With the continuous updating of building construction technology, the choice of building sealant is becoming more and more important. Among them, it is particularly important to choose the professional and targeted construction sealant and control the construction quality.
There are many types of building sealants, including silicone, polyurethane, polysulfide, acrylic, butyl, asphalt and oil-based resin modified products. At present, the building sealant used in China is mainly silicone, polysulfide, polyurethane three room temperature curing elastic sealant, and the most widely used silicone sealant.
How to choose sealant is the key. The choice of building seal is mainly based on its performance characteristics, as follows.

1. Concrete bonding
Most of the PC boards used in the market are concrete slabs, so the building sealant should have good adhesion to concrete. Due to the nature of the concrete itself, ordinary sealants are not easily bonded on their surfaces. When selecting a building sealant, concrete should be considered as an alkaline porous material, and whether the release agent used during demolding remains on the surface of the PC board.

2, joint displacement
When a sealant is selected, its mechanical properties are also important. The displacement of the joint should be considered in the design to determine the width of the joint, which is the deformation of the sealant within the maximum allowable range. For concrete joints of 10~35mm, it is generally required that the sealant has good displacement capacity and elastic recovery rate, so that it can adapt to joint displacement.

3, weather resistance
The weather resistance of building sealant will affect its service life. Due to the specific molecular structure of silicone sealant, it is not enough to damage its structure even when the highest energy ultraviolet radiation is applied, which ensures the silicone sealant has good UV resistance. It has a clear advantage in weather resistance.

(1) not bonded to the substrate
The main reason was that the adhesion test was not carried out before construction, the curing temperature was too low, and the relative humidity was too high. During construction, the curing temperature should be increased, the curing time should be extended, the substrate should be surface treated or the sealant replaced.

(2) Slow curing speed
The main reason is that the ambient temperature is low, the humidity is low, the glue joint is too narrow, too deep, and the sealant expires. During construction, the curing temperature and humidity should be increased, two times of glue or double-sided glue should be applied, and the sealant should be replaced.

(3) Producing bubbles
The main reason is that the glue is entrapped in the air, the moisture invades the glue joint, and the substrate reacts with some sealant. During construction, the glue should be glued evenly, continuously, and filled with interfaces, and the interface and accessories must be dry.

(4) Starting the drum
The main reason is that the plate size is large, the expansion coefficient is large, the joint is deformed, the temperature difference between the plates is large, and the ambient humidity is low. During the construction, the sealant with a relatively fast curing speed should be selected, and the panel temperature should be reduced by appropriate shading measures.

(5) Cracking and leaking water
The main reason is that the seam is too narrow, the seal is not in place, the displacement ability of the sealant is insufficient, and the thickness of the sizing is too thin. During construction, the joints shall be designed according to the specifications, and the sealant with good displacement ability shall be selected and constructed according to the operation specifications to ensure the thickness of the sealant and avoid the three-side bonding.

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