# Experimental Evaluation of the Durability of Concrete Repair Materials
## 3 Results and Discussion
### Freeze-Thaw

Table 4: Chloride depth and diffusion coefficient test results for various concrete specimens. Figure 11: _Cont._  
Figure 10: Relative dynamic elastic moduli of concrete specimens with target compressive strength of (**a**) 20 MPa and (**b**) 40 MPa. Freeze-thaw is more severe in areas with a large daily temperature variation, and these results show that all the considered repair methods have significant repair effects in terms of durability. However, in terms of strength, repair methods that include epoxy are most effective. As described, when a crack occurs in a structure, moisture penetrates along the crack, and when the temperature reduces to subzero, the moisture freezes and the volume expands. As such, repeated temperature changes may occur, and in the end, the structure may  
Figure 11: Compressive strength of concrete specimens with target compressive strength of (**a**) 20 MPa and (**b**) 40 MPa. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Target Strength (MPa)**} & \multirow{2}{*}{**Notch Width (mm)**} & \multirow{2}{*}{**Repair Method**} & \multicolumn{2}{c}{**Relative Dynamic Elastic Modulus (\%)**} & \multicolumn{2}{c}{**Compressive Strength (MPa)**} \\ \cline{5-6}  & & & **100 Cycle** & **200 Cycle** & **300 Cycle** & **(MPa)** \\ \hline \multirow{6}{*}{20} & - & \multicolumn{1}{c}{Intact (no notch)-NN} & - & - & - & - \\ \cline{3-6}  & & \multicolumn{1}{c}{Notched (unrepaired)-N} & 90.8 \(\pm\) 0.74 & 84.6 \(\pm\) 1.80 & 78.2 \(\pm\) 0.96 & 17.5 \(\pm\) 0.66 \\ \cline{3-6}  & \multirow{2}{*}{2} & Epoxy-E & 96.5 \(\pm\) 1.62 & 94.5 \(\pm\) 2.36 & 82.9 \(\pm\) 2.14 & 19.2 \(\pm\) 1.74 \\ \cline{3-6}  & & \multicolumn{1}{c}{Impregnant-I} & 98.8 \(\pm\) 1.22 & 93.8 \(\pm\) 1.81 & 88.1 \(\pm\) 0.57 & 18.4 \(\pm\) 1.23 \\ \cline{3-6}  & & \multicolumn{1}{c}{Epoxy/impregnant-E and I} & 97.9 \(\pm\) 2.10 & 95.7 \(\pm\) 2.41 & 90.7 \(\pm\) 2.59 & 19.1 \(\pm\) 2.77 \\ \cline{3-6}  & & \multicolumn{1}{c}{Notched (unrepaired)-N} & 97.0 \(\pm\) 5.67 & 90.2 \(\pm\) 0.78 & 82.5 \(\pm\) 1.93 & 16.2 \(\pm\) 0.59 \\ \cline{3-6}  & \multirow{2}{*}{5} & Epoxy-E & 95.8 \(\pm\) 1.73 & 92.8 \(\pm\) 0.74 & 85.8 \(\pm\) 0.71 & 18.4 \(\pm\) 1.16 \\ \cline{3-6}  & & \multicolumn{1}{c}{Impregnant-I} & 95.1 \(\pm\) 0.45 & 90.8 \(\pm\) 1.40 & 84.2 \(\pm\) 1.53 & 17.3 \(\pm\) 1.40 \\ \cline{3-6}  & & \multicolumn{1}{c}{Epoxy/impregnant-E and I} & 96.0 \(\pm\) 4.41 & 91.6 \(\pm\) 3.27 & 87.3 \(\pm\) 1.90 & 18.7 \(\pm\) 0.74 \\ \hline \multirow{6}{*}{40} & - & \multicolumn{1}{c}{Intact (no notch)-NN} & - & - & - & - \\ \cline{3-6}  & & \multicolumn{1}{c}{Notched (unrepaired)-N} & 96.7 \(\pm\) 2.58 & 90.7 \(\pm\) 1.93 & 84.9 \(\pm\) 2.57 & 29.6 \(\pm\) 2.41 \\ \cline{3-6}  & \multirow{2}{*}{2} & Epoxy-E & 97.2 \(\pm\) 3.62 & 98.8 \(\pm\) 2.36 & 93.0 \(\pm\) 3.05 & 32.7 \(\pm\) 0.68 \\ \cline{3-6}  & & \multicolumn{1}{c}{Impregnant-I} & 96.5 \(\pm\) 1.75 & 91.2 \(\pm\) 3.13 & 88.2 \(\pm\) 2.00 & 29.8 \(\pm\) 0.37 \\ \cline{3-6}  & & \multicolumn{1}{c}{Epoxy/impregnant-E and I} & 96.0 \(\pm\) 2.48 & 93.4 \(\pm\) 2.63 & 92.2 \(\pm\) 3.33 & 34.9 \(\pm\) 1.41 \\ \cline{3-6}  & & \multicolumn{1}{c}{Notched (unrepaired)-N} & 95.7 \(\pm\) 2.00 & 89.1 \(\pm\) 2.98 & 82.7 \(\pm\) 2.22 & 27.9 \(\pm\) 1.37 \\ \cline{3-6}  & & \multicolumn{1}{c}{Epoxy-E} & 92.7 \(\pm\) 2.90 & 88.8 \(\pm\) 2.73 & 87.0 \(\pm\) 2.04 & 32.2 \(\pm\) 0.97 \\ \cline{3-6}  & & \multicolumn{1}{c}{Impregnant-I} & 98.8 \(\pm\) 1.22 & 93.8 \(\pm\) 1.81 & 91.7 \(\pm\) 1.19 & 28.8 \(\pm\) 0.38 \\ \cline{3-6}  & & \multicolumn{1}{c}{Epoxy/impregnant-E and I} & 94.9 \(\pm\) 2.25 & 94.9 \(\pm\) 2.02 & 95.4 \(\pm\) 1.86 & 35.7 \(\pm\) 1.09 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Relative dynamic elastic modulus and compressive strength test results for various concrete specimens. be detached and destroyed. Therefore, in this study, in the case of freeze-thaw resistance, epoxy and epoxy/impregnant repair appears to be the most effective.