Author
Cassie Hintz
Other affiliations: North Carolina State University
Bio: Cassie Hintz is an academic researcher from University of Wisconsin-Madison. The author has contributed to research in topics: Asphalt & Dynamic shear rheometer. The author has an hindex of 8, co-authored 10 publications receiving 577 citations. Previous affiliations of Cassie Hintz include North Carolina State University.
Papers
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TL;DR: The linear amplitude sweep (LAS) test as discussed by the authors uses cyclic loading with systematically increasing load amplitudes to accelerate damage and provides sufficient data for analysis in less than 30 min.
Abstract: Current asphalt binder specifications lack the ability to characterize asphalt binder damage resistance to fatigue loading. Multiple accelerated testing procedures that attempt to efficiently and accurately characterize the contribution of asphalt binders to mixture fatigue are under investigation. One of these tests, which has received significant acceptance by experts and has been submitted as a draft AASHTO standard, is the linear amplitude sweep (LAS) test. This procedure uses viscoelastic continuum damage mechanics to predict binder fatigue life as a function of strain in the pavement. The LAS test uses cyclic loading with systematically increasing load amplitudes to accelerate damage and provides sufficient data for analysis in less than 30 min. Although results of the current LAS testing protocol are promising, the time and the complex numerical procedures required for the analysis have raised concern. In addition, insufficient damage accumulation was observed when the strain amplitudes proposed in...
267 citations
TL;DR: The linear amplitude sweep (LAS) test has been proposed as a surrogate to the time sweep (TS) test, which is a conventional fatigue test consisting of repeated cyclic loading at constant amplitude as mentioned in this paper.
Abstract: The linear amplitude sweep (LAS) test has recently been approved by AASHTO as a provisional standard and is currently being considered for specification of asphalt binder fatigue resistance. The LAS test is a cyclic torsion test conducted in the dynamic shear rheometer (DSR) that uses increasing loading amplitudes to accelerate damage. The LAS test has been proposed as a surrogate to the time sweep (TS) test, which is a conventional fatigue test consisting of repeated cyclic loading at constant amplitude. The TS test is considered unsuitable for specification because of the uncertainty in the test duration required to induce and quantify fatigue. Recent ruggedness testing efforts have shown that the LAS test cannot be conducted by all DSRs. This study evaluates a simpler amplitude ramping procedure that resolved the difficulties encountered with some rheometers. Additionally, a simple specification parameter is introduced to offer a practical approach to define damage tolerance. The definition of failure ...
140 citations
TL;DR: In this article, the effect of age hardening in warm mix asphalt binders and mixtures compared with hot mix asphalt (HMA) binders with respect to fatigue damage was evaluated.
Abstract: The use of warm mix asphalt (WMA) has been increasing in recent years due to its ability to reduce the production temperatures of asphalt concrete The long-term implications of reduced production temperatures and, hence, reduced short-term ageing on long-term performance remain largely unknown This study evaluates the effect of age hardening in WMA binders and mixtures compared with hot mix asphalt (HMA) binders and mixtures with respect to fatigue damage Two WMA technologies are considered: foaming by water injection and Evotherm modification For this study, the asphalt mixtures were subjected to laboratory conditioning in a forced air convection oven to simulate long-term field ageing according to AASHTO R30 The asphalt mixtures and extracted binders were subjected to linear viscoelastic and fatigue characterisation following ageing Because oxidative ageing occurs within the asphalt binder phase of asphalt concrete, this paper focuses on the relative performance of WMA and HMA binders at various a
100 citations
TL;DR: In this paper, the authors demonstrate that fracture can explain the changes in loading resistance during fatigue testing in the dynamic shear rheometer (DSR) in asphalt binder.
Abstract: Asphalt binder fatigue resistance is important in determining overall pavement fatigue performance. One procedure commonly used to characterise asphalt binder fatigue resistance is the time sweep test, which consists of repeated cyclic loading in the dynamic shear rheometer (DSR). Generally, apparent changes in complex modulus and phase angle with respect to number of loading cycles are used to define fatigue performance. Although results from DSR testing have been shown to correlate well with asphalt mixture fatigue performance, the mechanisms responsible for changes in binder properties in the DSR were previously not well understood. Results in this study demonstrate that fracture can explain the changes in loading resistance during fatigue testing in the DSR. Under cyclic torsional loading of cylindrical specimens, fracture manifests as a circumferential crack that starts at the periphery of a sample and propagates inward, reducing the effective sample radius. Digital visualisation of binder specimens ...
84 citations
01 Jan 2011
TL;DR: In this paper, the effect of age hardening on fatigue damage resistance is investigated by means of the recently developed Linear Amplitude Sweep (LAS) test, which is an accelerated cyclic fatigue test that uses incrementally increasing load amplitudes to generate damage in the binder.
Abstract: Oxidative aging in asphalt binders is generally accepted to be the cause of
hardening of the asphalt over time. To adequately predict long-term pavement
performance, it is necessary to understand how aging affects binder properties.
