# Effect of Fireproof Coatings on the Post-Fire Behavior of CFRP Composite Sheets
## 4 Conclusions  
This paper investigates the effect of two self-developed fireproof coatings on the fire resistance of CFRP composite sheets, focusing on the effects on post-fire flexural properties. Based on the findings of this study, the following conclusions can be summarized:  
1. After fire exposure, the post-fire flexural properties of uncoated CFRP sheets experience a significant reduction.
2. The proposed fireproof coatings significantly enhance the post-fire flexural strength and modulus of CFRP sheets up to a maximum achievable enhancement level of approximately 95% of the initial performance before fire exposure, with the coating thickness, type, and CFRP sheet thickness influencing the enhancement effect.
3. CFRP sheets coated with Type C1 and C2 coatings of more than 25 mm thickness demonstrate a fire-resistance duration of up to 2 h under the large-space fire condition. According to the Chinese specification GB50016-2014, under the large-space fire condition, CFRP sheets coated with Type C1 and C2 coatings of over 25 mm thickness meet the requirements of fire-resistance class III (columns), class I (beams), and class I (floor slabs), respectively.
4. CFRP sheets coated with Type C1 and C2 coatings of 35 mm thickness demonstrate a fire-resistance duration of up to 0.75 h under standard fire conditions. According to the Chinese specification GB50016-2014, under the standard fire condition, CFRP sheets coated with Type C1 and C2 coatings of 35 mm thickness meet the requirements of fire resistance class IV (columns), class IV (beams), and class III (floor slabs), respectively.
5. Additional experimental studies are required to comprehensively assess the impact of these coatings on the mechanical performance of CFRP composites across a broader spectrum of fire conditions, providing guidance for the safe fire protection design of CFRP in new infrastructure and structural reinforcement applications.  
Conceptualization, X.Q. and X.J.; methodology, X.Q. and X.J.; software, K.W.; investigation, K.W. and Y.X.; data curation, X.Q.; writing--original draft preparation, K.W. and Y.E.; writing--review and editing, X.Q. and X.J.; visualization, K.W.; supervision, X.J.; project administration, X.Q. and X.J.; funding acquisition, X.Q. and Y.X. All authors have read and agreed to the published version of the manuscript.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Study**} & \multirow{2}{*}{**CFRP Type**} & \multirow{2}{*}{**Fireproof Measure**} & **Mass Fraction (\%)** & \multirow{2}{*}{**Thickness (\(\text{mm}\))**} & \multicolumn{2}{c}{**Fire Resistance Duration**} \\ \cline{5-6}  & & & & **Tickness (\%)** & & **Large-Space** & **Standard** \\ \hline This study & Sheet & Non-intumescent fireproof coating & - & 25 & \textgreater{}2 h & - \\ [PERSON] et al. [30] & Bar & Intumescent coating & - & - & \textgreater{}2 h & 8 min \\ [PERSON] et al. [19] & Sheet & Intumescent coating & - & 0.5 & \textgreater{}2 h & 3 min \\  & & high-silica needed felt & - & 24 & \textgreater{}2 h & 1.5 h \\ [PERSON] et al. [41] & Tendon & & - & 45 & \textgreater{}2 h & 1.5 h \\  & & Ceramic fiber felt & - & 24 & \textgreater{}2 h & \textgreater{}2 h \\ [PERSON] et al. [31] & Sheet & Ammonium polyphosphate (APP) & 20 & - & 0.5 h & - \\  & & fire retardant powder & 40 & - & 0.5 h & - \\ \hline \hline \end{tabular}
\end{table}
Table 5: Comparison with previous studies.  
**Funding:** This research was funded by the Natural Science Foundation of China (52278207, 52278206), the National Key R&D Program of China (2020 YFD1100403), the China State Construction Technology R&D Program (CSCEC-2020-Z-1), the Chongqing Natural Science Foundation (CSTB2022 NSCQ-MSX1219), and the Fundamental Research Funds for the Central Universities.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** Data are not publicly available due to privacy or ethical restrictions.  
**Conflicts of Interest:** The authors declare no conflict of interest.