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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.

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.

Safety Evaluation of Signalized Restricted Crossing U-Turn Intersections

Sat, 06/02/2018 - 20:33
Safety Evaluation of Signalized Restricted Crossing U-Turn Intersections
by Hummer,JE; Rao,S.
2017.
US1 DTH680 2017S36 - MAIN


This study evaluated restricted crossing U-turn (RCUT) intersection and was conducted by the DCMF program for the Evaluation of Low-Cost Safety Improvements Pooled Fund Study. RCUT is defined as a three-approach or four-approach intersection where minor street left-turn and through movements (if any) are rerouted to one-way downstream U-turn crossovers. RCUTs are also known as superstreets, J-turns, reduced conflict intersections, and synchronized streets. Previous research has shown that unsignalized RCUTs are generally safer than conventional options. However, there are no known studies specific to the safety of signalized RCUTs. The objective of this effort was to collect and analyze crash data to develop a crash modification factor (CMF) for signalized RCUTs. This study collected and analyzed crash data before and after conversion of 11 intersections from conventional to RCUT design. The intersections were in suburban areas on four- or six-lane arterials. For most individual sites and groups of sites examined, odds ratio tests showed that there were high-quality comparison sites available, and regression to the mean was not an issue. The project team recommends a CMF of 0.85 for overall crashes and 0.78 for injury crashes for the conversion of a conventional intersection to an RCUT intersection. Based on those CMFs, the project team produced an estimated benefit-to-cost ratio of 3.6 to 1.0 when considering safety and operations or 2.6 to 1.0 considering safety only.

Safety Evaluation of Edge-Line Rumble Stripes on Rural Two-Lane Horizontal Curves

Sat, 06/02/2018 - 20:25
Safety Evaluation of Edge-Line Rumble Stripes on Rural Two-Lane Horizontal Curves
by Himes,S; Gross,F; Persaud,B; Eccles,K.
2017.
US1 DTH680 2017E26 - MAIN


The Development of Crash Modification Factors (DCMF) program conducted safety evaluations of edge-line rumble stripes (ELRSs) on rural two-lane horizontal curves for the Evaluation of Low-Cost Safety Improvements Pooled Fund Study. This study evaluated the application of ELRSs on rural two-lane horizontal curves. ELRSs are a variation of common shoulder rumble strips used to alert drowsy or distracted drivers when they are leaving the travel lane to the right. ELRSs are installed with the edge-line pavement marking placed directly over the rumble strip. Geometric, traffic, and crash data were obtained at treated rural two-lane horizontal curves in Kentucky and Ohio. To account for potential selection bias and regression-to-the-mean, an empirical Bayes before–after analysis was conducted using reference groups of untreated rural horizontal curves with similar characteristics to the treated sites. The analysis also controlled for changes in traffic volumes over time and time trends in crash counts unrelated to the treatment. Owing to a small sample for the reference group in Kentucky and a simultaneous statewide curve warning sign upgrade program in Ohio, alternative reference sites were used to account for annual trends. The results for Kentucky indicated statistically significant reductions for total, injury, run-off-road (ROR), and nighttime crashes, with crash modification factors (CMFs) of 0.75, 0.64, 0.74, and 0.63, respectively. The results for Ohio indicated statistically significant reductions for all crash types, with total, injury, ROR, nighttime, and nighttime ROR CMFs of 0.79, 0.79, 0.78, 0.75, and 0.71, respectively. The two States’ results could not be combined because of the statewide curve signing program in Ohio. It is important to note that all crash types considered in this research excluded intersection-related and animal crashes. Benefit–cost (B/C) ratios were estimated to be 331:1 for Kentucky and 477:1 for Ohio. If ELRSs were used as a curve-specific treatment, the B/C ratio would likely be much smaller because of the higher installation cost; however, these results suggest that the treatment can be highly cost effective.

