Analysis And Solution Of Cracking Causes Of Weather Proof Silicone Sealant

Due to various reasons, Weather proof Silicone Sealant often produces cracks and bubbles in the construction process, which brings great inconvenience to owners and construction personnel. The reasons and solutions for the cracks and bubbles are summarized below.

Analysis of crack causes:

1. The curing mechanism of weather proof Silicone Sealant absorbs moisture from the air and solidifies by penetrating from the outside to the inside. Under standard experimental conditions (temperature of 232 and relative humidity of 50% 5%), the surface drying time of the sealant is about 40 minutes, and the first day of solidification is about 2mm. The deeper the solidification, the slower the solidification. Within one or two days after construction, a layer (approximately 1-2 millimeters) is formed on the surface of the colloid, so the ability to withstand external environmental influences does not reach 5% after complete solidification. Cracks can occur when subjected to uneven forces such as wind pressure and vibration.

2. Equipment with high expansion coefficient (such as aluminum plate, aluminum plate, or PVC) can have significant displacement changes depending on temperature.

3. The injection thickness of weather proof Silicone Sealant is insufficient or not tight: JGJ 102-2003 "Technical Specification for Glass Curtain Wall Engineering" 10.3.7 stipulates that the construction thickness of silicone building sealant must be greater than 3.5mm, and the construction width must be less than twice the construction thickness. The newly revised JGJ 102 specification this year will increase the low construction thickness to 5mm. The small construction thickness of 3.5mm in the original specification does not meet the actual usage requirements, and the construction thickness of silicone building sealant directly affects the quality of the project.

4. The construction is irregular, the design glue is 16 mm, the actual large glue is 30 mm, and the small glue is less than 10 mm. The foam rod models used are 16 mm and 18 mm. The standard requires that the size of foam rod is greater than 25% of the actual sealant width.

5. Plastic selection error. The roof has long exposure to sunlight, and the material undergoes significant deformation due to thermal expansion and cold shrinkage. Generally, the displacement capacity of weather resistant adhesives is 25%, which does not meet the requirements for the use of roof buildings. In 2009, the China Curtain Engineering Committee commissioned an expert group to draft the "Technical Specification for Daylighting Roofs", which has clear requirements for the elongation of weather proof Silicone Sealant.

Suggestion:

(1). It is recommended to apply glue at different times during seasons with significant temperature changes in spring, summer, autumn, and winter, and make curtains to block sunlight to avoid direct exposure to sunlight on both sides of the construction.

(2). A. The foam rod should be stored in a dry environment. When installing the foam rod, do not pull the foam rod too tightly, and do not poke or rub the foam rod with sharp tools. B. The size of the foam rod is usually 25% larger than the interface size.

(3). Correctly construct according to standard requirements.

(4). The roof and daylighting roof should use MF898 large displacement weather proof Silicone Sealant with a displacement capacity of 100/50.

Restrictions on the use of weather proof Silicone Sealant

It cannot be used as a silicone structural sealant. It shall not be used on all materials that have leaked oil, plasticizers, or solvents (such as the surface of sunken wood). Silicon sealant needs to absorb moisture from the air and harden, so it cannot be used in poorly ventilated areas. Do not use in areas with continuous flooding or areas with year-round humidity. Construction shall not be carried out when the surface temperature of the material is below 4 or above 40. matters needing attention

This product complies with relevant national standards. Before use, please conduct compatibility testing and construction in accordance with national engineering specifications and technical requirements.

Transportation and Storage

This product is a non flammable and explosive substance and can be transported as a general non hazardous material. This product is stored in a dry, ventilated, and cool place below 27, with a storage period of 12 months from the date of production