<p><p><div><h2>Project Summary/Scope:</h2>A portion of Kentucky Route 11, located 11.7 km (7.3 miles) north of Beattyville, Kentucky, was about 9.6 km (6 miles) in length. Four types of chemical stabilization (Atmospheric Fluidized Bed Combustion (AFBC), cement, hydrated lime, multi-cone kiln dust) of subgrade were conducted on this portion of Route 11, which was divided into seven sections that consisted of one unstablized section and six chemical stabilized sections. The study presented in this paper focuses on analyzing the feasibility of the AFBC byproduct as the stabilization agent for two sections.</p><p>Subsurface Conditions: The subsurface consisted of inter-bedded layers of shale, sandstone, and coal. Liquid limit and plasticity indices of natural soils were in a range of 36 to 43% and 12 to 15%, respectively. Approximately 70% of the particles passed the No. 200 sieve.</p><p>Two sections stabilized using the AFBC byproduct, measuring 1.35 km (0.84 miles) and 1.74 km (1.1 miles) long, were compacted to the dry density specification. The percentage of stabilizer was selected at the point when no increase or a slight increase occurred in unconfined compression strength with an increase of stabilizer percentage. Seven and 10% of the AFBC byproduct were selected for two sections. In-situ CBR values ranged from 34 to 53, seven days after construction, and from 10 to 54 from October of 1987 to March 1999.</p><p>Overall, satisfactory performance was achieved over a 12-year period.<br><h2>Performance Monitoring:</h2>Heave or differential swellings occurred in several places two months after construction of the base courses on two AFBC-stabilized sections. The swelling of stabilized subgrades consisted of primary and secondary swelling. The maximum primary swell value ranged from 1.8 to 8.8 cm (0.7 to 3.5 inches). The secondary swell value was very small over a period of 5 years.<br><h2>Project Technical Paper:<strong> </strong></h2>Hopkins, T.C., and Beckham, T.L (1999). “Long-Term Performance of a Highway Subgrade Stabilized with an Atmospheric Fluidized Bed Combustion Material.” 1999 International Ash Utilization Symposium, Center of Applied Energy Research, University of Kentucky, Kentucky, 1-12<br><h2>Date Case History Prepared:</h2>November 2012</p><p></div></p></p>