Development and Evaluation of a Non-Tracking Asphalt Emulsion for Tack Coats and Fog Seals

Fri, 05/04/2018 - 20:42
Development and Evaluation of a Non-Tracking Asphalt Emulsion for Tack Coats and Fog Seals
by Kucharek,AS; Esenwa,M; Varamini,S; Bickle,E; Cormier,A.
2017.
Proceedings of the Sixth-Second Annual Conference of the Canadian Technical Asphalt Association (CTAA): Halifax, Nova Scotia.
CA6 AIH___ 2017P15 - MAIN


Tack coats are thin applications of asphalt emulsion between the layers of a pavement structure with the role of enhancing adhesion. Fog seals are thin emulsion applications to pavement surface for protecting the surface from oxidation and water ingress, as well as reducing the risk of raveling and stone loss. One of the downsides of using asphalt emulsions for these applications is the required breaking and curing time. Even after curing, traditional emulsion grades will track onto nearby surfaces. Slow curing fog seals require longer road closures and/or a light sand application before trafficking. This paper presents the development stages of a non-tracking emulsion developed for bond coats and fog seals. The emulsion was formulated and engineered to be fast curing and provide a hard, non-tracking surface, suitable to support traffic without the use of sand application. Its tracking properties were assessed using novel tracking and curing tests, and its performance as a bond coat was measured using the tack coat shear test developed by McAsphalt. Trial projects of tack coating and fog seals were conducted from 2013 to 2016 throughout several Canadian provinces. Performance to date in the field, as well as some observed challenges, are presented.

Predicting HMA Fatigue Using the Double Edge Notched Tension Test and Multiple Stress Creep Recovery Test

Fri, 05/04/2018 - 20:11
Predicting HMA Fatigue Using the Double Edge Notched Tension Test and Multiple Stress Creep Recovery Test
by Aurilio,M; Mikhailenko,P; Baaj,H.
2017.
Proceedings of the Sixth-Second Annual Conference of the Canadian Technical Asphalt Association (CTAA): Halifax, Nova Scotia.
CA6 AIH___ 2017P14 - MAIN


Fatigue resistance is an important factor for high quality Hot Mix Asphalt (HMA). Asphalt cements containing higher concentrations of polymer are known to be more strain tolerant, which can provide improved fatigue resistance in HMA. Use of polymer modified asphalt cement is a proven way to improve fatigue performance. Many municipalities and the Ontario Ministry of Transportation have implemented the Double Edge Notched Tension (DENT) test to improve the fatigue performance of the asphalt cement and the corresponding HMA. The DENT test is performed at an intermediate temperature that should correspond with fatigue performance. The Multiple Stress Creep Recovery (MSCR) test is an environmental test that measures the compliance and elastic response of an asphalt binder. The MSCR test is conducted at the high-performance grade temperature based on the local 7-day maximum temperature. The results from this research have shown that there is no clear relationship between increasing concentration of polymer modification and DENT performance. On the other hand, the percent recovery showed a very good correlation with polymer modification and performance. Based on the information presented in this paper, the MSCR is ultimately expected to be validated by HMA fatigue testing while the DENT is not.

Safety Evaluation of Red-Light Indicator Lights at Intersections

Tue, 05/01/2018 - 19:27
Safety Evaluation of Red-Light Indicator Lights at Intersections
by Himes,S; Gross,F; Persaud,B; Eccles,K.
2017.
US1 DTH680 2017S16 - MAIN|INTERNET


