Steel building is a form of construction. Non-intumescent fireproofing materials have superior fireproofing effects and can provide effective fireproofing and thermal insulation protection for steel structures. However, the modification and innovation of non-intumescent fireproofing materials are insufficient in China at present. Seafoam has a good thermal stability and a low thermal conductivity, having a thermal insulation effect, which can be used as a filler for fireproof coating or fireproof board. Seafoam can effectively improve the fire resistance of fireproof coating or fireproof board. Seafoam mineral fibers dispersed in a low concentration solution can form a stable high-viscosity suspension, so they can be dispersed and modified with other fillers and added to fireproof coating or fireproof board slurry. Therefore, the fire performance of seafoam fiber fireproofing materials can be improved. In this work, a modified seafoam fiber was added to fireproof coatings for improving the fire performance of non-intumescent fireproof coatings. This modified fiber as a kind of modified fiber was prepared via mixing seafoam fiber, magnesium hydroxide fiber and silicon oxide fiber under high-speed mixing and adding polymer modifier. In addition, the physical and chemical properties and fire performance of the finished product were also analyzed.

In this work, 5-70 mm hydromagnesite fibers were ground in a mill to obtain the fibers with the lengths of < 5 mm. Subsequently, 1-5 mm seafoam fibers and 3-6 mm silicon oxide fibers were selected, and 50% seafoam fibers, 30% hydromagnesite fibers, 8% silicon oxide fibers, 5% organic bentonite, 1% polymer water-absorbent resins, 1% starch ether, 5% hydroxypropyl methyl cellulose ether were mixed as raw materials in a dry mixer for 30 min to obtain the modified seafoam fibers. The modified seafoam fibers were analyzed based on the physical phase characterization. Cement, kaolin, modified fiber, and fire protection additives in different weight ratios were added to the dry mixer and stirred for 300 s, and then an expanded vermiculite was added to the mixer and stirred for 120 s, and six groups of fireproofing coating samples were obtained. Afterwards, the samples were then stirred slowly in a cement sand mixer according to a mass ratio of fireproofing coating:707 emulsion: water of 1.0∶0.2∶0.8 and mixed for 5 min to make the mixture homogeneous. After mixing, the fire resistance, bond strength and compressive strength of the samples were characterized.

Based on the fire resistance test analysis of fireproofing materials doped with six different contents of modified seafoam fibers (i.e., 10%, 12.5%, 15%, 17.5%, 20% and 22.5%), the fireproofing and thermal insulation properties of fireproofing coatings are gradually improved with the increase in the addition of modified seafoam fibers. Their fireproofing and thermal insulation properties enhance with the increase in the doping of modified seafoam fibers, indicating that modified seafoam fibers play a key role in the fireproofing coatings. Seafoam fibers play a key role in fireproof coatings. The fireproof performance is obviously better than that of two commercial fireproof materials. The analysis by X-ray diffraction patterns shows that Mg(OH)₂ is added to the modified seafoam fiber. According to the TG-DTG analysis, Mg(OH)₂ decomposes into MgO during the heat process, and MgO is a kind of superior heat-insulating and insulating material, indicating that the modified seafoam fibers greatly improve the fire-insulating and heat-insulating performance. The FTIR analysis shows that there are a large number of Si—O—Si bonds in the sample, and that there is a large number of Si—O—Si bonds in the sample. There are a lot of Si—O—Si bonds in the sample, so that the modified seafoam fibers maintain its original adsorption and rheological properties. The appearance and morphology of the fireproof coating after combustion show that the silicon oxide fibers improve the crack resistance of the fireproof coating.

In this paper, the modified seafoam fiber was prepared via mixing seafoam fiber, magnesite fiber, silicon oxide fiber and some polymer modifiers in a certain proportion. The modified seafoam fiber had a better fireproofing and thermal insulation performance, the magnesite fiber could further reduce the thermal conductivity of the material, and the silicon oxide fiber could ensure that the fireproofing coating was not easy to crack. To meet the national standards of bonding strength and compressive strength of the basis, the fireproof coating with 20% of the modified seafoam fibers had the optimum fire insulation performance. At the effective fire prevention time of 185 min, the coating had a bonding strength of 0.042 MPa and a compressive strength of 0.461 MPa. Compared with some other commercial fireproofing materials, the coating had a fireproofing effect and some application prospects.