Study on the Effect of Thickness and Gradation of Geosynthetic-Reinforced Base Layer on CBR Values of a Three-Layer Pavement System

Document Type : Original Article

Authors

Arash mahmmodi ¹

sajjad gholipour ²

masoud makarchian ¹

¹ Department of Civil Engineering, Faculty of Engineering, Bu-Ali Sina University, Hamedan, Iran

² Engineering Faculty of Khoy, Urmia University of Technology, Urmia

10.22067/jfcei.2025.92220.1345

Abstract

ABSTRACT: The use of geosynthetics in soil reinforcement for increasing load-bearing capacity, reducing settlement, and preventing pavement cracking is an effective alternative to conventional methods such as the use of cement and lime. In this study, modified CBR tests were conducted on soil samples reinforced with three types of geosynthetics to investigate the effects of various parameters. The pavement layers included: the surface (a sand and gravel mixture), the subgrade layer (clay with a fixed thickness), and the base layer (two types of sand with thicknesses of 3, 6, and 9 cm and two different gradations). The results showed that placing geosynthetics at the interfaces between layers, especially geocomposites, increased the load-bearing capacity by a factor of 1.2 to 4.5 times compared to the unreinforced condition. Additionally, as the base course thickness and particle size increased, the load-bearing capacity improved; however, the effectiveness of the geosynthetics at the layer interfaces decreased. These findings confirm the important role of geosynthetics in optimizing pavement design.

Keywords

Geosynthetic

CBR

Bearing Capacity

Reinforcement of Base Layer

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