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Characterizing Near-Road Air Pollution Using Local-Scale Emission and Dispersion Models and Validation Against In-Situ Measurements

Tue, 08/29/2017 - 21:39
Characterizing Near-Road Air Pollution Using Local-Scale Emission and Dispersion Models and Validation Against In-Situ Measurements
by Wang,A; Fallahshorshani,M; Xu,J; Hatzopoulou,M.
2016.
Canadian Transportation Research Forum 51st Annual Conference - North American Transport Challenges in an Era of Change//Les défis des transports en Amérique du Nord à une aire de changement Toronto, Ontario, May 1-4, 2016.
CA6 AIP_10 2016P09 - INTERNET


Traffic-related air pollution is associated with a number of chronic and acute health effects (Crouse, Goldberg, Ross, Chen, & Labrèche, 2010; United States Environmental Protection Agency, 2008). In particular, a number of studies have established positive associations between various health outcomes (e.g. cancers, heart attacks, asthma) and exposure to nitrogen dioxide (NO2), an accepted marker of traffic-related air pollution (Parent et al., 2013; Wu, Wilhelm, Chung, & Ritz, 2011). In urban areas, air pollution is affected largely by the built environment, traffic composition and meteorological conditions (Weichenthal, Farrell, Goldberg, Joseph, & Hatzopoulou, 2014). In this study, we developed a traffic simulation for four consecutive road segments along a busy corridor in Montreal. The four segments exhibit different configuration and built environments, yet they share almost the same traffic characteristics. Based on the traffic simulation results, we simulated emissions of nitrogen oxides (NOx) and modeled the resulting NO2 concentrations along the road. We conducted the dispersion of traffic emissions along the four different segments under varying traffic and meteorological conditions using three different dispersion models with vastly different dispersion algorithms (CALINE 4, OSPM, and SIRANE). In-situ roadside measurements of NO2 concentrations were also conducted in order to validate and inter-compare the models.

The Tale of Taxi Reforms in Two Cities: The Failure of Closed Entry

Tue, 08/29/2017 - 21:39
The Tale of Taxi Reforms in Two Cities: The Failure of Closed Entry
by Monteiro,J; Prentice,BE.
2016.
Canadian Transportation Research Forum 51st Annual Conference - North American Transport Challenges in an Era of Change//Les défis des transports en Amérique du Nord à une aire de changement Toronto, Ontario, May 1-4, 2016.
CA6 AIP_10 2016P08 - INTERNET


At times, the taxicab industry has come under attack, for service quality, control of supply, tariffs and the regulatory system. Examples of this are statements such as ... The local taxi service in Toronto was labelled as the worst in North America.[1] “Tight control on taxicab supply and government-set tariffs have resulted in consumers paying an exaggerated price for a stale and uninspired service.”[2] More recently one writer states “...Toronto’s taxicab industry is in a state of crisis… Public perception of the entire industry is low, the government appears to have little understanding of how to manage and regulate industry efficiently, and none of these issues show any signs of improving.”[3] The purpose of this paper is to examine the failure of closed entry taxi regulation. The paper provides a comparative analysis of the regulatory experience in Toronto and Ottawa. The next section presents the historical background of the taxicab regulation and experimentation in Toronto. Subsequently, the same is done for the City of Ottawa. Opinions on why the cities failed to deregulate are offered in the penultimate section. Finally, a few concluding remarks are made.

SMARTPLANS: Simulation Model for Assessing the Ramifications of Transportation Policies and Land-Use Scenarios

Tue, 08/29/2017 - 21:39
SMARTPLANS: Simulation Model for Assessing the Ramifications of Transportation Policies and Land-Use Scenarios
by Maoh,H; Gingerich,K.
2016.
Canadian Transportation Research Forum 51st Annual Conference - North American Transport Challenges in an Era of Change//Les défis des transports en Amérique du Nord à une aire de changement Toronto, Ontario, May 1-4, 2016.
CA6 AIP_10 2016P07 - INTERNET


