Predicting the Friction Coefficient of High-Friction Surface Treatment Application Aggregates using the Aggregates\u27 Characteristics

Providing Sufficient Pavement Surface Friction (I.e., Skid Resistance) between Vehicle Tires and Pavement Surface throughout the Pavement Service Life is Considered to Be One of the Main Objectives of Highway Design. Moreover, Vehicle Safety, the Amount of Consumed Fuel, and the Wearing Rate of Vehicle Tires Generally Are Influenced by Pavement Surface Friction. in This Study, a Comprehensive Experimental Testing Program Was Conducted on Different Aggregate Sources, Including Calcined Bauxite and Five Alternative Local Sources, to Assess their Friction Characteristics. the Testing Program Included a British Pendulum Tester (BPT) and a Dynamic Friction Tester (DFT), Which Were Used to Evaluate the Friction Characteristics of the Proposed Aggregates, Along with Basic and Durability Properties Tests. the Aggregate Imaging Measurement System (AIMS) Technique Was Applied to Evaluate the Aggregate Characteristics Due to Micro-Deval Degradation. This Study Provides Two Empirical Models for the Friction Characteristics of High-Friction Surface Treatment (HFST)-Application Aggregates based on the Experimental Results. the First Model Correlates the Friction Coefficient at 20 Km/h (DFC20) with the British Pendulum Number (BPN). the Second Model Expresses DFC20 as a Function of Polishing Resistance of Aggregates, Which is Represented by the Initial and Terminal Aggregate Texture and Angularity Values Measured using the AIMS Device with an overall Coefficient of Determination (R2) of 0.949. the Aggregate Characteristics (I.e., Particle Angularity and Surface Texture) Align Well with the Microtexture Characteristics of the Investigated Sources

A Simplified Mechanistic-Empirical Flexible Pavement Design Method for Moderate to Hot Climate Regions

Flexible pavement structure design is a complex task because of the variability of design input parameters and complex failure mechanisms. Therefore, the aim of this study is to develop and implement a simplified Mechanistic-Empirical (M-E) pavement design method based on the 1993 American Association of State Highway and Transportation Officials (AASHTO), the National Cooperative Highway Research Program (NCHRP) 9-22, and NCHRP 1-37A and 1-40D projects. This simplified methodology is implemented into a computer code and a user-friendly software called “ME-PAVE”. In this methodology, only two equivalent temperatures, as per the NCHRP 9-22 project, are estimated to adjust the dynamic modulus of the asphalt layer(s) for Asphalt Concrete (AC) rutting and AC fatigue cracking prediction instead of using the hourly climatic data, as in the AASHTOWare Pavement ME. In ME-PAVE, the structural responses at critical locations in the pavement structure are determined by a Finite Element Module (FEM), which is verified by a Multi-layer Elastic Analysis (MLEA) program. To ensure that the simplified methodology is practical and accurate, the incorporated transfer functions in the proposed simplified methodology are calibrated based on the Long-Term Pavement Performance (LTPP) data. Based on statistical analyses, the built-in FEM results exhibit very similar trends to those yielded by MLEA, with a coefficient of determination, R2 of 1.0. For all practical purposes, the proposed methodology, despite all simplifications, yields acceptable prediction accuracy with R2 of 0.317 for the rut depth compared to the current practices, NCHRP 1-37A and 1-40D (R2 = 0.399 and 0.577, respectively); while the prediction accuracy for fatigue cracking with R2 of 0.382 is comparable to the NCHRP 1-40D with R2 of 0.275. Nonetheless, the standard error for both distresses is in good agreement based on the investigated data and the developed methodology. Finally, the conducted sensitivity analysis demonstrate that the proposed methodology produces rational pavement performance