Accelerated Loading Evaluation of Stabilized BCS Layers in Pavement Performance

摘要

BCS is short for blended calcium sulfate, a recycled fluorogypsum mixture that has been used in Louisiana as a roadway base for more than a decade. Without further chemical stabilization, the major concern of using raw BCS as a pavement structural layer is its moisture susceptibility. In order to verify the efficiency of laboratory-derived BCS stabilization schemes and further assess related field performance and potential cost benefits, an accelerated pavement testing (APT) experiment was recently conducted at Louisiana Transportation Research Center (LTRC) using the Accelerated Loading Facility (ALF). The APT experiment included three different base test sections: the first one contained a granulated ground blast furnace slag stabilized BCS base course (called BCS/Slag), the second used a fly ash stabilized BCS base course (called BCS/Flyash), and the third had a crushed limestone base. Except for using different base materials, the three APT sections shared a common pavement structure: a 2-in. asphalt wearing course, an 8.5-in. base course, and a 12-in. lime-treated working table layer over an A-6 soil subgrade. Each section was instrumented with one multi-depth deflectometer and two pressure cells for measuring ALF moving load induced pavement responses (i.e., deflections and vertical stresses). The instrumentation data were collected at approximately every 8,500 ALF load repetitions; whereas, non-destructive deflection tests and surface distress surveys (for surface rutting and cracking) were performed at every 25,000 ALF load passes.