This paper reports on the development of SMARTPLANS, a successor of the IMULATE Integrated Urban Model (IUM) that was originally developed for the Hamilton metropolitan area. SMARTPLANS is developed as a full-fledged IUM that can be used to simulate various land use and transportation scenarios. While it shares some features with IMULATE, it also builds on ideas from the MUSSA and URBANSIM models. On the land use side, the model can simulate the decisions affecting land development, land prices, household location and firm location, whereas the transportation system of SMARTPLANS is based on the well-known four-stage model. The User Interface (UI) of the model is developed with three features in mind: 1) fine tuning the model parameters through the user interface without the need for computer programming; 2) using the UI to extend the model by including additional land use and transportation components or categories; and 3) transferability and application of the model to different urban areas. The remainder of the paper is organized as follows: a background section is provided at first to highlight the underlying principles that need to be considered when developing an IUM. This is followed by a section that describes the modeling framework of SMARTPLANS. The fourth section provides an empirical illustration of SMARTPLANS based on model parameters from Halifax, Nova Scotia. It also provides recommendations for future research.

Planning for Real or For Show? An Analysis of the Completion of Montreal's Transportation Plans

Tue, 08/29/2017 - 21:39
Planning for Real or For Show? An Analysis of the Completion of Montreal's Transportation Plans
by Barrieau,P; Silvestrin-Racine,V.
2016.
Canadian Transportation Research Forum 51st Annual Conference - North American Transport Challenges in an Era of Change//Les défis des transports en Amérique du Nord à une aire de changement Toronto, Ontario, May 1-4, 2016.
CA6 AIP_10 2016P06 - INTERNET


Quebec's transportation ministry has proposed over the decades three different transportation plans in 1979, 1988 and 2000. However, like many transportation planning documents around the world, their publication doses not necessarily imply completion. The purpose of this study is to investigate if the transportations plans are being completed as proposed or not. Furthermore, it is important to note that we are not looking at all investments in public and individual transportation, only those that are presented in the three transportation plans. Our research question was fairly simple: Does the government of Quebec actually follow-thru with the projects proposed in the transportation plans it proposes for Montreal?

An Analysis of the Status of Undergraduate Transportation Management Education in the United States

Tue, 08/29/2017 - 21:39
An Analysis of the Status of Undergraduate Transportation Management Education in the United States
by Stewart,RD; Burger,N; Hansen,E.
2016.
Canadian Transportation Research Forum 51st Annual Conference - North American Transport Challenges in an Era of Change//Les défis des transports en Amérique du Nord à une aire de changement Toronto, Ontario, May 1-4, 2016.
CA6 AIP_10 2016P05 - INTERNET


The cost effective and environmentally beneficial management of transportation systems in the United States is essential for the economy and the nation’s civilization. Ensuring a steady supply of educated individuals with a background in transportation is key to the ongoing efficient management of transportation systems. This paper examines one hundred and seventy of the non-engineering undergraduate degrees in the fields of supply chain management, logistics, and transportation, including joint majors present within universities in the United States. The curriculum for each degree was evaluated to determine the extent to which the students were taught transportation and related courses. Each university’s relevant degree website was also examined to catalog additional best practices in education, such as required internships, that were used to support teaching transportation outside of formal classroom instruction.

Assessment of Exposure to Traffic-Related Air Pollution in a Lrge Urban Area: Impacts of Individual Mobility and Transit Investment Scenarios

Tue, 08/29/2017 - 21:39
Assessment of Exposure to Traffic-Related Air Pollution in a Lrge Urban Area: Impacts of Individual Mobility and Transit Investment Scenarios
by Shekarrizfard,M; Hatzopoulou,M.
2016.
Canadian Transportation Research Forum 51st Annual Conference - North American Transport Challenges in an Era of Change//Les défis des transports en Amérique du Nord à une aire de changement Toronto, Ontario, May 1-4, 2016.
CA6 AIP_10 2016P04 - INTERNET


The hypothesis that exposure to traffic-related air pollution increases the risk of developing different illnesses (e.g., cancer during childhood) has been demonstrated by various investigators (Crouse et al., 2010; Hamra et al., 2015). Therefore, the need for urban air quality prediction associated with transportation policies is important for health impact assessment (Bhalla et al., 2014; De Nazelle et al., 2011). However, only a few modeling tools are able to include projection in associated traffic related parameters (e.g., traffic allocation) in the prediction of future air quality concentrations and the impact of population mobility on urban air pollution is often ignored. Estimating the various states of air quality associated with transport policies, infrastructure investments and individuals’ mobility are keys to more meaningful urban design and development.

