Construction Cycle 6

Construction Cycle 6 (CC6) began in April 2010 with the construction of six rigid pavement structures. Traffic tests were conducted from August 30, 2011 to April 25, 2012. Post-traffic investigations continued through 2014.

Three research objectives were planned for the CC6 pavement structures. The primary objective was to determine the effect of concrete flexural strength on rigid pavement structural life. Three separate rigid pavement test items with similar cross sections but different target values of concrete flexural strength were designed and constructed. The second objective was to perform side-by-side comparisons of rigid pavements on different stabilized base materials. The comparative base materials used were hot-mix asphalt (FAA Item P-403) and econocrete (FAA Item P-306). The third objective focused on performing comparisons of two types of isolation joints, thickened edge and steel-reinforced.

The general test setup is shown in the Test Area Diagram. Test items are designated using the 3-letter code MRS (referring to: Medium-strength subgrade, Rigid pavement structure, Stabilized base), followed by a number and a letter. The number (1, 2, 3) corresponds to the target strength of the concrete surface (500, 750 and 1000 psi respectively), while the letter (N, S) refers to the north or south half of the test item. North (N) test items were constructed with P-403 base and south (S) test items with P-306 base.

The traffic applied to each test item varied by load and number of passes, but in general the same loads and passes were applied to test items north and south. All vehicle loads simulated a full-scale 2D (dual-tandem) aircraft landing gear. The wander pattern consisted of nine discrete tracks approximating a normal traffic distribution. A total of 274 sensors were installed in the test sections for recording the response. At many locations, strain gages were installed in pairs at the top and bottom of the concrete slab.