This study introduces Virginia's efforts to apply high-speed texture measurement as a tool to improve the uniformity of hot-mix asphalt (HMA) pavements. Three approaches for detecting and quantifying HMA segregation through measuring pavement surface macrotexture were evaluated: (1) applying the methods proposed in NCHRP Report 441, which build on the ability to predict the expected "non-segregated" macrotexture; (2) using acceptance bands for texture similar to those used for HMA density; and (3) considering the standard deviation of the macrotexture as a measure of construction uniformity. Based on the findings from a series of field tests, the researchers concluded that macrotexture measurement holds great promise as a tool to detect and quantify segregation for quality assurance purposes. None of the available equations for predicting non-segregated macrotexture (the approach in NCHRP Report 441) was found to work for all the construction projects evaluated. Additional information is necessary to establish target macrotexture levels. The acceptance bands approach produced reasonable results in most of the field-verification experiments, but it was significantly influenced by the actual variability within the section. An approach that used target levels of standard deviations was selected for further testing and implementation on a pilot basis

Two years ago, the author completed a study with researchers at Virginia Tech that was designed to develop a tool to measure and control segregation of hot-mix asphalt pavements. This earlier work focused on the application of high-speed texture measurements and ultimately proposed an approach that would discourage segregation by establishing limits on allowable fluctuation of pavement macrotexture. Rather than emphasize segregation detection and measurement, the proposed special provision promoted new-surface uniformity. The activities discussed in this report represent the next step in the process of understanding the relationship between the uniformity and surface characteristics of hot-mix asphalt. The study documents the typical "texture profile" for Virginia's most common surface mixes. It revisits the texture-fluctuation provision proposed in the earlier project and delves into an expanded use of elevation profiles for promoting uniformity. Although the major findings and conclusions from this work do not specifically support a texture-based "segregation specification," the study does advocate continued dedication to material and construction uniformity. Alternatives to a texture-based specification include quality measures that recognize variability of traditional quality characteristics (such as percent defective and percent within limits specifications) and a new approach to reporting and using ride quality data, i.e., "roughness profiles." Whether specifically required or used voluntarily to comply with provisions that have stringent variability components (e.g., ride, texture, density), a properly functioning and operated material transfer vehicle is a proven contributor to good hot-mix uniformity. If the vehicle (at $900/mile) eliminates an estimated $3,000 per lane-mile loss in service life due to low-level segregation, the benefit-to-cost ratio is greater than 3.

Bearing Capacity of Roads, Railways and Airfields includes the contributions to the 10th International Conference on the Bearing Capacity of Roads, Railways and Airfields (BCRRA 2017, 28-30 June 2017, Athens, Greece). The papers cover aspects related to materials, laboratory testing, design, construction, maintenance and management systems of transport infrastructure, and focus on roads, railways and airfields. Additional aspects that concern new materials and characterization, alternative rehabilitation techniques, technological advances as well as pavement and railway track substructure sustainability are included. The contributions discuss new concepts and innovative solutions, and are concentrated but not limited on the following topics: · Unbound aggregate materials and soil properties · Bound materials characteritics, mechanical properties and testing · Effect of traffic loading · In-situ measurements techniques and monitoring · Structural evaluation · Pavement serviceability condition · Rehabilitation and maintenance issues · Geophysical assessment · Stabilization and reinforcement · Performance modeling · Environmental challenges · Life cycle assessment and sustainability Bearing Capacity of Roads, Railways and Airfields is essential reading for academics and professionals involved or interested in transport infrastructure systems, in particular roads, railways and airfields.