Department of Civil Engineering, Urmia University, Urmia, Iran
Abstract
The flexible pavements are usually composed of two or several asphalt layers, granular material layers (base and subbase) and also subgrade. In the Mechanistic-Empirical Pavement Design Guide (MEPDG), based on the elastic theory, an elastic modulus or in other words the resilient modulus is considered for stiffness characterization of these layers. To determine the resilient modulus, the standard laboratory method is the cyclic triaxial test. This test is a precise and the only direct method to determine the resilient modulus of subgrade soil materials. In this method, the test is performed on cylindrical soil specimens and cyclic (repeated) triaxial loading is applied. The current accepted methods for determination of soil resilient modulus are AASHTO T 307 standard and NCHRP 1-28A protocol. In this paper, in order to obtain a proper and analytical understanding of the laboratory methods for determining this modulus, background and technical aspects of these two methods were discussed. Results showed that although NCHRP 1-28A protocol gives more realistic values for resilient modulus in comparison with AASHTO T 307 method, but due to the complexity of the test apparatus, as well as load and specimen deformation measurements, it is not possible to conduct it extensively, especially in laboratories in Iran. However, this paper by presenting the challenges of these methods, can be a comprehensive guide for researchers and engineers involved with the resilient modulus of soil materials.
Mohammadi, V., Solatifar, N., & Eslami Haghighat, A. (2019). Comparison of AASHTO T 307 and NCHRP 1-28A Methods for Determination of Soil Resilient Modulus. Road, (), -.
MLA
Vahid Mohammadi; Nader Solatifar; Abbas Eslami Haghighat. "Comparison of AASHTO T 307 and NCHRP 1-28A Methods for Determination of Soil Resilient Modulus". Road, , , 2019, -.
HARVARD
Mohammadi, V., Solatifar, N., Eslami Haghighat, A. (2019). 'Comparison of AASHTO T 307 and NCHRP 1-28A Methods for Determination of Soil Resilient Modulus', Road, (), pp. -.
VANCOUVER
Mohammadi, V., Solatifar, N., Eslami Haghighat, A. Comparison of AASHTO T 307 and NCHRP 1-28A Methods for Determination of Soil Resilient Modulus. Road, 2019; (): -.