## 2 Experimental Work
All of these panels had an overall depth of 127 mm and a span of 1.52 m. Widths of panels varied between 0.41 and 0.46 m, depending on the reinforcement configurations. The designate Type A-NA represents deck type A with natural aggregate concrete on top of sUHPC. Similarly, Type A-RA denotes deck type A with recycled aggregate concrete on top. Details of geometry, steel fibers volume fraction and reinforcement are provided in Table 1. The cross-sectional and longitudinal configurations of the three types of panels are shown in Figures 2-4. Design of sUHPC panels was experimental because no specific guidelines are available for such type of composite concrete deck panels. For deck type A (as shown in Figure 2), the bottom steel plate is stay-in-place welded with the bottom tension reinforcement, inclined continuous shear reinforcement, and compression reinforcement. Conventional shear reinforcement was used in deck type B (as shown in Figure 3). Deck type C as shown in Figure 4 had two \(40\times 40\) mm sUHPC ribs running in the longitudinal direction. Transverse reinforcement along the width at regular intervals was passed through the ribs to develop the composite connection between two discrete concrete layers. Rebars with the yield strength of 250 MPa were used in all specimens. Compressive strength was determined by testing three \(150\times 300\) mm cylinders for each concrete type and is reported in Table 1. Reference mix design for UHPC by [PERSON] [25] was adopted for the preparation of sUHPC, except that 30% of the cement content was replaced with GGBS. Similarly, in RA concrete, 30% of natural/virgin coarse aggregates were replaced with recycled aggregate. Physical properties of materials for sUHPC are presented in Table 2. Table 3 shows the mix designs for sUHPC, NA/RA concrete. Figure 1: Preparation of high strength concrete (HSC)/high strength fiber-reinforced concrete (HSFRC) prestressed deck panels. Figure 2: Details of deck type A (units in mm). During casting, sUHPC was introduced from one end of the formwork and was allowed to flow to the other end. Whenever more material was required, it was introduced behind the leading edge of the flowing material. The same casting method was used for all the specimens to maintain similar fiber distribution. The traditional method of moist curing was used. Specimens were sealed with plastic sheets for 28 days to prevent the loss of moisture. \begin{table}
\begin{tabular}{c c} \hline \hline
**Constituents** & **Physical Properties** \\ \hline Cement & Grade 52.5 OPC \\ GGBS & Grade 100, 12.5 μm, activity index = 98\% \\ Recycled CA & Crushed RC; particle size range = 5–10 mm \\ Sand & Fineness modulus \textgreater{} 2.4 \\ Silica fume & Nano-silica, grade 900, 0.15 μm \\ Superplasticizer & Poly-carboxylate type \\ Steel fibers & Mild steel, plain, \(\phi 0.2\times 12.5\) mm \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Constituent material properties for sustainable ultra-high performance concrete (sUHPC). Figure 4: Details of deck type C (units in mm). Figure 3: Details of deck type B (units in mm). \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & \multicolumn{2}{c}{**sUHPC**} & \multicolumn{2}{c}{**NA Concrete**} & \multicolumn{2}{c}{**RA Concrete**} \\ \hline
**Constituents** & **Mix Design** & **Design** & **Mix Design** & **Design** & **Mix Design** & **Design** \\  & **(kg/m\({}^{3}\))** & **Ratios** & **(kg/m\({}^{3}\))** & **Ratios** & **(kg/m\({}^{3}\))** & **Ratios** \\ \hline Cement & 498 & 1.00 & 403.3 & 1.00 & 403.3 & 1.00 \\ GGBS & 214 & 0.43 & - & - & - & - \\ Natural Aggregate & - & - & 935.2 & 2.32 & 654.6 & 1.62 \\ Recycled Aggregate & - & - & - & - & 280.6 & 0.70 \\ Fine sand & 1020 & 2.05 & 863.2 & 2.14 & 863.2 & 2.14 \\ Quartz powder & 211 & 0.42 & - & - & - & - \\ Silica fume & 231 & 0.46 & - & - & - & - \\ Superplasticizer & 40 & 0.08 & 4.03 & 0.01 & 4.03 & 0.01 \\ Steel fibers & 156 & 0.31 & - & - & - & - \\ Water & 109 & 0.22 & 188.4 & 0.47 & 188.4 & 0.47 \\ \hline \hline \end{tabular}
\end{table}