Early Evaluation of Long-Term Pavement Performance Specific Pavement Studies-2, Colorado

Abstract

The Long-Term Pavement Performance (LTPP) Program included the construction of rigid pavement sections for evaluation. These test sections, designated Specific Pavement Studies (SPS)-2, were constructed on the basis of an experiment matrix that includes pavement slab thickness [202 mm (8 in.) and 280 mm (11 in.)], base type (permeable asphalt-treated base, lean concrete base, and dense-graded aggregate base), widened lane of 4.27 m (14 ft) and state standard lane of 3.66 m (12 ft), and drainage (with and without pavement edge drains). In addition, a standard Colorado Department of Transportation design section was constructed to provide a performance comparison. The performance of these test sections after 4 years of service is discussed. The results are based on deflection, profile, and distress data collected by the LTPP Program. Virtually no distress and no change in ride quality are evident in these pavement test sections at this time. However, the evaluation of deflection data provides an early indication of anticipated variation in test section performance. Currently, no difference can be identified between the deflection magnitude of the widened-lane section and the state standard section with tied concrete shoulders. However, both these sections exhibit lower deflections at this time than those sections with untied shoulders. High deflections of 202-mm sections indicate that perhaps these sections do not provide adequate structural strength for this roadway.