## 3 Correlation and Implementation
### In Situ Measurements  
The in situ traditional point measurement methods are based on the material modulus or density that must be correlated to verify the intelligent compaction measurement value. A variety of measurement methods documented in the studies are the Falling Weight Reflectometer (FWD), Light Weight Reflectometer (LWD), Plate Load Test (PLT), Dynamic Cone Penetration (DCP), Cone Penetration Testing (CPT), Sand Cone Replacement Method, Nuclear Gauge (NG), radio isotope method, and Electrical Soil Density Gauge [3]. Studies have proven that modulus- or stiffness-based measurement correlates better with ICMV than other methods [26]. Considering this, the stiffness-based measurement method PLT has been adopted for the correlation and verification in this study. The PLT is a suitable method for evaluating the ultimate bearing capacity, shear strength, and deformation parameters without any effect of sample disturbance. It measures material characteristics by accessing the force applied over time and by measuring the amount of penetration due to that force. Over the period, different countries have developed their coded approach for the PLT. The Korean Road Transport Cooperation standard is named KS F 2310 and is widely adopted in Korea. Table 5 shows the criteria for the bearing coefficient of the PLT according to Korean standards.  
The PLT procedure adopted was as follows,  
1. Select the test area with the level surface or make it as level as the plate size. Remove any loose material or embedded fragments.
2. Install the bearing plate and force measurement system.
3. Add a 0.35 kg/cm\({}^{2}\) load to stabilize the plate and adjust the force measuring gauge to zero.
4. Add 0.35 kg/cm\({}^{2}\) loads in incremental steps and record the settlement against each incremental load.
5. The test terminates when the settlement reaches 1.5 cm or when the applied force exceeds the material's yield point.
6. Identify the load strength at the 0.25 cm settlement for each interval of test and calculate the bearing coefficient kg/cm\({}^{3}\) by comparing it with the Korean Standard.  
The PLT was conducted on both sites with different soil conditions. The test was conducted on eight different spots on each site. The location of each spot test was recorded using RTK-GPS, and all the test points were evenly distributed on both sites. Each spot was compacted with three passes of a roller with pass times of 1 to 3 s, 8 to 10 s, and 18 to 20 s, respectively. The PLT test was conducted by applying the load for the same time interval for each pass. So, 24 PLT tests were conducted for each site for 24 passes at eight different spots. The roller was stopped at the settlement of 0.25 cm for each spot. The photograph of the PLT arrangement at the construction site is shown in Figure 7. The PLT test data are shown in Table 6.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline  & **Type** & **Pavement of** & **Pavement of** \\  & **Cement Concrete** & **Asphalt Concrete** \\ \hline \multicolumn{2}{c}{Settlement (cm)} & 0.125 & 0.25 \\ \hline \multirow{3}{*}{
\begin{tabular}{c} Bearing \\ coefficients \\ \end{tabular} } & Embankment & 10 or more & 15 or more \\  & On ground & 15 or more & 20 or more \\ \cline{1-1}  & Auxiliary substratum, backfilling & 20 or more & 30 or more \\ \hline \hline \end{tabular}
\end{table}
Table 5: Criteria for the bearing coefficient of the PLT according to Korean standards [35].  
The contaminated soil replacement site consisted of soil, whereas the event stadium construction site consisted of gravel and rock aggregate. The result clearly shows that the bearing capacity of the event stadium construction site was higher than the contaminated soil replacement site as their geological conditions differed. Even at the same site, every spot has a different range of bearing coefficient values, meaning different compactions. These different bearing coefficient values can help test the developed intelligent compaction system and compare it with both sites.