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Lignes directrices pour l’utilisation des panneaux d’affichage de la vitesse

Mon, 11/05/2018 - 18:56
Lignes directrices pour l’utilisation des panneaux d’affichage de la vitesse
by Ermatinger,V; Guglielmino,M; Kellner,S; Kozak,DA; Lovicsek,M; Otten-Andrew,M.
2017.
CA6 ARH_65 2017A63Z - MAIN


Les panneaux d’affichage dynamique de la vitesse sont utilisés dans plusieurs provinces et territoires du Canada. Ils permettent aux conducteurs de voir leur vitesse, habituellement affichée à côté du panneau indiquant la limite de vitesse permise. Ces dispositifs sont destinés à faire prendre conscience aux conducteurs des limites de vitesse en affichant en temps réel la vitesse à laquelle ils conduisent leur véhicule. On a pu constater qu’ils sont efficaces peu de temps après leur installation. Les Lignes directrices pour l’utilisation des panneaux d’affichage de la vitesse ont été mises au point afin de définir les meilleures pratiques et de fournir des recommandations pour la conception et l’utilisation de panneaux d’affichage de la vitesse dans le contexte canadien pour diverses situations. Ces Lignes directrices permettent et favorisent l’uniformité dans l’utilisation des dispositifs dans tout le Canada; elles ont été rédigées dans le but de servir de document de référence détaillé complémentaire à utiliser conjointement avec le Manuel canadien de la signalisation routière (MCSR).

Guide de conception, de construction, d’entretien et d’inspection des murs de soutènement de sol stabilisé mécaniquement

Mon, 11/05/2018 - 18:41
Guide de conception, de construction, d’entretien et d’inspection des murs de soutènement de sol stabilisé mécaniquement
by Van Dyk,A; Bathurst,RJ; Maher,M; Boone,S.
2017.
CA6 ARH_63 2017D21Z - MAIN


Les murs de soutènement de sol stabilisé mécaniquement (MSSM) sont depuis longtemps utilisés comme murs de soutènement, mais il n’est pas toujours évident de déterminer qui est l’ultime responsable de la conception, de l’assurance de la qualité, de la gestion des actifs et de la réparation des murs, ainsi que de la surveillance en service des murs déjà construits, en particulier en cas de problèmes importants relativement à la construction ou la tenue en service. Le présent guide offre aux maîtres d’ouvrages, ingénieurs, fournisseurs et entrepreneurs des MSSM des lignes directrices pratiques en matière de sélection, de conception, de construction et d’inspection de ces ouvrages, surtout dans le cadre de projets de travaux publics. Le guide a été élaboré sur la base de l’examen de la littérature existante, complétée par de l’information transmise par divers intervenants dans ce domaine. Il ne cherche pas à reproduire les très nombreuses lignes directrices de conception déjà publiées, ni l’information connexe. Il vise plutôt à mettre en évidence les diverses facettes de l’état actuel de la pratique au Canada et à proposer des modifications à la pratique actuelle afin de corriger certaines lacunes.

Manual for Bridge Evaluation

Sun, 11/04/2018 - 20:40
Manual for Bridge Evaluation
Highway Committee on Bridges and Structures.
3rd Edition.
2018.
US6 ABK___ 2018B62 - MAIN


This manual has been developed to assist bridge owners by establishing inspection procedures and evaluation practices that meet the National Bridge Inspection Standards (NBIS). The manual has been divided into eight sections, with each section representing a distinct phase of an overall bridge inspection and evaluation program. This edition updates Sections 3: Bridge Management Systems; 4: Inspection; 6: Load Rating; and 7: Fatigue Evaluation of Steel Bridges.

Short Sea Shipping in Canada: Alive or Dead?

Mon, 10/08/2018 - 19:39
Short Sea Shipping in Canada: Alive or Dead?
by Frost,J.
2017.
Canadian Transportation Research Forum 52nd Annual Conference - Canadian Transportation: 150 Years of Progress//Les transports au Canada : 150 ans de progrès - Winnipeg, Manitoba, May 28-31, 2017.
CA6 AIP_10 2017P33 - INTERNET


This paper is based on research carried out for the recent Canadian Transportation Act Review. It examines the potential for short sea shipping in the Great Lakes / St. Lawrence region and considers international best practices and their relevance to Canada. We revisit a study undertaken by MariNova in 2005, which examined the potential for a short sea service between Halifax augmented by a brief analysis of a Montreal-Hamilton service. The analysis removes all of the constraints previously identified and re-considers its viability. The study also examines the potential role for government, in terms of promoting investment in short sea shipping. For the purposes of this paper we consider short sea shipping to include container, roll-on, roll-off (ro-ro), bulk as well as tug-and barge operations, providing interregional, intraregional and transhipment services. Our definition does not include passenger ferries, although a significant amount of commercial cargo is carried on most of Canada’s ferry services, particularly in the Newfoundland trade.

