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Burrard Bridge Renewal and Transportation Improvement Project

Fri, 09/21/2018 - 20:32
Burrard Bridge Renewal and Transportation Improvement Project
by Kenny,R; Liaw,A.
2018.
TAC 2018: Innovation and Technology: Evolving Transportation - 2018 Conference and Exhibition of the Transportation Association of Canada.
CA6 ARH_10 2018A5109 - INTERNET


Burrard Bridge is one of three City-owned bridges that cross False Creek, a body of water separating the high-density downtown core and medium-density neighbourhoods to the south. The bridge was opened in 1932 as a six-lane vehicular bridge with sidewalks on both sides. The bridge was built in the Art Deco style and City Council included it on the City's Heritage Register in 1986. Over the years, the City has completed a series of rehabilitation projects and upgrades to keep the bridge safe and functional. The role of the bridge has evolved over the years, primarily in response to accommodating a growing number of cyclists using the bridge. Prior to 2009, people walking and cycling shared the sidewalks on both sides of the bridge. As the number of people crossing the bridge using active transportation grew, the shared sidewalk became increasingly hazardous for pedestrians and cyclists. Safety was a particular issue for people cycling, as they were directed to ride in a narrow area adjacent to motor vehicle traffic and a minor error (or conflict with a pedestrian) could cause them to fall off the sidewalk onto the roadway. In 2009, the City reallocated a southbound travel lane from general purpose traffic and prohibited pedestrians from using the east sidewalk in order to create a protected bicycle lane in each direction (refer to Appendix). Since then, walking and cycling volumes have increased significantly with cycling growing by over 30%. The Transportation 2040 Plan, adopted by Council in 2012, includes a zero transportation related fatality goal and identifies the False Creek Bridges as an area of focus for active transportation improvements to address gaps in the pedestrian and cycling networks. Burrard Bridge is one of the busiest active transportation corridors in the city, with 10,000 walking and cycling trips on a busy summer day. It also carries approximately 55,000 motor vehicles, 13,000 transit passengers, and 500 trucks on a typical day.

Best Practices for Harmonizing Road Construction Specifications and Standards: A Manitoba Assessment

Fri, 09/21/2018 - 20:32
Best Practices for Harmonizing Road Construction Specifications and Standards: A Manitoba Assessment
by Kavanagh,L; Afuberoh,A; Shalaby,A.
2018.
TAC 2018: Innovation and Technology: Evolving Transportation - 2018 Conference and Exhibition of the Transportation Association of Canada.
CA6 ARH_10 2018A5108 - INTERNET


This paper presents best practice guidelines and strategies for harmonizing provincial and municipal highway construction standards and specifications in Manitoba. Developing common construction standards with stakeholders of diverging goals can be challenging, but beneficial. The adoption of a consistent set of standards and specifications in a jurisdiction could minimize redundancy, identify critical requirements that need to be retained to maintain performance, cut construction and compliance costs, simplify the process of meeting requirements, and reduce complexity for those that are tasked with testing and standard compliance. Therefore in this study, a survey questionnaire was developed and sent to the provincial and municipal highway agencies, contractors, aggregate producers, and testing labs in Manitoba. The purpose of the survey questionnaire was to obtain input on harmonizing provincial and municipal specifications and standards for asphalt, concrete, granular base and rip-rap, and grading roadway projects. The survey questions focused on identifying key issues of harmonization including barriers to change, benefits, trade-offs, common goals, potential risks, cost-effectiveness, and quality control and quality assurance delivery mechanisms. The results of the survey recommendations for harmonizing standards and specifications are presented. The recommendations can be used by highway agencies to quickly implement the best practices, thereby realizing the benefits of harmonizing standards and specifications in their jurisdictions.

