Used of Geogrid In Road Construction

Abstract

Geogrid reinforcement is gaining acceptance as an effective way of improving on the properties of naturally occurring soils for road pavement construction. In many tropical countries, weak lateritic subgrades are common and often rejected after proof rolling during construction due to poor strength. The specific objectives of this research were to 1) Determine the effect of strength of geogrid reinforcement material on the California Bearing Ratio of a sample of relatively poor lateritic subgrade material under soaked and unsoaked conditions and 2) Establish the effect of geogrid reinforced subgrade on the design thickness of low volume paved roads. A natural lateritic subgrade soil was selected and tested without reinforcement. Then by placing a layer of a tri-axial geogrid above the third layer within the sample height, the effects of geogrid reinforcement on California Bearing Ratio values are investigated. This was undertaken for two strengths of geogrid in both soaked and unsoaked conditions. The California Bearing Ratios of the soil–geogrid subgrade was used to determine the pavement layer thicknesses for a low volume paved road using the Transport Research Laboratory Road Note 31 method of pavement design. The results indicate that base course layer thickness reduction as a result of geogrid reinforcement for a subgrade decreases with increasing traffic class. A minimum of 15% base course layer thickness reduction was observed for a surface dressed road with natural gravel base course.