Tentative Program for 2015 CTAA Conference November 15-18, 2015

Abstracts (In Tentative Program Order)

1. “Development of Performance Specifications for Flexible Pavements in Ontario” Dale Smith, Stephen Lee, and Tom Kazmierowski

Increasing portions of federal, provincial and municipal resources are being allocated to preserve and maintain Canada’s roadways. Currently, most materials and construction specifications for pavement rehabilitation and construction activities provide little or no linkage between quality assurance methods and the in-service performance of the treatment. The Ministry of Transportation of Ontario (MTO) is moving to develop and implement performance specifications to bridge this gap. MTO defines performance specifications as specifications that describe how the finished product should perform over time.

This paper will describe the framework used to develop and implement performance specifications for flexible pavements in Ontario. Details on modelling the performance requirements, measuring performance and setting of acceptance criteria will be presented. Implementation of these specifications in traditional Design-Bid-Build contracts and in innovative warranty based alternate delivery contracts will be discussed.

2. “Laboratory Crack Testing of Hot Mix Asphalts Containing Vacuum Tower Asphalt Extender” Jason C. Wielinski, Andreas Horton, Anthony J. Kriech and Gerald A. Huber

Vacuum Tower Asphalt Extender (VTAE), also known as recycled engine oil bottoms or re-refined vacuum tower bottoms are blended with paving grade bitumen to improve low temperature properties. Some road owner agencies have expressed concerns regarding the use of VTAE in asphalt mainly related to premature cracking and accelerated aging of the asphalt binders. Previous research completed has shown, that binder aging and HMA mixture properties, including resistance to moisture damage, stiffness and fatigue are not compromised with the inclusion of VTAE in the liquid bitumen.

The objective of this research is to analyze the cracking potential of asphalt mixtures with varying levels of VTAE using multiple crack testing procedures. Two sources of VTAE were mixed with neat asphalts at 3%, 6% and 9% resulting in six PG 58-28 binders with VTAE . A neat PG 58-28 binder was utilized as the control binder for the study. These seven binders were mixed with aggregates at the same percentage resulting in a mixture meeting state DOT volumetric requirements.

The HMA mixes were then tested for cracking potential using two protocols; the semi-circular bend (SCB) test and the disc shaped compact tension (DCT) test. Although different in how the mixtures are subjected to strains, they both measure how much energy is required to proprgate a crack inthe mixture. Higher energy levels would suggest the mixture would be less prone to cracking in service. The results could show if the source or amount of VTAE in the binders influence cracking potential.

A partial set of the mixes was also subjected to laboratory long term aging and then tested for cracking potential. The purpose of this analysis was to evaluate if mixtures with VTAE blended binders undergo accelerated aging causing embrittlement and cracking in the mixture compared to mixtures with neat binders

3. “Ontario’s Initiative to Enhance Asphalt Cement Quality” Seyed Tabib, Chloe Johnson, and Pamela Marks

The Ontario Ministry of Transportation (MTO) has identified many instances of premature pavement cracking that has been linked to differences noted in asphalt cement characteristics that are not currently distinguished by Performance Graded Asphalt Cement (PGAC) specifications. MTO, in conjunction with Queen’s University, developed two testing methods to better predict the cracking that was occurring: the Double Edge Notched Tension (DENT) test and the Extended Bending Beam Rheometer (ExBBR) test.

In 2010 MTO wrote a cracking performance specification which led to the question: What was the best strategy to select better quality asphalt cement? Discussions with the asphalt industry resulted in MTO incorporating and evaluating three different strategies in over 30 projects identified in 2011. In addition to the routine AASHTO M320 compliance criteria, the projects included one of the following three strategies as acceptance to enhance the quality of asphalt used on the projects:

a. A lower, PGAC low temperature grade

b. Double Edge Notched Tension (DENT) test and Extended Bending Beam Rheometer (ExBBR) test criteria

c. Multiple Stress Creep Recovery (MSCR) test criteria (Non-recoverable creep compliance and percent recovery)

A comprehensive monitoring plan was established to collect test results, annual pavement performance, as well as other relevant construction data such as mix design parameters, field compaction, air voids, and asphalt cement content. Half of the pavements will be four years old in 2015 and some trends in performance are starting to appear.

This paper examines initial cracking performance of the test sections, and evaluates the relationship of field cracking to the test results for DENT, MSCR, and ExBBR. Preliminary conclusions on the effectiveness of the chosen strategies are assessed for their effectiveness in supporting Ontario’s selection of quality asphalt cement.

4. “Visualization and Quantification of Hot Mix Asphalt Characteristics using X-Ray Computed Tomography” Magdy Shaheen, Adil Al-Mayah, Susan L. Tighe

Hot Mix Asphalt (HMA) is a very complex heterogeneous material. Proper materials characterization and performance prediction are essential for accurate pavement design. In this aspect mixture morphology plays an important role, since it deals with gradation, air-void distribution and mixture volumetric properties. To understand how these morphology parameters influence the performance of the mixture, one of the best ways is to investigate the mixture using X-Ray Computed Topography (CT) system. It can be utilized to find key mixture morphology parameters related to the log-term performance, which will provide advanced characterization method to capture the relation between morphology and performance.

This paper will present an overview on imaging techniques in HMA characterization. This will include image acquisition and analysis methods for both Two Dimensional (2D) and Three Dimensional (3D) images. The application and limitation of X-Ray CT in quantification HMA damage will be explored.

In addition, a case study for quantifying the internal structure by morphology of HMA mixes using the CT imaging system will be analyzed. Images will be collected before and after four- point bending fatigue tests to identify the HMA microstructure changes. Three components in the HMA microstructure will be identified; aggregate, mastic and air voids. This represents a good

contribution to the HMA fatigue evaluation because the damage is directly estimated from the HMA without empirical transfer functions. This research finding will provide better understanding of the relation between HMA internal structure and performance.

5. “Study of Post-Compaction and of the Use of Confining Pressure when Measuring the Complex Modulus of a Full-Depth Reclamation Material” Apparao Gandi, Julien Kagabo, Alan Carter, Dharmaveer Singh

As our road infrastructures ages, rehabilitation is an alternative to reconstruction as a way of maintaining the level of service desired. In Québec, for more than twenty years, Cold- In-Place Recycling (CIR) and Full-Depth Reclamation (FDR) have been reliable rehabilitation techniques, restoring pavement condition at an affordable cost and a lower footprint on the environment. Besides their growing popularity in the construction industry, further developments are needed to better understand their behavior in the field by an adequate characterisation. For instance, reproducing in the laboratory field conditions is yet to be accomplished. As an attempt to achieve this objective, post compaction has been applied on CIR and FDR samples in order to simulate influence of early-life traffic curing.

