Pavement Coring and DCP Testing. In this task, APTech will perform pavement coring and conduct limited DCP testing on the Green Street section. The cores will be used to determine the thickness of the existing asphalt surface and the underlying layers, to assess the integrity of the pavement layer materials, and to examine the condition of the layer interfaces. A total of 16 cores are proposed, consisting of 8 cores in each direction and staggered by lane. For a given direction, it is anticipated that 4 cores will be extracted from the inside travel lane, 3 cores from the outside travel lane, and 1 core from the left turn lane (4 cores per direction x 2 directions = 8 total cores). Moreover, it is anticipated that 4 cores will be extracted from the intersection approach pavement, 2 cores from the intersection itself, and 2 cores from the intersection leave pavement (8 total cores). It is anticipated that all of the coring can be completed in 5 to 6 hours (based on an assumed production rate of 20 to 24 cores per day). All cores will be 4 inches in diameter and core holes will be patched with an appropriate cold-mix patching material. In conjunction with the coring, APTech will conduct DCP tests at 4 core hole locations. These tests measure the in situ strength of subgrade soils or unstabilized base and subbase layers. The penetration rate values obtained can then be converted to Illinois Bearing Ratio (IBR) values for use in the Illinois Department of Transportation (IDOT) design procedures. The expected time for performing the 4 DCP tests is 1 hr. Hence, the combined coring and DCP work can be completed within 1 day. To minimize traffic control problems during the coring and DCP operations, APTech will restrict work done within the intersection to a weekend day morning (such as a Sunday morning when traffic volumes are expected to be light). Work done outside the intersection will take place on a weekday between the hours of 9 am and 3 pm.
