## 6 Conclusions  
Based on the results and discussion presented above, the following conclusions can be obtained:  
1. All-light ceramsite-concrete-strengthened concrete short-column specimens had obvious ductile failure characteristics. All-light ceramsite concrete could enhance the plastic deformation capacity of the strengthened short column, which could enhance the safety performance of the strengthened short column. When the epoxy resin interface agent was used, the damage process of the specimen was the slowest, and the damage degree was the lightest. Its ductile damage characteristics were most obvious. The ductile failure characteristics were relatively weak when the post-installed rebar  
Figure 11: The relation between load–raising effect and \(\alpha_{cs}\) stress curve. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Test Number** & **Interface Treatment** & **Strengthening Effect** & \(\alpha_{cs}\) \\ \hline C3 & Chiseling & 2.108 & 0.807 \\ \hline C5 & Post-installed rebar & 2.109 & 0.810 \\ \hline C4 & Interfacial agent & 2.199 & 0.849 \\ \hline C6 &
\begin{tabular}{c} Post-installed rebar + \\ interfacial agent \\ \end{tabular} & 2.327 & 0.916 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Relationship between interface handling method and \(\alpha_{cs}\). alone was used. Ceramsite concrete, used as a layer for strengthening, could achieve more excellent ductility than ordinary concrete. (2) The combined interface treatment method had the largest impact on the reinforcement effect, and the load-bearing capacity improvement ordered as follows: post-installed rebar + epoxy resin interface agent, epoxy resin interface agent, post-installed rebar, and chiseling. The ultimate load-bearing capacity was improved most significantly when the bonding surface was post-installed rebar + epoxy resin interface agent. It was 5.8% higher than when an epoxy resin interface agent was used and 19.7% higher than when only post-installed rebar was used. (3) The shear stress on the interfaces at the beginning of loading was mainly carried by the bonding force of the new-to-old concrete itself. In the case of using post-installed rebar + interface agent, the epoxy resin interface agent played a major role in the pre- and mid-loading period by increasing the bond between new-to-old concrete. The post-installed rebar started to function only in the mid- and late-loading period. (4) The strain in the strengthening longitudinal bar at the beginning of loading was the same as that in the existing longitudinal bar and increased linearly with the load. The strain growth of the two was not synchronized in the late-loading period, and the strain in the existing longitudinal bar grew rapidly and nonlinearly, while that in the strengthening longitudinal bar continued to grow linearly. The failure of the strengthened column specimen started from the existing concrete column. After the existing concrete column was deformed significantly, the outer solids bulged and cracked immediately afterward. Finally, the whole specimen lost its bearing capacity. (5) The formula in the specification GB50367-2013 is also applicable to ceramics concrete. However, \(\alpha_{\text{cs}}\) needs to be adjusted appropriately because it is strongly influenced by the interface treatment. Considering the safety factor, 0.8 is recommended when a single interface treatment (chiseling, interface agent, implantation of reinforcement) is used. When the interface treatment of implanting reinforcement and adding interface agent is used at the same time, it can be set as 0.9 for calculation. Conceptualization, H.Z. and H.C.; Methodology, H.Z. and H.C.; Software, P.L. and Z.F. ; Validation, H.C. and Z.G. ; Formal Analysis, H.Z. ; Investigation, H.C.; Resources, H.Z. ; Data Curation, H.C. and Z.F. ; Writing--Original Draft Preparation, H.C. and Y.C. ; Writing--Review and Editing, H.Z. and Z.F. ; Visualization, Z.F. ; Supervision, H.Z. ; Project Administration, H.Z. ; Funding Acquisition, H.Z. and Y.C.