For CIR and FDR, there is little data available to be used in a mechanical-empirical pavement design method. At early age, it’s complicated to perform complex modulus tests on those materials because of they have little cohesion. To overcome that problem, complex modulus tests with a confining pressure was performed on FDR materials.

FDR materials were made in laboratory with 50% reclaimed asphalt pavement and 50% virgin aggregates and treated with foamed asphalt. For post compaction, it was done with the LPC slab compactor at room temperature. For the confining pressure, a new setup was built in order to be able to apply a confining pressure when testing at different frequencies and different temperature.

The results of this study showed that post-compaction can have a big effect on the mechanical properties of those materials at young age. As for the complex modulus test with confining pressure, it was found that 1) the test can be done even if the material is very fresh, and 2) the obtained results make more sense than the actual value used in mechanical-empirical pavement design.

6. “New Technology for Asphalt Compaction: A Contractor’s View and Experience” Russ Perry, Bonnie Robertson, Eric Shaw

Advancements in the field of asphalt paving have focused almost entirely on the mix itself with advancements in the equipment nearly non-existent. In the field of asphalt paving, experience is held in the highest regard and there is an extremely high resistance to change. It is widely known that current compaction methods produce defects during construction. The phenomenon of hairline cracks often observed on surface of finished asphalt mats is a well-known example.

Over the past 25 years research results showed these cracks or defect in the asphalt layer are responsible for the often reported premature failure of our roads. This unexpected early failure of our roads leads not only to wasted investments on both initial structure and later rehabilitation, but also to a lower level of service for our road network. Research into these hairline cracks has shown that the current steel drum rollers are the main contributor to their occurrence. This research has led the development of a new asphalt compactor “AMIR”.

This paper discusses the historical development of congenital compaction equipment including their advantages and limitations as well as their contribution to the phenomenon of construction cracks, hair-checking. The paper also presents the experience gained from working with the new compaction technology and exploring the potential of using it to produce finished pavements with no defect and at the same time meeting the MTO standards and specifications with fewer rollers

on the job and with less number of passes. In particular the new technology; AMIR, offers a crack free surface with a tighter texture along with improved edge and centerline joint compaction. In addition, AMIR compacted asphalt was found to be much less permeable than traditionally compacted asphalt.

7. «Enrobés modifies au sable de bardeau d’asphalte» Frédéric Nöel

L’incorporation de bardeau d’asphalte dans la fabrication d’enrobés bitumineux est en train de prendre de l’ampleur en Amérique de Nord. Le bardeau est incorporé dans l’enrobé sous forme de particules issues d’un broyage/déchiquetage. La limite actuelle de recyclage de bardeau incorporé sous cette forme est de 3.0 à 5.0 %. L’incorporation de la partie sable du bardeau d’asphalte seulement permet des teneurs en recyclage supérieures à 10 %, voire 15 % tout en offrant des caractéristiques rhéologiques assez différentes de celles des enrobés classiques contenant des matériaux recyclés ou non.

Le principe de la technique consiste à cribler les particules de bardeau déchiquetées pour séparer les agglomérations fibres/bitume de la composante sable du bardeau. Ensuite, contrairement à la pratique actuelle de recyclage de bardeau, seul le sable de bardeau est recyclé dans l’enrobé pour favoriser l’obtention d’un mélange complètement homogène. Enfin, la formulation des enrobés incorporant un forte teneur en sable de bardeau est basée sur une caractérisation des propriétés mécaniques des enrobés plutôt qu’une analyse volumétrique de l’enrobé après compactage. Les formules d’enrobés modifiés au sable de bardeau ont des teneurs totales en bitume de l’ordre de 8 %. Cette forte teneur en bitume peut être séparée en une composante dure (3 %) et une composante molle (5 %).

Cet article présente comment la caractérisation en laboratoire des propriétés mécaniques de formulation d’enrobés ainsi modifiés a permis de démontrer les avantages de cette technique. Il a été déterminé que l’orniérage, la fissuration thermique et le module de l’enrobé étaient proche des valeurs normalement obtenue pour la même formulation sans recyclage. Là où il y a une différence significative, de là l’intérêt de cette technique, c’est la résistance à la fatigue qui est augmenté pour un enrobé avec une teneur élevé en sable de bardeau par rapport aux enrobés classiques.

TRANSLATION “Asphalt Mixes Modified with Asphalt Shingles Sand” Frédéric Nöel

The use of asphalt shingles in hot mix asphalt is gaining popularity in North America. The asphalt shingles is incorporated in the HMA as particles produced by grinding of the shingles. The actual limit of recycled asphalt shingles that ca be incorporated in this form if 3.0% to 5.0%. The incorporation of only the sand part of the recycled asphalt shingles allows the use of 10%, even 15% while offering rheological properties slightly different than those observed for regular HMA with or without recycled materials.

The technique consists in sieving the grinded asphalt shingles to separate the fibre/bitumen agglomerate from the sand part. Then, contrary to the actual practice, only the sand is recycled in HMA to obtain a completely homogeneous mix. The mix design of HMA with high quantity of recycled asphalt shingle’s sand is based on the mechanical properties of the mix instead than on the volumetric of the mix after compaction. The HMA modified with recycled asphalt shingles’ sand have approximately 8% binder. This high binder content can be separated into a hard component (3%) and a soft component (5%).

This paper presents the advantages of using recycled asphalt shingles’ sand in HMA according to a laboratory characterization. It was shown that the rutting resistance, the thermal cracking and the modulus of the mix is similar to HMA without recycled materials. However, there is significant difference, and this is where this technique is very advantageous, with the fatigue resistance which is higher for those mixes than for normal HMA.