Assessing Asphalt Ignition Oven Performance and its Impact on the Asphalt Content Test Result

Fri, 09/21/2018 - 20:32
Assessing Asphalt Ignition Oven Performance and its Impact on the Asphalt Content Test Result
by Sinclair,J; Wenz,M.
2018.
TAC 2018: Innovation and Technology: Evolving Transportation - 2018 Conference and Exhibition of the Transportation Association of Canada.
CA6 ARH_10 2018A5107 - INTERNET


This report examines the use of the asphalt ignition oven temperature-time series generated during the asphalt content by ignition test method in identifying erroneous test results. The study was undertaken to provide an empirical tool for asphalt laboratory staff in troubleshooting and validating asphalt content test results. Results of the data analysis show that some variations in testing procedure can be identified through the temperature-time series. In particular, the first tests performed each day are readily discernable from subsequent tests, even after allowing significant oven warm-up time. Variations in sample size or asphalt content are also shown to create differing temperature-time series; however, the difference is not significant enough to identify errors on individual tests, it is only demonstrable across the group averages. Despite the differences in temperature-time data, no conclusive difference in the accuracy of the test results was found. It is concluded that the monitoring of the temperature-time series may be a valuable tool in identifying systematic and gross errors introduced during the asphalt content by ignition test method. However, while the preliminary results of this study demonstrate that differences do exist, additional testing should be undertaken to assess the reliability of the proposed method under real-world scenarios. Additional trials will also be required to identify any other procedural variations which result in differences in the temperature-time trend.

Armstrong Avenue Reconstruction Phase 1

Fri, 09/21/2018 - 20:32
Armstrong Avenue Reconstruction Phase 1
by Brown,A.
2018.
TAC 2018: Innovation and Technology: Evolving Transportation - 2018 Conference and Exhibition of the Transportation Association of Canada.
CA6 ARH_10 2018A5106 - INTERNET


Armstrong Avenue in Georgetown Ontario is one of the Town’s industrial hub’s within Halton Hills. In 2013, the Town of Halton Hills initiated the process to reconstruct Armstrong Avenue with a forecast construction date of 2017-2019. The project was broken into two phases. Phase 1 (approx. 1310m) and Phase 2 (approx. 1310m) (Appendix A). Through an Ontario Municipal Class Environmental Assessment study it was identified as a section of road in need of active transportation and improved traffic operations to service the multiple industrial/commercial businesses (approx. 115) (Appendix B). In 2013, the Town of Halton Hills developed a Community Sustainability Strategy (Strategy) where the four pillars of sustainability: cultural vibrancy, economic prosperity, environmental health and social wellbeing, were identified and are recognized in the all of the Town’s work including Armstrong Avenue Reconstruction - Phase 1 project.

Application of Artificial Intelligence on Quality-Control Tool for Optimum Binder Content Determination of OGFC Mixtures

Fri, 09/21/2018 - 20:32
Application of Artificial Intelligence on Quality-Control Tool for Optimum Binder Content Determination of OGFC Mixtures
by Mejias,Y; Gunaratne,M.
2018.
TAC 2018: Innovation and Technology: Evolving Transportation - 2018 Conference and Exhibition of the Transportation Association of Canada.
CA6 ARH_10 2018A5105 - INTERNET


In some transportation agencies including the Florida Department of Transportation (FDOT) use Open Graded Friction Course (OGFC) mixture to improve skid resistance of asphalt pavements under wet weather. FDOT designs OGFC mixtures using a pie plate visual draindown method FM5-588, which depends on the Optimum Binder Content (OBC) and represents if the mixture has sufficient bonding between the aggregate and asphalt binder, otherwise known as the asphalt binder draindown (ABD). In the FM5-588 the OBC is determined based on visual inspection by trained and experienced technicians. In order to eliminate the human subjectivity involved in aforesaid method, an artificial intelligence (AI) methodology for prediction of the OBC using digital images of the test specimens, perceptual image coding and General Regression Neural Network was created. Then, the author developed a quality control tool (QCT) for the aforementioned AI method to enhance its reliability when implemented by other agencies and contractors. QCT is developed using three quality control imaging parameters of ABD of the test specimen images. In general, this study found that the newly developed AI software provides satisfactory and reliable estimations of OBC and that the QCT will enhance the reliability and accuracy of the AI OBC estimation software.

