Tài liệu Airfield and highway pavements 2017 testing and characterization of bound and unbound pavement materials

d from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/03/19. Copyright ASCE. For personal use only; all right Airfield and Highway Pavements 2017 Testing and Characterization of Bound and Unbound Pavement Materials Selected Papers from the Proceedings of the International Conference on Highway Pavements and Airfield Technology 2017 Edited by Imad L. Al-Qadi, Ph.D., P.E. Hasan Ozer, Ph.D. Eileen M. Vélez-Vega, P.E. Scott Murrell, P.E. Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/03/19. Copyright ASCE. For personal use only; all rights reserved. AIRFIELD AND HIGHWAY PAVEMENTS 2017 TESTING AND CHARACTERIZATION OF BOUND AND UNBOUND PAVEMENT MATERIALS PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON HIGHWAY PAVEMENTS AND AIRFIELD TECHNOLOGY 2017 August 27–30, 2017 Philadelphia, Pennsylvania SPONSORED BY The Transportation & Development Institute of the American Society of Civil Engineers EDITED BY Imad L. Al-Qadi, Ph.D., P.E. Hasan Ozer, Ph.D. Eileen M. Vélez-Vega, P.E. Scott Murrell, P.E. Published by the American Society of Civil Engineers Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/03/19. Copyright ASCE. For personal use only; all rights reserved. Published by American Society of Civil Engineers 1801 Alexander Bell Drive Reston, Virginia, 20191-4382 www.asce.org/publications | ascelibrary.org Any statements expressed in these materials are those of the individual authors and do not necessarily represent the views of ASCE, which takes no responsibility for any statement made herein. No reference made in this publication to any specific method, product, process, or service constitutes or implies an endorsement, recommendation, or warranty thereof by ASCE. The materials are for general information only and do not represent a standard of ASCE, nor are they intended as a reference in purchase specifications, contracts, regulations, statutes, or any other legal document. 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Errata: Errata, if any, can be found at https://doi.org/10.1061/9780784480939 Copyright © 2017 by the American Society of Civil Engineers. All Rights Reserved. ISBN 978-0-7844-8093-9 (PDF) Manufactured in the United States of America. Airfield and Highway Pavements 2017 iii Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/03/19. Copyright ASCE. For personal use only; all rights reserved. Preface An ever-growing number of highway and airport agencies, companies, organizations, institutes, and governing bodies are embracing principles of sustainability in managing their activities and conducting business. Overarching goals emphasize key environmental, social, economic, and safety factors in the decision-making process for every pavement project. Therefore, the theme of the conference was chosen as “Sustainable Pavements and Safe Airports.” It is dedicated to the state-ofthe-art and state-of-practice areas durability, cost-effective, and sustainable airfield and highway pavements. In addition, recent advancements and technologies to ensure safe and efficient airport operations are included. This international conference provides a chance to interact and exchange information with worldwide leaders in the fields of highway and airport pavements, as well as airport safety technologies. This conference brought together researchers in transportation and airport safety technologies, designers, project/construction managers, academics, and contractors from around the world to discuss design, implementation, construction, rehabilitation alternatives, and instrumentation and sensing. The proceedings of 2017 International Conference on Highway Pavements and Airfield Technology have been organized in four (4) publications as follows: Airfield and Highway Pavements 2017: Design, Construction, Evaluation, and Management of Pavements This volume includes papers in the areas of mechanistic-empirical design methods and advanced modeling techniques for design of conventional and permeable pavements, construction specifications and quality, accelerated pavement testing, pavement condition evaluation, and network level management of pavements. Airfield and Highway Pavements 2017: Testing and Characterization of Bound and Unbound Pavement Materials This volume includes papers in the areas of laboratory and field characterization of asphalt binders, asphalt mixtures, base/subgrade materials, and recent advances in concrete pavement technology. This volume also features papers for the use of recycled materials, in-place recycling techniques and unbound layer stabilization methods. Airfield and Highway Pavements 2017: Pavement Innovation and Sustainability This volume is dedicated to the papers featuring most recent technologies used for structural health monitoring of highway pavements, intelligent compaction, and innovative technologies used in the design and construction of highway pavements. The volume also includes papers in the area of sustainability assessment using life-cycle assessment of highway and airfield pavements and climate change impacts and preparation for pavement infrastructure. © ASCE Airfield and Highway Pavements 2017 Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/03/19. Copyright ASCE. For personal use only; all rights reserved. Airfield and Highway