## 2 Materials and Methods
### Field Test Construction  
The constructability of hardfill on-site was examined through a field test construction using field compaction equipment. The construction specifications (lift thickness, number of roller passes) were established, and the strength range for the hardfill was derived in preparation for actual future construction of a hardfill dam. Furthermore, field test results were compared with the indoor laboratory tests and numerical analysis results. The field test construction site was a spoil area in the Danyang underwater weir construction site, i.e., the same place where the aggregate was collected for the indoor laboratory tests. The hardfill field mixing was performed by applying three unit water contents of 70, 85, and 100 kg/m\({}^{3}\) and a unit cement content of 80 kg/m\({}^{3}\) to the aggregates with a maximum particle size of 80 mm with a PSD similar to the lower limit of the PSD in the indoor test. The compaction conditions for the vibration roller were eight roller passes (six vibrated passes and two non-vibrated passes). The lift thicknesses of one layer were set as 50 cm and 75 cm, respectively. As a result, a total of six cases were tested.  
The planned scale of the test construction was a compaction height of one floor on a floor area with a total width of 19 m and length of 44 m. Construction was performed by dividing sections for each test case according to material mixing conditions and lift thickness. Once each section was compacted using the vibration roller, the degree of compaction was measured by the sand cone method [32]. After measuring the field compaction degree, the corresponding section was covered with curing cloth, and a sufficient volume of water was sprayed for the first 2 to 3 d. Then, the specimens were cured for 28 d. Once  
Figure 2: Preparation of a large specimen for unconfined compressive strength test. (**a**) Material placement; (**b**) material mixing; (**c**) sample compaction; (**d**) sample curing; (**e**) large specimen; (**f**) uniaxial compressive strength test.  
curing was completed, the cores were collected, and a uniaxial compressive strength test was performed [33; 34].  
Table 4 and Figure 3 show the field test construction conditions and process, respectively.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Material (Mixing Ratio)** \\ \hline Aggregate & PSD between upper- and lower-limit PSD with 80 mm max. particle size \\ \hline Cement content per unit volume & 80 kg/m\({}^{3}\) \\ \hline Water content per unit volume & 70, 85, 100 (kg/m\({}^{3}\)) \\ \hline
**Hardfill Test Construction** \\ \hline Size & One fill lift with a floor area of 19 m width and 44 m length, which was partitioned into six parts for a total of six test cases \\ \hline Lift thickness & 50, 75 (cm) \\ \hline Compaction & Eight passes with a vibration roller (six vibrated passes and two non-vibrated passes) \\ \hline \hline \end{tabular}
\end{table}
Table 4: Conditions of field test construction.  
Figure 3: Field test construction and core collection. (**a**,**b**) Material transportation and placement; (**c**) compaction by vibration roller; (**d**) measurement of lift thickness; (**e**) measurement of field compaction (sand cone method); (**f**) curing after compaction; (**g**) core collection; (**h**) core aged 28 d.