Arctic Pilots for Canadian Corridors

Mon, 10/08/2018 - 19:14
Arctic Pilots for Canadian Corridors
by Beveridge,L.
2017.
Canadian Transportation Research Forum 52nd Annual Conference - Canadian Transportation: 150 Years of Progress//Les transports au Canada : 150 ans de progrès - Winnipeg, Manitoba, May 28-31, 2017.
CA6 AIP_10 2017P32 - INTERNET


The Canadian Marine Pilots’ Association (CMPA) recommended in their submissions to the Canadian Transportation Act Review Panel (2014), and more recently to the Minister of Transport (2016) to consider the structure and administration of a new pilotage service when assessing its potential role in the Arctic. As such, the purpose of this paper is to explore pilotage for Canadian arctic waters in the context of the Northern Marine Transportation Corridors (NMTC) Initiative as a means of improving the safety of navigation and the protection of the marine environment. To aid the analysis, the CMPA’s principles of organizing pilotage in Canada will be relied upon: to protect the public interest (i.e., safety); rigorous standards for qualifying as a pilot; recognition of regional differences in operating conditions, navigational challenges, types of marine traffic and supporting infrastructure; and the responsiveness of pilotage to changes in technology, vessels, infrastructure, and traffic patterns. The paper will begin with a brief overview of the necessity of the service, followed by a discussion of how pilotage could be offered in the Canadian Arctic, including how the service relates to the NMTC Initiative, how it could be administered, and what qualifications would be required of an Arctic pilot.

Modelling the Influence of Fused Grid Neighbourhood Design Principles on Greenhouse Gas Emissions with Emphasis on Street Connectivity

Mon, 10/08/2018 - 18:38
Modelling the Influence of Fused Grid Neighbourhood Design Principles on Greenhouse Gas Emissions with Emphasis on Street Connectivity
by Rahman,MN; Masoud,AR; Idris,AO.
2017.
Canadian Transportation Research Forum 52nd Annual Conference - Canadian Transportation: 150 Years of Progress//Les transports au Canada : 150 ans de progrès - Winnipeg, Manitoba, May 28-31, 2017.
CA6 AIP_10 2017P31 - INTERNET


Transportation is one of the major contributors of Greenhouse Gas (GHG) emissions all over the world. In Canada, transportation was the second largest source of GHG emissions in 2014, accounting for 23% of the total emissions nationwide (Environment Canada, 2016). At the provincial level, 38.4% of British Columbia’s GHG emissions came from the transportation sector (BC Ministry of Environment, 2016). Such high levels of GHG emissions can be attributed to the large expansion of the urban road network and automobile dependency in North America. It is very important to shift the paradigm and start planning our communities in a way that hinder automobile dependency and encourage people to use more sustainable modes of transportation. The fused grid model consists of several 16-hectare modules (ideally four) that provide vehicular accessibility for local traffic only and keep non-local traffic on the periphery of the modules while maintaining full pedestrian/cyclists accessibility via central green spaces and off-road pathways as shown in Figure 1. Perimeter roads in the fused grid model facilitate through traffic as per the following spacing: 1) collectors at 400 metres; 2) minor arterials at 800 metres; and 3) arterials at 1,600 metres. The classification, spacing, and alignments of the perimeter roads can be designed according to the existing ground conditions and planned land use activities. The model also provides convenient local services and amenities within a five-minute walking distance by classifying blocks located between the perimeter one-way couplet roads as mixed land use zones. All intersections in the neighbourhood are controlled by roundabouts or three-way intersections to reduce the severity of collisions. Several studies have been found in the literature that address the benefits of the fused grid model in various aspects including: safety (Sun and Lovegrove, 2013), traffic performance (IBI Group, 2007), walkability (Frank and Hawkins, 2007), and transportation modal share (Masoud et al. 2017). While previous research like Frank and Hawkins (2007) and Masoud et al. (2017) has concluded that applying fused grid principles will result in more walking and less driving, which obviously would result in reducing GHG emissions, none of the previous research quantified by how much would GHG be reduced and thus quantifying its social benefits.

