Dolomite Clay was introduced in a traditional intumescent flame retardant system which contains ammonium polyphosphate/expandable graphite/melamine (APP-EG-MEL) to evaluate its effects on char morphology and fire performance. The effect of dolomite clay on the fire-resistance and thermal properties of expandable graphite based Intumescent fire retardant coatings has been investigated by using Bunsen burner fire test and thermal gravimetric (TG) techniques. The current study describes the effects of Dolomite Clay on the heat shielding performance of intumescent passive fireproofing coatings during fire testing. The fire performance of dolomite clay reinforced intumescent coating formulations were evaluated by Bunsen burner fire test according to ASTM E-119. Results showed that the dolomite reinforcement in IFRC formulation significantly reduced the steel substrate temperature up to 180 °C after 1 hour of fire exposure. The coating degradation was studied using thermogravimetric analysis (TGA). The physical morphology and alignment of intumescent char residue were studied by field emission scanning electron microscopy (FESEM). TGA analysis revealed that IFD (8) containing 8 wt. % of dolomite clay enhanced residual weight by 37.30%. It is suggested that Dolomite clay can enhance the fire performance and can significantly affect the formation of dense and continuous char if incorporated as a filler in conventional intumescent fire resistive systems.

---

In this research, five formulations of intumescent fire retardant coating were developed while using bisphenol A BE-188 as epoxy resin with tetra ethylene tetraamine H-2310 as a curing agent. This formulation contained an acid source (APP), a carbon source (EG), a blowing agent (Melamine-MEL), an additive (Boric acid-BA), alone with Bisphenol based binder system and Dolomite filler with the difference in weight percentage (0-8 wt.%) .All materials were purchased from Sigma-Aldrich (M) Sdn Bhd. Malaysia. IFD (0) is the controlled formulation while IFD (2) - IFR (8) are added with Dolomite filler with the difference in weight percentage. For all IFR coating formulations, selected weight percentage of APP, MEL, BA and Dolomite filler were grounded for 1 min by using a grinder. This was followed by mixing with epoxy and hardener with all ground material and expandable graphite (EG) using shear mixture at 40 rpm for 20 min. After 20 minutes, hardener was added and been mixed for another 10 minutes. The total process is 30 minutes for each sample. The formulation then coated on steel substrate having a cross-sectional area of 10 cm2 . The coating was applied using a brush on the steel substrate .The coated steel substrates were cured at ambient temperature for 24 hours. Coating thickness was maintained at 1.5 mm it was ensured by digital Vernier caliper measurement. Table 1 showed five intumescent coating formulations (ICF) designed to study the effects of dolomite clay on fire performance and thermal shielding of the IFRC. The char was characterized by FESEM. The residual weight was investigated using Thermogravimetric Analysis (TGA).

---

Improved Thermal Performance: Dolomite clay enhances the thermal stability of intumescent coatings, significantly reducing the temperature of the steel substrate during a fire. The study shows a reduction from 270°CC to 180°CC, which is critical in preventing structural collapse.

Strength and Stability: The structural orientation of dolomite, with its ring-based structure, improves the mechanical strength and stability of the char layer. This means the coating remains intact and effective even at high temperatures.

Prevention of Structural Collapse: Enhanced fire resistance and lower substrate temperatures help prevent the collapse of steel structures during a fire, ensuring the safety of occupants.

Reduced Economic Losses: Effective fire retardant coatings can prevent extensive damage to buildings, machinery, and other assets, minimizing economic losses.

Meeting Fire Safety Regulations: The incorporation of dolomite clay helps in meeting stringent fire safety regulations and building codes, ensuring legal compliance.

Encouragement of Further Research: The success of dolomite clay in enhancing fire retardant properties encourages further research and development in the field, potentially leading to more innovative solutions.

---

Char forming process in intumescent coatings has completely proceeded in the first five minutes of bunsen burner fire test and by the time the formed protecting shields had the best heat insulation capacity, after 25 minutes, the thermocouple reaches 260 °C in IFD (0). While in the case of dolomite reinforced coatings maximum temperature was below 180 °C. Substantial variations can be noticed in the temperatures profiles of neat fire resistive coatings (IFD (0)) and dolomite reinforced fire resistive coatings, shown in figure (2). It was observed that the temperature profile of the highly dolomite containing coatings is very divergent to the control coatings formulation. The addition of dolomite reduced the backside temperature of steel from 270 °C to 180 °C after one hour of fire exposure. The maximum protection against heat was observed in the case of the IFD (8) which was reinforced with the highest quantity of dolomite clay. After first 5 minutes of Bunsen burner test, the degradation of the intumescent ingredient including dolomite starts. This is the point where to intumesce foamy char layer instigate to develop over the surface and thus provide shield protection to the underlying substrate. Once the intumescence char has been developed over the surface temperature profile of each neat or clay reinforced, all formulations attained steady state (figure 2). After this, fire proofing relayed on the quality of char produced[10]. Without filler char have cracked surface and incapable of providing better insulation. On the other hand, char which has dolomite clay filler in its ingredient have exhibited denser and continuous structure to restrict heat from penetration

Growing Construction and Industrial SectorsGlobally, construction activities are on the rise, driven by urbanization, infrastructure development, and industrial expansion. This growth fuels demand for advanced fire safety solutions in commercial, residential, and industrial buildings.

Legislative Requirements: Stringent fire safety regulations and building codes in many countries mandate the use of fire retardant materials in construction. This regulatory pressure increases the adoption of intumescent coatings.

Abundant Supply: Dolomite clay is abundantly available, particularly in Malaysia, ensuring a cost-effective supply chain.

Economic Efficiency: The use of dolomite clay at an 8% incorporation rate is effective, reducing material costs while maintaining high performance.