## 3 Test of Masonry Prisms Strengthened with SFRM Overlay
### Result of Tests for Masonry Prisms
#### 3.2.2 Compression Test Result  
The result of the compression tests for masonry prisms made of red clay bricks and concrete bricks is summarized in Tables 7 and 8, respectively. The average compressive strengths for red clay brick prisms and concrete brick prisms without strengthening designated with RP and CP in Tables 7 and 8 are 14.5 and 16.3 MPa, respectively, which are not significantly different. However, the elastic moduli for RP and CP are 1382.7 and 3951.1 MPa, respectively, which shows significantly higher stiffness for concrete brick prisms than for red clay brick prisms. Mechanical properties such as compressive strength and elastic modulus for red clay brick prisms were enhanced effectively by overlaying mortar. Comparing RB0 and RB1.3 in Table 7, the SFRM with a sufficiently high fiber volume fraction, at 1.3%, is significantly more effective than the mortar without fibers. The highest compressive strength among red clay brick prisms was obtained for RB1.3 among strengthened red clay brick prisms and the amount of increase was 61%. In a similar manner, CB1.3 showed the highest compressive strength among concrete brick prisms in Table 8 due to the largest amount of the strengthening overlay and steel fibers. However, the increase in the compressive strength reaches only 26% of the strength for bare prisms denoted by CP and the elastic modulus decreased by 6%. Figures 12 and 13 plot compressive stress-strain relation for prisms made of red clay bricks and concrete bricks, respectively. In these figures, it is observed that RB1.3 specimens show the most prominent enhancement in both strength and deformability. In case of CB1.3, the strength increase is significant only in one specimen, but deformability is enhanced for all three specimens. Consequently, the strengthening effect of SFRM for masonry prisms in compression is more remarkable for red clay brick prisms than for concrete brick prisms. From the above observation, it is supposed that the weaker and softer characteristics of red clay bricks make the strengthening effect of SFRM more prominent in comparison with application on concrete bricks. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Specimens**} & \multicolumn{2}{c}{**Average**} & \multicolumn{2}{c}{**Rate of Increase (\%)**} \\ \cline{2-6}  & **Peak Load** & **Compressive** & \multirow{2}{*}{\(\mathbf{E_{m}}\) **(MPa)**} & **Compressive** & \multirow{2}{*}{\(\mathbf{E_{m}}\)} \\  & **(kN)** & **Strength (MPa)** & & & **Strength** & \\ \hline RP & 244.6 & 14.5 & 1382.7 & - & - \\ RS1.0 & 305 & 18 & 2356.9 & 25\% & 70\% \\ RS1.3 & 380.3 & 22.5 & 2872.1 & 55\% & 108\% \\ RB0 & 296.9 & 17.5 & 2764.8 & 21\% & 100\% \\ RB1.0 & 311.1 & 18.4 & 2552.7 & 27\% & 85\% \\ RB1.3 & 394.9 & 23.3 & 2534.5 & 61\% & 83\% \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Compression test results for masonry prisms in red clay brick. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Specimens**} & \multicolumn{2}{c}{**Average**} & \multicolumn{2}{c}{**Rate of Increase (\%)**} \\ \cline{2-5}  & **Peak Load** & **Compressive** & \multirow{2}{*}{\(\mathbf{E_{m}}\) **(MPa)**} & **Compressive** & \multirow{2}{*}{\(\mathbf{E_{m}}\)} \\  & **(kN)** & **Strength (MPa)** & & & **Strength** & \\ \hline CP & 275.6 & 16.3 & 3951.1 & - & - \\ \hline CS1.0 & 317.1 & 18.7 & 4030.5 & 15\% & 2\% \\ \hline CS1.3 & 323.6 & 19.1 & 4360.6 & 17\% & 10\% \\ \hline CB0 & 334.4 & 19.8 & 3626.6 & 21\% & \(-8\%\) \\ \hline CB1.0 & 319.9 & 18.9 & 3687.1 & 16\% & \(-7\%\) \\ \hline CB1.3 & 348.3 & 20.6 & 3717.5 & 26\% & \(The pictures of masonry prisms for compression tests after the termination of tests are presented in Figure 14. The specimen RP without strengthening failed with vertical cracks, as shown in Figure 14a. The strengthened specimens RB0 and RB1.3 failed accompanying separation between mortar overlay and masonry, as shown in Figure 14b,c.