The Greening of Canada’s Road Motor Vehicles: An Assessment

Mon, 10/08/2018 - 18:03
The Greening of Canada’s Road Motor Vehicles: An Assessment
by Hagag,A; McKeown,L.
2017.
Canadian Transportation Research Forum 52nd Annual Conference - Canadian Transportation: 150 Years of Progress//Les transports au Canada : 150 ans de progrès - Winnipeg, Manitoba, May 28-31, 2017.
CA6 AIP_10 2017P30 - INTERNET


There is a growing recognition of the relationship between patterns of urban land use and related levels of air pollutants (Abotalebi and Kanaroglou, 2015; Dimatulac & Maoh, 2016; Glaeser, 2011; Giuliano & Agarwal, 2011; Tyler, 2000; Zimmerman & Wiginton, 2016). The connection in this relationship is evolving land use patterns in Canada which have helped to encourage and sustain a dependency on motor vehicles. Consequently, Greenhouse Gas (GHG) emissions in Canada from the operation of motor vehicles increased by over one-third (35%) from 1990 to 2007, whereas the growth rate of population was less than 20% over the same period (Terefe, 2010). As party to the 2016 United Nations Framework Convention on Climate Change’s Paris Agreement, Canada has committed to reducing its GHG emissions to 30% below 2005 levels by 2030. With transport there are two complementary approaches to help reach this reduction target. The first is to encourage a modal shift (Gullo & Rosales, 2016). In the urban context, this shift would be from motor vehicles to public transit, relying on policy options of full-cost pricing (e.g. tolling) and related land-use planning (e.g. Smart Growth, intensification). The second approach is to encourage more fuel efficient fleets. For the road motor vehicle fleet, this would entail a higher proportion of alternative fuel vehicles (AFV). This study investigates the extent to which provincial vehicle registration files (VRF) can be used as a source of information to profile the road motor vehicle fleet by fuel type. Such a profile is critical as a benchmark going forward in order to track changes in the motor vehicle fleet composition. The paper begins with an overview of the relationship between transportation and urban form as well as the current contribution of the transportation sector to Canada’s GHG emissions. After describing the provincial VRFs, the paper defines a typology and then estimates the motor vehicle fleet by fuel type. We conclude with an examination of possible next steps in this effort.

Asphalt Re-recycling

Thu, 10/04/2018 - 19:29
Asphalt Re-recycling
by Kriz,P; Tardiff,BJ; Sta. Maria,SR; Shirts,RD.
2017.
Proceedings of the Sixth-Second Annual Conference of the Canadian Technical Asphalt Association (CTAA): Halifax, Nova Scotia.
CA6 AIH___ 2017P19 - MAIN


Use of Reclaimed Asphalt Pavement (RAP) is beneficial to both road owners and builders as it allows for significant raw material cost reduction, while potentially maintaining expected pavement service life. In upcoming decades, the recycling of previously recycled pavements (i.e. re-recycling) will become widespread. There is currently little technical knowledge on how or how many times asphalt pavement can be recycled while sustaining its expected durability. A novel asphalt binder aging method involving thin layers, heat, water spray, and UV radiation was developed to simulate approximately 20 years of in-service aging. The aged binder was recovered and blended with a softer, virgin binder. The blend was subjected to the next aging cycle. The process was repeated four times to simulate four recycling cycles (80 years) at 25 percent RAP addition. Three virgin binders were tested: standard Performance Grade (PG), one grade softer PG, and standard PG softened with paraffinic oil to one PG softer binder. Very detailed chemical and rheological analyses were performed to understand the impact of multiple recycling on irreversible chemical changes and evolution of rheological properties over the time. Results indicated that at moderate recycling levels, re-recycling is a viable option if an appropriate virgin binder is used.

