Characterizing the cracking and fracture properties of geosynthetic interlayer reinforced HMA samples using the Overlay Tester (OT)
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2015 Elsevier Ltd. All rights reserved. Reflective cracking is one of the undesirable distresses occurring in hot-mix asphalt (HMA) overlays; costing highway agencies millions of tax payer dollars in maintenance and rehabilitation activities. To mitigate this distress, crack-impeding interlayer materials such as geosynthetic interlayers are specified to protect the HMA overlays as part of maintenance and rehabilitation strategies. Currently however, there is no universally standardized laboratory crack test method to aid in the selection of the most appropriate geosynthetic interlayer material for maximum crack resistance and performance. This study was undertaken to evaluate the laboratory cracking-resistance and fracture performance of different geosynthetic interlayer materials embedded in HMA samples. As a means to investigate its applicability for testing interlayer materials, the Overlay Tester (OT), in a monotonic tensile loading mode (3.375 mm/min) at 0 C, was explored as the study test method. Eight different geosynthetic interlayer products with different properties were compared to a 'control specimen' using a dense-graded HMA mix. Although field validation is still warranted, the study results indicated a substantial improvement (over 20%) in the laboratory crack and fracture performance of the geosynthetic interlayer reinforced samples over the Control samples; suggesting that use of these interlayer materials may be beneficial in mitigating reflective cracking in HMA overlays. For the test conditions considered, the OT test in monotonic tensile-loading mode also exhibited promising potential as a rapid crack test method for testing geosynthetic interlayer materials. The sample crack failure mode, test repeatability, and statistical variability in the test data were generally within reasonable expectations.
