Common methods of degreasing: 1. Alkaline cleaning method: it is mainly a method of degreasing by saponification reaction of oil, which is the simplest and oldest method. However, for oils that are difficult to saponify, the degreasing efficiency is low. Because it will wet the ground and affect the construction progress, it is necessary to comprehensively consider the choice. Second, the cleaning method of surface cleaner: For mineral oil that cannot undergo saponification reaction, it is necessary to use surfactant (emulsifier) to emulsify oil and water to form a stable emulsion, so as to achieve the purpose of degreasing. This method can be carried out at room temperature, and it is not easy to cause safety problems. This is an efficient and low-cost security method. However, resinated oil and oil infiltrated into micropores are difficult to remove. In addition, surfactants are prone to foaming. Third, organic solvent cleaning method: using the solubility of organic solvents to remove oil is a common oil removal method with high oil removal efficiency, which is suitable for all kinds of oil stains. Generally, it does not corrode the ground, but it cannot remove inorganic salts and alkaline substances at the same time.