Prince Edward Island’s Experience with Hot In-place Asphalt Recycling

Thu, 10/04/2018 - 18:40
Prince Edward Island’s Experience with Hot In-place Asphalt Recycling
by Yeo,S; Sherren,M; Pigott,S.
2017.
Proceedings of the Sixth-Second Annual Conference of the Canadian Technical Asphalt Association (CTAA): Halifax, Nova Scotia.
CA6 AIH___ 2017P18 - MAIN


The local geology of Prince Edward Island (PEI) primarily consists of material soft in nature that does not meet traditional aggregate specifications for the production of Hot Mix Asphalt (HMA) or other surface treatments. Therefore, roughly 95 percent of PEI’s HMA aggregates must be obtained and imported from off-Island sources. The associated work, expense, and environmental impact involved has raised the Department’s interest in the viability of asphalt recycling as a potential surface treatment option. As a trial basis, the Department committed to recycling ten, one-kilometer sections of road ranging in classification from Local to Collector roads in 2016. Acceptance or rejection of the work was largely based on the ability of the Contractor to achieve the specified penetration values of the modified binder and visual inspection for defects, as well as requirements for cross slope, grade and joint construction of the completed HIR. The HIR process was constantly monitored in the field by Department staff and although not forming part of the specifications, properties such as compaction, smoothness, and asphalt cement content were monitored. This paper is an account of our experiences and lessons learned from the recent application of HIR undertaken within the Province of PEI.

Performance-based Asphalt Mixture Development Process to Optimize Material Durability and Pavement Design

Tue, 09/04/2018 - 20:37
Performance-based Asphalt Mixture Development Process to Optimize Material Durability and Pavement Design
by Croteau,JM; Pianarosa,S; Harrison,T; Slawinsky,C; Brissaud,L.
2017.
Proceedings of the Sixth-Second Annual Conference of the Canadian Technical Asphalt Association (CTAA): Halifax, Nova Scotia.
CA6 AIH___ 2017P17 - MAIN


In the summer of 2015, Standard General Inc. – Calgary (SGIC), a subsidiary of Colas Canada Inc., introduced a new paving material called Betoflex® with the goal of resolving a recurring permanent deformation issue of two taxiways leading to Runway 17/35 at the Calgary Airport. The 2015 mixture was developed using the French Level 2 methodology to ensure that rutting resistance performance was achieved while maintaining good mixture workability to facilitate placement and compaction. In the spring/summer of 2016, Level 4 testing was performed on various Betoflex® mixtures that could potentially be used in the Calgary area. Level 4 testing was also performed on typical mixtures used in Calgary to benchmark Betoflex® with local mixtures. The Level 4 mix-design provides information for pavement design (stiffness modulus and fatigue resistance) using the French ALIZÉ-LCPC software. This paper provides an overall perspective of the engineering of asphalt mixtures to achieve “in-service” performance not only for durability (moisture resistance and rutting), but also for pavement design performance (stiffness modulus and fatigue resistance). It also discusses how the ALIZÉ-LCPC pavement design software uses Level 4 mix-design information to optimize pavement thicknesses and/or pavement performance reliability with respect to fatigue and large radius rutting.

Laboratory Study on the Effect of Asphalt Binder Rejuvenators on the Cracking Resistance of Hot Mix Asphalt

Tue, 09/04/2018 - 19:35
Laboratory Study on the Effect of Asphalt Binder Rejuvenators on the Cracking Resistance of Hot Mix Asphalt
by Wielinski,JC; Magill.L; Campbell,C; Huber,GA.
2017.
Proceedings of the Sixth-Second Annual Conference of the Canadian Technical Asphalt Association (CTAA): Halifax, Nova Scotia.
CA6 AIH___ 2017P16 - MAIN


Asphalt binder rejuvenator use in Hot Mix Asphalt (HMA) has been gaining momentum not only to delay aging of the asphalt binder, but also to permit higher levels of binder replacement from recycled materials. In this study, an HMA mixture was designed with approximately 35 percent binder replacement from Reclaimed Asphalt Pavement (RAP). Per specifications, a binder grade adjustment from PG 64-22 to PG 58-28 was required. The control mixture contained a neat PG 58-28 binder. Three experimental binders contained asphalt binder that were a blend of PG 64-22 plus rejuvenator materials to produce a PG 58—28 binder. HMA mixtures containing all four asphalt were tested for cracking and rutting resistance. The laboratory study indicated that the control and experimental mixes had no difference I rutting resistance. Under short-term aging, all three experimental mixtures with rejuvenators had improved cracking resistance as measured by the Illinois Flexibility Index Test (IFIT). Under long-term aging conditions, no significant difference was observed among the control and the three experimental mixtures according to the Disc-Shaped Compact Tension (DCT) test. However, IFIT testing of long-term aged specimens showed improved cracking resistance for two of the three experimental mixtures compared to the control.

