Eggshell, a novel bio-filler for intumescent fire protective coating

This study focuses on the characterization of eggshell, a new bio-filler for water-based intumescent fire protective coating. The coating is a water-based intumescent coating system into which fire retardant agents, ammonium polyphosphate (APP) phase II, melamine (MEL) and pentaerythritol (PER), recycled chicken eggshell (CES) as a bio-filler and silica fume (SF) as a binder have been incorporated. The influence of filler and binder on the properties and fire-resistive performance of the coatings applied on the steel plates were investigated by using thermogravimetric analysis (TGA), scanning electron microscope (SEM), small scale Bunsen burner test and furnace test. Thermal stability of chicken eggshell (CES) as bio-filler was compared with that of commercial calcium carbonate filler by TGA. The results indicated a higher thermal stability for the CES. TGA results showed that by adding CES as well as silica fume (SF) as a binder has increased the residue weight and anti-oxidation of the coatings. The combination of CES and SF with flame retardant additives led to the best fire resistance performance, the highest thermal stability and the densest surface structure.