracks, or any damage.

 

 

Ready Mix Concrete

 

On-site production of standard concrete using a labour force and primitive concrete mixer is a common trend in India. But ready-mix concrete has been an answer to this, as it allows the construction team to avoid the mixing process, including reducing labour and equipment costs.

 

According to K Newman, a lecturer on ready-mix concrete from the Indian Concrete Institute, ready-mix concrete is known as a specialised material in which aggregates, cement, as well as other ingredients are weighted and batched at a central plant location, then either mixed in a truck or an industrial sized main mixer before it is delivered to the construction site in a condition ready for placing by the customer.

 

The quality of the concrete produced is much better than on-site-mixed concrete, i.e., hand-mixed or machine concrete. Ready-mix concrete is especially useful on congested sites or even in road construction where there is little or no space for a mixing plant and storage space for aggregates.

 

In this method, getting quality control is relatively easy as the mixing and batching of concrete are completed at the mechanised central batching plant. This mixing method can be beneficial in many places, i.e., congested areas, large construction sites, at-night concreting work, etc. The cement/water ratio can be controlled more efficiently with ready-mix concrete than other mixing methods. Mixing the admixtures, like fly ash and cement, in precise quantities as they are proportioned correctly at the central plant. When this is done at the construction site, it is common to overuse chemicals. These types of difficulties can be easily avoided using ready-mix concrete.

 

In the past 15 years, the use of ready-mix concrete has grown. This remarkable technology has proven highly beneficial on many construction sites, especially in poorer communities or quickly growing areas, where archaic mixing practices are no longer productive. Ready-mix concrete has become a popular alternative to the on-site concrete mixer process. More individuals are now aware of the benefits ready-made cement can offer and often suggest it to others. This word-of-mouth marketing will accelerate the growth of ready-mix concrete globally, particularly in developing countries.

 

 

About BS Power

 

BS Power manufactures various high-performance construction equipment suitable for anyone who has decided to embark on a journey in the world of agriculture, forestry, and construction, including those who have been in the world of construction. If you want to know more about construction products such as concrete and a concrete mixer and how these materials and tools are used, visit us today!