Development of an IDEAL Cracking Test for Asphalt Mix Design and QC/QA

Fri, 08/31/2018 - 19:34
Development of an IDEAL Cracking Test for Asphalt Mix Design and QC/QA
by Zhou,F; Im,S; Sun,L; Scullion,T.
2017.
Asphalt Paving Technology 2017: Journal of the Association of Asphalt Paving Technologists - Newport Beach, California, March 19-22, 2017.
US6 AFN___ 2017P21 - MAIN


The focus in recent years has been to make asphalt mixes more affordable, and this has led to the increased use of recycled materials and binder modifications. Consequently, one often-heard complaint is that the recent mixes are more susceptible to cracking. There is an urgent need for a practical cracking test for routine use in the process of mix design, quality control, and quality assurance testing. This paper develops an indirect tensile asphalt cracking test (IDEAL-CT). The IDEAL-CT is typically run at room temperature with 150-mm diameter and 62-mm high cylindrical specimens with a loading rate of 50 mm/min. The IDEAL-CT is a simple (no instrumentation, cutting, gluing, drilling, or notching of specimens), practical (minimum training needed for routine operation), and efficient test (test completion less than one minute). The test can be performed with regular indirect tensile strength test equipment. As described in this paper, the IDEAL-CT is sensitive to key asphalt mix components and volumetric properties including reclaimed asphalt pavement and recycled asphalt shingles content, asphalt binder type, binder content, aging conditions, and air voids. The proposed test also has a much lower coefficient of variation than traditional repeated load cracking tests. Furthermore, the IDEAL-CT results were compared with field cracking data collected from the Federal Highway Administration’s accelerated load facility, Texas SH15 and SH62, and MnROAD. The IDEAL-CT characterization correlated well with field performance in terms of fatigue, reflective, and thermal cracking. Last but not the least, the ruggedness test performed in this study indicated that the IDEAL-CT, after combining both statistical and practical views, could be considered as rugged with all four variables: specimen thickness, loading rate, test temperature, and air voids.

Alternative Methodology for Assessing Cracking Resistance of Hot Mix Asphalt Mixtures with Overlay Tester

Fri, 08/31/2018 - 19:34
Alternative Methodology for Assessing Cracking Resistance of Hot Mix Asphalt Mixtures with Overlay Tester
by Garcia,VM; Miramontes,A; Garibay,J; Abdallah,I; Carrasco,G; Lee,R; Nazarian,S.
2017.
Asphalt Paving Technology 2017: Journal of the Association of Asphalt Paving Technologists - Newport Beach, California, March 19-22, 2017.
US6 AFN___ 2017P20 - MAIN


Several highway agencies have either implemented or considered implementing performance tests to predict the cracking potential of asphalt concrete (AC) mixes in the laboratory setting. One such test, the overlay tester (OT), simulates the opening and closing of cracks induced by daily temperature variations and tensile strain generated by traffic loads. The variability of the OT results is expressed as a major concern in reliably characterizing cracking potential of AC mixes. A more fundamental analysis process and more mechanistic performance indicators were implemented that consider the two stages of the cracking mechanism (i.e., crack initiation and crack propagation). The repeatability of the proposed performance indices, critical fracture energy and crack progression rate, seems to be better than the current criterion based on the number of cycles to dissipate 93% of the initial maximum peak load. The proposed cracking methodology and associated preliminary failure limits seem to characterize and satisfactorily discriminate the cracking resistance of AC mixes. Given its promise in this study, the proposed OT test method is recommended as a routine test during the mix design process of AC mixes to predict and screen their cracking susceptibility.

Development of a New Methodology to Effectively Predict the Fracture Properties of RAP Mixtures

Fri, 08/31/2018 - 19:34
Development of a New Methodology to Effectively Predict the Fracture Properties of RAP Mixtures
by Yan,Y; Roque,R; Hernando,D; Lopp,G.
2017.
Asphalt Paving Technology 2017: Journal of the Association of Asphalt Paving Technologists - Newport Beach, California, March 19-22, 2017.
US6 AFN___ 2017P19 - MAIN


