Initial Approach to Performance (Balanced) Mix Design: The Virginia Experience

Abstract

Performance mix design (PMD) of asphalt mixtures, often referred to as balanced mix design, is a design methodology that incorporates performance testing into the mix design process. The Virginia Department of Transportation (DOT), like many owner agencies, is interested in ways to specify asphalt mix designs better in an effort to make its roadway network more sustainable, longer lasting, and more economical. By adding performance criteria through a PMD framework, that goal can be achieved. Further, a PMD framework should allow for the development of new, innovative methods to increase pavement recyclability, new performance additives, and other means to enhance pavement performance. This paper provides details and documentation of the approach being taken by the Virginia DOT in their efforts to develop a PMD specification. Aspects of development presented include PMD method options, selection of performance tests, and determination of acceptance criteria. A discussion about validating specifications with in-service performance data and addressing quality control and quality assurance is also provided. Although additional work is needed for full development and implementation, the methodology being applied has been found to provide useful outcomes for the Virginia DOT even in the initial stages of development.

Balanced Mix Design and Benchmarking: A Case Study in Establishing Performance Test Thresholds

“…VDOT’s BMD specification has become well known throughout the southeastern United States. The objective of this paper is to outline and discuss the research study conducted and process used to develop the BMD specification for VDOT, and provide deeper insight into the execution of the study briefly discussed in the philosophical BMD benchmarking paper published by Diefenderfer and Bowers ( 14 ). Eleven representative dense graded asphalt mixtures from a 2015 research study were sampled and used to benchmark current asphalt mixture performance in Virginia on each of the prospective BMD tests.…”

Laboratory and Field Evaluation of Pre-Treated Dry-Process Rubber-Modified Asphalt Binders and Dense-Graded Mixtures

“…For example, a report summarizing BMD recommendations for Minnesota Department of Transportation recommended that, first, materials/mixes should be selected according to current practices, then baseline mixture performance established using rutting and cracking tests, and finally, binder content adjusted according to the best performing design iteration ( 15 ). States such as Virginia and Missouri are moving toward developing a specification for implementing BMD by investigating different cracking and rutting tests to establish appropriate state-wide thresholds ( 16 , 17 ). On the other hand, agencies such as Illinois Tollway have already implemented BMD principles in their mix designs, which has allowed them to use innovative technologies, such as a chemically engineered dry-process GTR (referred to as DP-GTR), in their mixes to improve performance ( 18 ).…”

Ảnh hưởng của hàm lượng phụ gia ZAG1 đến một số tính năng của bê tông asphalt

“…Xu hướng thể hiện kết quả này phản ánh đúng bản chất của phụ gia ZAG1 với chất nền là nhựa PE. Nếu lấy giới hạn chỉ số kháng nứt CTIndex tối thiểu cho phép theo Sở GTVT Bang Virginia là 80 [18], thì hỗn hợp 0,7% ZAG1 và 0,9 % ZAG1 đều có chỉ số CTIndex thấp hơn. Với mục tiêu đảm bảo được sự cân bằng cho hỗn hợp bê tông asphalt có sử dụng phụ gia ZAG1 về chống hằn lún vệt bánh xe và chống nứt, tỷ lệ phụ gia ZAG1 tối ưu nằm trong khoảng tỷ lệ phụ gia thỏa mãn đồng thời độ hằn lún vệt bánh xe và chỉ số kháng nứt.…”