Search for a Practical Laboratory Cracking Test for Evaluating Bituminous (HMA) Mixes
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As an effort toward developing a simple and practical laboratory cracking test method that can be used routinely, on a daily basis, to optimize Hot-Mix Asphalt (HMA) designs, various monotonic loading "single shot" cracking tests were comparatively evaluated in the laboratory alongside the repeated (dynamic) loading Overlay Tester (OTR) test. These monotonic crack tests included the Indirect Tension (IDT) test, Semi-Circular Bending (SCB), Overlay Tester in a monotonic loading mode (OTM), and Disc-Shaped Compact Tension Test (DSCTT). The research methodology entailed characterizing the cracking resistance potential of various commonly used Texas HMA mixes of known field cracking performance, with different mix-design variables. The corresponding findings indicated that while the monotonic loading tests, particularly the OTM and IDT are much simpler, more practical and more repeatable with lower variability in the test results, the dynamic loading OTR test, where both crack initiation and propagation phases are sufficiently accounted for, exhibited superior screening capabilities in terms of the HMA cracking resistance potential and sensitivity to mix-design variables such as the asphalt-binder content and temperature variations. Overall, the results indicated that both the IDT and OTM could potentially serve as routine surrogate and/or supplementary crack tests to the OTR, subject to field validation. ASCE 2014.
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Design, Analysis, and Asphalt Material Characterization for Road and Airfield Pavements