The existing design method for RAP mixtures assumes virgin and RAP binders fully blend. However, full blending may not occur and the impact of partial blending on mixture cracking performance is still unclear. A previous study revealed that RAP gradation, which is not currently considered from the standpoint of binder blending, controls the distribution of RAP binder within a mixture and consequently affects cracking performance. The objective of this study was to develop a methodology that overcomes the uncertainty of blending and effectively predicts fracture properties of RAP mixtures. This methodology is based on the evaluation of the interstitial component (IC) of a mixture (i.e., the fine portion that governs cracking performance) by means of a direct tension test named ICDT test. Two RAP sources and four RAP contents were considered. ICDT specimens were produced by blending the fine portion of RAP and virgin aggregate with virgin binder in the same way and corresponding proportions as in RAP mixtures. Binder and mixture fracture properties from the previous study were used for comparison. Mixture and IC exhibited almost similar reduction in fracture energy density (FED) with increasing RAP content, whereas fully blended binder exhibited a less pronounced reduction. This indicated that IC better simulated the actual blending that occurred in mixtures. Mixtures with coarsely graded RAP (less RAP content in the IC) exhibited better fracture properties; thus, the key to satisfactory cracking performance appears to be minimizing the amount of RAP in IC. Consequently, the stiffening effect of RAP on the fine portion that controls cracking performance should be directly evaluated, instead of placing focus on the fully blended binder or the whole mixture. The ICDT test was proven to be a valuable tool to predict fracture properties of RAP mixtures.

Assessing the Effects of RAP, RAS, and Warm-Mix Technologies on Fatigue Performance of Asphalt Mixtures and Pavements Using Viscoelastic Continuum Damage Approach

Fri, 08/31/2018 - 19:34
Assessing the Effects of RAP, RAS, and Warm-Mix Technologies on Fatigue Performance of Asphalt Mixtures and Pavements Using Viscoelastic Continuum Damage Approach
by Cao,W; Mohammad,LN; Elseifi,M.
2017.
Asphalt Paving Technology 2017: Journal of the Association of Asphalt Paving Technologists - Newport Beach, California, March 19-22, 2017.
US6 AFN___ 2017P18 - MAIN


The objective of this study was to evaluate the effects of incorporating recycled materials, i.e., reclaimed asphalt pavement (RAP) and recycled asphalt shingles (RAS), and the use of warm-mix technologies on fatigue performance of asphalt mixtures and pavement structures using the viscoelastic continuum damage (VECD) approach. For this purpose, ten mixtures from the full-scale test lanes constructed at the Federal Highway Administration (FHWA) Accelerated Loading Facility (ALF) were acquired and characterized in the laboratory. The dynamic modulus test and direct tension cyclic fatigue test were employed to assess the linear viscoelastic property and fatigue characteristics, respectively. Within the VECD framework, two parameters, namely material fatigue sensitivity (MFS) and structure fatigue sensitivity (SFS) were developed to represent the fatigue resistance of asphalt mixtures and their performance in pavement structures, respectively. Both parameters can be easily obtained via the strain-based fatigue simulation using the experimental data without extra requirements on the specimen failure location and the number of cycles to failure in the cyclic fatigue test. The validity of MFS was verified by the critical strain energy release rate obtained from semi-circular bend (SCB) testing at intermediate temperature. Based on the obtained dynamic modulus and MFS data, an increase in the content of recycled materials was able to enhance the stiffness of hot-mix asphalt (HMA) mixtures while compromising the fatigue resistance. Implementation of warm-mix technologies benefited materials’ fatigue performance but the improvement was not substantial. Use of soft binder yielded pronounced fatigue benefits for HMA mixtures with high RAP content. The proposed SFS parameter resulted in the same performance ranking of the ALF lanes as the measured fatigue lives. Moreover, quantitatively a power-law function was found to adequately correlate SFS with the field measurements.

Evaluation of Foamed Warm Mix Asphalt with Reclaimed Asphalt Pavement: Field and Laboratory Experiments

Fri, 08/31/2018 - 19:34
Evaluation of Foamed Warm Mix Asphalt with Reclaimed Asphalt Pavement: Field and Laboratory Experiments
by Xie,Z; Tran,N; Taylor,A; Julian,G; West,R; Welch,J.
2017.
Asphalt Paving Technology 2017: Journal of the Association of Asphalt Paving Technologists - Newport Beach, California, March 19-22, 2017.
US6 AFN___ 2017P17 - MAIN


