Diagrams depict how to make cement and the way cement is used in concrete production

cement and concrete production

I'm preparing for the IELTS test, therefore I really need your help to promote my writing skill.
The diagrams given illustrate how to make cement and the way cement is used in concrete production for construction aim.
As can be seen from the two pictures, the process of cement producing starts with crushing and ends with packaging after three other main phases of the process, whereas there is only one step in the concrete making method.

The first diagram depicts how cement is made. In the first stage, raw materials including limestone and clay are crushed into powder. These crushed ingredients then are mixed well together before being delivered to the next equipment in the subsequent step. In this stage, a machine called rotating heater is operated to heat the compound of crushed limestone and clay to a specific temperature. The end product, which is one of the major materials of concrete, then comes out after being ground by a grinder and is packaged in identical bags in the final phase.

The other diagram shows concrete production. This building substance is made by mixing four elements namely cement, water, sand and gravel with the exact rate 15%, 10%, 25% and 50% respectively.

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This is ok but I think your opening paragraph should end with 'for construction purposes'
Not 'for construction aim'.
Purposes seems more fitting in that context than aim.

Try to be more specific with your image descriptions. Don't just call these diagrams. Describe these as "illustrative diagrams" since these are drawings of 2 different procedures. Additionally, you should mention that these are 2 separate diagrams early on. Within the first sentence if possible. You should have divided the run on sentence in the first paragraph. It is too long and should be divided into at least 2 separate sentences for that part of the presentation.

The second paragraph is acceptable. However, the last paragraph is another run on sentence that does not properly analyze the concrete production instruction. Do not compress all of the information into a single sentence. That type of presentation will always be confusing and unclear to the reader. The only way to maintain clarity in this presentation is for you to be specific about the procedure explanation. Look at the diagram for cement, there are still phases of mixing before you arrive at a concrete product. Depict the procedures to create the 3-5 minimum sentence requirement.