8. “Investigation of Diffusion-Controlled Oxidative Aging in Asphalt Mixture” Prabir Kumar Das, Niki Kringos, Hassan Baaj, Susan Tighe

Viscoelastic properties of asphalt mixtures evolve with time due to the impact of several factors. Among these factors, binder aging is probably the most critical one. Aging of asphalt mixtures is an irreversible process and contributes to a reduction of the durability of pavements and eventually increases the maintenance cost. Aging depends not only on binder physicochemical properties but also on the mixture morphology, which is a combination of aggregate packing, porosity, air void distribution and their interconnectivity. However, the latter one has been ignored in most of the previous research projects in the field. The aim of this study is to develop fundamental understanding and identify dominant parameters of aging in asphalt mixtures by considering both physicochemical properties of binders and mixture morphology.

In order to achieve this objective, an oxidative aging mechanism based on a diffusion-reaction process was developed. To investigate the aging gradient along the depth of the mixture, diffusion controlled oxidative aging on dense and open graded asphalt samples were investigated numerically. These samples were scanned with computerized tomography (CT) X-ray scanner to obtain the detailed 3D structures. It was observed that the dense graded asphalt sample contains both interconnected and trapped air-voids, while in case of open graded mix, mostly all of the air-voids are interconnected. Since air-void distribution and aggregate gradation play a vital role in oxidative aging, this mixture morphology information was used as a key parameter in this numerical modeling. To analyse the obtained results, each asphalt sample was subdivided into three sections: top, middle and bottom. As the top surface was assumed to be exposed to atmospheric air, the analyses indicated that for both of the asphalt samples, the top and middle section aged more than the bottom section. In the case of open graded asphalt, mostly all the air-voids were found to be interconnected, thus the open graded asphalt sample aged more than the dense graded one. The fundamental mechanism of aging and dominant parameters which were identified in this study can assist the development of successful design protocols and material selection process.

9. “In-situ Permeability of Newly Constructed Asphalt Pavement Surfaces As an Indicator of Long Term Pavement Performance” Moustafa Awadalla, A. O. Abd El Halim, Y. Hassan, I. Bashir, F. Pinder

Generally certain asphalt mix properties, including in-situ density of finished asphalt pavements, are measured during and following construction and are used by contractors and agencies as quality indicators. The agencies rely on the degree of conformance of these quality parameters which are specified through certain construction standards and specifications, to assess the quality of finished pavements and ensure long term performance..

A comprehensive research study was designed and performed to investigate the relationship between in-situ permeability and the quality of asphalt pavement construction and performance. At the present time, the density of the finished asphalt layer is the most common quality parameter used to assess the quality of construction of given asphalt pavements. However, it has been reported in the literature that meeting relative densities or specified compaction values of newly constructed asphalt mixes does not necessarily ensure the optimal level of permeability in the finished pavement which is required for good performance and service life. Therefore, a permeability criterion may be needed along with an assessment tool that is simple, effective,

reliable and capable of confirming the specified requirements. Such requirements would better ensure that the finished pavement will provide its expected long term performance.

This paper describes the details of a comprehensive research that incorporates both field and laboratory tests to develop a new permeability assessment criterion. The investigation provides data and results supporting the newly proposed criterion including the relationships between physical and mechanical properties of asphalt pavement.

The testing program includes the measurements of in-situ field permeability as well as permeability testing on recovered asphalt cores, including different asphalt mixes, different ages, and from various locations across and along several Ontario highway sections. This experimental investigation also includes various laboratory tests on both the recovered field cores and laboratory prepared Superpave Gyrator Compactor (SGC) specimens to explore the relationships between them.

The results of the research investigation confirm that in-situ density or compaction alone does not adequately ensure the desired asphalt pavement properties. This study recommends the addition of a permeability criterion to guide construction practices towards the construction of low permeability pavements, for agencies to realize the maximum service life and to ensure good performance for all specified asphalt mixes.

10. “The Selection, Construction and Five Year Performance Evaluation of Highway 1 Rehabilitated with Hot-In-Place Recycling” Vipin Sharma, Christian Babuin, Brad Hogg, Alan Schmidt

BC Ministry of Transportation and Infrastructure (BC MoTI) undertakes many pavement rehabilitation projects each year utilizing various rehabilitation strategies such as mill and inlay, mill and inlay plus overlay, overlay, Hot-in-place recycling (HIPR) etc. As part of the pavement rehabilitation program, roughly 1.8 million m2 of the pavement surface is rehabilitated annually in BC using HIPR. The useful service life of a HIPR varies between 8 – 14 years from project to project.

Tetra Tech evaluated an 18 km. long section of Highway 1 from Sagebrush Overpass to Kokanee Overpass near Kamloops BC in 2009 on behalf of the BC MoTI. Based on review of historical information, the pavement surface was about 17 years old with a 20 year design traffic of 20.4 million ESAL’s. The BC MoTI’s network level pavement condition data collected in 2007 indicated good ride quality with average IRI of 1.43 m/km and average Pavement Distress Index (PDI) of 6.9 within the project limits. Some localized failed areas with high severity distresses were also observed during site reconnaissance in 2009. Review of the pavement strength testing data indicated that the majority of the pavement surface was structurally adequate to support the design ESAL’s.

Asphalt pavement cores were extracted from the pavement and the asphalt mix from the existing pavement was tested to determine the feasibility of the mix for rehabilitation using HIPR. Review of the laboratory test results indicated that the asphalt mix in the existing pavement was considered suitable for rehabilitation using HIPR. Asphalt cement in the existing pavement was determined to be hardened, and subsequently a softer asphalt cement was used for the admix to improve the performance of the recycled mix.

Considering that the existing pavement structure was adequate and the pavement was in fair condition, HIPR with the addition of a 20% virgin admix was selected as a rehabilitation treatment for the roadway. As the fast lanes were observed to be in relatively better condition than the slow lanes, it was decided to complete the HIPR treatment for the slow lane only and complete the rehabilitation of the fast lane at a later date.

The slow lanes were rehabilitated using HIPR in 2010 and the pavement is performing well with the majority of the pavement surface providing a smooth ride with few visible distresses.

This paper documents the criteria used in the evaluation and selection of HIPR as the preferred rehabilitation option, the asphalt mix quality testing from the time of construction, and an update on the performance 5 years after the construction was completed.

The MoTI is looking at rehabilitating the fast lanes in 2015 using the HIPR as a rehabilitation strategy.