Warm mix asphalt (WMA) technology and reclaimed asphalt pavement (RAP) materials have been increasingly used in asphalt paving mixtures due to environmental and cost benefits. Combining WMA and RAP offers more economic and environmental benefits compared to using either alone. To evaluate the combined effect of WMA and RAP, two WMA mixtures with 20% and 30% RAP were produced using water-injection plant foaming, and they were compared with two comparable HMA mixtures with 20% and 30% RAP. The four mixtures were paved on I-70 near Eagle, Colorado, in May 2013. Laboratory performance properties of plant-produced mixes and field performance of the four test sections after 13, 25, 38 months were evaluated. The research results showed that the effect of water foaming WMA and RAP was not significant on the laboratory performance properties, construction quality and field performance. Thus, water-injection plant foaming WMA could be used to produce WMA mixtures with 20% and 30% RAP at a lower production temperature. These sections will continue to be monitored to evaluate their long-term performance and compare with the laboratory test results.

Impact of High Recycled Mixes on HMA Overlay Crack Development Rate

Fri, 08/31/2018 - 19:34
Impact of High Recycled Mixes on HMA Overlay Crack Development Rate
by Al-Qadi,IL; Wu,S; Lippert,DL; Ozer,H; Barry,MK; Safi,FR.
2017.
Asphalt Paving Technology 2017: Journal of the Association of Asphalt Paving Technologists - Newport Beach, California, March 19-22, 2017.
US6 AFN___ 2017P16 - MAIN


Illinois has many years of experience using various reclaimed materials in highway construction, and in recent years, recycled asphalt shingles (RAS) have been adopted for use in hot-mix asphalt (HMA), along with much higher amounts of reclaimed asphalt pavement (RAP). These reclaimed asphalt materials usually contain aged asphalt binders, which may increase the mix brittleness and hence, pose a challenge for maintaining a flexible pavement and ensuring good performance. To counter these hard asphalt binders, softer asphalts are incorporated into the HMA. The goal is for the final mix to provide acceptable mix properties for the life of the pavement. To determine the impact of recycled materials on pavement performance, this study monitored nine field projects in terms of the testing, construction, and performance of surface mixes that have a variety of asphalt binder replacement (ABR) levels from RAP and RAS which used different virgin asphalt binder grades. Simple performance tests (Hamburg wheel tracking test and the Illinois flexibility index test (I-FIT)) were used to evaluate the mix designs. Flexibility index (FI) from the I-FIT showed good correlation with field crack development, especially after first year performance of the mix. Early-age field performance showed that placing the HMA overlay directly over existing bare concrete pavement or milling off all the HMA and placing the new overlay on concrete pavement results in higher extents of cracking in early age than the sections that left an HMA layer in place. Regardless of which mix type is designed and what material sources are used, the performance of the mix should be evaluated to ensure it has sufficient flexibility to resist cracking before the mix is used in road construction. This allows owners and contractors to use low-cost reclaimed and recycled materials to the extent possible without negatively impacting pavement performance.

Performance Evaluation of Plant-Produced Warm Mix Asphalts Containing RAP and RAS

Wed, 08/29/2018 - 23:23
Performance Evaluation of Plant-Produced Warm Mix Asphalts Containing RAP and RAS
by Arshadi,A; Steger,R; Ghabchi,R; Zaman,M; Hobson,K; Commuri,S.
2017.
Asphalt Paving Technology 2017: Journal of the Association of Asphalt Paving Technologists - Newport Beach, California, March 19-22, 2017.
US6 AFN___ 2017P15 - MAIN


In the present study, rutting performance, cracking resistance, and durability of five plant-produced asphalt mixes containing 12% reclaimed asphalt pavement (RAP) and 3% recycled asphalt shingles (RAS) and produced with different warm mix asphalt (WMA) technologies were evaluated through characterization of extracted asphalt binder and performance tests conducted on asphalt mix specimens. For all of the extracted and recovered asphalt binders, continuous grades and the difference between critical low temperatures, Tcr parameter, were determined from the performance grading and a Glover-Rowe (G-R) damage zone was evaluated at 45°C and 10 rad/s. It was revealed that application of a rejuvenating agent (RA) significantly reduced the high PG grade of the overall asphalt binder. The binder test results also indicated that the chemical-additive-based WMA technology had an advantage over the foaming-based technology in terms of asphalt binder durability. Furthermore, application of RA improved the asphalt binder durability. Comparison of G-R parameters of the recovered asphalt binders showed that using RA and lowering the virgin binder high PG true grade improves the overall binder ductility and damage resistance. Asphalt mix performance tests included dynamic modulus, flow number, and semi-circular bend. The dynamic modulus test data indicated that application of RA and lowering the virgin binder high PG grade lowered the mix stiffness at low frequencies. Comparison of the methods to compensate the effects of highly aged RAP and RAS binders indicated that the mix prepared with RA and one level high PG grade drop performed better than the mix prepared by dropping the PG grade by two levels in terms of cracking resistance and rutting performance. The findings give credence to utilization of rejuvenating agents and softer virgin binders in balanced RAP/RAS mix design approaches.

