Zirconium phosphate (ZrP) recently introduced in intumescent fire protective coating has shown improvement in developing ceramic layer. The tubular halloysite clay (THC) due to its unique molecular structure can be combined with ZrP to enhance fire resistance by developing a strong silica network on the char surface. This study is aimed to investigate the synergistic effects of tubular halloysite clay and zirconium phosphate fillers to improve the thermal performance of the intumescent coating. The control coating formulation and a range of coating formulations using a combination of weight percentage of THC and ZrP were developed to study the influences of fillers on fire performance. The char expansion and fire resistance tests of the coatings were conducted using furnace fire test and Lab scale fire jet. Thermal stability of the coating was determined by TGA and char was characterized by FESEM, XRD, FTIR and XPS. Water-resistance test of the coating was performed according to ASTM D-870. Results showed that the reinforcement of THC-ZrP showed promising improvement on the performance of IFC and substrate temperature was far below the critical temperature, 550 °C. Sample HZ 5 showed the least backside steel substrate temperature of 219 °C. Expansion rate of char was found reduced with the addition of THC but improved the char compactness. The addition of THC and ZrP in IFC improved 18% fire resistance performance and 5% residual wt. Of char. Char morphology showed silica network, XRD and FTIR confirmed the presence of silicon. Water absorption test showed 95% less water absorption (HZ-5) compared to control coating. Post water immersion, fire test showed 7% increase in substrate temperature which is 18% less than control coating after water immersion fire test.

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Zirconium phosphate powder was purchased from Sichuan Hongchang Plastics Indus. Co. Ltd. China. Expandable graphite, boric acid, ammonium polyphosphate, melamine and tubular halloysite clay were purchased from Sigma Aldrich (M) Sdn Bhd. Malaysia. BE-188 (BPA) resin and H-2310 polyamide amine were used as a binder and brought from Mc-Growth Chemical Sdn Bhd. Malaysia. TSA Industries, Ipoh Sdn Bhd, Malaysia supplied structural steel A36. The thickness of steel plates was 1.50 mm ± 0.05. SEM test was conducted to analyze the orientation of tubular halloysite clay and zirconium phosphate used in this study and presented in Fig. 1.

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Steel Structural Integrity: Steel loses half its load-bearing capacity at temperatures exceeding 500°C, leading to potential collapse within an hour during a fire. Intumescent coatings help maintain the structural integrity of steel by preventing it from reaching critical temperatures.

Environmental Safety: Traditional halogenated flame retardants have been restricted due to their toxic emissions. New regulations favor the use of safer, non-toxic fire retardants, positioning intumescent coatings as a compliant and preferred choice.

Thermal Barrier:The intumescent coatings form a thermal barrier, reducing heat transfer to the substrate and thereby limiting fire damage to the structure.

Effective Char Formation: The combination of THC and ZrP enhances the char formation, which acts as an insulating layer, thereby significantly improving fire resistance.

Versatility: Intumescent coatings can be easily applied to various substrates, including steel, wood, and concrete, without altering their bulk properties.

Non-Toxic: Unlike traditional flame retardants, the newer formulations do not release harmful compounds upon degradation, making them safer for the environment and human health.

Water Resistance: The coatings exhibit excellent resistance to water absorption, maintaining their protective qualities even after prolonged exposure to moisture.

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The weather tests indicated that the coating was strengthened with the inclusion of THCs and ZrP. THCs and ZrP layer structure and hydrophobic characteristic the main strategies to improve the water resistance of the coating. G. Wang [26], observed similar behaviour of coating for water resistance when glass flakes were added in an intumescent protective coating, due to its flaky assembly decrease the movement of fire. It was concluded that the intracellular structure of graphite flakes improves water and ion penetration routes via the coating [59]. The structure of such fillers can, therefore, be concluded to boost the water-resistance efficiency of the intumescent layer.

Cost-Effectiveness: Although advanced coatings may initially be more expensive, their superior performance and longer-lasting protection can lead to cost savings in terms of reduced damage and maintenance.

Industry Adoption: The construction industry, along with sectors like oil and gas, transportation, and manufacturing, are increasingly adopting advanced fire protection systems to safeguard assets and ensure compliance with safety regulations.

Market Growth: The global market for fire protection materials is growing. According to market research reports, the fire protection coatings market is expected to witness significant growth over the next decade due to the rising demand for safer building materials.

Superior Fire Resistance: The new formulations combining THC and ZrP have demonstrated enhanced fire resistance, maintaining substrate temperatures below critical levels for longer durations. This significantly improves the safety of steel structures during fires.

Ease of Application: Intumescent coatings can be easily applied to a wide range of substrates without affecting their bulk properties, making them versatile for various construction materials.