Interstate 86
The Portland cement concrete (PCC) highway I-86 in Hinsdale, near Olean in Cattarugus County, was reconstructed using unbonded jointed plain concrete pavement overlay. The process involved three treatments of the existing jointed reinforced concrete pavement (JRCP): rubblization, crack and seat, and no treatment. On top of each type of treated existing concrete, a three inch (7.6 cm) interlayer of Type I permeable base was applied and then the new surface PCC pavement layer was added. A test section of full-depth asphalt concrete was also constructed with instrumentation by Ohio University.
In addition to testing the different methods of reconstruction, additional experiments are being conducted on I-86. One of these is the testing of JRI+ joints from Spain. The JRI+ joint is a plastic form that works as an alternative to traditional dowelled joints. The forms are arranged so adjacent slabs form interlocking tabs as they shrink during the curing process, and the system also creates a water-tight joint. Five JRI+ joints are installed in each test section.
Description
One 200 m test section of each type has been instrumented to determine which method provides the best and most economical long-term performance. The pavement responses from the instrumented sections, which will be monitored for the next six years, in conjunction with a cumulative fatigue damage analysis, will enable the prediction of the long-term performance of these techniques and allow a recommendation of the most cost-effective reconstruction technique.
Monitored parameters include weather information (air temperature, precipitation, relative humidity, solar radiation, wind speed, and wind direction), pavement and soil temperature, base and subgrade volumetric moisture content, depth of frost penetration, and water table depth.
Slab curling and warping will also be measured using a dipstick and either a traveling laser or traveling wheel beam. Load response data, including strains, pressures, and deflections, will be collected during periodic controlled vehicle tests using SHRP protocols. The New York State Department of Transportation (NYSDOT) will conduct regular Falling Weight Deflectometer (FWD) measurements that ORITE will analyze.
Traffic at the I-86 experiment is monitored with a weigh-in-motion (WIM) system. A full load spectrum will be collected and made available for the Mechanistic-Empirical Pavement Design analysis.
Mechanical properties of each material used in the pavement are evaluated through extensive laboratory testing and back calculation using finite element methods. These inputs are suitable for Levels 1, 2, and 3 of the Mechanistic-Empirical Pavement Design method as given in NCHRP report 1-37A. Ultimately the NCHRP Mechanistic-Empirical Design Guide will be calibrated for the state of New York using data from this and other projects. This will allow NYSDOT to move beyond the 1993 AASHTO Guide for Design of Pavement Structures to create roads that will handle the ever-increasing traffic demands made on New York’s roads and will better weather the state’s climatic conditions.
The JPCP overlay over untreated preexisting JRCP experienced a more severe response to environmental factors compared to the overlays placed over broken & seated or rubblized JRCP. Additionally, it can be concluded that at the center of the slab and mid-span along the wheel paths, the breaking and seating of the preexisting concrete would lower the change in strains and stress to values comparable to those experienced using a rubblized base. Based on the results and analysis presented, it is recommended to use one of these fracturing techniques, rubblization or breaking and seating, before placing a JPCP overlay.
The untreated section generally experienced a slightly smaller dynamic response compared to the other two sections, but results were comparable for all treatments. The FWD test results showed that the untreated section typically experienced the lowest deflections while the C&S and rubblized sections showed the highest values at the right wheel path and slab’s centerline respectively. These results are sensitive to the location and placement of the FWD. The dynamic responses are also considerably smaller in magnitude than the environmental responses.
It is thus recommended that existing PCC pavement should not be left untreated before applying an overlay. If the subgrade is weak, the break and seat approach is recommended. If the subgrade is strong, the rubblization method is better. The treatment cost should also be considered.