3.3. Impact of Mixing Duration

The mixing duration is very critical. We have to make sure we meet at least a minimum mixing duration as stipulated by the guidelines of the manufacturer.

Mixing duration is crucial because it determines how well the materials blend. Each type of mixer machine and its capacity will require different minimum mixing durations. Following the manufacturer's guidelines ensures that the concrete mixture reaches the desired consistency and quality.

Think of mixing a cake batter. If you don't mix it long enough, you'll have lumps of flour, and the cake won't rise properly. However, if you mix it too long, it can become tough. The same principle applies to concrete mixing durations.

Generally, if you go for a lesser duration, then what is needed? What will happen? You will not get a homogenous mix that is a main problem and if you go for a very high duration, mixing duration also is not good because as you know that as you add water to the concrete, your cement starts setting.

Not mixing long enough results in an uneven mixture, which can lead to weak concrete. Conversely, mixing for too long can cause evaporation of water, affecting workability and the integrity of the concrete as the cement begins to set prematurely. Therefore, it is essential to find a balance in the mixing duration.

Picture a chef who is cooking pasta. If they don’t stir the pasta long enough, it can stick together and not cook evenly. But if they leave it on the stove too long, it will become mushy. Both under-mixing and over-mixing concrete can lead to structural issues, just as imperfect pasta can lead to a bad meal.

This is what I told you. This table is available. It is taken from IS 4925 which gives you a guideline for concrete batching and mixing. The mixing duration is given in seconds. It varies for different types of mixer machines.

The IS 4925 guidelines provide specific mixing durations for various types of mixers. For example, non-tilting mixers often require longer mixing times compared to pan type mixers. These guidelines help ensure that all concrete mixtures meet the necessary quality standards.

Imagine following a recipe that specifies the exact time to bake bread. If you ignore those timings, you may end up with bread that is too doughy or burnt. Similarly, following mixing time guidelines helps produce quality concrete.

So, how to find the cycle time of the concrete mixer machines? It is nothing but your loading time, mixing time, and discharging time.

Cycle time refers to the total time needed to complete a batch of concrete. It is composed of loading time, mixing time, and discharging time. Each of these components can vary based on the equipment and method of operation, making it important for accurate project planning and efficiency.

Consider an assembly line in a factory. Each step from loading parts onto the line, assembling them, and then packaging takes a certain amount of time. Just like a factory, understanding and optimizing cycle time in concrete mixing ensures that your project runs smoothly and efficiently.

Now, how to calculate the productivity of your batch? Generally, we know that concrete is producing batches. Batch by batch, we produce it. So, how do you know the batch production in meter cube per hour? It depends upon your batch size and it depends upon your batch cycle time.

To estimate the productivity of a concrete batching plant, you need to know the size of each batch and how long it takes to complete a cycle (including loading, mixing, and discharging). The formula combines these factors to project output in cubic meters per hour.

If you were to bake cookies, your batch size would be the number of cookies you can bake at once, and cycle time would be how long it takes to mix, shape, and bake them. Understanding these details helps manage how many batches you can produce in a given time.

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