How does the insulating layer formed by non-expanding fire retardant coating maintain structural integrity under high-temperature flames?
Publish Time: 2025-10-11
With the continuous improvement of building safety standards, fire protection of steel structures has become an essential component of architectural design. To ensure the stability of steel structures in fires, non-expanding fire retardant coatings are widely used. This thick-coated fire retardant coating not only offers excellent fire resistance but also maintains its structural integrity under high-temperature flames, effectively protecting steel structures from fire damage.1. Material Selection and Formulation DesignThe key to non-expanding fire retardant coatings lies in their material selection and formulation design. These coatings primarily consist of inorganic insulating materials, such as silicates, aluminum phosphates, and refractory cements, as base materials, along with lightweight insulating aggregates such as expanded perlite, expanded vermiculite, and sepiolite.4 These materials have low thermal conductivity and excellent fire resistance, effectively preventing heat transfer to the steel structure. Furthermore, added chemicals and reinforcing materials further enhance the coating's overall strength and durability, ensuring the insulation maintains a stable physical form even under extreme temperatures and resists cracking or flaking.2. Impact of Construction Techniques on Structural IntegrityIn addition to the inherent properties of the material, construction quality is also a significant factor influencing the structural integrity of the insulation layer. Non-expanding fire retardant coatings are typically applied by spraying, requiring a uniform and dense coating thickness. Proper application methods ensure the absence of voids or weak spots within the coating, thereby enhancing the overall compressive strength of the structure. For example, in practice, applicators must strictly control spray pressure, gun movement speed, and the thickness of each coat to avoid dripping or excessively thick areas that prolong drying time.10 Furthermore, when applying multiple layers, sufficient curing time must be ensured between coats to form a strong and continuous protective layer.3. Measures to Counteract Thermal StressWhen exposed to high-temperature flames, steel structures heat up rapidly, increasing the temperature difference between the inside and outside of the coating and generating significant thermal stress. To overcome this challenge, non-expanding fire retardant coatings are designed with thermal expansion coefficient matching in mind. By selecting appropriate additives and fillers, the coating's thermal expansion coefficient is brought as close as possible to that of the steel itself, reducing stress concentrations caused by temperature differences. Furthermore, the fiber material within the coating absorbs and disperses thermal stress to a certain extent, preventing the formation and development of cracks. 6 Furthermore, certain specially designed coatings can form a glaze-like layer at high temperatures, sealing micropores and further enhancing insulation and maintaining structural integrity. 14. Long-term Stability ConsiderationsGiven that buildings may experience multiple fire threats of varying severity throughout their lifecycle, non-expanding fire retardant coatings must also exhibit excellent long-term stability. This means that the coating must continue to provide reliable fire protection even after prolonged exposure to natural conditions such as sunlight, rain, and alternating heat and cold. To ensure this, the R&D team subjects the product to a series of rigorous tests, including weathering and damp-heat aging tests, to ensure it maintains its performance in a variety of harsh environments. 7In summary, the ability of non-expanding fire retardant coating to maintain its insulation's structural integrity even under high-temperature flames is due to carefully selected raw materials, a scientifically designed formulation, and rigorous and meticulous construction techniques. It not only relies on its excellent fire resistance to withstand flames, but also relies on its strong compressive strength and adaptability to handle complex thermal environments.