Alignment of Weight Restrictions on Nine-Month Primary Highways to Mitigate Climate Impacts of Earlier Spring

Fri, 09/21/2018 - 20:32
Alignment of Weight Restrictions on Nine-Month Primary Highways to Mitigate Climate Impacts of Earlier Spring
by Imran,S; Lui,A.
2018.
TAC 2018: Innovation and Technology: Evolving Transportation - 2018 Conference and Exhibition of the Transportation Association of Canada.
CA6 ARH_10 2018A5104 - INTERNET


Saskatchewan’s Ministry of Highway and Infrastructure (MHI) has a highway vehicle weight management system to maximize highway infrastructure utilization for economic activities while protecting highways to ensure a longer service life. The provincial highway system is generally managed in three allowed vehicle weight categories: i) Primary highways with year round access, ii) secondary highways that are weight restricted during early spring, and iii) nine-month primary highways that allow primary weight for 9 months and secondary weight for the remaining three spring months. The categories were established according to highway pavements’ structure capability to handle vehicle weight. The weight restriction on secondary and nine-month primary highways is mainly to protect these lower standard pavements from spring-thaw damage. The secondary highways are subject to the spring weight restriction based on weather triggers (thermistor data). However, to allow for planning freight operations, the nine-month primary follows a fixed schedule where the weight is reverted to secondary for three spring months every year. MHI conducted a study to evaluate if the timing of the three-month secondary weight reversion for nine-month primary highways could be changed to align better with early spring-thaw period. Extensive analysis of historical temperature data, historical spring weight restriction dates, and Benkelman Beam Deflection data from various locations in the province was conducted. The study concluded that due to the different geographical and climatic conditions in the province, highways in the south of the province are more vulnerable from early spring-thaw than those in the north. While the current timing of the three-month secondary weight reversion for nine-month primary highways creates an unacceptable risk for highways in the south, they were found adequate for highways in the north. As a result, a new policy has implemented the secondary weight reversion 15 days earlier for nine-month primary highways in the south than in the north.

A Study on Pavement Network Condition and Reporting in the Province of Alberta Through a Questionnaire Survey

Fri, 09/21/2018 - 20:32
A Study on Pavement Network Condition and Reporting in the Province of Alberta Through a Questionnaire Survey
by Newstead,B; Hashemian,L; Bayat,A.
2018.
TAC 2018: Innovation and Technology: Evolving Transportation - 2018 Conference and Exhibition of the Transportation Association of Canada.
CA6 ARH_10 2018A5103 - INTERNET


Government agencies such as municipalities own several lane kilometers of roadways all in varying conditions depending on their traffic loads, environment, material types, and construction methods. Managing a vast inventory of assets can be challenging and depending on the size of the municipality, sufficient resources may not always be present for municipalities to accurately understand their networks’ needs. Size of municipalities notwithstanding, funding to maintain these networks always remains a challenge. Finite funds are constantly competing against other priority infrastructure as well as politically motivated projects being broadcasted the loudest. Moreover, not all networks are created equal; some networks may be more rural and require different treatment and maintenance needs compared to an exclusively urban environment. Understanding all these parameters is critical in order to grasp the complexities and challenges that Alberta municipalities and agencies face when maintaining their transportation networks. To determine these answers, a questionnaire survey was conducted to the Pavement Management Users Group in Alberta. The results showed several consistencies related to the use of traditional pavement treatment methods, such as mill, overlay, and conventional reconstruction. This study noted, however, that there exists a gap in the use of preservation methods, such as microsurfacing, being used around the province of Alberta, as well as staff resource and asset management challenges. This survey provides a unique insight into the treatment selections and resources dedicated to roadways and strategies around the province.

A Study in Practice: Evaluating the Life Expectancy of an MSE Wall with Steel Strip Reinforcement

Fri, 09/21/2018 - 20:32
A Study in Practice: Evaluating the Life Expectancy of an MSE Wall with Steel Strip Reinforcement
by Mirmirani,S; Rrokaj,T.
2018.
TAC 2018: Innovation and Technology: Evolving Transportation - 2018 Conference and Exhibition of the Transportation Association of Canada.
CA6 ARH_10 2018A5102 - INTERNET


In over 50 years since the invention of Reinforced Earth walls, structures have been designed to fulfill a variety of retaining solutions for infrastructure projects, as well as mining, marine, industrial, commercial and residential projects. Over the service life of these projects, owners may decide to change the scope of structures. These changes may include: design life extension, wall height increase and other alterations in geometry, changes in loading configuration, etc. To accommodate these modifications, structures must be assessed based on new scope, in addition to incorporating design changes. This paper will present an inspection and evaluations program though a case study where specific assessment methods and techniques have been utilized to demonstrate whether Mechanically Stabilized Earth (MSE) walls can be stable for the required changes in scope. The assessment method includes visual inspections, strip sample extractions, and corrosion assessment. Since the service life of the structure is dependent on the strength of the soil reinforcements, by evaluating the strength of the test samples, the stability and remaining design life of structures at the current state can be determined. Following a similar method, the stability of a structure can be evaluated if loading conditions or geometry configurations need to be changed over the remaining structure’s design life.

