# Effects of Grout Compactness on the Tensile Behavior of Ground Splice Sleeve Connectors
## 4 Conclusions and Remarks  
1. The grout compactness determines the failure modes of GSS connectors. Generally, the failure mode of GSS connectors with higher grout compactness is rebar rupture, while the failure mode of GSS connectors with lower compactness is the bond-slip failure mode of rebar-grout.
2. The tensile tests of GSS with different compactness showed that the tensile bearing capacity decreases with the decrease of grout compactness. For example, when the compactness is 50%, the tensile capacity of the sleeve is close to 60% of the fully compact tensile capacity.
3. The bond-slip model of rebar-grout material is deduced and the formula of tensile bearing capacity of GSS with the grout compactness into consideration is proposed in this paper. The proposed formula can be used to determine whether reinforcing remedies or re-grouting is needed for sleeves that are not fully grouted during construction.  
All in all, the grout compactness has become the dominant factor for failure modes and bearing capacity of GSS connectors, and the proposed tensile bearing capacity formula of GSS can be used to determine whether reinforcing remedies or re-grouting is required in the case of incompact sleeve grouting during construction. Note that the above-mentioned conclusions and remarks are only validated by limited experimental results, and more experimental data and numerical simulation are needed to validate the proposed models and methods in the future.  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline
**Types** & \(T_{b}\)**/**kN** & \(P_{b}\)**/**kN** & \(P_{u,c}\)**/**kN** & \(P_{u,c}\)**/**\%** & \(P_{u,c}\)**/**kN** & **Mode** & \(R_{r}\) & \(\sigma_{r}\) \\ \hline D18-100\% & 156.69 & 125.14 & 125.14 & 0 & 143.69 & II & 1.15 & 1.89 \\ D18-90\% & 156.69 & 122.92 & 122.92 & 1.8 & 132.88 & II & 1.08 & 0.30 \\ D18-70\% & 156.69 & 119.84 & 119.84 & 4.2 & 102.20 & II & 0.85 & 1.01 \\ D18-50\% & 156.69 & 76.55 & 76.55 & 38.8 & 79.33 & II & 1.04 & 4.02 \\ D20-100\% & 183.13 & 163.09 & 163.09 & 0 & 179.79 & II & 1.10 & 1.51 \\ D22-100\% & 234.07 & 244.11 & 234.07 & 0 & 226.40 & I & 0.97 & 3.10 \\ D25-100\% & 278.08 & 262.70 & 262.70 & 0 & 288.24 & II & 1.10 & 3.72 \\ \hline \end{tabular}
\end{table}
Table 6: Prediction results.  
**Author Contributions:** [PERSON], [PERSON] and [PERSON] designed the experiment; [PERSON], [PERSON] and [PERSON] performed the experiments and wrote the paper; [PERSON] revised and finalized the paper. All authors have read and agreed to the published version of the manuscript.  
**Funding:** The work was supported by the National Key R&D Program of China (Grant No. 2016 YFC0700700) and the Key R&D Program of Fujian Science & Technology Department (Grant No. 2017Y4012). In addition, the authors are appreciated to the anonymous referees for their constructive comments and valuable suggestions.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** Not applicable.  
**Conflicts of Interest:** The authors declare no conflict of interest.