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Various tests are used to characterise the strength and resilience of granular materials used in the subbase of a pavement system, but there is a limited understanding of how particle properties relate to the bulk material response under various test conditions. Here, we use discrete element method (DEM) simulations with a mechanistically based contact model to explore influences of the material properties of the particle on the results of two such tests: the dynamic cone penetrometer (DCP) and the resilient modulus tests. We find that the measured resilient modulus increases linearly with the particle elastic modulus, whereas the DCP test results are relatively insensitive to particle elastic modulus. The DCP test results are also relatively insensitive to inter-particle friction coefficient but strongly dependent on the particle shape. We discuss strengths and weaknesses of our modelling approach and include suggestions for future improvements. [ABSTRACT FROM PUBLISHER]

Ultrasonic tomography is an emerging method of nondestructive concrete pavement diagnostics which can be used for improved quality assurance/quality control during concrete pavement construction and assist in rehabilitation decision making. Detection of flaws using ultrasonic tomography requires significant effort and user expertise. To address these limitations, a quantitative method for determining the presence of defects in concrete pavements was developed. The proposed method is an adaptation of the recently developed impact-echo signature analysis method (IESA), which is used for comparison of impact-echo signals. The proposed two-dimensional ultrasonic tomography signature analysis (2D-UTSA) method was used to compare two-dimensional B-scans obtained using a commercial test system in field trials at the Minnesota Rd. Research Facility and the Federal Aviation Administration's National Airport Pavement Test Facility. Analysis of the results showed that the 2D-UTSA method is capable of identifying subsurface defects. [ABSTRACT FROM AUTHOR]

Pavement design optimisation is an active area of research. Due to a large number of parameters, such as thickness of layers, material properties, climatic conditions, affecting pavement performance, it is usually not feasible to determine an optimal design using a trial and error approach. In order to make the design calculation computationally tractable, the process can be posed as an optimisation problem. Previous investigations in this vein have suffered from the limitations of a specific pavement analysis tool, specific design goals and specific optimisation algorithms. This paper presents a general computational framework, combining Mechanistic-Empirical Pavement Design Guide and Design Analysis Kit for Optimisation and Terascale Applications, to overcome these shortcomings. The framework's promise is demonstrated through its application to a minimum cost pavement design problem using both direct and surrogate-based (SBO) optimisation approaches. The SBO formulation is shown to achieve significant savings in required computational time with a minimal loss of accuracy in the determined optimal design. [ABSTRACT FROM AUTHOR]

Dowels are inserted at the mid-depth of joints in jointed concrete pavements that are exposed to heavy loading to provide load transfer and reduce pumping and faulting. Dowel alignment tolerances in North America have traditionally been strict, although not based on substantial performance data. In this paper, new laboratory testing methods are proposed for evaluation of the effects of dowel misalignment on concrete joint behavior. In these tests, dowels with various levels of rotations and translations were subjected to pullout and shear loading. It was found that dowel misalignment does not have a significant effect on pullout and shear forces for certain ranges of misalignments, which far exceed the tolerances recommended by the Federal Highway Administration. At the same time, it was found that extreme cases and combinations of misalignment resulted in a significant decrease in initial stiffness and shear capacity. Therefore, there is a need for the establishment of rational alignment tolerances. The results of this study provide important information for the development of such tolerances. [ABSTRACT FROM AUTHOR]