4th Avenue Flyover Project Overview

Fri, 09/21/2018 - 20:32
4th Avenue Flyover Project Overview
by Chapman,J.
2018.
TAC 2018: Innovation and Technology: Evolving Transportation - 2018 Conference and Exhibition of the Transportation Association of Canada.
CA6 ARH_10 2018A5101 - INTERNET


As a demonstration project of the Pedestrian Strategy, The City of Calgary collaborated with students from Langevin School, the University of Calgary’s Landscape Architecture program, the Bridgeland Riverside Community Association (BRCA), Calgary Drop-In Centre and other stakeholders to imagine how the space beneath the 4 Avenue flyover could become a valued community space and walking corridor. The project involves piloting innovative technical measures (transportation, art and bioretention) and non-traditional engagement and design approaches under the umbrella of placemaking and tactical urbanism.

TAC 2018: Innovation and Technology: Evolving Transportation - 2018 Conference and Exhibition of the Transportation Association of Canada

Fri, 09/21/2018 - 20:32
TAC 2018: Innovation and Technology: Evolving Transportation - 2018 Conference and Exhibition of the Transportation Association of Canada
2018.
TAC 2018: Innovation and Technology: Evolving Transportation - 2018 Conference and Exhibition of the Transportation Association of Canada.
CA6 ARH_10 2018A5101-64 - INTERNET

Re-exploring the AASHTO 1993 Method for a Cost-Effective Pavement Design in Manitoba

Mon, 09/10/2018 - 20:36
Re-exploring the AASHTO 1993 Method for a Cost-Effective Pavement Design in Manitoba
by Ahammed,MA.
2018.
TAC 2018: Innovation and Technology: Evolving Transportation - 2018 Conference and Exhibition of the Transportation Association of Canada.
CA6 ARH_10 2018A5148 - INTERNET


Pavement structures costs constitute to the majority of the total costs of highway construction projects. Therefore, it is important to optimize each pavement structure to avoid an under-deign or overspending on any project. In the past, Manitoba was using the Benkelman Beam Rebound (BBR) deflection method for the rehabilitation design. A mixed approach, together with several environmental and structural adjustments, was used in pavement design for the new construction or reconstruction projects. The assumed or estimated values of subgrade and layer materials stiffness did not well represented the materials those are in place or use in Manitoba. These led to an overdesign for most rehabilitation and some new construction projects. Due to several limitations of the AASHTOWare Pavement ME Design approach, that yet to be resolved, Manitoba has undertaken major changes to its existing design practices for cost-effective pavement structures. These include the use of more reliable/reasonable design traffic loading, layer materials and subgrade stiffness and drainage properties, pavement drainage condition, subgrade soils frost susceptibility, serviceability and reliability. As a result, significant cost savings are being realized. This paper presents an overview of Manitoba’s new approach and outcome to share with other agencies, designers and students.

Replacement of the City of Saskatoon’s Historic Traffic Bridge

Mon, 09/10/2018 - 19:41
Replacement of the City of Saskatoon’s Historic Traffic Bridge
by DeGrow,K; Richer,J.
2018.
TAC 2018: Innovation and Technology: Evolving Transportation - 2018 Conference and Exhibition of the Transportation Association of Canada.
CA6 ARH_10 2018A5147 - INTERNET


Originally built in 1907, the Traffic Bridge was Saskatoon’s first bridge to carry vehicular traffic. The Traffic Bridge was designed as a 5-span Parker through truss and came into being when residents of the Village of Nutana agreed to merge with the Town of Saskatoon and the Village of Riversdale to form the City of Saskatoon. The heritage value of the Traffic Bridge lies in its status as a landmark in the community, its form, massing, and location, the engineering technology used (steel truss architecture), and the original concrete piers and abutments. Throughout its 103-year history, the bridge has been used for horse and carriage, street car, and modern vehicle use. The bridge also has historical notoriety as Saskatoon’s only marine disaster when the sternwheeler S.S. City of Medicine Hat collided broadside into the southern-most pier of the bridge and sank on June 10, 1908. The bridge was closed in August 2010 due to public safety concerns due to advanced deterioration of critical structural members. In 2010, the City commissioned a needs assessment and planning study of the Traffic Bridge, which investigated multiple alternatives and potential replacement, included extensive public consultation, regulatory review and debate, as well as City Council presentations. Many elements of the existing bridge were to be incorporated into the new bridge. Engineering studies were completed on the existing elements to determine strengths and compatibility with the new structure. A P3 model was used for the design and construction of the replacement bridge. Many challenges presented themselves during the design and construction of the structure and these challenges provided unique resolutions. The bridge is currently under construction, and upon completion, the contractor will be responsible for the maintenance of the bridge for the next 30 years.

