01150950

Component

This paper describes the effectiveness of combining forensic investigation and Falling Weight Deflectometer (FWD) deflection analysis in selecting the most economical best performing rehabilitation remedy for a prematurely failing thin flexible pavement. The project is a four lane divided primary road, about 3 miles long and part of Route 3 in Lancaster County, Fredericksburg District, Virginia. The two west bound lanes were constructed in 1992 with pavement structure consisting of 4.5 inches asphalt concrete on top of 6 inches dense graded aggregate, which rested on a 6 inches soil cement treated layer, on top of the natural subgrade. Within two years of service, it showed white stains at the surface, but no distresses were observed. In 1998 several areas in truck lane failed in fatigue and alligator cracking. The first rehabilitation activity, in 1998, was to mill and replace the asphalt layers, a total of 4.5 inches, without identifying the failure mechanism. This activity proved ineffective and the pavement failed in the same mode but more severely in 1999. Determination of the failure mechanism based on forensic investigation and deflection testing was finally considered, in 2000. The failure mechanism showed that dense plain aggregate which was loaded with fines acted as a weak link between the top and bottom stiff layers and lead to entrapment of moisture (in the absence of pavement edgedrain) and the premature failure due to the truck loading in the truck lane. Based on the forensic investigation and FWD deflection testing, it was decided to remove the asphalt layers and in-place cement stabilize the plain aggregate layer for the truck lane only to provide much stronger pavement by eliminating the weak link. This unique and selective rehabilitation approach resulted in two different treatments one for the truck lane, where most of the heavy loading is applied, and one for the passing lane where light loading is applied. The pavement has performed very well during the last eight years without any signs of distresses. This paper documents the lessons learned from this project, over a span of 17 years.

01147878

10-2215

English

13p

2010

Transportation Research Board 89th Annual Meeting

DVD

Figures; Photos; References (3) ; Tables (2)

Alligator cracking; Asphalt concrete; Case studies; Dense graded aggregates; Falling weight deflectometers; Flexible pavements; Pavement distress; Pavement maintenance; Subbase (Pavements)

Virginia

Highways; Maintenance and Preservation; Pavements; I22: Design of Pavements, Railways and Guideways

Transportation Research Board Annual Meeting 2010 Paper #10-2215

PRP, TRIS, TRB

Jan 25 2010 11:01AM