Pavements 2017: Airfield Pavement Technology and Safety This volume is dedicated to recent advances in the area of airfield pavement design technology and specifications, modeling of airfield pavements, use of accelerated loading systems for airfield pavements, and airfield pavement condition evaluation and asset management. The papers in these proceedings are the result of peer reviews by a scientific committee of more than 90 international pavement and airport technology experts, with three to five reviewers per paper. Recent research was presented in the technical podium and poster sessions including the results from current Federal Aviation Administration (FAA) airport design, specifications, and safety technologies; design and construction of highway pavements; pavement materials characterization and modeling; pavement management systems; and innovative technologies and sustainability. The plenary sessions featured the Francis Turner Lecture by Dr. Robert Lytton and the Carl Monismith Lecture by Dr. David Anderson. In addition, two technical tours were offered: Philadelphia International Airport and the Center for Research and Education in Advanced Transportation Engineering Systems (CREATEs) Lab of the Henry M. Rowan College of Engineering at Rowan University. Three workshops were presented prior to the conference: hands-on FAA’s FAARFIELD software, design and construction of permeable pavements, and environmental product declarations. The editors would like to thank the members of the scientific committee who volunteered their time to review the submitted papers and offered constructive critiques to the authors. We are also grateful for the work of the steering committee members in planning and organizing the conference: Katie Chou, Jeffrey Gagnon, John Harvey, Brian McKeehan, Shiraz Tayabji, and Geoffrey Rowe; as well as the local organizing committee chaired by Geoffrey Rowe and members including James A. McKelvey, Timothy Ward, Ahmed Faheem, and Yusuf Mehta for their help with the technical tours. Finally, we would like to especially thank the ASCE T&DI staff who helped put the conference together: Muhammad Amer, Mark Gable, Drew Caracciolo, and Deborah Denney. Imad L. Al-Qadi, Ph.D., P.E., Dist. M.ASCE, University of Illinois at Urbana-Champaign Hasan Ozer, Ph.D., M.ASCE, University of Illinois at Urbana-Champaign Eileen M. Vélez-Vega, P.E., M.ASCE, Kimley-Horn Puerto Rico, LLC Scott D. Murrell, P.E., M.ASCE, Applied Research Associates © ASCE iv Airfield and Highway Pavements 2017 v Contents Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/03/19. Copyright ASCE. For personal use only; all rights reserved. Asphalt Mixture Characterization Establishing Design Limits for Cracking Properties of Asphalt Concrete with Overlay Tester .................................................................................................... 1 Victor M. Garcia, Jose Garibay, Imad Abdallah, and Soheil Nazarian Development of the Duplicate Shear Test for Asphalt Mixtures ......................... 13 Mohammadreza Khajeh Hosseini, Stefan A. Romanoschi, Reza Saeedzadeh, and Nickey Akbarieh Development of Asphalt Concrete Dogbone Shape Specimens for Uniaxial Tension Testing ......................................................................................................... 25 A. R. Archilla and J. Corrales-Azofeifa Monitoring the Deformation of Asphalt Concrete under Repeated Tensile and Shear Stresses through Micro Cracks Healing Cycles ..................... 38 S. I. Sarsam and H. K. Husain Effect of Asphalt Rejuvenating Agent on Rutting Properties of Aged Reclaimed Asphalt Pavement .................................................................................. 50 Nassim Sabhafer and M. Hossain Laboratory Performance of Superpave Mixes for Perpetual Pavements ........... 63 B. A. Priyanka, Goutham Sarang, B. M. Lekha, and A. U. Ravi Shankar Influence of Coal Combustion By-Products Physiochemical Properties on Aging Related Performance of Asphalt Mastics and HMA .................................. 73 Emil Bautista, Ahmed Faheem, Clayton Cloutier, and Konstantin Sobolev Characterization of Recycled Materials in Asphalt Mixtures Effect of RAP on Cracking and Rutting Resistance of HMA Mixes ................... 86 R. Saha, B. Karki, A. Berg, R. S. Melaku, and D. S. Gedafa Rutting Susceptibility of Asphalt Mixes with High RAP Content Using Rheological and Performance-Based Test Methods .............................................. 95 Syed Ashik Ali, Rouzbeh Ghabchi, Shivani Rani, Musharraf Zaman, and Craig Parker © ASCE Airfield and Highway Pavements 2017 vi Assessment of Emulsified RAP Cold Mixes via Non-Destructive Testing......... 107 Ilker Boz, Xuan Chen, and Mansour Solaimanian Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/03/19. Copyright ASCE. For personal use only; all rights reserved. Effects of RAP Sources for Performance Testing of Asphalt Concrete ............ 119 Hasan M. Faisal, Umme A. Mannan, A. S. M. Asifur Rahman, Md. Mehedi Hasan, and Rafiqul A. Tarefder Constitutive Modeling and Characterization for Asphalt Mixtures Direct Characterization of Aging Diffusion in Asphalt Mixtures Using Micro-Indentation and Relaxation (MIR) ............................................................ 129 M. Alsalihi, A. Hosseini, and A. Faheem A Laboratory Evaluation of Aging on the Viscoelastic Material Functions of Asphalt Concrete and Its Binder..................................................... 