01687982

Component

http://www.trb.org/Main/Blurbs/178401.aspx

The Louisiana Department of Transportation and Development (LADOTD) contracted 10.4 million tons of Superpave asphalt mixture from April 2009 to June 2013, which cost a total of $780 million. With significant financial and temporal investment in asphalt pavement systems, it is critical to ensure the pavement will meet performance expectations and provide years of service. To address this concern, LADOTD has made efforts to improve conventional asphalt mixture procedures through specification modification. For Louisiana mixtures, which are typically rut-resistant, balanced-mixture design commonly results in increased asphalt content. In 2016, LADOTD has implemented new specification requirements to increase the asphalt content of asphalt mixtures. This was accomplished by reducing the number of gyrations at Ndesign, as well as increasing the minimum void in mineral aggregate (VMA) and voids filled with asphalt (VFA) requirements. This paper documents Louisiana’s experience with the development of a balanced mixture design by complementing volumetric criteria with the Hamburg loaded wheel tester (HLWT) and semicircular bend (SCB) tests for high-temperature and intermediate-temperature performance, respectively. The objective of this study was to evaluate the effects of the 2016 LADOTD specification modification on the laboratory performance of asphalt mixtures. Mixtures were produced in accordance with newly implemented specifications to achieve a balance with respect to rutting and fatigue cracking. Eleven plant-produced mixtures were collected from six field projects using the newly implemented balanced specification criteria. HLWT and SCB data were compared between mixtures produced under the new specification with that of mixtures produced using the previous specification criteria. The findings indicate that with respect to rut resistance, the 11 mixtures produced using the 2016 LADOTD specifications exhibited improved or similar performance to mixtures produced using the 2006 LADOTD specification. Mixtures containing polymer modified binders resulted in improved rutting performance when compared to unmodified binders. Fifty percent of the mixtures designed according to the 2016 LADOTD specifications met or exceeded the cracking criteria of 0.5 kJ/m2 as determined by the SCB test.

01685369

English

pp 15-29

2018-10

Transportation Research Circular

Digital/other

Figures; Photos; References; Tables

Asphalt mixtures; Asphalt pavements; Asphalt tests; Laboratory tests; Mix design; Performance based specifications; Performance tests

Louisiana

Highways; Materials; Pavements

TRIS, TRB, ATRI

Nov 15 2018 11:21AM

• Balanced RAP–RAS–Recycling Agent Mix Design for Project-Specific Conditions
• Development and Implementation of the Illinois Flexibility Index Test: A Protocol to Evaluate the Cracking Resistance of Asphalt Mixtures
• Evaluating Balanced Mixture Design for New Jersey to Enhance Asphalt Mixture Durability
• Mixture Design for Better Field Compaction
• Optimized Mix Design Approach: Contractor’s Perspective