People have adopted many different methods and developed several theories as the basis for concrete mix design.
I only need to mention a small part of it to awaken your memory.
Our current habit is (unfortunately, almost everyone does) to design concrete mix proportions based on experience, such as using a 1:2:4 mixture without considering the special types of raw materials and the amount of mixing water used, and with little or no consideration for the strength of the concrete being manufactured.
Undoubtedly, this method is very crude and primitive, and thoughtful engineers would not adopt it.
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