In this paper, the effect of age hardening on fatigue damage resistance is
investigated. Six asphalt binders used in construction of sections that are part
of the Strategic Highway Research Program Long-Term Pavement
Performance (LTPP) study were tested by means of the recently developed
Linear Amplitude Sweep (LAS) test. The LAS test is an accelerated cyclic
fatigue test that uses incrementally increasing load amplitudes to generate
damage in the binder. The framework of viscoelastic continuum damage
(VECD) was used to analyze the LAS results in order to develop fatigue laws
for each LTPP binder. The LTPP asphalt binders were tested at five different
age levels: un-aged, rolling thin film oven (RTFO) aged, pressure aging vessel
(PAV) aged, double PAV aged, and quadruple PAV aged. Results indicate that
laboratory aging changes the relationship between fatigue life and strain
applied significantly and systematically. The changes are such that aging
appears to improve binder fatigue resistance at low strain levels but
deteriorates fatigue resistance at high strain levels. The changes are highly
asphalt specific; for some binders the changes are less than for others. These
trends were verified by conducting time sweep tests and are fairly repeatable.
Keywords: age, fatigue, asphalt binder, viscoelastic continuum damage
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1Graduate Research Assistant, University of Wisconsin, Madison, WI
2Research Associate, University of Wisconsin, Madison, WI
3Senior Engineer, Fushun Research Institute of Petroleum & Petrochemicals, Sinopec
4Professor, University of Wisconsin, Madison, WI
The oral presentation was made by Ms. Hintz.
39 citations
Cited by
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TL;DR: The results show that the use of BIM for transportation infrastructure has been increasing, although the research has mainly been focusing on roads, highways, and bridges, and a major need for a standard neutral exchange format and schema to promote interoperability is revealed.
256 citations
TL;DR: In this paper, the state-of-the-art approaches for increasing the amount of reclaimed asphalt pavement (RAP) in asphalt mixtures above 40% are summarized and methods to optimise the mix design as well as production technology in order to allow manufacturing of such sustainable mixtures are described.
Abstract: Asphalt is the most recycled material in the USA at a re-use rate of 99%. However, by average only 10–20% reclaimed asphalt pavement (RAP) is used in a given mix design and large part of the RAP is degraded for use in lower value applications. The amount of RAP in asphalt mixtures can be significantly increased with the application of good RAP management practice, readily available modern production technologies and advanced knowledge of mix design. This paper summarises the state-of-the-art approaches for increasing the amount of RAP in asphalt mixtures above 40%. The production challenges and common pavement distresses of very high RAP content mixtures are identified and methods to optimise the mix design as well as production technology in order to allow manufacturing of such sustainable mixtures are described. The best practices for RAP management and economic benefits of high RAP use are also discussed.
249 citations
TL;DR: In this paper, the effects of different rheological indices which present tighter and clearer correlation with asphalt mixture performance in evaluating asphalt binder aging behaviors, these indices including complex modulus (G∗) and phase angle (δ) master curves, rutting factor, zero shear viscosity (ZSV), non-recoverable compliance (Jnr), fatigue factor (G ∗·sinδ), and DSR function (DSRFn).
246 citations
TL;DR: A holistic evaluation of the feasibility of producing 100% recycled asphalt pavement mixtures is presented in this article, where a cradle-to-gate analysis of environmental effects indicated 18 kg or 35% CO2eq savings per t of produced 100% RAP asphalt mixture compared to virgin mix, while cost analysis showed at least 50% savings in material related expenses.
Abstract: a b s t r a c t A holistic evaluation of the feasibility of producing 100% recycled mixtures is presented. Eleven tech- nologies readily available for producing 100% Reclaimed Asphalt Pavement (RAP) hot asphalt mixtures are described in the article and the complementary video (http://youtu.be/coj-e5mhHEQ). The recorded performance of 100% RAP mixtures is analyzed along with identification of typical high RAP distresses. Recommended mix design procedures and the best RAP management strategies are described. A cradle- to-gate analysis of environmental effects indicated 18 kg or 35% CO2eq savings per t of produced 100% RAP asphalt mixture compared to virgin mix, while cost analysis showed at least 50% savings in material related expenses.
241 citations
01 Jan 2014
TL;DR: A holistic evaluation of the feasibility of producing 100% recycled asphalt pavement (RAP) mixtures is presented in this paper, where a cradle-to-gate analysis of environmental effects indicated 18 kg or 35% CO2eq savings per t of produced 100% RAP asphalt mixture compared to virgin mix, while cost analysis showed at least 50% savings in material related expenses.
Abstract: a b s t r a c t A holistic evaluation of the feasibility of producing 100% recycled mixtures is presented Eleven tech- nologies readily available for producing 100% Reclaimed Asphalt Pavement (RAP) hot asphalt mixtures are described in the article and the complementary video (http://youtube/coj-e5mhHEQ) The recorded performance of 100% RAP mixtures is analyzed along with identification of typical high RAP distresses Recommended mix design procedures and the best RAP management strategies are described A cradle- to-gate analysis of environmental effects indicated 18 kg or 35% CO2eq savings per t of produced 100% RAP asphalt mixture compared to virgin mix, while cost analysis showed at least 50% savings in material related expenses
216 citations