https://orcid.org/0000-0001-8348-1580
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ABSTRACT
Currently, Egypt is using the [AASHTO, Citation1993. Guide for design of pavement structures. Washington, DC: American Association of State Highway and Transportation Officials] guide for the flexible pavement structural design. In this method the resilient modulus (MR) of the unbound granular base/subbase materials and subgrade soils is a measure of material stiffness used for characterisation. It is considered one of the major factors affecting the pavement layerthicknesses. However, in Egypt, California Bearing Ratio (CBR) is the main strength parameter used for characterisation of the unbound materials and subgrade soils due to its availability and simplicity. In this research, a comprehensive experimental testing programme was conducted on different unbound granular base/subbase materials typically used in pavement construction projects in Egypt. The testing programme includes MR, CBR, and basic material properties. The effect of aggregate gradation on MR is investigated. A model predicting MR as a function of the basic material properties is proposed. The MR–CBR relationship adopted in the current Egyptian Code of Practice is verified based on the testing results. The experimental data warranted the calibration of the current model. The calibrated model has reasonable goodness of fit statistics and yields rational MR estimates for the local materials.
Acknowledgments
The authors would like to thank the Egyptian National Institute of Transport (ENIT), Ministry of Transport in Egypt for funding this project through investment plan of ENIT. The authors would also like to thank the staff and technician at the Highway and Airport Engineering laboratory at Mansoura University and also, all ENIT staff who contributed to the technical, administrative, and financial aspects.
Disclosure statement
No potential conflict of interest was reported by the authors.