**1. Introduction**

According to world fire statistics, there are more than 322,000 people per year suffering in fire accidents due to the ineffectiveness of fire protection systems. Hence it is important to implement an effective fire protection system in every building to protect the occupants and building whenever there is a fire outbreak. Intumescent fire protective materials perform as a passive fire protection system and play a crucial role in fulfilling the fire safety building regulations to effectively stop the advance of a fire. Steel structure starts to lose its mechanical properties (temperature >500 ◦C) and tends to buckle, leading to failure of the building structures. Indeed, the fire safety rules and regulations in buildings are of paramount importance to ensure the evacuation time and safety for occupants [1].

Intumescent coatings are mainly designed to reduce the heat and fire propagation on the substrate. Interior decorative materials in buildings are mostly combustible products that are a serious hazard in a fire. In general, most of the flame-retardant materials were developed due to the smoke and toxic gas produced from thermal decomposition of the commonly deployed brominated flame-retardant products [2]. Fires are unavoidably used to produce a lot of energy and heat, which might lead to serious injury or death [3–5].

The applications of fire protective coatings are one of the most effective ways to protect different substrates toward a fire. The expansion process of intumescent fire protective coating is due to the physical and chemical interactions of three main flame-retardant additives: (1) Ammonium polyphosphate (APP) acts as an acid source, (2) pentaerythritol (PER) acts as a carbon source and (3) melamine (MEL) acts as an expanding agent. The use of flame-retardant ingredients may prevent a small flame towards a major catastrophe. The polymer binder turns out to be important due to two extensive properties: It contributes to the char layer growth and controls the development of even char foam structure [6,7]. Several advantages of using intumescent fire protective coatings over other approaches of structural fire protection are the artistically attractive appearance it gives to the substrates, fast application, easy to cover complex details and maintaining the intrinsic properties of steel structures [8,9].

This research highlights a renewable chicken eggshell (ES) flame-retardant bio-filler and its important role in industrial coatings. ES waste is an aviculture by-product, which causes a serious conservation risk due to its disposal constitutes. ES waste comprises about 5% organic materials and 95% calcium carbonate in calcite form [10,11]. ES waste can create new value by being converted into profitable products. Its biochemical composition and accessibility make ES a latent source for renewable flame-retardant bio-filler, which improved mechanical and thermal properties of coatings and bio-polymer composites [12–21]. ES also offers benefits for various industrial applications, as it is lightweight, inexpensive, environmentally friendly, has high thermal stability and is available in bulk quantities [22–31]. In this research work, the performance of a steel plate coated with an intumescent coating was tested by using a Bunsen burner. In addition, the fire propagation and fire behavior of intumescent coatings were tested according to BS 476: Part 6 and ISO 5660-1 [32,33], respectively. These thin-film intumescent coatings were evaluated with respect to fire behavior analysis with thermal characteristics in a cone calorimeter and the fire-resistive performance.