11. “Development of a synthetic binder which can be adapted to create a coloured pavement mixture and the performance review of the 2009 Front Street Project in Dawson City, Yukon” Todd Strynadka, Jean-Martin Croteau, Jeff Jarvis, Dr. Guy Doré

In 2009, the Yukon Highways and Public Works, Yukon Cold Climate Innovation Centre and Skookum Asphalt of Whitehorse, Yukon partnered to construct the Front Street Project in Dawson City, Yukon. The Front Street Project required the application of a light coloured surface paving system. Research and Development was conducted to produce a petroleum-based synthetic binder that could meet the Performance Grade requirements of the wide temperature range prevalent in Dawson City. In addition to the synthetic binder, a pigment was used to develop a pavement mixture colour that matched the colour of the historic gravel streets in Dawson City. The lighter pavement was also required to provide a high albedo to minimize solar heat absorption and related degradation of the underlying permafrost. Unique construction and maintenance procedures were developed and implemented for the construction of the unique pavement in an isolated location. Yukon Highways and Public Works, in collaboration with the Yukon Cold Climate Innovation Centre, have been monitoring the performance of the pavement and the permafrost impacts in order to evaluate the potential benefits of the light coloured pavements in permafrost environments. A five year performance review will be presented in the paper.

The adaptation of the petroleum-based synthetic binder to meet the requirements of a conventional bituminous binder Performance Grade for Northern Canada led to further study of this product to meet other Canadian applications. Due to the binder being relatively clear in thin film it was discovered that the pavement material takes on the natural colour of the aggregates or can be adapted to match multiple colours through the addition of organic or mineral pigments. Solar reflectance measurements were conducted on light coloured pavements and conventional pavements to compare surface reflectance of the materials. Further development has shown that a wide range of mix colours can be developed with the synthetic binder having equivalent rheological properties to conventional Performance Grade bituminous binders and the final mixture maintaining conventional pavement mixture performance properties. This section of the paper will share test data collected.

12. “3-D Paving Experience at the National Corvette Museum” Todd Mansell, Terry Humphrey

This paper covers some of the challenges in paving a 3.2 kilometer high-speed motorsports track to meet challenging materials and construction specifications for ride quality and durability. The project was all new construction, starting with native base materials, engineered fill and two lifts of asphalt pavement. The existing clay sub-grade soil required stabilization with lime to reduce the Plasticity Index. The sub-grade was stabilized to a depth of 30 cm, followed by a lift of dense-graded, crushed limestone aggregate that was spread by asphalt pavers to a nominal depth of 20 cm. The base aggregate was trimmed to final elevation by motors graders under 3-D blade control. The base lift of asphalt was then placed on the crushed limestone base using three-dimensional screed control and the surface lift of asphalt was placed using two-dimensional grade control systems. The bituminous material used for the base course was a 19 mm, dense-graded

Superpave warm mix asphalt. The asphalt cement was a non-modified PG 64-22. The uncompacted depth of the base course was 50 mm. The design of the track specified a hot-on-hot longitudinal joint to promote both increased joint density (durability) and joint appearance (precise match).

Before the start of the project, there was a significant amount of planning and training. Two wide paving kits (left and right) were ordered for the paver set up for 6-metre wide paving. The crew practiced with the wide-width paving kit on parking areas at the Motor Sports Park before starting the race course. Paving speeds were carefully calculated so the two echelon pavers would be in balance and would consume the hourly tonnage in a consistent fashion without stopping. This project was the first time that the paving crews were exposed to 3-D control. The contractor’s technology team set up 17 Universal Total Stations (UTS) and installed 3-D controls on the paver when the crew paved the parking areas. The paving crew was ready to go when production paving started on the race course. Finally, the quality control team had the compaction process planned at the start of production paving. They confirmed that the rolling patterns would get the required density and that the breakdown rollers could stay ahead of the tender zone.

This paper will focus on four main segments of asphalt paving: first, a discussion of the planning needed for and implementation of echelon paving with two asphalt pavers; second, an examination of a wide-width paving kit; third, an introduction to the use of three-dimensional screed control used on the project; and finally, an analysis of the rolling patterns used by four double-drum, vibratory asphalt compactors.

13. “Engineering Design and Asset Management Of Flexible Pavements For Design Build Finance Operate (P3) Projects In Western Canada” Art Johnston, Bryan Palsat, Dave Palsat

With increasing frequency, roadway corridor development and improvement projects are being procured through the Design Build Finance Operate (DBFO) Public Private Partnerships (P3s). In these procurement environments the nature of the pavement design and engineering requirements change in several significant ways compared with the traditional Design Bid Build (DBB) in that the consequences of poor pavement performance (risk) in most aspects is transferred from the Owner to the DBFO partners, the Designer, Builder and Operator/Concessionaire. The Concessionaire has a tendency to look for more robust designs from the Design Build Joint Venture (DBJV) team while the Builder is more interested in providing as little pavement structure as possible. This leaves the Designer with the challenge to ensure that the optimum pavement solution in terms of Net Present Value (NPV) is arrived at, while limiting the risk of unacceptable pavement performance. This is in stark contrast to the DBB process where the builder is attempting to maximize pavement quantities and increase payment. At the same time in a DBFO environment, all of the partners wish for the lowest possible bid cost to win the project.

In Western Canada all DBFO pavement solutions have been in the form of flexible pavements. This paper will examine some of the reasons for this, compared to other jurisdictions where rigid pavements have been favored. This paper will also illustrate how enhanced pavement data collection and performance modeling is key to optimizing the initial pavement design solution during the pursuit stage. It will also demonstrate how performance modeling can be adapted for asset management on behalf of the facility operator to optimize maintenance and rehabilitation during the operating period, thereby maximizing profits.

In addition, this paper also discusses the requirements of pavement design and engineering components through the bid, build, transfer (from builder to concessionaire), operations and hand back (to the Owner) DBFO process. It describes the methodology for arriving at the lowest NPV life cycle cost that meets the project’s pavement performance and hand back requirements.

It describes how accurately predicting pavement performance and quantifying the associated risk of underperformance which can significantly increase the confidence of the DBJV and Concessionaire in the processes which can make a team more competitive. Finally it discusses the role of the pavement engineers in the DBFO delivery and the challenges posed by the relationships between Builder, Operator/Concessionaire and Owner.

