Development of Cost-Effective High-Modulus Asphalt 5. Report Date Aug. 2021 Concrete (HMAC) Mixtures Using Crumb Rubber and Local Construction Materials in Louisiana

One of the emerging solutions to enhance the durability of asphalt pavements is the use of a French asphalt mix
known as “High-Modulus Asphalt Concrete (HMAC).” This mix uses a hard asphalt binder, high binder content
(about 6%), and low air voids content as compared to Superpave mixtures. The key objective of this study was
to develop a cost-effective HMAC mixture using crumb rubber and local materials in Louisiana. To achieve this
objective, four HMAC mixtures were prepared using two asphalt binders (PG 82-22 and PG 76-22 plus 10%
crumb rubber) and two Reclaimed Asphalt Pavement (RAP) contents (20% and 40%); additionally, a
conventional Superpave mixture in Louisiana was prepared as a control mixture. The laboratory performance
of these five mixtures was evaluated in terms of workability, dynamic modulus, rutting resistance, and cracking
resistance. The AASHTOWare Pavement ME Design software was also used to estimate the long-term field
performance of these mixtures. Results indicated that the HMAC mixture prepared with 10% crumb rubber and
20% RAP successfully met the French mix design specifications for HMAC and LaDOTD specifications. This
HMAC mix outperformed the control Superpave mix in terms of dynamic modulus, rutting resistance, and
cracking resistance. Additionally, this HMAC mixture can reduce the required asphalt thickness by 1.5 or 2
inches based on traffic level. The cost-effectiveness analysis indicated that this HMAC mixture was more costeffective
than conventional Superpave mixtures in Louisiana. In addition, this mixture is environmentallyfriendly
since it can reduce the disposal of scrap tires in landfills.