Investigating Near-Road Particle Number Concentrations Along a Busy Urban Corridor with Varying Built Environment Characteristics

Tue, 08/29/2017 - 21:39
Investigating Near-Road Particle Number Concentrations Along a Busy Urban Corridor with Varying Built Environment Characteristics
by Xu,J; Wang,A; Hatzopoulou,M.
2016.
Canadian Transportation Research Forum 51st Annual Conference - North American Transport Challenges in an Era of Change//Les défis des transports en Amérique du Nord à une aire de changement Toronto, Ontario, May 1-4, 2016.
CA6 AIP_10 2016P03 - INTERNET


This study presents an innovative design for an air pollution data collection campaign on two sides of the road during the winter months, using a portable weather station in order to assess the effects of meteorology at street level. Despite the low predictive power of the statistical models (which are only meant to be used to understand the strengths of certain predictors), our results themselves provide insight into the complex nature of near-road air pollution. We highlight the important role of meteorological factors such as temperature, humidity, wind speed, and wind direction. It is also worth noting that although land use variables were not included in the final model explaining mean UFP concentrations, their indirect impacts could be interpreted by the presence of wind direction as a random effect. In addition, traffic was also shown to be a notable contributor in explaining variations in UFP concentrations. With regards to the absolute UFP difference on two sides of the road, the primary finding was that wind orthogonality and speed act as important predictors. Winds orthogonal to the road have a tendency to increase differences on two sides of the road. However, the most substantial impact on air pollution was the presence of buildings on both sides of the road, which is evidently common in major cities.

A Consumer Latent Class Choice Model to Assess Prospects for Electric Vehicles in Canada

Tue, 08/29/2017 - 21:39
A Consumer Latent Class Choice Model to Assess Prospects for Electric Vehicles in Canada
by Ferguson,M; Mahmoud,M; Higgins,C; Abotalebi,E; Kanaroglou,P.
2016.
Canadian Transportation Research Forum 51st Annual Conference - North American Transport Challenges in an Era of Change//Les défis des transports en Amérique du Nord à une aire de changement Toronto, Ontario, May 1-4, 2016.
CA6 AIP_10 2016P02 - INTERNET


The purpose of this analysis is to derive an improved understanding of how Canadian households view electric vehicles of varying types and whether they are seen, or could be seen, as viable household vehicles. The data for this analysis were derived from a sample of approximately 20,000 Canadian households accessed via an online survey panel. The survey was offered in both official languages. Participants were screened against three criteria: age (older than 18), whether respondent is one of the decision-makers in most or all important financial decisions made by the household, and whether the household is at least somewhat likely to purchase or lease a new or used vehicle sometime within the next several years.

Simulating Transportation and Environmental Outcomes of Electric Vehicle Adoption Scenarios: An Application to the Windsor Census Metropolital Area

Tue, 08/29/2017 - 21:39
Simulating Transportation and Environmental Outcomes of Electric Vehicle Adoption Scenarios: An Application to the Windsor Census Metropolital Area
by Dimatualc,T; Maoh,H.
2016.
Canadian Transportation Research Forum 51st Annual Conference - North American Transport Challenges in an Era of Change//Les défis des transports en Amérique du Nord à une aire de changement Toronto, Ontario, May 1-4, 2016.
CA6 AIP_10 2016P01 - INTERNET


The focus of this paper was to evaluate the potential transportation and environmental impacts from different electric vehicle (EV) adoption and urban forms scenarios in the Windsor Census Metropolitan Area (CMA) in 2031. The results reinforce some of the previous findings in the literature. It is found that a compact urban development coupled with significant EV adoption can lead to significant reduction in energy and emissions. This in turn will promote sustainable transportation outcomes in the region. While the conducted analysis mainly relied on conventional techniques (linear regression and 4-stage modeling), the results are sensible and shed light on the role that EVs can play to reduce emissions and energy consumption in the future.

