Arkansas Department of Transportation’s Liquid Anti-Strip Additive SS David Henning State Construction Engineer ARDOT Construction Division

How Did We Get Here? 4 rehabilitation projects on I-40 in Western Arkansas completed since 2012: 2” mill and inlay of previous rubblization and full depth ACHM projects 48.1 miles total $31.8 million (total of all four projects) Existing shoulders retained, some bridge deck work Contractors used sandstone aggregates from existing quarries on these mill and inlay projects

The results after 4 to 6 years of traffic?

ARDOT efforts since completion of the projects: $850,000 in materials since FY 2015 for repairs to these areas of I-40 in D-8 Milling and Inlaying of a Mill and Inlay Frequent ACHM patching (more frequent in winter) Complaints from Motorists and Elected Officials Coring and evaluation of affected sections in Spring / Summer 2018

Findings Water unable to escape the main lanes due to the shoulders being left in place Insufficient application of tack Presence of water, insufficient tack, wet winter conditions, and high traffic caused stripping in the surface layer and extreme fatigue cracking Stripping occurring at the bottom of the surface layer, from 2” – 3” deep. ACHM below the milled surface was intact and showed no signs of deterioration. Surface mix placed on mill and inlay jobs used highly absorptive sandstone aggregates and no anti-strip additives

Recommendations Resulting from Reviews Include milling and/or overlay of existing shoulders on future interstate rehab projects to avoid creating “bathtub” effect Establish procedures/committee for type of remediation on future interstate overlay projects Identify types of aggregates that are prone to stripping and require use of anti-strip additives in mix designs utilizing those aggregates

First Draft Based on the recommendations from Materials, a SS was drafted to require mix designs which used crushed gravels or crushed sandstone to use an anti-stripping additive. This draft SS was presented to the AAPA at the quarterly Quality Initiative meeting on June 28, 2018. Issues brought up: what about mixes that only use a small portion of these types of aggregates (ex: mixes with Limestone aggregates)-what about terminal blending?

Feedback from Industry Would terminal blending be possible-that way no plant modifications would be necessary? What about plants that use limestone or gravel aggregates and have to use other aggregates due to 60% limitation in wearing courses? Industry recommended requiring the use of an anti-strip additive in all mixes rather than for just certain aggregates. Add bullets 2 and 3 with mouse click.

The Final Version

Questions?