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accepted performance-based mix design procedure. Every agency has its own approach, and many have experienced raveling, thermal cracking, compaction problems, low early strength, and overly long curing times. ARC researchers from the University of Nevada Reno propose using the Superpave gyratory compactor to achieve performance-related CIR mixture design. With the new procedure, different mixtures with various ratios of emulsion and water are used to identify the number of gyrations required to achieve target air voids and specimen height. The UNR team has also found that adding hydrated lime improves moisture resistance and slows raveling. Cohesion testing shows that CIR performance can be further improved with longer curing times and that properly designed CIR mixtures have fairly good resistance to permanent deformation. Click HERE to read more.
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Asphalt Research Correspondent |
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An FHWA Research Program Comprising Western Research Institute, Texas A&M University, University of Wisconsin-Madison, University of Nevada-Reno, Advanced Asphalt Technologies and the National Center for Asphalt Technology. |
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Vol 7 Issue 1 March 2013 |
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Mix Design Procedure for cold-in-place recycling for rehabilitation of deteriorated asphalt pavements.
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University of Wisconsin Madison leads testing of a procedure to specify fatigue resistance Extensive research has shown that mechanical characteristics of the asphalt binder/mastic phase contribute to fatigue failure of asphalt mixtures. The current |
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WANTED UNR team seeks agencies with CIR projects to participate in the validation and refinement of the proposed CIR mix design procedure. Contact psebaaly@unr.edu |
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University of Nevada Reno tests a mix design Process for performance-related cold-in-place recycling The two most common techniques for rehabilitating asphalt pavements are asphalt overlay and cold-in-place recycling (CIR). Asphalt overlay can be prepared in a hot central plant using either 100% new materials or a combination of new materials and recycled asphalt pavements (RAP). The cold-in-place alternative provides environmental, energy, and worker health benefits. But while CIR has been widely used, there is still no universally |
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Please Visit the ARC website to find references and links to publications, presentations and other useful information. . Questions or comments? E-mail us at psebaaly@unr.edu or call 775-784-6565. To remove your name from our mailing list, please click here. |
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specification to evaluate asphalt fatigue resistance is based on the linear viscoelastic properties of the material, but this approach cannot characterize actual damage resistance. To improve the current specification, the Time Sweep (TS) was developed during NCHRP Project 9-10 (1). The time sweep consists of applying repeated sinusoidal cyclic loading at fixed amplitude to an asphalt binder specimen using the Dynamic Shear Rheometer (DSR), typically using 8-mm diameter parallel plate geometry. The time sweep test is based on the definition of fatigue damage, which is the degradation of material integrity under repeated loading. The procedure allows for selection of load amplitude, thus allowing for consideration of pavement structure and traffic loading. However, the time sweep test is not a practical method for specification of asphalt binder fatigue resistance due to the uncertainty in testing time. Now, researchers at the University of Wisconsin Madison are proposing a surrogate binder test called the Linear Amplitude Sweep (LAS) to measure fatigue resistance of asphalt binders. Like the time sweep, the LAS uses oscillatory loading on the dynamic shear rheometer with 8-mm parallel plate geometry. First, a frequency sweep provides characterization of the undamaged binder sample, and loading amplitudes are systematically increased to accelerate damage. Total testing time is approximately 10 minutes. The modified LAS test can be used similarly to the Time Sweep test, to rank materials according to their damage tolerance. Preliminary results suggest that the procedure is able to identify the asphalt binder’s contribution to mixture fatigue. In September 2012, the ARC research team from the University of Wisconsin Madison presented an updated draft AASHTO standard procedure to the Federal Highway Administration Binder Expert Task Group in Minneapolis. Inter-laboratory testing to further evaluate the method is underway. Click HERE to read more. |
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What Do You Getwith 3D-Move Analysis 2.0?ü Static/dynamic analysis ü Uniform contact pressure distribution (circle, ellipse and rectangle) ü Non-uniform contact pressure distribution from database ü Non-highway vehicle loading (e.g.. forklift ü Braking/non-braking condition (interface shear stresses) ü Dynamic variation of tire load (dynamic loading coefficient) ü Text, tabular, or graphical results and as Excel spreadsheet files ü Help and examples |
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lets you analyze pavement response under a variety of vehicle loading conditions Now with Pavement Performance Evaluation and other features that make it more powerful and easier to use.
More than 400 users from over 40 countries have downloaded the original 3-D Move Analysis. Its finite-layer approach treats each pavement layer as a continuum and uses the Fourier transform technique to handle complex surface loadings such as multiple loads and non-uniform tire–pavement contact stress distribution. 3-D Move Analysis lets you account for tire imprints of any shape, including those generated by wide-base tires. 3D-Move Analysis is computationally more efficient than moving load models based on the finite element method. 3D-Move Analysis accommodates viscoelastic material properties, so it is ideal for modeling asphalt concrete. Find it at the ARC website: http://www.arc.unr.edu/Software.html. |
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Announcing 3D-Move Analysis 2.0 |