What principles should be followed and what considerations are necessary when designing the mix proportions for ordinary waterproof concrete using the absolute volume method?

The mix design for ordinary waterproof concrete is carried out using the absolute volume method, and the following principles should be taken into account: 1. First, the impermeability requirements must be met, while also considering compressive strength, workability, erosion resistance, and frost resistance. 2. The type of cement shall be determined based on the requirements for the concrete’s water resistance, durability, and operating conditions; the cement grade should be no lower than 425, and the amount of cement used should be at least 320 kg/m3. 3. Determine the water-cement ratio based on the requirements for impermeability, workability, and strength. 4. Determine the water volume and select the slump based on structural conditions and construction methods. 5. Determine the sand ratio based on the particle size of sand and stones as well as the void ratio of the stones (the sand ratio must not be less than 35%). 6. For ordinary waterproof concrete, the ratio of cement to sand is preferably 1∶2 to 2.5.