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Daytona Beach


Civil Engineering

Document Type

Book Chapter

Publication/Presentation Date



For decades, geogrids have been used successfully to improve performance in both paved and unpaved roadway construction. Even though the current state of practice differentiates between the design methodology incorporating geogrids in paved and unpaved roadways, the true improvement contribution of geogrids is to the base layer, or to the layer that is placed directly on top of it. It has been established that the three reinforcement mechanisms by which geogrids enhance roadway performance are: lateral restraint, bearing capacity increase and membrane tension support. In order to quantify these mechanisms and their contribution to the roadway performance improvement, two Cyclic Plate Load (CPL) tests were carried out, one on a paved section with a hot mix asphalt (HMA) top layer, and the second on an unpaved section. The tests included control and reinforced sections. Each test was instrumented with Linear Variable Differential Transducers (LVDTs) at the surface and subgrade levels that measured the displacements at these levels while the cyclic loads were applied. The paper presents the results in terms of the Reinforcement Improvement Ratio (RIR) which is calculated as the ratio between the number of load cycles of the reinforced section divided by the number of cycles of the control section at the same level of displacement. It was found that RIR is almost identical for surface displacements for both paved and unpaved roadway sections indicating the similar lateral restraint effect of the used product. The bearing capacity increase and membrane tension support vary between paved and unpaved sections depending on the level of displacement at the base course and subgrade contact. The results of those two tests were used to put an emphasis on quantifying the mechanism by which the geogrid contributes to the roadway performance improvement regardless whether it is paved or unpaved. The results could be used empirically to modify the current state of practice for geogrid contribution in paved and unpaved roadways. It should be noted that the terms soil reinforcement and soil stabilization have been used interchangeably to indicate the above soil improvements using geogrids.

Publication Title

Geosynthetics: Leading the Way to a Resilient Planet



Taylor & Francis Group