Fire-resistive performance of intumescent flame-retardant coatings for steel

The purpose of this work is to study the efficiency and effect of different intumescent flame-retardant formulations on the performance of steel in the event of a fire. The formulations are based on flame-retardant additives into which silica fume (SF) as a binder and chicken eggshell (CES) as a flame-retardant filler have been incorporated to synthesize water-based intumescent coatings. The influence of binder and filler on the properties and fire-resistive performance of the coatings were investigated by using thermogravimetric analysis (TGA), scanning electron microscopy (SEM), small scale Bunsen burner test and furnace test. TGA results showed that by adding SF alone or in combination with CES, the residual weight and thermal stability of the coatings were increased, while showing improved surface structure in the SEM images. The combination of SF, CES and flame retardant additives showed the best fire protection performance with the highest thermal stability, greatest expansion and densest surface structure while having sufficient adhesion to remain in place during fire exposure.

Graphical abstractThe variation of temperatures recorded from the protected (formulation C) and unprotected steel plates during the heating and cooling phases of the furnace test were compared to the furnace and Eurocode fire curves (Fig. 10). The steel plate protected with coating C experienced a lower initial temperature rise than the unprotected steel plate. The difference between the temperatures of the protected and unprotected steel plates increased to almost 450 °C after about 22 min. The furnace test results show that the steel plate with fire protection could maintain its integrity and properties (Fig. 10a) whereas the steel plate without fire protection exhibited severe deformation due to loss of strength and stiffness (Fig. 10b).Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► APP II, MEL and PER were chosen as main flame retardant additives in this study. ► SF acts as a binder and CES acts as a flame retardant filler. ► Addition of SF and CES into flame retardant additives showed the best fire protection. ► Steel plate protected with the best formulation could maintain its integrity. ► The unprotected steel plate exhibited deformation due to loss of strength.