Operational State Assessment and Treatment Strategies
for Existing&nbsp;Fire-Retardant
Coatings in Highway Tunnels

LI Yuhao; WANG Hailin; JIAO Ao; WANG Jianhua; FAN Chuangang; ZHANG Guo; CHENG Ruiqi

doi:10.3973/j.issn.2096-4498.2025.05.017

Tunnel Construction >

2025 , Vol. 45 >Issue 5: 1018 - 1026

DOI: https://doi.org/10.3973/j.issn.2096-4498.2025.05.017

Operational State Assessment and Treatment Strategies for Existing Fire-Retardant Coatings in Highway Tunnels

LI Yuhao ,
WANG Hailin ,
JIAO Ao ,
WANG Jianhua ,
FAN Chuangang ,
ZHANG Guo ,
CHENG Ruiqi

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(1. Hunan Provincial Communications Planning, Survey & Design Institute Co., Ltd., Changsha 410200, Hunan, China; 2. School of Civil Engineering, Central South University, Changsha 410075, Hunan, China)

Online published: 2025-05-20

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Abstract

The authors investigate the operational state of fire-retardant coatings in tunnels on 16 highways in Hunan Province, China. Numerous in-service tunnels are equipped with fire-retardant coatings, with thicknesses ranging from 12 to 20 mm. In 82% of the tunnels, the coatings have shed, posing a safety risk to tunnel traffic. However, assessment methods and treatment measures for evaluating the operational state of these in-service fire-retardant coatings remain limited. Based on the key performance indices outlined in relevant fire-retardant coating standards and the actual operational states observed in highway tunnels in Hunan Province, a coating operational state assessment model is developed. This model incorporates evaluation indices such as the shedding area rate, shedding frequency, bulging area rate, crack length and number, and average daily tunnel traffic flow. In addition, the types of coating defects, along with their occurrence and development mechanisms, are analyzed, and treatment measures are proposed for different operational state levels of existing fire-retardant coatings. A field assessment test conducted on the Paishaping tunnel yields an operational state value of 85.20—classified as a good level—which aligns with the assessment results provided by three independent testing and assessment units.

Key words： highway tunnels; fire-retardant coatings; state assessment; operational safety

Cite this article

LI Yuhao , WANG Hailin , JIAO Ao , WANG Jianhua , FAN Chuangang , ZHANG Guo , CHENG Ruiqi .

Operational State Assessment and Treatment Strategies for Existing Fire-Retardant Coatings in Highway Tunnels

[J]. Tunnel Construction, 2025 , 45(5) : 1018 -1026 . DOI: 10.3973/j.issn.2096-4498.2025.05.017

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