Behavior of Unpaved Roads Under Different Conditions

Abstract

This paper presents the results of a laboratory study performed on unpaved roads. Both unreinforced wearing layers and layers reinforced with geosynthetics were considered for their construction and study, as geosynthetics are reported to improve the behavior of the granular layers. Reinforcement was introduced by means of a polyester geogrid. Four different types of soils were considered in the study, each one with different percentages of sand, silt and clay. The soil layers were placed, compacted and tested with the optimum water content. Traditional soil characterization was performed, which included particle size analysis, density of solid particles, consistency limits, compaction and California Bearing Ratio. Wheel Tracking tests were performed to study the unpaved road behavior in the different conditions. In the majority of the tests, a compressive material was used beneath the soil layer, to simulate the existence of a weak and deformable subgrade. The results of the study conducted to the following main conclusions: soil D, the one with the highest percentage of fines, shows the best performance under the Wheel Tracking test, for all conditions under study; soil A, the coarsest soil, performed worst; soils B and C improve their performance significantly when the geogrid reinforcement was included.