Remaining Service Life Analysis of Concrete Airfield Pavements at Denver International Airport Using the FACS Method

Abstract

Denver International Airport (DEN) has completed a comprehensive pavement evaluation of the entire airfield using the Geospatial Airfield Pavement Evaluation and Management System (GAPEMS). The comprehensive use of TabletPCs and GPS for distress mapping, photographic documentation, core sampling, structural evaluation, and mapping of legacy construction data has provided the pavement engineer with more data and a clearer big picture of the pavement condition. Traditional declining Pavement Condition Index (PCI) value was found to be ineffective as a means of forecasting remaining life for several reasons including the grouping of slabs unrelated to type of distress. The averaging of slabs in groups of 20 slabs for concrete is an inherent flaw in the PCI method when averaging slabs of highly variable distresses. A new pavement remaining life calculation method called the “FACS Method” was developed that used the acronym from four separate failure modes of concrete pavement: Fatigue, Alkali Silica Reaction (ASR), Cracking, and Spalling. Using geospatial mapping of all distresses and the additional data including geospatial photography, the team was able to develop a network forecast of remaining life based on each of the four failure modes by evaluating data at the individual slab level. This improved method of remaining life analysis was implemented at DEN and resulted in significant savings in the slab replacement program. GAPEMS Data Collection Denver International Airport (DEN) has completed a comprehensive pavement evaluation of the entire airfield using the Geospatial Airfield Pavement Evaluation and Management System (GAPEMS) (McNerney and Kelley 2007). The pavement evaluation included approximately 125 miles of continuous deflection data of the Rolling Dynamic Deflectometer (RDD) to evaluate the structural capacity of the pavements (Bay and Stokoe, 1998). Pavement evaluation also included 200 core locations and 128 cores tested for alkali silica reaction (ASR) by petrography. Archived construction records were geospatially coded for date of concrete placement, lot number, mix design, and method of construction. Forensic analyses using the distress and construction data found there is a significant difference in remaining service life because of differences in the coarse aggregates.