The effectiveness of using the field diagnosis and falling weight deflectometer (FWD) mechanistic analysis in reducing a 65-km (40-mi) segment of asphalt pavement to project level segments is discussed, along with selecting a cost-effective rehabilitation strategy. A mechanistic-based analysis was performed on the deflection basins measured from I-85 in Virginia to backcalculate the layer moduli. The 65-km segment was divided into structurally homogeneous sections based on the back-calculated layer moduli. The data of each homogeneous section were analyzed further to assess the in situ structural capacity, to identify weak layers, to estimate the remaining structural life, and to determine the current and future rehabilitation needs. It was found that some sections have almost no remaining structural life, and others have remaining structural life of more than 10 years. A comparison was made between the FWD–field diagnosis rehabilitation program and a visual inspection rehabilitation program. Results of the comparison indicated that the visual inspection rehabilitation program resulted in selecting thicker overlays for some of the project sections (overdesigned) and thinner overlays for the other sections (underdesigned). It is estimated that the difference between the FWD–field diagnosis rehabilitation program and the visual inspection rehabilitation program for the overdesigned sections is in the range of 45 percent of the construction cost (savings). Life-cycle cost analysis (LCCA) was performed to quantify the difference between the two rehabilitation programs for the underdesigned sections. Results of the LCCA indicated that the FWD–field diagnosis rehabilitation program would result in 26 percent and 42 percent reduction in the construction cost and user delay cost, respectively.

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Inadequate drainage of surface water, subsurface water, or both can have a significant impact on pavement performance and long-term maintenance costs. This paper discusses how groundwater (subsurface water) that is not adequately controlled can negatively affect the performance of pavement functionality. Forensic methods used to identify the sources of groundwater and measures that are taken to remediate the problem are explained. Forensic investigation revealed that serious consideration in the design of pavements must be given to regional groundwater conditions and the impact possible on both the integrity and the functionality of the pavement and thus on the safety and the comfort of the traveling public.

This paper highlights the challenges in developing practical concrete pavement patching specifications for the Virginia Department of Transportation (DOT). Several hypothetical scenarios were analyzed with HIPERPAV to provide a general idea about the sensitivity of the parameters that affect the performance of concrete patches. The study concluded that the use of a maturity meter in the Virginia DOT special provisions will allow a rapid decision to be made regarding early opening to traffic after concrete repairs and will eliminate the need for testing during construction. Specifying a compressive strength of 1,600 psi (11,030 kPa) for opening to traffic will not adversely affect the patch. Contractors can use HIPERPAV to compare various strategies including placement time and traffic opening time for a particular concrete mix. In general, at higher mix temperatures, the peak stress-to-strength ratio is consistently higher over longer times. It is important to control or minimize the base and subbase temperature before concrete is poured. Higher early cracking potential is associated with patch mixes with a lower water–cement ratio. The early cracking potential is higher in longer patches compared with shorter patches in spite of the similar strength gain requirements for opening to traffic. The risk of failure is low for a shorter patch when the traffic opening time is reduced.

Field and laboratory forensic investigations were used to identify the failure mechanism of a jointed plain concrete pavement with a subsurface drainage system in Virginia. Similar to many states' practice, this subsurface drainage system consists of open-graded drainage layer and edge drains to provide positive drainage for the pavement. The investigation included a review of construction practices and pavement performance records, a visual distress survey, nondestructive testing using a falling weight deflectometer, roughness measurements using a profiler, coring and boring for materials testing, observation wells, subgrade soil classification, mineralogy, determination of concrete compressive strength, edge drain camera inspection, and slab removal. On the basis of the investigation, it was concluded that lack of positive drainage along with heavily loaded truck traffic resulted in premature failure. The water entering the pavement because of poor joint sealing was trapped in the open-graded drainage layer; this led to severe faulting, midslab cracks, pumping, and eventual failure of the pavement.