Canadian Transportation Research Forum 51st Annual Conference - North American Transport Challenges in an Era of Change//Les défis des transports en Amérique du Nord à une aire de changement Toronto, Ontario, May 1-4, 2016

Tue, 08/29/2017 - 21:39
Canadian Transportation Research Forum 51st Annual Conference - North American Transport Challenges in an Era of Change//Les défis des transports en Amérique du Nord à une aire de changement Toronto, Ontario, May 1-4, 2016
2016.
Canadian Transportation Research Forum 51st Annual Conference - North American Transport Challenges in an Era of Change//Les défis des transports en Amérique du Nord à une aire de changement Toronto, Ontario, May 1-4, 2016.
CA6 AIP_10 2016P01-73 - INTERNET

Part of the Problem or Part of the Solution? How Canada's Railways Can Help Address Climate Change

Tue, 08/29/2017 - 19:39
Part of the Problem or Part of the Solution? How Canada's Railways Can Help Address Climate Change
by Gullo,M; Rosales,E.
2016.
Canadian Transportation Research Forum 51st Annual Conference - North American Transport Challenges in an Era of Change//Les défis des transports en Amérique du Nord à une aire de changement Toronto, Ontario, May 1-4, 2016.
CA6 AIP_10 2016P11 - INTERNET


Canada’s engagement in COP 21 and the statements made by the Prime Minister reaffirm the country’s commitment to combating climate change, and the federal government’s intentions to play a more instrumental role in driving down emissions in Canada and abroad. Canada plans to reduce its greenhouse gas (GHG) emissions by 30 per cent below 2005 levels by 2030. While nearly 30 per cent of Canada's GHG can be attributed to the transportation sector, the policy approach to addressing emissions within the sector has been fragmented and developed in a bit-part way. Only four of ten provinces have a policy regime in place to address emissions, of which three apply (or intend to apply) cap and trade mechanisms and one relies on taxation. In Ontario and Quebec, certain segments of the aviation and shipping industries are excluded entirely. For railway carriers with operations spanning multiple political boundaries, the resulting effect is a requirement to participate in a series of regional initiatives that lack cohesion and have been brought forward in uncoordinated way. Canada’s railway industry has a long history of working with the federal government to reduce emissions produced by locomotives. Since 1995, the industry has held a series of Memorandum of Understanding (MOU) with the Federal Minister of Transport that have provided the platform for identifying pragmatic solutions for reducing emissions. The sector is currently working through its third MOU which establishes voluntary GHG emission reduction targets from 2011 to 2016 for Class I freight, shortline, and intercity passenger railways

AAPT Symposium - Balanced Mix Design: Implementation of a Balanced Asphalt Mixture Design Procedure: Louisiana's Approach

Tue, 08/22/2017 - 20:38
AAPT Symposium - Balanced Mix Design: Implementation of a Balanced Asphalt Mixture Design Procedure: Louisiana's Approach
by Mohammad,LN; Cooper III,SB.
2016.
Asphalt Paving Technology 2016: Journal of the Association of Asphalt Paving Technologists - Indianapolis, Indiana, March 13-16, 2016.
US6 AFN___ 2016P30 - MAIN


Conventional asphalt mixture design methodologies such as Superpave, Marshall, and Hveem are used to determine the optimum asphalt binder content by means of physical and volumetric laboratory measurements. All three procedures ensure the materials proportion and quantity of the asphalt cement binder are adequate to meet stability and durability concerns. However, with the increased use of recycled materials, there is a need to develop laboratory mechanical tests in order to evaluate the quality of the asphalt cement binder to complement the Superpave volumetric mixture design procedure. An important component to successful mixture design is the balance between volumetric composition and material compatibility. Balanced asphalt mixture design offers innovation in designing mixtures for performance and evaluation of the quality of a mix design relative to the anticipated performance using a rational approach. This research documents the selection of laboratory mechanical tests, in addition to volumetric requirements, that can ascertain a mixture’s resistance to common asphalt pavement distresses. Factors in the selection of laboratory mechanical tests such as availability of standard test procedures, advantages and limitations, laboratory-to-field correlations, and sensitivity to mixture composition are reviewed. Further, an implementation framework and case histories is also discussed.

