The aim of this website is to bring together information relevant to Balanced Mix Design (BMD). Through monthly postings, we are working to give our reader a better understanding of BMD procedures, applications, and updates. In this blog, we will highlight publications with interesting BMD research and developments. Additionally, we will provide feedback on conferences, shows, meetings, and general tips. Although the COVID-19 pandemic has delayed some of these events, we are still hoping to attend the 95th AAPT Annual Meeting and the 2020 TXAPA Annual Meeting which are both scheduled for mid-September.
By our next posting, the COVID-19 situation will hopefully look a little clearer. Until then, we hope you stay safe and find a way to enjoy this strange period of time. Below we have featured two recent BMD reports that we have found to have innovative and useful BMD solutions.
Developing a BMD Framework
NCHRP 20-07 task 406 Development of a Framework for Balanced Mix Design is an excellent piece of research executed by NCAT. They cover candidate tests and many states’ practices while looking for areas that require attention. The objective of the document was to develop a framework that would allow states to create a BMD system appropriate for their needs. The framework is to be presented in the format of an AASHTO recommended practice and will provide highway agencies with options on which performance tests to use, and how to incorporate them into an overall mix design framework.
FHWA-HIF-19-103 report - Index-Based Tests for Performance Engineered Mixture Designs for Asphalt Pavements is another excellent report which brings Balanced Mix Design under the umbrella of Performance Engineered Mix Design (PEMD). Rather than BMD, it uses the term indexed based PEMD. This is done to differentiate index tests from mechanistic tests, which are also included under the PEMD umbrella. To put it simply, index tests output a number and mechanistic tests output a measure of the material’s property, such as modulus. The number from the index test relates to the material’s field performance, whereas a value such modulus is a fundamental property of the material and can be used in performance prediction software such as AASHTOWareTM. This report looks at the crucial test selection process and is extremely useful.