April 02, 2024

Water leakage will reduce the durability and safety of the building engineering structure, because there are gaps and cracks in cement products, and there are also gaps and cracks in masonry blocks and mortar. Water enters them and if the temperature drops to zero degrees below, the water freezes into ice, and its volume expands by about 90%, which will directly squeeze the material, causing the surface layer of the material to erode. At the same time, the remaining water inside is squeezed, causing compressive stress inside the material, causing cracks or further expansion of the cracks. . The greater the porosity of the material, the more cracks, the greater the water content and the greater the ambient humidity, the more serious the situation. As the service life increases, this situation becomes more and more serious. As a result, the bonded cross section of the material continues to decrease, the cracks continue to increase and widen, and the load-bearing capacity of the material also continues to decrease. The destruction of the concrete protective layer will also cause the steel bars to corrode, and the effective cross-section of the steel bars will continue to decrease; in addition, the volume of the corroded steel bars will expand by about 1-4 times, which will squeeze the concrete, causing cracks or cracks to expand further, or even Failure of concrete protective layer. All of these will result in reduced structural durability and safety. Collective damage caused by water includes direct penetration of water, intrusion of rainwater, capillary water and capillary moisture accumulation caused when the temperature drops to the dew point, water absorbed by water-retaining agents, or moisture seeping into the wall from the ground. In addition, the negative impact of water may also be caused by hygroscopicity of salts and contamination by microorganisms.

Water is a destructive influence on building construction materials such as concrete, masonry and natural stone. Traditional sealing and waterproofing materials mainly use organic materials, such as asphalt, plastic waterproofing membranes, and some metal components to form a certain waterproof function to seal and protect the building and its structural components from moisture and water, also known as Waterproof membranes. Modern building waterproofing materials have developed into cement-based waterproofing materials, which have been successfully used in Europe for more than 40 years, especially in the construction of historical buildings. Buildings to be protected are often exposed to cyclic or chronic moisture (surface water, seepage water), low hydrostatic pressure (groundwater), or a combination of higher engineering hydrostatic pressures. The unique water resistance of cement-based materials makes this type of waterproof material particularly suitable for waterproofing wet rooms, water tanks, and pools. Due to their excellent water and weather resistance, they are often used for exterior surface protection.

The harm of water vapor to buildings requires that buildings should be both waterproof and breathable. The highest temperature on black roofs in summer can reach 85°C. Under 85℃ sealing conditions, water will produce a pressure of 1.46x108Pa (1445 atmospheres) on surrounding buildings. Since buildings are mostly composed of inorganic materials such as silicate, these materials are porous and breathable, which can greatly reduce the pressure of water vapor on the building. However, the pressure generated by water vapor is still very harmful to the building. This hazard is very obvious, especially in parts of buildings with poor air permeability. The harm of water vapor to buildings often causes peeling between the waterproof layer and the base layer, bulging of the waterproof layer, and cracking of overlapping joints, which results in a greatly reduced life span of the waterproof layer and water channeling under the waterproof layer.

In order to protect the building, it is necessary to find a waterproofing agent that can prevent moisture from entering from the outside without inhibiting the outward transfer of moisture formed inside. Domestic waterproofing agents used in waterproof mortar can be divided into four categories according to their main ingredients: ① Waterproofing agents based on chloride metal salts, which can easily cause corrosion of steel bars; ② Sodium silicate ( This kind of waterproof mortar is a waterproofing agent based on water glass). This kind of waterproof mortar generally only uses its quick-setting effect and adhesion in engineering for repairing leaks and surface treatment; ③ Based on water-repellent substances (fatty acids) Metal salts), although the unit cost of this type of product is relatively low, its main disadvantage is that it takes a long time to mix and is difficult to disperse and greatly reduces the strength of the cement product; ④ Organosilicon waterproofing agent, this type of waterproofing agent has good mixing performance, making it The mortar as a whole is waterproof and maintains long-term effects. It has no negative impact on the bonding strength of the surface and is environmentally friendly. While preventing moisture from entering the mortar, it also keeps the mortar open and allows water vapor to diffuse.

The pore structure is an important feature of hardened cement stone. Silicone waterproofing agent forms microcrystals in the micropores and capillary pores inside the mortar to block water penetration, thereby achieving permanent waterproofing of the building. It is a new type of waterproofing agent with Rigid waterproof material with good application prospects. Among the many types of waterproofing agents, silicone waterproofing agents play an important role in building waterproofing due to their excellent hydrophobic, antifouling, weathering resistance and durability properties. They can be sprayed on building surfaces in the form of aqueous solutions or emulsions, or they can be the powder form is directly mixed into cement mortar or concrete as a waterproofing agent, and chemically combines with the cement to form a strong overall rigid waterproofing to improve the waterproofing, weather resistance and durability of the mortar and concrete.