Incorporating a fly-ash stabilised layer into pavement design

This paper describes a case history where the structural support afforded by a fly-ash stabilised layer was accounted for explicitly during the design of two flexible pavements. Pavements were designed and constructed at two sites in southern Wisconsin employing a layer stabilised in situ with fly ash. One pavement is for a residential subdivision. The other is a test section located in a secondary highway that was recently reconstructed. A control test section employing a conventional cut-and-fill approach was also constructed in the secondary highway. Fly ash was used to increase the strength and stiffness of the fine-grained subgrade at both sites, which was soft prior to stabilisation. Pavements at both sites were designed using the 1993 American Association of State Highway and Transportation Officials (AASHTO) method for flexible pavements so that their structural number would be equivalent to that of the conventional pavement originally called for in the design. Measurements of California Bearing R...