Structural Sealant is a type of silicone sealant that has high strength, large bearing capacity, anti-aging, corrosion resistance, and performance within the expected service life. It is mainly used in structural joint bonding.
Dow 995 Silicone Structural Sealant is a one-component, self-priming, shelf-stable, neutral cure, elastomeric adhesive specifically formulated for silicone structural glazing applications. It exhibits excellent unprimed adhesion to most building substrates.
Structural Sealant is an adhesive that can be used to bond and connect structural components. It is an anti-aging, anti-corrosion and high-strength adhesive that can bear a certain load and maintain its performance in different environments. It is often used in building joint structural components that require relatively large bearing capacity and long service life.
Moisture resistance is the ability of a material to resist moisture in the air or water. It is an important quality for many materials and it can be tested for compliance with certain requirements.
The most commonly used moisture resistance test is called cyclical humidity testing. This type of moisture testing is intended to evaluate a material’s resistance to the deteriorative effects of high-humidity and heat conditions that are common in tropical environments.
This test is often performed in an environmental chamber that cycles the relative humidity between high and low temperatures. This provides alternate periods of condensation and drying, which are necessary to simulate the corrosive effects that can occur when exposed to high levels of moisture.
While the exact number of cycles required for a particular test depends on the product, this test is typically completed in ten 24-hour cycles. Each cycle contains two 8-hour linear ramp excursions that begin at 90-95% humidity and end at 25degC.
In addition, the testing facility should be equipped with a temperature control device that regulates the temperature of the chamber and its surrounding environment. It should be able to maintain the specified temperature for the entire period of the cycle, without any fluctuation.
Generally, the test requires the use of steam, or distilled and demineralized water, having a pH value between 6.0 and 7.2 at 23degC. It is also important to avoid the application of rust or corrosive contaminants to the test samples.
Another factor that affects the moisture resistance of a material is its Structural Sealant ability to accommodate joint movement. This is a characteristic that can be found in a variety of materials, including plastics, rubber, and polyurethanes.
Sealants may accommodate this movement by one of two mechanisms: internal flow under stress, or a more general ability to deform, but recover when the stress is removed. The most effective sealants are those that have both of these features.
The thermal resistance of structural sealant is important for determining its service life. This is particularly relevant for a wide range of sealant applications, such as sealing of linear joints or fire stopping penetrants in fire-rated walls and floors.
In order to assess the thermal resistance of structural sealant, it must be tested at different temperatures in a controlled environment. This testing can be done using a temperature probe, a thermocouple or a thermal conductivity instrument (C-Therm Trident).
Another way of assessing the thermal resistance is to measure its thermal expansion coefficient. This is a mathematical function that measures the rate of change in the material’s thermal expansion with time.
It is a very powerful tool that can be used to understand the thermal response of materials in 1-dimensional, steady-state situations and is often an invaluable tool for understanding heat transfer problems in real applications.
Structural silicones are typically characterized by their excellent resistance to heat, and are a common choice for many applications that require bonding or sealing in areas where there is exposure to high temperatures. These include valve covers, axle housings, water and oil pump seals, solenoid covers and more.
In addition to providing good resistance to the heat, structural silicones are also resistant to UV radiation and ozone. They are also considered to be environmentally friendly and have a good adhesion to a variety of surfaces, making them suitable for a wide range of uses.
Therefore, the thermal stability of structural silicones is a key consideration when designing products that will be exposed to extreme environmental conditions or that will be subjected to repeated heating and cooling cycles. This is a particularly critical issue when evaluating structural silicones for use in fire-rated buildings, as they may be exposed to both direct fire and the spread of fire throughout the building.
The thermal properties of structural sealants are often based on their tensile or shear strength, which must remain above a certain value during exposure to extreme temperatures. This is a requirement of the European Technical Assessment Group (ETAG) 002-1 standard, which stipulates that a minimum of 75% of the mean tensile and shear strength values measured at -20 degC and +80 degC should be retained by the end of exposure.
Structural Sealant is an adhesive that is used for sealing between components such as glass, window frames and stone. It also helps transmit the internal and external forces of a bonded material so that the joint doesn’t fail.
One of the most important attributes of structural sealant is the ability to withstand exposure to chemicals, liquids and gases. These are often present in industrial processes and may be hazardous to personnel or property, so it’s critical to use the right products for the job.
As a result, Henkel has developed a range of products with high levels of resistance to liquids and gases. They include the SS-3004 fast cure chemical resistant silicone RTV rubber for coating applications, Chemseal a precompressed primary seal that is NSF compliant and a variety of other products designed to be effective in demanding environments.
In the spirit of safety in use, we also offer a naturally aged product that has undergone 23+2 years of aging and still squeaks out the win when it comes to tensile and shear strengths, as shown in Table 1. This performance, coupled with the best quality adhesive available from Henkel, makes this sealant a real contender for Safety in Use as defined by ETAG 002.
While structural and weatherproof sealants are both worthy candidates for the honors of being the best at achieving their intended purpose, there are many different criteria to be considered when choosing the right type of material. A combination of factors including temperature, humidity, exposure to chemicals and the quantity of water in the application can all play a role in selecting the best option.
Structural Sealant is a high-strength, anti-aging and durable adhesive that can bond, seal, connect and repair various structures. Suitable for heavy-duty and long-term structural bonding applications, it is often used in the construction of joints in precast concrete components such as pipe, manhole, and precast box sections, and also in water storage, treatment, and conveyance infrastructure projects.
A wide range of structural silicone sealants are Structural Sealant available for use with precast concrete, from ‘butyl’- and ‘bitumen’-based products to elastomeric materials like LOCTITE(r) and TEROSON(r) sealants. These elastomeric materials have excellent adhesion and flexibility in both cold and hot temperatures, making them ideal for sealing joint surfaces that are prone to expansion or contraction.
While some elastomeric sealants can be applied using a trowel or brush, Henkel’s LOCTITE(r) and teroson(r) products can be applied directly to the joint surface by hand. These ‘applied from the roll’ products can maintain their flexible consistency for many years, enabling them to adapt to joint conditions and withstand environmental stresses.
When using a preformed flexible joint sealant, it’s important to position the sealant rope as close to the joint’s centerline as possible. This will help ensure the entire sealant rope remains in the joint after the adjoining concrete component compresses it.
It’s also vital to never stretch the sealant rope. This is because it reduces the cross-sectional area of the sealant and can cause inconsistencies between how the sealant carries the weight of the adjoining concrete component. This can compromise the strength and durability of the structural silicone sealant.
The initial mechanical strength test is conducted to assess the strength of a structural silicone sealant after it has been exposed to tensile and shear forces acting on the joint at varying temperatures. Ideally, these tests will show that the mean tensile and shear strength values measured at -20 degC and +80 degC do not drop below a minimum of 75% of the corresponding values observed at 23 degC.
Another crucial criterion for safety in use is that the residual tensile strength after accelerated aging should still equal or exceed 75% of the original tensile and shear strengths measured at 23 degC. This requires the failure mode after aging to be >=90% cohesive in nature.