AAPT Symposium - Balanced Mix Design: Discussion of: Moving Forward from Performance-Based Design to True Balanced Mixture Design in New Jersey

Tue, 08/22/2017 - 20:38
AAPT Symposium - Balanced Mix Design: Discussion of: Moving Forward from Performance-Based Design to True Balanced Mixture Design in New Jersey
by Bennert,T.
2016.
Asphalt Paving Technology 2016: Journal of the Association of Asphalt Paving Technologists - Indianapolis, Indiana, March 13-16, 2016.
US6 AFN___ 2016P29 - MAIN

AAPT Symposium - Balanced Mix Design: Development and Implementation of Balanced Mix Design in Texas

Tue, 08/22/2017 - 20:38
AAPT Symposium - Balanced Mix Design: Development and Implementation of Balanced Mix Design in Texas
by Zhou,F; Scullion,T.
2016.
Asphalt Paving Technology 2016: Journal of the Association of Asphalt Paving Technologists - Indianapolis, Indiana, March 13-16, 2016.
US6 AFN___ 2016P28 - MAIN


This paper briefly presents the development, implementation, and challenges of balanced mix design method in Texas.

AAPT Symposium - Balanced Mix Design: Optimized Mix Design Approach - Contractor's Perspective

Tue, 08/22/2017 - 20:38
AAPT Symposium - Balanced Mix Design: Optimized Mix Design Approach - Contractor's Perspective
by Buchanan,S.
2016.
Asphalt Paving Technology 2016: Journal of the Association of Asphalt Paving Technologists - Indianapolis, Indiana, March 13-16, 2016.
US6 AFN___ 2016P27 - MAIN


Mix durability related performance issues have been observed in recent years with a commonly reported contributing factor being a deficiency in mix asphalt binder content. In many instances, these performance issues are occurring with mixes that have met all governing mix specifications. As a result, asphalt mix specifications are changing rapidly as agencies search for solutions to improve durability. Lower design gyrations (Ndesign), lower target air voids, and increased voids in the mineral aggregate (VMA) are among the implemented specification modifications. Often, individual specification changes are implemented without evaluating their potential conflict with other specification items or at a rate that makes establishing true “cause and effect” on mix performance difficult or impossible to determine. Oldcastle Materials recognizes the need for improved mix performance and has developed a framework for an Optimized Mix Design Approach (OMEGA) in which innovation and mix engineering efforts are emphasized. The ultimate design approach objective is determining the optimum mix binder content for the specific mix design application (e.g., design traffic, pavement layer location, climate, etc.). This is accomplished through an enhanced materials evaluation and selection process, along with appropriate performance testing (stability and durability/cracking) to help ensure the desired end result performance is provided by the designed mix.

AAPT/ISAP International Forum: Bitumen: Current Situation and Future Challenges

Tue, 08/22/2017 - 18:37
AAPT/ISAP International Forum: Bitumen: Current Situation and Future Challenges
by Read,J; Airey,G; Krishnan,JM; Tabatabaee,N; Sousa,J.
2016.
Asphalt Paving Technology 2016: Journal of the Association of Asphalt Paving Technologists - Indianapolis, Indiana, March 13-16, 2016.
US6 AFN___ 2016P26 - MAIN


Presentations and Discussion: Bitumen's World Market (Read,J); Input from Europe (Airey,G); Input from India and the Far East (Krishnan,JM); Current Situation and Challenges of Asphalt in the Middle East (Tabatabaee,N), and; Use of Rubber in Bitumen Modification and Interaction between Rubber and Bitumen (Sousa,J). Presentation slides on the CDROM, discussion in print and on CDROM.

