What material is the safety slogan of reinforced protective shed generally made of?

brief introduction of concrete: concrete, abbreviated as "tóng", refers to the general name of engineering composite materials in which aggregate is bonded into a whole by cementing materials. Generally speaking, the word concrete refers to cement as cementing material and sand and stone as aggregate; Cement concrete, also known as ordinary concrete, which is mixed with water (including additives and admixtures) in a certain proportion and obtained by stirring, 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, and statistics should be made according to the experimental data, and the relationship between concrete strength and water-cement ratio should be put forward, and then the water-cement ratio corresponding to concrete preparation strength (fcu.) can be obtained by graphic method or calculation method. When a number of different mix proportions are used for concrete strength test, one of them should be the benchmark mix proportion, and the water-cement ratio of other mix proportions should be increased and decreased by .2 ~ .3 respectively compared with the benchmark mix proportion. 2. Aggregate consumption: (1) Crushed stone consumption per cubic meter G The crushed stone consumption per cubic meter of high-strength concrete VS is .9～.95m3, so the crushed stone quality per cubic meter is G=VS× loose bulk density of crushed stone (2) Sand consumption per cubic meter sss = [G/(1-QS)] qsqs-sand ratio, which should be determined by experiments and generally controlled at 28 ~. 3. Water consumption: when calculating the mixture ratio of high-strength concrete, its water consumption can be corrected by water reduction rate method based on the water consumption of ordinary concrete. Deducting the water reduction calculated by 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 cement content should be relatively high, but it should be noted that the cement dosage should not be too high, otherwise it will cause problems such as too fast heat release or too large shrinkage during hydration. Generally, the dosage of high strength concrete cement should not exceed 55kg/m3. 5. Trial mixing adjustment: The calculated mixture ratio results should be verified by trial mixing and 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 of the mixture and the calculated value does not exceed 2% of the calculated value, it is not necessary to adjust. When it is greater than 2%, it shall be adjusted according to the provisions of Code for Mix Design of Ordinary Concrete JGJ55—2. After the concrete mixture ratio is determined, the mixture ratio shall be verified by repeated tests for not less than 6 times, and the average value shall not be lower than the prepared strength value to ensure its stability.