The behaviour of a recycled road base aggregate and quartz sand with bender/extender element tests under variable stress states

Abstract

The paper focuses on laboratory testing investigating the small strain dynamic properties of a recycled road base material of a single fraction. A widely examined quartz sand was also used in the study for comparison purposes. The shear wave velocities (V_s) and primary wave velocities (V_p) were measured in both isotropic and anisotropic stress states with bender/extender element inserts implemented in a stress path triaxial apparatus. Subsequently, the small strain constrained modulus (M_max), Young’s modulus (E_max) and Poisson’s ratio (ν) were derived and further analysed. For the measurement of sample volumetric strains, particularly under the application of stress anisotropy, local strain gauges were used to capture the changes of their radius while the deviatoric compressive load was gradually increased. The responses of the two materials during isotropic compression and swelling as well as under the application of stress anisotropy were thoroughly stated and quantified.

Keywords:

• Recycled road base aggregate
• bender elements
• extender elements
• stress anisotropy
• Young's modulus
• Poisson ratio
• demolition materials
• shear wave velocity
• primary wave velocity

Acknowledgements

The experiments of this study have been conducted at the Soil Mechanics Laboratory of UNSW Australia, School of Civil and Environmental Engineering, Centre for Infrastructure Engineering and Safety. The authors would like to thank the anonymous reviewers for their constructive comments and detailed suggestions that helped us to improve the quality of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The authors acknowledge the financial support by the grant from the Research Grant Council of the Hong Kong Special Administrative Region (HKSAR), China Project No. 9041880 [CityU 112813] and the start-up grant of the College of Science and Engineering, City University of Hong Kong [Code: 7200533-ACE].