Is the sealant easy to crack? This construction plan can help you!

On February 21, 2016, the Central Committee of the Communist Party of China and the State Council issued "Several Opinions on Further Strengthening the Management of Urban Planning and Construction", proposing that construction enterprises should be encouraged to construct and assemble on site. Strive to take about 10 years to make prefabricated buildings account for 30% of new buildings; on March 5, Premier Li Keqiang proposed in the government work report to vigorously develop steel structures and prefabricated buildings to improve construction standards and quality. ......

With the rise of prefabricated buildings, the selection of sealants for the joints of prefabricated building exterior wall panels is becoming more and more important. The sealant is required to have excellent adhesion, weather resistance, paintability and other basic requirements. Said, "Three points depend on quality, seven points depend on construction", and using a reasonable construction plan is the guarantee to ensure excellent product performance.

When using sealant for prefabricated buildings, there are several important steps to pay attention to:

1. Seam cleaning

1. There will be foreign objects such as floating dust and cement laitance at the joints of the prefabricated building. These foreign objects are not conducive to the bonding between the sealant and the wall and need to be removed. Generally, use a grinder or a shovel brush to remove the unfavorable bonding. substance;

2. Then use a brush or compressed air to clean the dust, impurities, etc. remaining on the joint base surface due to grinding;

3. The surface of the treated substrate should be clean, dry, clean, dense and uniform in texture.

2. Selection of backing material

1. Use soft closed-cell circular or flat polyethylene strips as the backing material to control the sizing thickness of the sealant. Usually, the width of the backing material should be greater than the width of the seam by more than 25%;

2. Recommended sealant width: the thickness is between 2:1 and 1:1, and the thickness should not be less than 10mm (the thicker the sealant, the better the waterproof sealing effect and the longer the service life, but when the thickness of the sealant exceeds the width, it should not be Facilitate the elastic deformation of colloids). When the width of the seam is less than 10mm, it is recommended to cut the gap to more than 10mm, and when the width exceeds 30mm, it is recommended that the thickness of the sealant be 15mm.

3. Sealant sizing

1. If the primer needs to be used during construction, apply the primer according to the manufacturer's instructions, and then apply the glue. If the primer is missed, the sealant will not stick to the wall, and the waterproof sealing effect cannot be guaranteed; the primer does not need to be used. , After the above steps are completed, glue can be applied. When applying glue, probe the glue nozzle to the bottom of the seam, maintain a suitable speed, and continuously apply enough sealant with a little overflow to avoid the formation of a cavity between the glue and the foam rod;

2. After the sizing is completed, the sealant is compacted and smoothed, and the edges of the colloid and the gap are smeared to enhance the sealing effect;

3. For construction in summer and autumn when the temperature is high, a spatula needs to be used to modify the surface of the glue into a flat and beautiful plane shape; for construction in winter and spring when the temperature is low, the surface of the glue needs to be modified into a concave shape;

4. When applying glue at the "cross" interface or the "T" interface, you should squeeze a sufficient amount of sealant at the interface first, and pull the glue in other directions to ensure the connection effect at the sealant joint;

5. When the seam is larger than 30mm, the surface of the squeegee is easy to dent. It is recommended to construct in two steps, that is, press the sealant after half of the application, and then apply the other half;

4. Precautions

In order to ensure a better bonding effect, the following matters should be paid attention to when sealing the joints of prefabricated building wall panels:

1. The glue should be used at an ambient temperature of 5°C to 45°C;

2. It is not suitable for construction if the concrete base surface is not dry;

3. It is not suitable for construction in rainy weather;