Balanced Mix Design — It’s here to stay
You may prefer Superpave with volumetric design and its recipe-like strategy for designing asphalt mixes, but Balanced Mix Design (BMD) is increasingly becoming the new standard. That means asphalt designers and pavers can expect to see specifications based on BMD approaches more often in future projects.
Agencies, owners, engineers, and the asphalt industry in general are adopting BMD because asphalt performance tests over the past few decades have pointed to the need for a more comprehensive approach to mix design than Superpave provides.
Achieving the ideal balance of aggregates, asphalt binder, and additives is crucial for producing high-quality asphalt pavement that meets the specific performance requirements of a given project. A well-designed mix ensures optimal durability, stability, and resistance to various distresses, such as cracking and rutting, while also considering factors like traffic loads, climate conditions, and the desired service life.
BMD may strike many asphalt mix producers as a tall order to fill, given the number of variables that must be considered in the design process. Obvious variables that impact BMD are air voids, asphalt content, and RAP, but other factors — such as time in the silo, PG source/location, oven aging, and modifiers — also can have a significant impact. But by carefully analyzing the properties of individual materials and their interactions, asphalt mixes can be tailored to deliver superior performance, longevity, and cost-effectiveness, all of which makes balanced mix design a smart technology for achieving better performing pavements and highly satisfied clients.
If you haven’t considered or utilized a BMD approach to mix design, resources do exist to help you get started. NAPA has created a comprehensive Balanced Mix Design Resource Guide, plus a webpage of dedicated BMD resources. NAPA also provides a BMD Resource Guide. Engineering firms that specialize in asphalt pavement design can also help.
BATT Lab offers a wide array of services geared to BMD, including testing of materials and help with pavement design. Generally, BMD calls for two or more performance tests, such as a rutting test (Hamburg Wheel Tracking, IDEAL-RT), or cracking test (SCB, IDEAL-CT) to determine how well a mixture resists common forms of distress.
The increasing number of workshops, webinars, training classes, and research and pilot projects are proof positive that BMD is gaining momentum. The labs, plants, and offices of the asphalt industry are buzzing about how to implement BMD. It’s here to stay, and we advise our clients to get on board.
To learn how the BATT Lab can help you get started with BMD, contact us at info@blankenshipasphalttech.com or visit BATT online.
