The results of a field study carried out to investigate the performance of pavements incorporating open-graded drainage layers (OGDLs) are presented. OGDLs are used to ensure rapid and effective drainage of pavement structures and thus to improve pavement performance. Altogether, five paving projects built since 1975 and incorporating OGDLs are described and evaluated. The projects encompass flexible, composite, and rigid pavements, and include both asphalt-cement-treated and untreated OGDL materials. The evaluation was done in terms of: (a) pavement performance evaluation, with emphasis, where possible, on comparing adjacent sections with and without OGDLs; (b) occurrence and severity of major pavement distresses investigated by coring and trenching; (c) assessment of in situ drainage done by observing movement of water within the pavement structure; and (d) laboratory analysis of excavated OGDL materials. The results of this study show that the existence of OGDLs alone does not guarantee a better pavement performance. This can be achieved only if the OGDL is a part of a property designed internal drainage system. (Author/publisher)
Samenvatting