Evaluation of Penetration Resistance of Soils Reinforced with Geosynthetics Using CBR Tests

Abstract

The application of geosynthetics in roads, paved or unpaved, can extend the service life of pavements, reduce base course thickness and delay rutting development, as well as reinforce weak subgrade layers, the base–subgrade interface, or the base layer. Regarding the application of geosynthetics in roads, this paper uses laboratory CBR tests to investigate how geosynthetics can improve the penetration resistance of two site-won soils (coarse and fine), analysing the influence of several parameters. The test conditions influenced unreinforced and reinforced specimens similarly. The CBR test captured the beneficial effect of the inclusion of one reinforcement layer for both soils. However, when the coarse soil was reinforced with two or more layers of sheet reinforcements, the limitations of the CBR test had a significant impact on the test results. The lateral walls of the mould and the reinforcement layout may lead to misleading results in the CBR tests. These conclusions were qualitatively corroborated by comparisons with the stress–strain behaviour from triaxial tests. Considering its popularity in the design of roads, and to address limitations of the CBR test, a modified setup to carry out CBR tests of reinforced soil solutions is proposed. This setup aims to ensure that the reinforcement mechanisms mobilised during the CBR test are realistic.