REEVALUATION OF FLEXIBLE BASE IN THE FORT WORTH DISTRICT

Flexible base has been a predominant aggregate blend used in roadway structures for many years. It has served as a cheaper material for low to medium volume roads. The Fort Worth District has had some recent roadway failures that have been directly linked to failure of the flexible base. Recent assumptions attributed this to a wide range of triaxial values between the coarse and fine limits of the District's gradation band. Laboratory testing of the typical gradation confirmed this. A new large stone gradation was proposed and accepted to use in a test section on the construction project in Wise County. The section was constructed in August, 1999, and falling weight deflectometer data collected in September, 1999 and October, 2000.