Characterizing the Long-Term Rejuvenating Effectiveness of Recycling Agents on Asphalt Blends and Mixtures with High RAP and RAS Contents

Wed, 08/29/2018 - 23:23
Characterizing the Long-Term Rejuvenating Effectiveness of Recycling Agents on Asphalt Blends and Mixtures with High RAP and RAS Contents
by Yin,F; Kaseer,F; Aràmbula-Mercado,E; Epps Martin,A.
2017.
Asphalt Paving Technology 2017: Journal of the Association of Asphalt Paving Technologists - Newport Beach, California, March 19-22, 2017.
US6 AFN___ 2017P14 - MAIN


Although the use of high reclaimed asphalt pavement (RAP) and recycled asphalt shingles (RAS) contents in asphalt mixtures is desirable for environmental and economic reasons, these mixtures are prone to cracking, raveling, and other durability-related pavement distresses mainly due to the heavily aged recycled binders. Highway agencies and the asphalt paving industry have been exploring the use of recycling agents (RA) in order to produce these mixtures with desirable performance. This study focused on characterizing the long-term rejuvenating effectiveness of RA on asphalt blends and mixtures with high RAP and RAS contents. Materials from two field projects were used to prepare a number of asphalt blends and mixtures with various combinations of base binder, recycled material, and RA. These blends and mixtures were subject to various aging protocols prior to being characterized for their oxidation kinetics, rheological properties, and cracking resistance. The test results indicated that the RA evaluated in this study were effective in partially restoring the properties of recycled materials, but their rejuvenating effectiveness diminished with aging. Nevertheless, the recycled blends and mixtures with RA achieved equivalent or even better rheological properties and cracking resistance than those with an allowable amount of recycled materials per agency specifications but without RA. In addition, adding RA had no significant effect on the oxidation kinetics of the recycled blends, but increased their susceptibility to physical hardening in response to oxidation. Finally, the correlation between laboratory aging protocols for asphalt blends and mixtures were determined; the laboratory long-term oven aging protocols of five days at 85°C on compacted specimens and one day at 135°C on loose mix yielded binders with equivalent rheological properties to those subjected to rolling thin film oven (RTFO) plus approximately ten and 40 hours of pressure aging vessel (PAV), respectively.

Improving Cohesiveness of Porous Friction Course (PFC) Asphalt Mixtures

Wed, 08/29/2018 - 23:23
Improving Cohesiveness of Porous Friction Course (PFC) Asphalt Mixtures
by James,T; Watson,D; Taylor,A; Tran,N; Rodezno,C.
2017.
Asphalt Paving Technology 2017: Journal of the Association of Asphalt Paving Technologists - Newport Beach, California, March 19-22, 2017.
US6 AFN___ 2017P13 - MAIN


The use of porous friction course (PFC) provides numerous safety benefits and improves the noise quality of surrounding areas. Many agencies once used PFC for these reasons, but have since stopped using PFC due to performance issues. PFC pavements have reportedly been prone to raveling and cracking which leads to reduced service life. In addition, PFC is also typically more expensive than a dense-graded mix due to its use of high quality aggregates, modified asphalt binder and higher asphalt binder contents. Research is needed to extend the service life of PFC pavements in order to encourage agencies to start, or continue, use of PFC for its safety benefits. The objective of this research is to address the raveling and cracking distresses commonly seen by adjusting the asphalt and dust content of PFC mixes to improve durability. This was accomplished by using an array of performance tests to evaluate the effect of additional fine aggregate passing the 0.075 mm (P-0.075) sieve on two PFC mixtures: one that had good field performance (up to 18 years) and one that had poor field performance (less than eight years). It was found that the Cantabro test was a good indicator of mix performance and a maximum loss of 20% is recommended. The study revealed the importance of increased percent passing the 0.075 mm sieve to provide more durable PFC mix designs. An increased P-0.075 content had a positive effect on almost all of the results; thus, it is recommended that the current P-0.075 gradation band be expanded.

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