## 3 Results for Static Loading
### Flexural Test
#### 3.1.4 Fracture Toughness  
According to the ASTM 1018 Standard Test Method [30], fracture toughness is expressed through toughness indexes (Equation (2)) and residual strength factors (Equation (3)). \[I_{N}=\frac{Energy\ absorbed\ up\ to\ a\ certain\ multiple\ of\ first\ crack\ deflection}{Energy\ absorbed\ up\ to\ the\ first\ crack}. \tag{2}\]  
The subscripts \(N\) in these indexes are based on the elastoplastic analogy such that the scheme compares UHPFRCC with a conceptual material behaving in an ideally elastoplastic manner. Additionally, the residual strength factors represent the remaining strength in fibre-reinforced concrete \begin{table}
\begin{tabular}{c c c c} \hline \hline  & \multicolumn{2}{c}{**Undamaged Slabs**} & \multicolumn{2}{c}{**Damaged Slabs**} \\ \cline{2-4}  & **1 st Peak Defl. (mm)** & **Max Peak Defl. (mm)** & **Max Peak Defl. (mm)** \\ \hline No. of tests & 5 & 5 & 3 \\ Range & 2.3-4.0 & 9–24.7 & 10.7–21 \\ Average & 2.8 & 16.9 & 15.8 \\ SD & 0.7 & 6.3 & 5.2 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Deflection average value and standard deviation. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & \multicolumn{4}{c}{**Undamaged Slabs**} & \multicolumn{4}{c}{**Damaged Slabs**} \\ \cline{2-6}  & **G\({}_{IA}\) (0)** & **G\({}_{IB}\) (0)** & **G\({}_{L\_{TOT}}\) (0)** & **G\({}_{IA}\) (0)** & **G\({}_{IB}\) (0)** & **G\({}_{I\_{TOT}}\) (0)** \\ \hline No. of tests & 5 & 5 & 5 & 3 & 3 & 3 \\ Range & 32–175 & 80–164 & 148–290 & 31–110 & 65–75 & 99–175 \\ Average & 97.2 & 127.9 & 225.2 & 70.3 & 69.5 & 139.8 \\ SD & 56.7 & 32.5 & 65.9 & 39.3 & 5.3 & 37.9 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Fracture energy average value and standard deviation. \begin{table}
\begin{tabular}{c c c} \hline \hline  & \multicolumn{2}{c}{**Flexural Strength (MPa)**} \\ \cline{2-3}  & **Undamaged Slabs** & **Damaged Slabs** \\ \hline No. of tests & 5 & 5 \\ Range & 10–19 & 8–13 \\ Average & 14.4 & 11.2 \\ SD & 3.1 & 2.6 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Flexural strength average value and standard deviation. are derived from the toughness indexes. Residual strength factors state the residual strength factor between indexes \(I_{M}\) and \(I_{N}\) (with \(N>M\)) in terms of \(R_{M,N}\)[31]. \[R_{M,N}=C\times(I_{N}-I_{M}), \tag{3}\]  
where constant \(C=\frac{100}{(N-M)}\) is chosen such that for an ideally elastoplastic material, the residual strength factors assume a value equal to the stress at which the elastic to plastic transition takes place [24]. Given that toughness characterization is based on energy computations, an accurate measurement of deflections is very important, in particular, in the measurement of the first crack. Damaged slabs are not considered because the identification of the first crack is impossible (Tables 9 and 10). According to the JSC Standard SF-4 Method [32], the flexural toughness is expressed through flexural toughness factors (Equation (4)), determined from the area below the load-deflection curve (\(A_{OAFL}\)) until a deflection of span/150. \[FT=\frac{A_{OAFL}\times L}{(L/150)\times b\times h^{2}}. \tag{4}\]  
In Equation (4), \(L\) is the clear span of the slab, \(b\) and \(h\) are the width and height of the slab, respectively. Both damaged and undamaged slabs were analyzed for flexural toughness factor (Table 11). However, the flexural toughness factors are specimen geometry-dependent, which makes an exact correlation with the field performance rather difficult [24].