141 A. S. M. Asifur Rahman, Hasan M. Faisal, and Rafiqul A. Tarefder Application of Ultrasonic Pulse Velocity Testing of Asphalt Concrete Mixtures to Improve the Prediction Accuracy of Dynamic Modulus Master Curve .......................................................................................................... 152 Pezhouhan Tavassoti-Kheiry, Ilker Boz, Xuan Chen, and Mansour Solaimanian Measured versus Interconverted Viscoelastic Material Functions of Asphalt Concrete .................................................................................................... 165 A. S. M. Asifur Rahman, Hasan M. Faisal, and Rafiqul A. Tarefder Asphalt Binder Characterization Asphalt Binder Properties and Airfield Pavement Cracking ............................. 176 Geoffrey Rowe Performance Grade and Moisture-Induced Damage Potential of Chemically-Modified Asphalt Binders and Mixes ............................................... 189 S. Rani, R. Ghabchi, S. A. Ali, M. Zaman, and E. A. O’Rear Effect of Asphalt Rejuvenating Agent on Cracking Properties of Aged Reclaimed Asphalt Pavement ................................................................................ 201 Nassim Sabhafer and M. Hossain Binder Rheology Based Dynamic Modulus and Phase Angle Predictive Models for Asphalt Concrete ................................................................................. 215 A. S. M. Asifur Rahman, Umme A. Mannan, and Rafiqul A. Tarefder Influence of Viscosities of PDA Pitch and Flux on Blended Bitumen Viscosity ................................................................................................................... 225 Uma Chakkoth, Parag Ravindran, and J. Murali Krishnan © ASCE Airfield and Highway Pavements 2017 vii Merits of Polymer Types Used with Different Local Bitumen Produced in Kurdistan, Iraq ................................................................................. 236 Faris Jasim, Agreen Azeez, and Mohammed Adam Mohammed Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/03/19. Copyright ASCE. For personal use only; all rights reserved. Creep Stiffness Master Curve of Recycled Asphalt Pavement (RAP) Modified Asphalt Binders Based on Binder Beam Rheometer (BBR) Test Data .................................................................................................................. 246 Umme Amina Mannan, Hasan M. Faisal, and Rafiqul A. Tarefder A Synthesis of Asphalt Foaming Parameters and Their Association in Foamed Binder and Mixture Characteristics ...................................................... 256 Biswajit K. Bairgi and Rafiqul A. Tarefder Concrete Pavement Technology Quality Management for Rubber Tire Concrete Applications in Highway and Airfield Pavements Construction .................................................. 268 Hossein Ataei and Chinmay Mattuga Narahari Experimental Analysis of Interface Shear Fatigue Performance of Ultra-Thin Whitetopping ....................................................................................... 283 K. Jayakesh and S. N. Suresha Probability Analysis of Flexural Fatigue Data of High Volume Fly Ash Concrete ................................................................................................................... 295 Aravindkumar Harwalkar and S. S. Awanti Comparing Methods for Determining In Situ Asphalt Stiffness Using Pavement ME .......................................................................................................... 308 N. D. Bech, J. M. Vandenbossche, A. Mateos, and J. T. Harvey Unbound Material Characterization for Base/Subbase Applications Analysis of Cyclic Behavior of Geomaterials Using Dissipated Energy Concept .................................................................................................................... 322 U. B. Arteaga and R. S. Ashtiani Field Performance Evaluation of Pavement Construction Platforms Utilizing Unconventional Large Size Aggregates Packed with Quarry Byproducts, and Higher Fines Aggregate Subgrade Layers .............................. 334 Issam Qamhia, Erol Tutumluer, Hasan Ozer, and Hasan Kazmee A System for Real-Time Measurement of Moisture in Aggregate Mixes Moving on a Conveyor Belt ................................................................................... 348 Linus Dep, Cheng Thao, and Finch Troxler © ASCE Airfield and Highway Pavements 2017 viii A Study on Use of Locally Available Moorum in Pavement Base and Sub-Base .................................................................................................. 360 Shubhakanta Barik, Mahabir Panda, and Prasanta Kumar Bhuyan Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/03/19. Copyright ASCE. For personal use only; all rights reserved. Characterization of Airfield Subbase Materials Using Precision Unbound Material Analyzer (PUMA) ................................................................................... 370 Qiang Li, Jeffery Stein, and Navneet Garg Aggregate Base and Subgrade Stabilization Critical Pavement Response Analysis of Pond Ash Stabilized Subgrade Using Non-Linear Approach ................................................................................. 382 Gaurav Gupta, Hemant Sood, and Pardeep Kumar Gupta In-Place Stabilization for the Rehabilitation of Taxiway S at Nashville International Airport ............................................................................. 