Experimental tests were performed to examine the relative fire resistance provided by several bonded coatings for normal weight concrete (NWC) panels that emulate a tunnel liner: ceramic tiling on mortar, spray-applied fire resistive material (SFRM), and intumescent paint (IP). Sixteen panel specimens (150-mm [6-in.] thick, 457-mm [18-in.] wide, and 610-mm [24-in.] tall) were subjected to one-sided heating using a gas-fired radiant panel, which can apply heat flux at intensities similar to hydrocarbon fuel fire. All specimens were cast from a single batch of NWC (approx. 40 MPa compressive strength) with a single curtain of steel reinforcing bars at 38-mm (1.5-in.) cover to the heated face. All specimens were vertically loaded to a service level of compressive uniaxial stress (approx. 14% of ambient specified compressive strength), which remained relatively constant during each test. Four bare concrete panel specimens were tested as a control group, and a ceramic tile finish was installed on six specimens in accordance with a current state department of transportation specification. The other six specimens were coated with fire resistive material (three each with SFRM and IP) at thicknesses corresponding to a 1-hr fire resistance rating per manufacturer specifications. Thermally-induced explosive concrete spalling was observed in 3 of 4 control specimens, 4 of 6 tiled specimens, and none of the 6 SFRM/IP coated specimens. The tiled finishes delaminated and eventually became fully detached from the concrete surface, thus providing negligible fire resistance compared to that provided by the SFRM or IP. Temperature time histories recorded within the outer 25-mm (1.0-in.) thickness of the heated concrete were used to evaluate the relative thermal resistance of each surface finish, as well as to validate a simplified thermal numerical model used for a brief parametric study. Post-fire removal of the surface finishes is also demonstrated.

进行了实验测试以检查模拟隧道衬砌的正常重量混凝土 (NWC) 面板的几种粘合涂层提供的相对耐火性：砂浆上的陶瓷瓷砖、喷涂防火材料 (SFRM) 和膨胀型涂料 (IP) . 16 个面板样本（150 毫米 [6 英寸] 厚，457 毫米 [18 英寸] 宽，610 毫米 [24 英寸] 高）使用燃气加热炉进行单面加热辐射板，可以以类似于碳氢化合物燃料火的强度施加热通量。所有样本均由单批 NWC（约 40 MPa 抗压强度）浇铸而成，在加热面 38 毫米（1.5 英寸）处覆盖一层钢筋。所有样本都垂直加载到压缩单轴应力的服务水平（大约 14% 的环境指定抗压强度），在每次测试期间保持相对恒定。四个裸露的混凝土面板样本作为对照组进行了测试，并根据国家交通部的现行规范在六个样本上安装了瓷砖饰面。其他六个样本涂有防火材料（三个分别涂有 SFRM 和 IP），厚度对应于制造商规格的 1 小时耐火等级。在 4 个对照样本中的 3 个、6 个瓷砖样本中的 4 个以及 6 个 SFRM/IP 涂层样本中均未观察到热致爆炸性混凝土剥落。瓷砖饰面分层并最终完全脱离混凝土表面，因此与 SFRM 或 IP 提供的耐火性相比，其耐火性可以忽略不计。外部 25 毫米（1.0 英寸）范围内记录的温度时间历程 ) 加热混凝土的厚度用于评估每个表面光洁度的相对热阻，以及验证用于简短参数研究的简化热数​​值模型。还演示了火灾后表面处理的去除。