Redeveloping the Bonatenture Highway as an Urban Boulevard

Mon, 09/10/2018 - 18:36
Redeveloping the Bonatenture Highway as an Urban Boulevard
by Carrière,J.
2018.
TAC 2018: Innovation and Technology: Evolving Transportation - 2018 Conference and Exhibition of the Transportation Association of Canada.
CA6 ARH_10 2018A5146 - INTERNET


The Bonaventure Project is a series of strategic undertakings aimed at providing user-friendly, functional and safe mobility options to all users. The Bonaventure Project Vision includes three main objectives: Create a prestigious, functional and user-friendly gateway into the downtown core; Facilitate the re-weaving of the urban fabric through the removal of an elevated highway structure in the urban environment; Support private sector driven urban development through the implementation of key strategic initiatives in the downtown core.

Practitioner's Guide to Planning, Designing, and Implementing Bicycle Highways in North America

Mon, 09/10/2018 - 18:15
Practitioner's Guide to Planning, Designing, and Implementing Bicycle Highways in North America
by Taciuk,A; Davidson,G.
2018.
TAC 2018: Innovation and Technology: Evolving Transportation - 2018 Conference and Exhibition of the Transportation Association of Canada.
CA6 ARH_10 2018A5145 - INTERNET


North American cities need excellent bicycle infrastructure between regional destinations to allow residents to cycle long distances. Planners must make long distance bicycle travel feasible if they are serious about treating cycling as a form of mass transportation (Transport for London, 2014). Bicycle highways are high quality bicycle routes that connect major destinations and are designed for safe and comfortable long-distance travel. They facilitate comfortable and safe long distance travel. Preliminary research has shown that they are effective in increasing ridership and attracting users from other modes such as cars or transit. The purpose of this review is to offer guidance on how practitioners can plan, design, and implement bicycle highways as part of a bikeway network. The study draws upon literature and design guidance and seven case studies that are emerging in Europe and Asia. Through this review we propose a definition for bicycle highways, differentiate them from other bikeway facilities, present research on their effects, and characterize their planning, design, and implementation. We conclude this papers with seven policy takeaways for North American practitioners.

Pile Driving Effects on a Steel Truss Railway Bridge During Rehabilitation

Mon, 09/10/2018 - 17:24
Pile Driving Effects on a Steel Truss Railway Bridge During Rehabilitation
by Osback,J.
2018.
TAC 2018: Innovation and Technology: Evolving Transportation - 2018 Conference and Exhibition of the Transportation Association of Canada.
CA6 ARH_10 2018A5144 - INTERNET


This paper summarizes the performance of a steel truss railway bridge near Saskatoon, SK, which remained in service during pile driving activities for pier rehabilitation and new pier construction. 289 H section piles were driven to embedment depths of 9 m for rehabilitation of existing concrete piers, and 12 m for new piers, for the western portion of the bridge, over an approximate one-month timeline. Piles for existing piers were driven within one metre of the existing pile caps, which were supported on timber piles. Monitoring instrumentation included surveying of prisms mounted to the bridge deck and piers and installation of tilt loggers, and a vibration monitoring system, to monitor the lateral deflection and accelerations, respectively, of the structure during pile driving. The collected data provides an understanding of the response of the bridge structure from pile driving into the hard foundation till, along with expansion and contraction effects due to extreme temperature variations. Survey and tilt logger data were found to correlate well together, and with changes in ambient temperature. Wave Equation Analysis of Pile Driving (WEAP) was conducted to estimate pile termination criteria and driving hammer performance. Pile Dynamic Analyzer (PDA) testing was conducted on 10% of the piles; 9 and 12 m long piles driven into Sutherland Till exhibited average vertical capacities in the range of 1,940 kN and 2,700 kN, respectively.

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.

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