## 5 Parametric Study
### Effect of Saw-Cut Length on Early-Age Crack Induction  
Based on field observations and above discussed FE results, the deeper saw-cut is more effective than the shallower saw-cut for inducing cracks over the desired locations in CRCP. Therefore, for the deeper saw-cut depth, three different cut-lengths as illustrated in Table 6 are taken into account. Crack induction from the saw-cut tips in terms of maximum concrete tensile stress and crack strains is evaluated with respect to the type of saw-cut based on cut-length.  
The shorter saw-cut exhibits the largest maximum tensile stress over the saw-cut tips than the conventional and longer saw-cut as illustrated in Figure 14. As per boundary conditions applied in the development of the FE model as demonstrated in Figure 5, the outer longitudinal face of the concrete slab is allowed to freely expand and contract under the prevailing external temperature field which meant to cause large volumetric changes in the outer part of the concrete slab with respect to the rest of slab. Therefore, the tips of longer saw-cut could not effectively take advantage of the large volumetric changes in the outer region of the concrete slab. This could be the possible reason for the lowest values of tensile stress from the tips of longer saw-cut in comparison to those of shorter saw-cut and conventional saw-cut.  
However, the development of maximum steel stress in the 3 rd longitudinal steel bar demonstrated in Figure 15 shows that the longer saw-cut could be a more effective attempt for initiating the greater cracking incidence which will ultimately lead to the development of the regular spaced crack pattern. The possible reason for this could be that the longer-saw-cut takes advantage of significant volumetric changes to a larger length that result in larger stress in longitudinal steel bars. However, the potential risk of steel corrosion would be significantly increased when the saw-cuts will be made longer into the concrete slab.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**No.** & **Saw-Cut Type** & **Depth, D (mm)** & **Length, L (mm)** & **Width (mm)** \\ \hline
1 & Shorter & 60 & 200 & 4 \\
2 & Conventional & 60 & 400 & 4 \\
3 & Longer & 60 & 600 & 4 \\ \hline \hline \end{tabular}
\end{table}
Table 6: Type of saw-cut based on cut-length.  
Figure 14: Comparison of maximum concrete tensile stress over the saw-cut tips along the length of concrete slab for different saw-cut lengths.  
The crack strain variation over the saw-cut tips with respect to time is shown in Figure 16. Being closer to the outer concrete slab face as per boundary conditions, the tips of shorter saw-cut experiences larger crack strains than those of conventional and longer saw-cut.  
Previous studies on the fatal distress in CRCP showed that most of the punch-out distress occurs in the outer lane of pavement slab [12; 18; 27; 29; 38; 39; 45; 46]. It has also been reported that the randomness (the presence of closely spaced and divided cracks) in the transverse crack pattern increases the potential risk of punch-outs development in CRCPs [11; 12; 16; 47; 48]. Therefore, the adoption of deeper saw-cuts with longer cut-length for CRCP could be an effective method to minimize the randomness in the transverse crack pattern.  
Figure 16: Comparison of crack strain over saw-cut tips for different saw-cut lengths.  
Figure 15: Comparison of maximum steel stress over along the length of the longitudinal steel bar for different saw-cut lengths.