Brief introduction of concrete: concrete, referred to as "tóng" for short: refers to the general name of engineering composite materials in which aggregates are bonded into a whole by cementing materials. Generally speaking, the term concrete refers to cement as cementing material and sandstone as aggregate; Cement concrete, also known as ordinary concrete, is made by mixing and stirring water (including admixture and admixture) in a certain proportion, which is widely used in civil engineering. Selection of raw materials and mix design of high strength concrete: 1. Determination of water-cement ratio: The calculation of water-cement ratio of high-strength concrete can't be based on the formula of ordinary concrete strength. Statistics should be made according to the test data, and the relationship between concrete strength and water-cement ratio should be put forward, and then the water-cement ratio corresponding to concrete mixing strength (fcu.0) can be obtained by graphic method or calculation method. When carrying out concrete strength test with multiple different mix proportions, one mix proportion should be the benchmark mix proportion, and the water-cement ratio of other mix proportions should be increased and decreased by 0.02 ~ 0.03 respectively. 2. Aggregate dosage: (1) Crushed stone dosage per cubic meter G0 high-strength concrete crushed stone dosage per cubic meter VS is 0.9~0.95m3, so the crushed stone mass per cubic meter is G0=VS× crushed stone bulk density (2) Sand dosage per cubic meter S00 =[G0/( 1-QS)]QQS- sand ratio. 3. Water consumption: when calculating the mixture ratio of high-strength concrete, its water consumption can be corrected by water reduction rate method according to the water consumption of ordinary concrete. The water reduction rate calculated by deducting the water reduction rate of admixture from the water consumption of concrete without admixture is the water consumption of concrete with water reducer. At this time, it is necessary to determine the water reduction rate of admixture through experiments. 4. Cement dosage: When producing high-strength concrete, the dosage of cement is very important, which directly affects the bonding force between cement mortar and aggregate. In order to increase the proportion of colloidal materials in mortar, the dosage of cement should be relatively high, but it should be noted that the dosage of cement should not be too high, otherwise it will cause problems such as excessive heat release or shrinkage during hydration. In general, the dosage of high-strength concrete cement should not exceed 550kg/m3. 5. Trial mixing adjustment: The calculated mixture ratio results should be verified by trial mixing. When mixing high-strength concrete, a forced mixer must be used, and high-frequency pressurized vibration should be used when vibrating to ensure the compactness of the mixture. It should be noted that the trial mixing amount should not be less than 1/4 of the rated amount of the mixer, and the mixing method of concrete and admixture should be consistent with the method used in actual production. 6. Determination of mixture ratio: When the absolute value of the difference between the measured density and the calculated value of the mixture does not exceed 2% of the calculated value, no adjustment is needed. When it is greater than 2%, it should be adjusted according to the provisions of Code for Design of Mix Proportion of Ordinary Concrete JGJ55—2000. After the concrete mixture ratio is determined, the mixture ratio shall be verified by no less than 6 repeated tests, and its average value shall not be lower than the prepared strength value to ensure its stability.