The Development of Crash Modification Factors program conducted the safety evaluation of red-light indicator lights (RLILs) at intersections for the Evaluation of Low-Cost Safety Improvements Pooled Fund Study. This study evaluated safety effectiveness of RLILs. RLILs are auxiliary lights mounted on signal heads, mast arms, or poles that are directly connected to a traffic-control signal. The RLIL activates at the onset of the red phase and allows an enforcement officer to observe red-light running from downstream of the intersection. This strategy is intended to reduce the frequency of crashes resulting from drivers disobeying traffic signals by providing a safer and more efficient means for police to enforce the red interval. Geometric, traffic, and crash data were obtained at treated four-legged signalized intersections in Florida. To account for potential selection bias and regression-to-the-mean, an empirical Bayes before–after analysis was conducted using reference groups of untreated four-legged signalized intersections with characteristics similar to those of the treated sites. The analysis also controlled for changes in traffic volumes over time and time trends in crash counts unrelated to the treatment. Results indicate statistically significant crash reductions for most crash types. Disobeyed signal crashes had an estimated crash modification factor (CMF) of 0.71. Total crashes, fatal and injury crashes, right-angle, and left-turn crashes had estimated CMFs of 0.94, 0.86, 0.91, and 0.60, respectively. The benefit-cost ratio estimated with conservative cost and service life assumptions was 92:1 for four-legged signalized intersections. The results suggest that the treatment, even with conservative assumptions on cost, service life, and the value of a statistical life, can be cost effective. In addition to the crash-related benefits, RLILs can improve the efficiency and safety of red-light running enforcement efforts. While this study did not evaluate the efficiency and safety impacts with respect to enforcement, it should be noted that RLILs do allow police to observe violators from a downstream position, eliminating the need for a second observer (upstream) and the need to pursue a violator through the red light.

Author's Closure: Comments on "Cold Winter and Early Pavements Cracking Observed in Ontario"

Fri, 04/27/2018 - 17:39
Author's Closure: Comments on "Cold Winter and Early Pavements Cracking Observed in Ontario"
by Uzarowski,L.
2017.
Proceedings of the Sixth-Second Annual Conference of the Canadian Technical Asphalt Association (CTAA): Halifax, Nova Scotia.
CA6 AIH___ 2017P22 - MAIN


The authors of the original 2015 paper entitled “Cold Winter and Early Asphalt Pavement Cracking Observed in Ontario” would like to acknowledge the detailed response provided by Dr. Keith MacInnis, Senior Technical Advisor, Canadian Asphalt Industries, Hamilton, Ontario. We also appreciate that the above noted paper generated interest and discussion around this critical topic. The subject described in the paper was of great importance to the road owners, and the Canadian Technical Asphalt Association (CTAA) is the best forum for this kind of discussion. This paper provides comments from the lead author of the paper in response to the comments that were provided by Dr. Keith MacInnis on the original 2015 paper.

Light Colour Asphalt Pavement

Fri, 04/27/2018 - 17:39
Light Colour Asphalt Pavement
by Uzarowski,L; Rizvi,R; Manolis,S.
2017.
Proceedings of the Sixth-Second Annual Conference of the Canadian Technical Asphalt Association (CTAA): Halifax, Nova Scotia.
CA6 AIH___ 2017P21 - MAIN


Light Colour Asphalt Pavement (LCAP) is a process of designing and constructing asphalt pavements that meets the Leadership in Energy and Environmental Design (LEED) Solar Reflective Index (SRI) requirement that at a minimum 50 percent of the hardscape can be constructed using materials having an SRI value of 29 or higher. The purpose of the development of LCAP is to provide developers looking to achieve LEED certification with a paving alternative that provides performance that is equivalent to conventional asphalt pavement, but that will also meet the requirement of LEED. The LCAP process includes aggregate selection, asphalt mix modification, placement of asphalt mic, stripping of surface asphalt film from new pavement, and evaluation of reflectivity of aggregates, mixes, and in-place pavements. The very light colour aggregate from Coco’s Badgley Island Quarry was identified as a suitable material for LCAP. Conventional new asphalt pavements have an SRI of about 0, and weathered asphalt pavements have an SRI of about 6. This paper describes the importance of LCAP technology in reducing the heat island effect, the benefits of using it, required testing, and practical development of a LCAP mix.

Investigation into Temperature Effect on AASHTO Back Calculated Subgrade Resilient Modulus

Fri, 04/27/2018 - 17:39
Investigation into Temperature Effect on AASHTO Back Calculated Subgrade Resilient Modulus
by Reggin,A; Palsat,B; Riessner,M; Juhasz,M.
2017.
Proceedings of the Sixth-Second Annual Conference of the Canadian Technical Asphalt Association (CTAA): Halifax, Nova Scotia.
CA6 AIH___ 2017P20 - MAIN


