Blended Calcium Sulfate (BCS) is a recycled fluorogypsum mixture that hasbeen used in Louisiana as a pavement base layer 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. It could cause both short-term construction difficulties and long-term performance problems. In order to verify the efficiency of BCS stabilization schemes that was obtained from laboratory results and further assess the field performance of stabilized BCS materials as well as related cost benefits, three accelerated pavement test sections including two of different stabilized BCS bases and one of a crushed stone base were recently tested at the Louisiana Pavement Research Facility (PRF) in Port Allen, LA. The three sections shared a common pavement structure. The only difference was the base course materials. Each test section was instrumented with one multi-depth deflectometer and two pressure cells for measuring related pavement responses. Surface distress survey and the falling weight deflectometer (FWD) testswere performed at the end of every 25,000 load repetitions. The overall accelerated loading results indicated that a test section containing the GGBFS stabilized BCS base outperformed other two sections by a significantlylarge margin. FWD backcalculation results indicated that the GGBFS stabilized BCS base generally possessed an in situ modulus value higher than that for an asphalt concrete layer and performed like a lean concrete. Cost benefit analysis results further indicated that when using the GGBFS stabilized BCS in lieu of a stone base in a flexible pavement design, the asphalt concrete thickness could be readily reduced and thus the construction costs might be saved immediately.
Abstract