14. “Characterization of Hot Mix Asphalt with Steel Slags and the Use of Laboratory Results in Mechanistic-Empirical Design” Emmanuel Dion, Daniel Perraton, Alan Carter, Kevin Bilodeau

Actually in Canada, the road structure design is based on an empirical approach. By following this approach, we can’t put easily in perspective the advantages of the use of new and more sustainable materials in the hot mix asphalt design. The mechanistic approach allows the valorizations of these new materials and the optimization of company products and in a perspective of improvement of the durability of the works. For that purpose, the LCMB developed a tool of prediction and evaluation of the behavior of a road (OPECC) based on mechanistic approach. By means of this tool, it is possible to quantify the evolution of fatigue cracking and rutting from the thermomechanical properties determined in laboratory. From the perspective of cost-performance analysis, OPECC allows the comparison of different solutions adopted by the professional engineer to optimize the pavement structure according to its priorities. The laboratory of road and bituminous materials (LCMB) has launched a project with the objective of showing the plus-value of an asphalt mixture incorporating secondary aggregate (EBA) form a conventional asphalt mixture ESG-10.

The first part of the project was to characterized both of the asphalt mixture and evaluated the life spend on a material level. The EBA’s mixture showed great mechanical resistance. By comparing the master curves of the tow mixtures, the EBA’s curve showed better resistance on low frequency due to the interlocking properties of the secondary aggregate added but was also more susceptible to temperature increase than the ESG-10. In term of fatigue resistance the EBA ε6 value was greater than expected and higher than the control mixture. Evidently the EBA’s property has a higher life spend than the ESG-10 on the material level.

Afterward, OPECC simulations has been run on three different road structure types, the rural, urban and highway. Each type of road structure was evaluated for a 25 years of services and was subject to the same climatic conditions. Only the traffic, the traffic growth and the layer thickness were different depending on the nature of the road type. The granular foundation properties remained the same through all the simulations. The simulations results showed higher rutting and fatigue cracking on all the road structure including the control mixture in the bituminous layers. Thus the higher life spends evaluated on a material level match the result on the mechanistic simulations.

This project showed that the life spends evaluated on a material level correlate the life spends obtained on a structural level. This paper also showed that the characterization on a themomecanical level of asphalt can lead to a life spends in a cost-performance analysis.

15. “Physical Hardening in Asphalt Binders, Mixtures and Real-World Pavements” Migle Paliukaite, Jamie-Lee Freeston, Graeme Gillespie, Russell Taylor and Simon A.M. Hesp

For over 100 years there has been a steady stream of publications that discuss research on the physical hardening phenomenon. In spite of this, current asphalt cement specifications rarely account for the non-equilibrium state that materials are tested under during specification grading. The physical hardening term was first coined by Shell Oil researchers to describe a relatively fast crystallization of waxes and a slower structuring/consolidation of the asphaltene phase (Blokker and Van Hoorn 1959). However, more detailed investigations had already been published many years earlier (Traxler et al. 1936 and 1937, Brown et al. 1957 and 1958). The most recent

understanding of the process also includes the slow formation of rigid amorphous phase(s) (Hesp et al. 2007, Kriz 2009).

The Ontario Ministry of Transportation has developed an extended bending beam rheometer (BBR) protocol that includes an assessment of asphalt cement’s tendency to change its properties during cold conditioning (MTO 2006). The protocol has been implemented with associated acceptance criteria on a significant number of paving contracts. Opposition to this effort persists because it is alleged that the process is only relevant for binders but does not occur in mixtures. Further, suppliers of asphalt cement object to the 72 h it takes to obtain test results for a grade and grade loss under the Ontario protocol. This paper is written in order to address both of these concerns. It is shown that physical hardening not only occurs in the asphalt cement but that it can also be a very significant factor in mixture performance and is able to explain performance contrasts in real-world pavements.

Basic shrinkage as it occurs in asphalt cements will be modeled with the Avrami equation for phase transformations in solids (Pechenyi and Kuznetsov 1990). A large number of binders will be compared in the context of the Avrami theory, showing that the physical hardening process involves the formation of crystal-type structures with only a very weak degree of order. It will also be shown that the Avrami theory can be used to predict 72 h results from tests after only 1, 3 and 24 h with a high degree of accuracy. Results obtained on various types of modified binders will be used to discuss what additives and processes produce superior quality binders from a durability perspective.

A review of the literature on asphalt mixture testing for physical hardening will be provided. A number of authors misinterpret their own test results, likely because of the confounding effects of hardening and microcracking. However, new test data for a large number of asphalt mixtures will be presented to show that stiffness, failure strain and strength can be affected by cold conditioning in very significant ways.

Evidence from real-world pavement trials and regular contracts will be provided to show that the process is critically important for the accurate prediction of long-term raveling, cracking and moisture damage. It will be shown that current AASHTO T 313 grades can be in error by as much as 10°C or more for hardening susceptible asphalt cements and that this invariably leads to premature and excessive cracking. It is hoped that the information provided will motivate others to take a closer look at Ontario’s extended BBR protocol.

16. «Formulation et caractéisation d’enrobé coulés à froid 100% recycles avec regénérant» Arbia, Garfa, Marie Quioc, Alan Carter, Anne Dony

Les enrobés coulés à froid, appelés ECF, sont des techniques de revêtement de surface destinées à apporter une bonne adhésion et étanchéité à la chaussée. La recherche dans ce domaine est plus que d’actualité et demeure un thème actif grâce à sa méthode de fabrication (technique à froid). L’objectif de ce travail de recherche est l’établissement d’une formulation d’ECF 100% avec des matériaux recyclés, ce qui contribue à la préservation de l’environnement. En outre, cette nouvelle formulation doit vérifier les critères imposés par le International Slurry Surfacing Association (ISSA).

La grande variabilité des constituants de ces mélanges ainsi que l’interaction entre eux et l’incorporation des matériaux recyclés contribuent à cette complexité dans la compréhension du comportement et les performances des enrobés coulés à froid. C’est dans ce cadre que plusieurs formulations ont été réalisées afin d’obtenir le mélange aux proportions optimales. Cette méthode consiste à l’évaluation de la performance de l’échantillon face aux différents essais ISSA suivant sa composition granulaire, son taux d’émulsion bitumineuse, le pourcentage d’eau, la teneur en ciment et d’autres additifs qui permettent la restauration du bitume vieilli. Il est à noter que la teneur en bitume vieilli a été considérée lors des formulations. Ces mélanges ont été testés

par trois types d’essais différents selon la norme de l’ISSA : essai de déplacement (horizontal et vertical), essai d’abrasion et essai de cohésion. Ces tests permettront de valider les performances des échantillons sur la chaussée.

