Expansion and Cracks from a Lime Fly-Ash Stabilized Gravel Base

摘要

Upon completion of a road project, expansion and cracking of the pavement structure start to appear, and continue to worsen over time. Through forensic study, it was found that the main cause of these distresses stems from the lime fly-ash stabilized gravel base course. This paper summarizes the analysis result of several approaches, including frost heaving, salt expansion and 'over burnt lime.' It was concluded that salt expansion is the main contributing factor. From the chemical analysis, the authors found that the main contributing factor is calcium sulfate, as the content of calcium sulfate is far beyond the normal level according to the principle of calcium sulfate crystallization and calcium sulfate crystal expansion. This paper discusses several possible solutions to prevent such distresses.