What does the durability of commercial concrete mean?

(1) Impermeability: refers to the performance of commercial concrete against the penetration of liquids and gases. Because there are interconnected pores and capillaries in the commercial concrete, as well as honeycombs and pores due to the lack of compaction, so that liquid and gas can penetrate into the commercial concrete, the intrusion of moisture and air will cause the steel to rust and cause harmful liquid and gas. Intrusion will deteriorate the quality of commercial concrete, and the result will affect the quality and long-term use of commercial concrete. The impermeability of commercial concrete is indicated by the impermeability mark P. For example, P4 means that under the action of the corresponding 0.4N/㎜2 water pressure, the 6 cylinder or cone test blocks of the specified size used for the impermeability test will still keep 4 test blocks impermeable. The impermeability marks of commercial concrete are generally divided into P4, P4, P6, P8, P10, P12.

(2) Frost resistance: refers to the ability of commercial concrete to resist freezing. Commercial concrete is often damaged by freezing in cold areas, especially in environments that are both exposed to water and subjected to freezing. This is because the water that penetrates into the commercial concrete will expand by 9% in volume after being frozen, causing the pores and capillaries inside the commercial concrete to be subject to considerable pressure. If the temperature rises, the freezing and thawing will cause repeated freezing and thawing. The concrete will be destroyed. The frost resistance of commercial concrete is indicated by the frost resistance label F. If the strength of the test block subjected to freezing and thawing is reduced by no more than 25% compared with the strength of the test block not subjected to freezing and thawing, the freezing resistance is considered qualified. The antifreeze label is expressed by the number of repeated freezing and thawing cycles that the test block can withstand. According to the number of freeze-thaw cycles, the frost-resistant labels of commercial concrete are generally divided into: F15, F25, F50, F100, F150 and F200.

(3) Corrosion resistance: refers to the corrosion resistance of commercial concrete in various corrosive liquids and gases. The main corrosive media for commercial concrete are sulfate solution, acidic water, active and or soft water with water pressure, sea water, concentrated alkali solutions, etc.

(4) Heat resistance: refers to the performance of commercial concrete that does not suffer damage to the internal structure under the action of high temperature, does not significantly lose its strength, and has certain chemical stability.