High Performing HMA Design Optimization


The use of quality materials (aggregates and asphalt binder) in optimal proportions is the key to producing optimally performing hot mix asphalt (HMA). The Superpave mix design standard in the US introduced specific volumetric and binder property requirements in HMA design. Different methods for HMA constituent proportioning have been proposed in various guidelines. The design process to determine the HMA blend is currently iterative and engineers rely almost exclusively on experience. This approach is time consuming and often does not result in cost-optimal HMA mixtures. This paper introduces a mixed integer linear programming (MILP) optimization model for hot-mix asphalt constituent proportioning. The MILP model minimizes the total mix cost while satisfying all the volumetric, binder and mix property specification requirements. The model has been successfully validated with real-life example. The aggregates and binder ratios from the model were in close agreement with those from the contractor. The Bailey ratios and the gradation constraints were also satisfied. The cost of the optimal mix was $0.804/Mg less than that of the contractors'. This marginal reduction might make all the difference in an industry that is highly competitive. The MILP model also demonstrated that adding RAP to the contractor's design would reduce the cost of the blend by $5.74/Mg. The virgin binder content was reduced by 1% because of the recycled asphalt contained in the RAP. This work represents the first successful attempt in incorporating both aggregate and asphalt performance requirements into the optimization formulation. Applying these models will ensure the minimum cost mix that meets all constraints and will increase profit margins for plant operators. Copyright © 2012 by SME.

Meeting Name

2012 SME Annual Meeting and Exhibit, SME 2012 (2012: Feb. 19-22, Seattle, WA)


Mining Engineering

Document Type

Article - Conference proceedings

Document Version


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© 2012 Society for Mining, Metallurgy & Exploration Inc. (SME), All rights reserved.

Publication Date

22 Feb 2012

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