Différentes formulation de ECF avec différentes teneur en eau, différent type d’émulsion et l’ajout de régénérant ont permis de vérifier l’impact de chacun des constituants sur le comportement mécanique des ECF. Des essais de simulation de vieillissement des ECF ont été mis au point et ont été effectués afin de voir la durabilité de ces matériaux.

Une formulation d’ECF avec 100% d’enrobé recyclé a été formulé avec succès. L’addition de régénérant ou d’additif, comme le biodiésel, a permis de faire des ECF en mobilisant une partie du bitume des enrobés recyclés, donc en utilisant moins de bitume vierge que pour un ECF sans matériaux recyclés. Les échantillons ayant subis les essais de déplacement et d’abrasion répondent aux critères exigés par la norme de l’ISSA, qui sont respectivement une déformation verticale maximale de 10 % et déformation horizontale maximale de 5% et une perte en masse maximale de 807 g/m2.

TRANSLATION “ECF Using 100% Recycled Materials” Arbia, Garfa, Marie Quioc, Alan Carter, Anne Dony

Cold mixes, called “ECF”, are surface coating techniques that provide good adhesion and sealing of the road. Research in this area is more relevant than ever and remains an active topic due to its method of installation (cold technique). The objective of this research is the development of a formulation of ECF using 100% recycled materials, which contributes to the preservation of the environment. Furthermore, this new formulation should pass the criteria imposed by the International Slurry Surfacing Association (ISSA).

The large variability of the components of these mixtures and the interaction between them and the addition of recycled materials contribute to the complexity in understanding the behavior and performance of cold mix. Within this context, several formulations were prepared to obtain the mixture with optimal proportions. This method involves evaluating sample performance against the various ISSA tests pertaining to its granular composition, the percentage of asphalt emulsion, the proportion of water, cement content, and other additives that allow the restoration the aged bitumen. It is noteworthy that the aged bitumen content was considered in the formulations. These mixtures were tested by three different ISSA standard test methods: displacement (horizontal and vertical), abrasion and cohesion tests. These tests will validate the sample performance on the road.

Different formulations of ECF with different water content, different type of emulsion and the addition of rejuvenator were used to verify the impact of each component on the mechanical behavior of the ECF. ECF aging protocols have been developed and were used in order to determine the durability of these materials.

A formulation of ECF with 100% recycled asphalt has been formulated successfully. The addition of rejuvenator or other additives, such as biodiesel, facilitated the making of ECF by mobilizing part of the bitumen in the recycled asphalt, thus reducing the need for virgin bitumen as compared to ECF without recycled materials. Samples subjected to displacement and abrasion tests met the criteria specified by ISSA Standard, which are respectively a maximum vertical deformation of 10%, a maximum horizontal deformation of 5% and a maximum weight loss of 807 g/m2.

17. “Effect of Storage Conditions on Physical Properties of Polymer Modified Asphalts” Dr. Huachun Zhai, Alejandro Rosalos

Researches and field evaluations have proved that the addition of polymers, especially SBS

polymers, in asphalt can effectively extend the range of performance temperatures of the base PG binders and improve the resistance to distresses such as rutting, fatigue and thermal cracking. The manufacture of PMAs requires high heat and high shear to achieve a homogenous mixture. When PMAs are manufactured, they are seldom used at once. They are usually stored in tanks under continuous heat to maintain the proper shipping temperature. Since polymers tend to degrade under elevated heat, the physical properties of PMAs will also change during storage. The functionality and physical properties of polymer modified asphalt are often affected by the thermal history or storage conditions of the PMAs. The extent to which the storage conditions influence the PMAs' properties is also dependent on polymer type and polymer concentration.

As a result, to ensure the quality of PMAs, it is really important to understand the “'shelf-life” of different PMA's under different storage conditions.

In this study, different polymers (SBS Linear, SBS Radial, Polyethylene, and EVA) and modification additives (PPA) are selected to modify PG 58-28 asphalt into a PG 70-28. The different modified asphalts are stored in an oven at constant temperature (163°C/325°F) for up to 2 months. To evaluate the effects of different storage temperatures and polymer concentrations on the physical properties of PMAs, SBS radial polymer modified PMAs at different concentrations are selected and stored at different temperatures. Samples are pulled at different time intervals. PG grading testes are then performed on all samples. Different rheological tests, such as Frequency Sweep, Multiple Stress Creep Recovery (MSCR) and Linear Amplitude Sweep (LAS) are tested on all samples using a dynamic shear rheometer (DSR). Several PG plus tests, such as elastic recovery (ER), ductility, and toughness and tenacity (TnT) are also performed. Fourier Transform Infrared Spectroscopy (FTIR) tests are conducted on all samples.

The results indicate that Elastomer (SBS type of polymers) modified asphalts are more sensitive to storage conditions versus Plastomer (PE and EVA) Modified Asphalts. Although both are changing versus time, the results for PG grading tests, MSCR, LAS and ER are less sensitive to storage conditions than that of ductility and TnT. Lower storage temperature extends the shelf­ life of PMAs. Different polymer contents react differently to changes in storage conditions.

18. “Field Evaluation of Pavement Preservation Treatments Incorporating Stress Absorbing Membrane Interlayer Technologies” Rhiannon Arsenault, Terry McCann, Steve Goodman

In 2011, the County of Lanark tendered the construction of a series of contiguous pavement preservation treatments along a 4.7 km section of Scotchline Road in Perth, Ontario. Unlike traditional practice however, three different Stress-Absorbing Membrane Interlayer (SAMI) technologies were placed upon the pavement surface and covered with microsurfacing. SAMI treatments placed under Hot Mix Asphalt (HMA) have been used in the past to retard reflective cracking, however the use of SAMI technology with thin preservation treatments may provide additional benefit as compared to un-reinforced systems.

The SAMI technologies included i) fibre-reinforced microsurfacing, ii) felt-reinforced chip seal, and iii) Fibremat while a control section received two layers of un-reinforced microsurfacing. The purpose of the experiment was to directly compare the performance of each individual treatment over time from a preservation perspective, as well as to determine whether any of the treatments provide cost-effective retardation/prevention of reflective cracking from the underlying pavement.

Prior to construction, AME was retained to complete a baseline condition survey to map existing cracking and other distresses that may influence the performance of the treatments. Placement

of the treatments was completed shortly thereafter followed by annual condition reassessments to observe performance with time. After three years in service, significant differences in performance have been observed. This paper discusses the three SAMI treatment technologies, observed performance to date, and the overall cost effectiveness under the conditions of the experiment. Recommendations are also provided to guide agencies that may wish to incorporate SAMI technologies into their pavement preservation program.

