## 2 Materials and Methods
### Laboratory Testing Methodology  
For the two selected variables, a parameter analysis was conducted. Rib spacings were selected according to what was achievable by mechanically altering (removing ribs from) a standard Grade 60 #6 (19.05 mm nominal diameter) bar [34]. The selection of such spacing \begin{table}
\begin{tabular}{c c c c c} \hline
500 kN Load Cell & Load applied to FGRB & 661.23F-01 MTS Systems & MGS Plus DAQ & 0.3\% \\
250 mm Actuator & Displacement of MTS & 322.41 MTS & MGS Plus DAQ & 1\% \\
250 mm LVDT & Displacement of rebar & Penny \& Giles SLS 190/250 & MGS Plus DAQ & 0.15\% \\
150 mm LVDT & Deformation of top plate & Penny \& Giles SLS 190/150 & MGS Plus DAQ & 0.15\% \\
100 mm LVDT & Deformation of bottom plate & Penny \& Giles SLS 190/100 & MGS Plus DAQ & 0.15\% \\ DOS—Rebar, 12m\(\epsilon\) & Strain along rebar & Author created & Luna ODSI-B Analyzer & 25 \(\upmu\epsilon\) \\ DOS—Pipe, 12m\(\epsilon\) & Strain along pipe & Author created & Luna ODSI-B Analyzer & 25 \(\upmu\epsilon\) \\ \hline \end{tabular}
\end{table} 
Table 1: Summary of instrumentation [30; 31; 32; 33]. Figure 3: The complete layout of the monitoring plan, including schematic views of global and component monitoring and cross-sectional layout of the DOS; not to scale. was seen in other research and fabrication was accomplished in a similar manner [7]. To confine the specimens, steel pipes were used. This is often done to replicate rock due to its practicality [7; 13; 35]. Grout annulus was selected by viewing the commercially available size of pipes while aiming to maintain a radial stiffness of around 1600 MPa/mm, which is equivalent to limestone or granite [35; 36]. These selected independent variables can be seen visually in Figure 4, along with the chosen labelling convention. This formed a 4 \(\times\) 5 parametric analysis, where an additional 4 control or repeated specimens were used. The full laboratory testing program can be seen in Table 2. All specimens were grouted using a 40% w/c cement grout. This value was selected as it is commonly featured in research and is within the standard range used by industry [5; 37; 38; 39; 40; 41]. The embedment length of 750 mm (anchorage length) was selected as previous research [36] had indicated that this would be sufficient to achieve rebar necking as the primary failure mechanism. This was done so that active embedment length at full loading could be observed. During the first round of testing significant air voids were observed. To address this, various grouting methods were tested with clear PVC pipes to identify the formation of any voids. With the insights gleaned during this protocol, a methodology was implemented from the remainder of the test specimen and no large voids were observed. These specimens were created by pumping grout through a commercially available grout pump (Kenrich's Gp-1). Specimens were pumped through the bottom from a hose barb and then externally vibrated. To confirm that air was not entrapped due to pumping, the density from the non-pumped cylinders were compared to the bulk density of the grout collected from the specimens after testing. This density comparison can be seen in Table 3. A detailed investigation of material properties was conducted through a literature review and also from a series of laboratory testing. The summary of material properties can be seen in Table 4.  
Figure 4: Specim selection and nomenclature: (**A**) rib spacing, (**B**) grout annulus.