Influence of Degree of Saturation (DOS) on Dynamic Behavior of Unbound Granular Materials

Junyu Sun,Dominic Ek-Leong Ong,Erwin Oh

doi:10.3390/geosciences11020089

Junyu Sun, Dominic Ek-Leong Ong + Show 1 more

Open Access

https://doi.org/10.3390/geosciences11020089

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Journal: Geosciences	Publication Date: Feb 15, 2021
Citations: 12	License type: CC BY 4.0

Affiliation: Griffith University

Abstract

The extensive application of natural unbound granular materials (UGMs) motivates studies into the mechanical properties of alternatives such as processed crushed rocks employed commonly as base or subbase layers. The rutting and settlement generated in base and subbase layers is widely restricted in many specifications and standards. In this research, the dynamic behavior including the resilient modulus (Mr) and the plastic strain (εεp) of the crushed rocks collected from Queensland in Australia will be tested by a series of repeated load triaxial test (RLT) tests to investigate the behavior of UGMs under the fluctuation of the degree of saturation (DOS) (59%–100%). In particular, the RLT specimens were prepared in the laboratory through proper gradation under optimum moisture content (OMC) and 100% standard proctor maximum dry unit weight. Results from the RLT tests showed that UGM specimens soaked at higher DOS generated lower resilient modulus and weaker resistance to heavy traffic volumes with significant accumulation of plastic strain. The Mr and εεp of the tested aggregates under different cyclic deviator stresses of 425 kPa and 625 kPa approximately linearly decreased and approximately linearly increased as the DOS increased with a certain number of cycles up to 50,000, respectively.

Highlights

Unbound granular pavement materials (UGMs), which mainly comprise rocks, gravels, and manufactured crushed rock, are generally heavily compacted in pavement structural systems as base and subbase materials to distribute the traffic loads from the surface layer above to the subgrade layer [1,2]
For all number of cycles, the corresponding resilient modulus decreased with the increase in the degree of saturation (DOS) of specimens
Similar to the result under around 70% DOS, under the vertical deviator stress of 625 kPa, there was a sudden decrease in the resilient modulus of the test after

Summary

Introduction

Unbound granular pavement materials (UGMs), which mainly comprise rocks, gravels, and manufactured crushed rock, are generally heavily compacted in pavement structural systems as base and subbase materials to distribute the traffic loads from the surface layer above to the subgrade layer [1,2]. For the differences between flexible and rigid pavement components, in rigid pavements with the concrete surface layer, the base layer is applied to level and structurally strengthen week subgrade [6]. For flexible pavements with an asphalt surface layer, the base and subbase layers are structural components that should provide enough strength to decrease the stress to levels that can be supported by the subgrade [6]. A separation between the surface layer and subgrade is provided by the subbase layer to avoid the subgrade fines being pumped to the surface layer through the joints during the traffic loading [6]

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Conclusion