19. “Five Year Performance of Quiet Asphalt Pavement Test Sections on Highway 405, Ontario” Heather Beattie, Seyed Tabib, Pamela Marks, and Chris Blaney

The study of quiet pavements is an increasingly important topic for highway agencies around the world. Growing traffic volumes on highways have led to increased noise generated from the tire-pavement contact of vehicles travelling at high speeds. In turn, the public has expressed concerns regarding the noise generated from highways. Traditionally, sound barrier walls have been used to mitigate highway noise. Economic concerns associated with sound barrier walls have led to a growing interest in alternate methods to reduce highway noise. One alternative is to build low noise generating pavements, also referred to as the quiet pavements.

In an effort to evaluate quiet pavements, the Ontario Ministry of Transportation (MTO) constructed a pavement with five test sections including: two different types of open friction course asphalt, stone mastic asphalt, open graded rubberized asphaltic concrete, and a standard Superpave dense graded asphalt mix. Construction was completed in 2009 and the On-Board Sound Intensity method was used to measure the pavement noise levels. Pavement permeability was also measured. Initial results showed a good correlation between the pavement permeability and noise levels – as permeability increased, noise levels decreased.

Since 2009, MTO has continued to monitor the test sections. After five years of service, MTO sought answers to two questions: Are the quiet pavement sections performing well structurally? Do the quiet pavement sections continue to mitigate noise?

Analysis of pavement condition data showed the quiet pavement sections were performing well structurally in comparison to the control section but that their noise mitigation properties were found to diminish over time. To investigate the latter, MTO attempted to reinstate pavement noise reduction properties by vacuum sweeping the test sections.

This paper presents pavement condition data (i.e., cracking, rutting, and roughness), pavement permeability, and tire-pavement noise levels collected since construction

20. “Six Year Performance of Ontario’s Freeway Fibre and Polymer Modifier Trial Project” Anne Holt and Pamela Marks

In 2008, the Ministry of Transportation Ontario (MTO) completed a demonstration project to evaluate the impact of fibre reinforcement and polymer modification on the performance of hot mix pavement in an urban freeway environment.

MTO has been carrying out trials evaluating asphalt since the implementation of Superpave in 1997, and while previous trials have primarily focused on binder aging and low temperature cracking, this project is intended to assess any reductions in reflective cracking, and improvements in fatigue performance. The existing concrete pavement was overlaid with two lifts of hot mix to form a composite pavement. The project sections comprised varying combinations of different polymer modifiers and performance graded asphalt cements. Fibres were used in all sections of the trial other than the control.

Monitoring in the form of field evaluation and automated pavement testing was conducted to assist in the evaluation of the performance of the pavement sections. Evaluation consisted of roughness, rutting, friction and cracking, and results are provided in this paper. Details on the

project, its construction, and conformance to the End Result specifications for the material properties of the asphalt and mix are also documented.

21. “Cold 2014 Winter and Early Asphalt Pavement Cracking Observed in Southwestern Ontario” Ludomir Uzarowski and Vimy Henderson, Gary MacDonald, John Rizzo, Gary Moore,

Properly designed and constructed asphalt pavements incorporating good quality materials are typically anticipated to require major rehabilitation after about 20 or more years of service. The life of pavement that went through major rehabilitation should be about 15 years without the need of any major intervention. It is common belief that this should be true if weather conditions are not extreme. In Southeastern Ontario the standard asphalt cement grade is PG 58-28;it is often bumped to PG 64-28 for heavier traffic and even to PG 70-28 for very heavy traffic. The asphalt mixes incorporating these asphalt cement grades should be able to withstand the winter temperature down to- 28°C. The 2014 winter was considered to be extremely cold in Southwestern Ontario with the temperature sometimes dropping to - 25°C or even lower, sometimes for extended period of time.

There was early pavement cracking observed recently on number of roads in Southwestern Ontario. It has been noted in the last few years and particularly after the 2014 winter. Pavements that were considered to be properly designed and had good quality control/quality assurance (QC/QA) results exhibited cracking after 2 to 3 years or sometimes even after less than a year. It has been also noticed in some municipalities that mainly the pavements that incorporated PG 64-28 grade have cracked. An investigation is carried out to determine if the cracking is related to very low winter temperature and particularly if it is related to asphalt cement and what testing should be able to screen poorly performing materials.

This paper describes the case studies of three municipal roads that incorporated PG 64-28 asphalt cement and exhibited very early cracking and also so called "good roads" that also incorporated PG 64-28 but did not exhibit any cracking. The investigation included pavement visual condition inspections, QC/QA results review and pavement coring and slab cutting investigation to evaluate the depth of cracking and obtain materials for laboratory testing. The recovered asphalt cement testing included conventional PG grade verification, Multiple Stress Recovery (MSCR} and Extended Bending Beam Rheometer (eBBR) tests and Double Edge Notch Test (DENT). In addition, the recovered asphalt cements were tested for the presence of zinc and molybdenum considered by some researchers to be the indicators of the presence of recycled engine oil in asphalt cement. This paper will present the results for cracked and uncracked pavements and provide initial recommendations for updates for asphalt cement specifications.

22. “Green Pavement Technologies Are Sustainable Only if They Deliver Acceptable Performance” Ludomir Uzarowski, Michael Maher and Susan Tighe

Green asphalt pavement technologies have a long history. They include innovative pavement materials as well as pavement rehabilitation methodologies. On the materials side these technologies have included the use of Reclaimed Asphalt Pavements (RAP) and asphalt shingles (RAS) in hot mix asphalt (HMA) and granular materials, crumb rubber in HMA, various additives to asphalt cements, recycled concrete as aggregates, steel slag, crushed glass and ceramic as HMA aggregates, and warm mix asphalt. On the pavement rehabilitation side green technologies have included pavement recycling such as hot-in-place recycling (HIR),cold in-place recycling-stabilization with asphalt emulsion and foamed asphalt, cold in-place recycling with expanded asphalt material (CIREAM), and full depth reclamation. This list of green technologies can be further expanded.

