Pavement Construction/Cross Section
Test Area Diagram
The diagram below shows the layout of MRS-1, MRS-2 and MRS-3, each of which consisted of a north test item and a south test item. Each test item consisted on 10 slabs, exclusive of slabs in transition areas. The concrete flexural strengths indicated in the diagram were target values, which were not necessarily achieved in the actual construction. In particular, the 28-day flexural strength for MRS-1 test items was closer to 650 psi than to the target 500 psi. Detailed material properties for the concrete and other materials used are available under “Material Properties.”
Transverse isolation joints were used to separate the test items. A reinforced isolation joint (FAA Type A-1) was installed at Station 405. A thickened-edge isolation joint (FAA Type A) was used at Station 510. This was done to compare the performance of the two types of isolation joints.
The CC6 rigid pavement test area was 300 feet long by 60 feet wide. The surface layer of the pavement consisted of Portland Cement Concrete (PCC) slabs, FAA item P-501. All slab dimensions were 15 feet by 15 feet by 12 inch thick. Slabs were placed individually in an alternating (chessboard) pattern using wooden forms. The slabs were doweled on all sides, with the exception of slab edges abutting the shoulder, and the isolation joints located in the transition areas.
The PCC layer was supported by a stabilized base. The stabilized base was of one of two types, either hot-mix asphalt (P-403) on the north side of the pavement, or econocrete (P-306) on the south side. In both cases, the base layers were 6 inches thick.
The subbase consisted of a 10 inch layer of compacted quarry blend screenings, a granular material complying with the FAA P-154 specification. Below the subbase, the clay subgrade had an average CBR of 8.