Fly-Ash Bases in the Atlanta District: Evaluation of Surface Treatment Bond and211 Year-Two Field Performance Evaluations

摘要

Hydrated fly ash is produced by allowing powder fly ash (Class C) from coal power211u001eplants to cure with moisture. The hydrated (cured) fly ash becomes a stiff 211u001ematerial that can be crushed to form a synthetic aggregate. When properly 211u001eprocessed and compacted to optimum moisture content, the hydrated fly ash 211u001econtinues to gain strength after placement as a base material. The Atlanta 211u001eDistrict has constructed six pavement sections since 1993 using hydrated fly ash 211u001eas the flexible base material. This research project was initiated to evaluate 211u001eand monitor performance and changes in material properties for these six 211u001epavements through the year 2001 and to evaluate a problem experienced during 211u001econstruction where the asphalt surface treatment did not bond well to the base. A 211u001elaboratory study was performed to investigate the bond strength of different 211u001etypes of prime materials to the fly-ash base. Curing extent of the base was also 211u001ea variable in the experiment. Results of the laboratory study revealed that the 211u001etype of prime material used during construction did not contribute to the 211u001einadequate bond achieved. It is more likely attributable to the extent of base 211u001ecure prior to application of an asphalt membrane. Construction recommendations 211u001eare provided in this report aimed at achieving adequate bond of the surface 211u001etreatment to the flay-ash base. Evaluation of pavement base performance was based 211u001eon visual documentation, falling-weight deflectometer tests, ground penetrating 211u001eradar, and compressive strengths of field cores. This report is an interim report 211u001edocumenting the performance evaluations conducted in the spring of 1998. This 211u001ereport covers the second annual evaluation in a series of five.