Leading Edge Forum - Asphalt Mix Cracking State of the Art: Materials, Design, and Testing

Mon, 08/21/2017 - 18:33
Leading Edge Forum - Asphalt Mix Cracking State of the Art: Materials, Design, and Testing
by Howard,IL; Baumgardner,GL; Monismith,CL.
2016.
Asphalt Paving Technology 2016: Journal of the Association of Asphalt Paving Technologists - Indianapolis, Indiana, March 13-16, 2016.
US6 AFN___ 2016P25 - MAIN


Mix testing that can properly characterize cracking of asphalt pavements is one of the most relevant present day issues for the industry. The 91st Annual Meeting (AM) of the Association of Asphalt Paving Technologists (AAPT) provides evidence to this effect as, in the assessment of the authors, cracking was far and away the meeting’s prevailing theme. The 91st AAPT AM began with a Leading Edge Workshop (LEW) that focused exclusively on cracking and associated test methods, and a key factor in most of the remaining content presented at the meeting was cracking. This paper stemmed from the 91st AM LEW in response to cracking’s perceived prevalence in the minds of so many AAPT members. The primary objective of this paper is to provide the state of the art in asphalt mix cracking from the perspective of the authors and to use this perspective to explain what has been accomplished in the cracking arena and what needs to be accomplished. First, a historical perspective beginning in the mid-1950s and ending in present day is presented that is generally divided into pre and post Superpave mix design. With this historical perspective as a reference, emphasis is shifted to the AM and LEW as they pertained to cracking. A set of prevailing themes was established and used as a segue into discussion of cracking test methods (first what has been accomplished and then what needs to be accomplished). Six areas were identified by the authors where advancement needs to be made with regard to mitigation of cracking: 1) closing the gap between the state of the art and the state of practice; 2) evaluating rapid mix test methods usable during production; 3) emphasizing education; 4) improving reliance on accelerated pavement testing; 5) improving cracking models; and 6) performing large test programs where parallel testing occurs on comparable mixes by way of several test methods.

Development of Oxidation Kinetics Models for Rheological and Damage Properties Based on "In-Service" Asphalt Binders

Mon, 08/21/2017 - 18:33
Development of Oxidation Kinetics Models for Rheological and Damage Properties Based on "In-Service" Asphalt Binders
by Wen,H; Liu,F; Cheng,J.
2016.
Asphalt Paving Technology 2016: Journal of the Association of Asphalt Paving Technologists - Indianapolis, Indiana, March 13-16, 2016.
US6 AFN___ 2016P24 - MAIN


Oxidative aging can lead to the susceptibility of asphalt pavement to cracking. Most studies on oxidative aging of asphalt binders are related to the prediction of the aging properties of asphalt binders based on oxidation kinetics. Development of kinetics models often involves short-term and long-term aging in the laboratory of original binder at different temperatures and for different times, and experiments of original and aged binder. However, for many rehabilitation projects or forensic studies, the original materials of pavements that were constructed years ago are not readily available to develop kinetic models. The development of a kinetic model based on asphalt binder in an in-service pavement is greatly needed to predict the properties of asphalt binder subjected to further aging for the purpose of overlay design, or to backcalculate the original properties of binder before aging for the purpose of forensic studies. This study develops a methodology to develop Arrhenius kinetics aging models using asphalt binders that already have been aged, instead of using original binders. Five asphalt binders (one neat and four modified) were included in this study and were subjected to three stage aging. The carbonyl areas of the aged binders were determined using Fourier transform infrared spectroscopy, and the rheological properties and damage properties were determined using a dynamic shear rheometer (DSR). First, the relationships among the model parameters of the oxidation kinetics models for the crossover modulus, DSR function, shear strength, and critical strain energy density of the asphalt binders were developed based on aging of original materials. Based on the relationships between model parameters and experiment results of asphalt binders that have been aged separately, Arrhenius kinetics aging models were developed. The effectiveness of these models which are developed based on aged binder were verified. The developed kinetic models for crossover modulus, DSR function, shear strength, and critical strain energy density of the asphalt binders can be used to predict the properties of asphalt binders subjected to further aging in the field for the design of overlays in the Mechanistic-Empirical Pavement Design Guide or Pavement ME, or to determine the properties of original asphalt binders before aging for the purposes of forensic studies, based on the cumulative aging effects of in-service pavement temperatures.

