Pavement Construction/Cross Section

Construction Cycle 3 (CC-3) involved the replacement of existing CC-1 test items and an existing Portland cement concrete (PCC) test strip with a series of four new flexible pavement sections with varying subbase thicknesses. All new test items were designated in the format LFC[-number], with the letters LFC referring to low-strength subgrade (CBR = 3.0), flexible pavement structure, conventional base material (i.e., using unbound aggregate base). The existing CC-1 test items and PCC test strip were removed to a depth of 3 feet into the existing clay subgrade. The new pavement surface consisted of 5 inches of P-401 hot-mix asphalt (HMA) placed in two 2-½-inch lifts. A tack coat was placed between the lifts. The base material consisted of 8 inches of P-209 crushed stone base placed in two lifts and compacted as one. The subbase was composed of uniformly graded, manufactured argillite screenings conforming to the FAA P-154 specification. Four subbase thicknesses were as follows:

• LFC-1: Flexible pavement structure with 16-inch P-154 unbound aggregate subbase.
• LFC-2: Flexible pavement structure with 24-inch P-154 unbound aggregate subbase.
• LFC-3: Flexible pavement structure with 34-inch P-154 unbound aggregate subbase.
• LFC-4: Flexible pavement structure with 43-inch P-154 unbound aggregate subbas