剑8-Test 3 Writing-P78-79
The diagram on the left side describes the stages and equipment used in the cement-making process while the right one illustrates how cement is used to produce concrete for building purposes.
As we can see from the diagram on the left side, limestone and clay are added into the crusher. After that, they become powder. Then the powder is added into a mixer before being transformed to the rotating heater. After heating and rolling, it is rolled by grinder. Finally, it becomes cement, which is usually stored in bags.
According to the right diagram, concrete, which can be used for building purposes, is made by adding four categories. Specifically, cement, water, sand and gravel (small stones) account for 15%, 19%, 25% and 50%, respectively. After adding all of them, the concrete mixer rool for a long time to make them mix well.
Therefore, we can see clearly from the two diagrams that both cement production and concrete production are physical changed processes, without chemical reaction.
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