Over the past 25 years, Alberta Transportation (AT) has collected successive datasets of Falling Weight Deflectometer (FWD) deflection data over their 21,000 km (almost entirely flexible) highway network. A study was conducted to investigate the variation in back calculated subgrade modulus between two or more test dates in different collection years using AT’s FWD inventory data. Presently, AT uses the AASHTO 1993 method for the design of flexible pavement rehabilitation. The AASHTO 1993 design method only applies a temperature correction to the FWD central deflection, which is not directly used for estimated subgrade support strength, and therefore does not account for subgrade strength variation as a function of temperature at the time of testing. This paper presents a subgrade modulus temperature correction model developed from the FWD inventory data. The model was able to reduce the variation of subgrade modulus by a statistically and practically significant amount. If implemented, the model can be incorporated into the pavement rehabilitation design method to either minimize the risk of an under-designed pavement from using a higher than typical back calculated subgrade modulus, or minimize the risk (added costs) of over-design from using lower than typical back calculated subgrade modulus.

Automated Vehicles Symposium 2017: Summary of a Symposium

Tue, 04/17/2018 - 19:41
Automated Vehicles Symposium 2017: Summary of a Symposium
2018.
Transportation Research Circular ; 232.
US6 AMF_75 C - MAIN


TRB's E-Circular 232: Automated Vehicle Symposium 2017: Summary of a Symposium highlights the themes from an event that took place on July 11–13, 2017 in San Francisco, California. The report follows the general symposium agenda. The presentations by speakers in the general sessions are summarized, including the highlights from the 25 breakout sessions. A list of the posters presented in two sessions is provided. The appendices provide a description of the key topics covered in the breakout sessions.

12-Year Performance Review of Bloomington Road (York Region Road 40) Rehabilitation Rehabilitation using Cold In-Place Recycling and a 6.7 mm Fine Stone Mastic Asphalt

Wed, 04/04/2018 - 20:46
12-Year Performance Review of Bloomington Road (York Region Road 40) Rehabilitation Rehabilitation using Cold In-Place Recycling and a 6.7 mm Fine Stone Mastic Asphalt
by Moore,T; Farashah,MK; Esenwa,M; Varamini,S; Kucharek,AS.
2017.
Proceedings of the Sixth-Second Annual Conference of the Canadian Technical Asphalt Association (CTAA): Halifax, Nova Scotia.
CA6 AIH___ 2017P13 - MAIN


Bloomington Road, Regional Highway 40 in the Regional Municipality of York, serves as a major artery for vehicles accessing Highway 404. The section under review between Kennedy Road and Highway 48 was built in 1969 and rehabilitated with an innovative pavement design in 2005. Prior to rehabilitation, the asphalt surface was severely oxidized with extensive thermal cracking, however, the longitudinal and transverse profiles of the roadway were in relatively good condition and there was no sign of major structural failures. Rehabilitation of the roadway consisted of Cold In-Place Recycling (CIR), a Heavy-Duty Asphalt Binder Course (HDBC) Hot Mix Asphalt (HMA), and a 6.7 mm rut-resistant fine-graded Stone Mastic Asphalt (SMA). This paper provides a review of the design and construction details for the pavement lifts, as well as material and process selection details. Special consideration is given to the curing of the CIR and the rut resistance of the SMA lift. This paper also presents a long-term field performance evaluation of the rehabilitated pavement section with quantified in-situ performance by means of field observations, laboratory evaluations of retrieved pavement specimens, and semi-automated pavement performance data survey collected by York Region over twelve years of in-service pavement life.

Using Complex Modulus (E*) Test to Evaluate Moisture Damage of Hot Mix with Glass Aggregates

Wed, 04/04/2018 - 19:38
Using Complex Modulus (E*) Test to Evaluate Moisture Damage of Hot Mix with Glass Aggregates
by Lachance-Tremblay,E; Vaillancourt,M; Perraton,D; Di Benedetto,H.
2017.
Proceedings of the Sixth-Second Annual Conference of the Canadian Technical Asphalt Association (CTAA): Halifax, Nova Scotia.
CA6 AIH___ 2017P12 - MAIN


