This reports document research that was performed to (1) determine causes of variability and tolerances for volumetric and mechanical properties of dense-graded asphalt mixtures measured within and among the three specimen types; and (2) propose a practice for state departments of transportation to incorporate these results in specifications and criteria for quality assurance, mix design verification or validation, and structural design and forensic studies. The research was conducted in two phases. In Phase I, datasets of laboratory and field test data were collected and pooled in a meta-analysis in an attempt to determine levels of variability in asphalt mixtures and the factors causing variability among and between the three specimen types. Despite the inclusion of 25 extensive datasets representing roughly 8,000 individual mixtures in the meta-analysis, the results of the analysis were inconclusive. Phase II was then undertaken—a program testing specimens from paving projects across the United States to quantify the effects of process-based factors on the variability of volumetric and mechanical properties of the specimen types. The key outcome of the research is a proposed practice for evaluating the cause and magnitude of variability within and among the three specimen types. In addition, tolerances of volumetric and conversion factors between the three specimen types of mechanical properties evaluated are proposed based on the average difference between specimen comparisons for the mixtures evaluated in Phase II. Agencies may use these proposed values to evaluate and adjust their current tolerances.

This reports document research that was performed to (1) determine causes of variability and tolerances for volumetric and mechanical properties of dense-graded asphalt mixtures measured within and among the three specimen types; and (2) propose a practice for state departments of transportation to incorporate these results in specifications and criteria for quality assurance, mix design verification or validation, and structural design and forensic studies. The research was conducted in two phases. In Phase I, datasets of laboratory and field test data were collected and pooled in a meta-analysis in an attempt to determine levels of variability in asphalt mixtures and the factors causing variability among and between the three specimen types. Despite the inclusion of 25 extensive datasets representing roughly 8,000 individual mixtures in the meta-analysis, the results of the analysis were inconclusive. Phase II was then undertaken--a program testing specimens from paving projects across the United States to quantify the effects of process-based factors on the variability of volumetric and mechanical properties of the specimen types. The key outcome of the research is a proposed practice for evaluating the cause and magnitude of variability within and among the three specimen types. In addition, tolerances of volumetric and conversion factors between the three specimen types of mechanical properties evaluated are proposed based on the average difference between specimen comparisons for the mixtures evaluated in Phase II. Agencies may use these proposed values to evaluate and adjust their current tolerances.

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.

"TRB's National Cooperative Highway Research Program (NCHRP) Report 763: Evaluation of the Moisture Susceptibility of WMA Technologies presents proposed guidelines for identifying potential moisture susceptibility in warm mix asphalt (WMA). The report also suggests potential revisions to the Appendix to AASHTO R 35, "Special Mixture Design Considerations and Methods for WMA" as a means to implement the guidelines."--publisher's description

A dozen papers from a December 1993 symposium in Dallas/Fort Worth, Texas. Among the topics are why the new proposed rheological properties of asphalt binders are required and how they compare to conventional properties, the development and use of the SHRP direct tension specification test, oxidatio