Abstract
Owing to the dense internal organization of high-strength concrete, water vapor generated within the concrete cannot be easily discharged to the outside. The increased internal vapor pressure leads to a phenomenon known as spalling. This study investigated the use of fire-protection covering methods for preventing the spalling of high-strength concrete in order to inhibit temperature transmission to concrete structure by covering the material and to minimize the increase in cross-section. The fire-protection covering methods considered included fireproof plaster boards, high-performance fireproof plaster boards, and a composite covering method (fireproof plaster board + intumescent coating system). Among these, the high-performance fireproof plaster board exhibited 20~40 % higher fire protection performance compared to the regular fireproof plaster board. If the composite covering material is exposed to high-temperature fires, especially above $500^{\circ}C$, a 4 mm-thick intumescent coating system extends up to at least 50 mm, thereby blocking most of the heat transferred inside the board and suppressing the temperature increase within the concrete. The above-mentioned mechanism leads to more than 40 % decrease in the coating thickness. The restrictive application of this method could reinforce fire protection performance on finishing parts of gypsum board in existing buildings.