Evaluation of the moisture damage of HMA is normally conducted on loose aggregate coated with binder or on HMA compacted samples; both methods having their respective disadvantages. Those tests are empirical and are susceptible to give misinterpretation of moisture damage. The complex modulus test for asphalt mixtures, also known as the dynamic modulus, characterizes the mixtures Linear Visco-Elastic (LVE) properties. This paper presents a method used at LCMB to evaluate the moisture damage of HMA samples based on LVE measurements. Two reference mixtures and three mixtures with glass aggregates were tested. One set of samples contained hydrated lime as an anti-stripping additive. First, the LVE properties of the samples were evaluated in a dry condition. Then, the samples were saturated with water and cured into a water bath at 60 deg C for 14 days and evaluated again. Overall, complex modulus test is very effective at evaluating the moisture damage of asphalt samples. This method has multiple advantages and many analysis options, which make it very interesting to evaluate moisture damage. Moreover, it was found that hydrated lime is a very effective anti-stripping additive. For some of the mixtures with anti-stripping agent, water soaking had little effect on the LVE properties.

Comparison of New Test Methods and New Specifications for Rutting Resistance and Elasticity of Modified Binders

Thu, 03/29/2018 - 21:37
Comparison of New Test Methods and New Specifications for Rutting Resistance and Elasticity of Modified Binders
by Moraes,R; Swiertz,D; Bahia,H.
2017.
Proceedings of the Sixth-Second Annual Conference of the Canadian Technical Asphalt Association (CTAA): Halifax, Nova Scotia.
CA6 AIH___ 2017P11 - MAIN


There is no consensus among state highway agencies as to the appropriate binder specifications required for adequate quality control and acceptance of modified binders. Supplemental tests have been adopted in addition to standard Performance Grade (PG) tests and are often referred to as “PG+” procedures. The Multiple Stress Creep and Recovery (AASHTO M332) test has been proposed to replace the AASHTO M320 for PG grading of binders. However, some agencies are concerned that asphalt binder formulation will change after adopting the new system, while others are unsure how to relate the current M320 grades to the new S, H, and V grades. In this study, testing of a large number of binders was completed and correlations between results of “PG+” test and MSCR tests were performed. Regarding the MSCR test, results show that the %R parameter is a good candidate to detect the presence, and potentially the quantity, of elastomeric modification. However, using universal limits for the MSCR %R parameter that are dependent on Jnr values in not practical nor useful since current binder formulations are controlled differently by agencies. Furthermore, no logical equivalency of M320 PG grades to M332 traffic grades was identified, so changes to binder formulations are anticipated.

Investigation of the Tensile Strength of Hot Mix Asphalt Incorporating Pulp Aramid Fiber

Thu, 03/29/2018 - 21:37
Investigation of the Tensile Strength of Hot Mix Asphalt Incorporating Pulp Aramid Fiber
by Saliani,SS; Carter,A; Baaj,H; Badeli,S.
2017.
Proceedings of the Sixth-Second Annual Conference of the Canadian Technical Asphalt Association (CTAA): Halifax, Nova Scotia.
CA6 AIH___ 2017P10 - MAIN


Premature cracking of flexible pavements is a very common problem in Canada. Nowadays, it is common to use several types of additives and modifiers to asphalt binders and asphalt mixes to improve their performance and increase the service life of flexible pavements. In order to mitigate pavement cracking, the asphalt mixes used in the pavement structure need to have a high resistance to fatigue or thermal cracking according to their position in the pavement structure. Several studies reporting on the use of fibers in asphalt concrete have been found in the literature. The objective of this project is to study the impact of the addition of Pulp Aramid Fiber (PAF) to Hot Mix Asphalt (HMA) in terms of mix design and indirect tensile strength. The optimum asphalt content of the fiber mixes is first determined and then the impact of fiber on their volumetric properties is investigated. Finally, the behavior of PAF in HMA is characterized by indirect tensile testing at different conditions. PAF mixes showed better ductility, even at lower temperatures, than the control mix. Therefore, PAF would lead to an improvement of the resistance to low temperature cracking and would delay crack propagation in the mix.

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