FIGURE 4 Partially filled top NPA geocell layer and were rejected. Figure 4 shows the top layer NPA geocell being stretched and filled with gravel. Pokharel (2010) emphasized the importance of compaction in geocell-reinforced structures, so the right degree of compaction was always the top priority in order to achieve the required strength. In subzero temperatures, the nuclear densometer compaction testing did not seem to give accurate results. Therefore, a controlled volume/ weight method was employed to guarantee that the required degree of compaction was achieved. The pad was divided into separate blocks and for each block the required weight of the material for a specified degree of compaction was calculated, and compaction continued until the exact compacted thickness of the fill material was achieved. This method was utilized for each subsequent layer of gravel fill to good success and helped ensure that adequate compaction was achieved. The structure performed as expected when the crane was brought to the site during spring thaw, when soil conditions are typically expected to be in their poorest state. The bottom layer improved the bearing capacity and served as the construction layer for the construction traffic, which otherwise would have needed layers of wooden mats to pass the truck traffic. After installation of the top structural area in some portions of the pad, a pile-driving rig was allowed to operate on the pad while installation was completed in other parts. During this time no significant rutting or differential settlement of the pad was observed. www.GeosyntheticsMagazine.com 0620GS_p20-27.indd 25 25 5/20/20 5:58 PMhttp://www.GeosyntheticsMagazine.com