Glass and Carbon Geogrid Reinforcement of Asphalt Mixtures

Mon, 08/21/2017 - 18:33
Glass and Carbon Geogrid Reinforcement of Asphalt Mixtures
by Zofka,A; Maliszewski,M; Maliszewska,D.
2016.
Asphalt Paving Technology 2016: Journal of the Association of Asphalt Paving Technologists - Indianapolis, Indiana, March 13-16, 2016.
US6 AFN___ 2016P23 - MAIN


Application of geogrids for asphalt layers in road and airport pavements has been studied since early 1980’s. This type of geosynthetics is feasible to mitigate reflective cracking and to prolong fatigue life, i.e. to reinforce asphalt layers within a pavement structure. Up to now, many laboratory and field studies have demonstrated significant benefits of using geogrids but still several aspects of their working mechanism within adjacent asphalt layers remain not fully understood and need to be further explored. This paper presents an initial part of a long-term study initiated in Poland in order to fully assess the benefits of using geogrids within asphalt layers. The first part of this paper presents a state-of-the-art review on geogrid applications in asphalt layers. The next part demonstrates and discusses the results obtained on geogrid reinforced beams under monotonic and cyclic loading conditions. Three types of large beams were prepared under laboratory conditions. One group comprises reference beams without any reinforcement and the other two were reinforced, respectively, with glass and carbon geogrids. Specimens were evaluated in a custom-made 3PB/4PB fixture at 13ºC in order to observe their behavior under force-controlled fatigue test and displacement-controlled fracture test. Results demonstrated a beneficial impact of fiber reinforcement on the development of beam deflections in the fatigue tests and significantly higher fracture energy in the post-peak softening region. These results will be used to prepare a new experimental campaign to closely investigate the reinforcement mechanism of geogrids within asphalt layers. The paper concludes with short- and long-term plans necessary to develop an official design procedure for the pavements with geogrid reinforced asphalt layers in Poland.

Fundamental Evaluation of Moisture Damage in Warm-Mix Asphalts

Tue, 08/08/2017 - 18:56
Fundamental Evaluation of Moisture Damage in Warm-Mix Asphalts
by Cucalon,LG; Kassem,E; Little,DN; Masad,E.
2016.
Asphalt Paving Technology 2016: Journal of the Association of Asphalt Paving Technologists - Indianapolis, Indiana, March 13-16, 2016.
US6 AFN___ 2016P12 - MAIN


Warm-mix asphalt (WMA) technologies have been used extensively in the last decade. The benefits of WMA have motivated contractors and agencies to expedite the implementation of this technology. However, some research studies have raised concerns regarding WMA laboratory performance in terms of resistance to moisture damage, while WMA has demonstrated good performance in the field. These experiences motivated further research to understand the fundamental characteristics of WMA. This study comprised a comprehensive evaluation of WMA prepared using different aggregate sources, asphalt binders, and WMA additives. A dynamic mechanical analyzer was used to test the mastic phase of conventional hot-mix asphalt and WMA. The test specimens were evaluated at different conditions—dry and wet—and at different aging stages—unaged and 3-month aged—in a controlled environmental room (i.e. 60°C). A fracture mechanics approach was used to analyze the test results. This approach incorporated fundamental material properties including adhesive bond energy between aggregates and asphalt binder. The results show that WMA performance improved with aging and the overall performance of the WMA can be improved if the selection of materials (i.e., aggregate source, asphalt binder, WMA technology) is optimized based on the compatibility of their surface energy. In addition, surface energy results were able to explain some findings from the mechanical testing related to moisture susceptibility of WMA.

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