Development of Low Smoke Environmental friendly Fire Retardant Intumescent Coatings for GI and Steel Structures

Abstract

Abstract Steel begins to lose its mechanical strength above 500 ºC and tends to distort, leading to the collapse of building structures during fire accidents. Fire retardant intumescent coating can protect the steel structure as it swells upon exposure to fire several times its original thickness producing a carbonaceous protective char. The carbonaceous char acts as a heat transfer barrier and protects the structure of steel physically and thermally The objective of the experimental work is to develop the composition of fire retardant intumescent coating with low smoke emission on reaction to fire. Specific fire retardant intumescent coatings were formulated with various compositions using additives (acid source, carbon source, and blowing agent), binder (water-based), and fillers. All the formulations were examined with the non-luminous premixed flame gas torch preliminary test, and the thickness of the char layer formed at the end of the experiment was observed and measured. It was observed that the composition formulated with a water-based binder can form a char layer of a maximum of 70 times the coating thickness. Various standard tests were performed to examine the water-based coating formulations. The results showed that coating composed of a water-based binder with a 50% addition of epoxy and hardener achieved the criteria of ignitability evaluation as per BS 476 Part 5 as it was not easily ignitible. Fire propagation index BS 476 Part 6 showed a Fire propagation index value of less than 12 which signifies that the heat generation rate was low. According to the surface spread of flame of products as per BS 476-Part 7, the coating was classified as class 1 as no flame spread was observed on the surface. Specific optical density value at 1.5 min was found to be less than 100 and less than 200 at 4 min as per ASTM E 662 which was meeting the criteria as per NFPA 230. Sample IC3 was found to nearly meet Non-combustibility criteria. It can be concluded that an environmental friendly fire retardant intumescent coating can be achieved with a water-based binder, additives, and fillers.