The authors of this paper have been involved in the above listed aspects of green asphalt technologies for almost 30 years and have written numerous papers on the subject. It is generally agreed that the main purpose for the use of green technologies is to make pavements

more sustainable in terms of: economics (improving cost effectiveness); environment (reducing use of scarce resources and greenhouse gas emissions); and social (bringing social benefits to the public). There are pavement rating systems that give credits for alternatives that use green technologies.

The purpose of this paper is to bring attention to the importance of the technical quality of green asphalt technologies. Although there are a large number of cases where they are used correctly, there are also a growing number of applications that have sometimes drastic negative impact on pavement performance. Poorly designed asphalt mixes with excessive or unknown RAP sources may ravel and crack early. It may become worse if excessive amount of RAS is added. Some asphalt cement additives cause mixes to become brittle and crack, particularly in winter. Poorly stabilized pulverized pavements significantly underperform. It is critical that when green technologies are applied that it is certain that they do not compromise the pavement performance and that proper quality procedure for material production, pavement and mix design and construction are known and followed. In many recycling technologies there is a maximum recycling ratio and this must be identified and adhered to.

This paper will describe some recycling failures and examples of poorly performing new pavements and focus on what are the criteria for selected technologies that must be followed to achieve success. It will also include a few practical examples of very poor pavement performance when the procedures were not followed.

23. “Use of the Hirsh Model to back-calculate the performance characteristics of the blended binder in Superpave Recycled Hot Mixtures” Xiomara Sanchez, Vince Aurilio, Susan L. Tighe,

When Reclaimed Asphalt Pavement (RAP) is incorporated in hot mix asphalt it is always uncertain the characteristics of the resulting binder. It is anticipated that some degree of blending occur between the aged asphalt contained in the RAP and the added virgin asphalt. Considering that the use of recycled hot mixtures is an extended practice in Ontario, this paper explores on the behaviour of conventional and non-conventional laboratory prepared mixtures combining different RAP content and virgin asphalt performance grade (PG). The aggregate gradation and volumetric properties of the six studied mixtures were analogous. Dynamic modulus test was conducted on replicate specimens using the asphalt mixture performance tester (AMPT) following the AASHTO TP79 standard. The resulting complex modulus of the mix (E*) was used to estimate the complex modulus of the binder (G*) through the Hirsch Model, and the resulting master curves were compared with the results from direct testing using the dynamic shear rheometer (DSR) on the extracted and recovered binder. From the results it can be concluded that it is possible to estimate the performance of the blended binder from the performance of the mix. The analyses also allowed verifying that the blending between the old and new binders occurring in the mix is incomplete.

24. “Optimization of Hot Mix Asphalt Surface Course Mix Design for Fatigue Resistance” Magdy Shaheen, Adil Al-Mayah, Susan L. Tighe

Fatigue cracking is considered to be a major load induced distress mode in Hot Mix Asphalt (HMA) surface layer. The construction cost of this layer is rather high compared to the other layers in a pavement structure and moreover, in the long run this is the layer that requires frequent maintenance. Therefore, the mix design of this layer has always been a key concern to pavement engineers, specially focusing on aggregate type, binder properties and binder content. Hence, optimizing the mix design of HMA for fatigue resistance may lead to longer lasting and better performing pavements.

This study investigates the fatigue resistance of two typical Superpave™ mixes used in Ontario for surface course construction (SP12.5 and SP12.5 FC2 mixes). An FC2 mix is a friction course in

which both fine and coarse aggregates obtained from crushed bedrock from the Ministry of Transportation, Ontario (MTO) Designated Sources for Materials (DSM) manual. Two Superpave Performance Grading (PG) binders and two traffic levels were used in these two mix designs. Four point bending tests and dynamic modulus tests were conducted to evaluate the performance of these asphalt mixtures. Moreover, the environmental impact on HMA fatigue resistance has also been investigated. This includes the effect of freeze and thaw cycles on flexural stiffness deterioration. To do so, the specimens were exposed to freeze and thaw cycles, which simulates one year of exposure.

The effect of aggregate type, binder type and binder content on the fatigue resistance will be presented. Thus, the outcomes of this research will help in design longer lasting pavements and better understanding of the fatigue performance of HMA surface layer.

25. “Complex Modulus and Fatigue Performances of a GB20 Mix Incorporating High Percentage of Reclaimed Asphalt Pavement” Asmaa Basueny, Alan Carter, Daniel Perraton

Nowadays, with increased demand and limited aggregate and binder supply, asphalt producers and road contractors have begun using reclaimed asphalt pavement (RAP) as a valuable component in HMA. As result, there has been renewed interest to use large quantities of RAP material in hot-mix asphalt mixtures.

Using RAP saves money for contractors and ultimately the state and local governments. The use of RAP also decrease the amount of construction debris placed into landfills and does not deplete non-renewable nature resources such as virgin aggregate and asphalt binder. Additionally, the use of RAP in new HMA lowers production cost, reduces transportation costs required to obtain quality virgin aggregate, and preserves environment (reduction in toxic and greenhouse gas emissions).

This paper presents the results of a project aimed at the characterization of hot-mix asphalt (HMA) containing large quantities of RAP material to support its implementation in construction projects. The project examined the dynamic modulus as well as the fatigue resistance (the main HMA material property required in the design of asphalt pavements). The experimental design for this study included the use of one type of virgin aggregate, one virgin binder (PG64-28), one source of RAP in the mixture containing 40% RAP mixtures (GB20 type). Four mixtures [three recycled mixtures containing RAP and one control virgin mixture] were designed and tested. Some RAPs used in this study was artificially aged in the laboratory using an accelerated aging process. There are two kinds of RAP added and mixed with the heated virgin aggregates: cold (ambient temperature) RAP or heated RAP in a microwave at 110°C.

In this study, cyclic tension-compression tests on cylindrical specimens are performed in order to investigate the mixtures’ stiffness and fatigue characteristics of RHMA mixtures. Complex modulus have been performed on a large range of temperature (from -35°C to +35°C) and frequencies (0,01 Hz to 20 Hz). All fatigue tests were performed at 10 Hz in controlled strain mode at 10°C. The results of stiffness testing of this study show that the addition of 40% RAP actually increases the stiffness compared with the neat base. Also, an increase in stiffness occurred as the recycled aged RAP was used in the mixture. Experimental results indicate that the fatigue performance of recycled mix, are observed to be similar or even better with respect to the virgin mix. In addition, the 40% RAP percentage was found to greatly change the fatigue resistance of mixtures.