396 M. O. Bejarano and D. Schilling Performance Evaluation of a Polymer Binder Stabilized Aggregate Mixture: A Pilot Study ........................................................................................... 406 Elie Y. Hajj, Murugaiyah Piratheepan, and Peter E. Sebaaly Geogrid/Geotextile Stabilization Numerical Analysis of Flexible Pavement Reinforced with Geogrids ............... 416 G. Leonardi, R. Palamara, and L. S. Calvarano Experimental Evaluation of the Interaction between Geosynthetic Reinforcements and Hot Mix Asphalt .................................................................. 428 G. H. Roodi, A. M. Morsy, and J. G. Zornberg © ASCE Airfield and Highway Pavements 2017 Establishing Design Limits for Cracking Properties of Asphalt Concrete with Overlay Tester Victor M. Garcia1; Jose Garibay2; Imad Abdallah, Ph.D3; and Soheil Nazarian, Ph.D., P.E.4 Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/03/19. Copyright ASCE. For personal use only; all rights reserved. 1 Research Assistant, Center for Transportation Infrastructure Systems (CTIS), Univ. of Texas at El Paso, 500 W. University Ave., Metallurgy Bldg., Room M-101A, El Paso, TX, 79968. E-mail: [email protected] 2 Lab Manager, Center for Transportation Infrastructure Systems (CTIS), Univ. of Texas at El Paso, 500 W. University Ave., Metallurgy Bldg., Room M-105, El Paso, TX, 79968. E-mail: [email protected] 3 Executive Director, Center for Transportation Infrastructure Systems (CTIS), Univ. of Texas at El Paso, 500 W. University Ave., Metallurgy Bldg., Room M-105, El Paso, TX, 79968. E-mail: [email protected] 4 Professor, Center for Transportation Infrastructure Systems (CTIS), Univ. of Texas at El Paso, 500 W. University Ave., Engineering Bldg., Room A-207, El Paso, TX, 79968 E-mail: [email protected] Abstract The premature cracking of the asphalt concrete (AC) layer in flexible pavements highlights the importance of a simple cracking performance test that can be used for routine applications during the design process of AC mixes. The overlay tester (OT) can be used to evaluate the formation and propagation of a crack within the AC specimens. This paper explains an alternative methodology for assessing the cracking potential of AC mixes using the OT test. The proposed methodology consists of two main stages: crack initiation and propagation. The fracture properties of the AC specimens are estimated from the critical fracture energy computed from the first OT loading cycle. The resistance of the AC mix to crack propagation is estimated from the crack progression rate, the rate of reduction in load carrying capacity of the AC specimen with the number of cycles. The process of selecting the limits for the critical fracture energy and crack progression rate to delineate the well and poor performing mixes is discussed here. The proposed cracking methodology and acceptance limits may provide a more comprehensive approach to predict and design the cracking potential of AC mixes. INTRODUCTION An asphalt concrete (AC) layer must have a balance of rutting and cracking resistance to perform satisfactorily in the field (Zhou et al., 2006). Laboratory testing is an indispensable first step in balancing the rutting and cracking potentials of AC mixes and to minimize the premature failure of the pavements. Over the past decade, the rutting performance of the AC mixes has been satisfactorily improved by employing the wheel-tracking devices, such as the Hamburg wheeltracking (HWT) test. One way to meet the rutting resistance requirements with the HWT test is using stiffer binders or lower asphalt contents. These measures may negatively influence the flexibility and cracking resistance of the AC mixes (Zhou et al., 2006). Several performance tests have been implemented to evaluate the cracking resistance of AC mixes in the laboratory setting (Ozer et al., 2016; Kim et al., 2006; Wagoner et al., 2005; Wu et al., 2005; Roque et al., 2002). One such test, the overlay tester (OT) test, assesses the reflective cracking susceptibility of AC mixes through an assessment of the number of cycles to failure using a 93% reduction in load as a failure criterion. Although the OT test seems to © ASCE 1 Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/03/19. Copyright ASCE. For personal use only; all rights reserved. Airfield and Highway Pavements 2017 simulate effectively the reflective cracking damage on AC specimens, the current specified performance index from this OT test method yields a high variability (Walubita et al. 2012). Zhou and Scullion (2003) upgraded and standardized the original Texas OT test procedure and corresponding specifications. They found the OT test results are sensitive to key components of AC mixes such as the asphalt binder content, air voids and aggregate properties (Zhou and Scullion, 2005). Zhou et al (2005) proposed a mix design approach that specifies both the HWT device and OT tests for rutting and cracking evaluation, respectively. Walubita and Scullion (2008) implemented the OT test to design several AC mixes in Texas. Additionally, several studies have documented a promising performance of the OT test to qualitatively predict the cracking resistance of AC mixes (Al-Qadi et al., 2015; Tran et al., 2012; Hajj et al., 2010; Bennert et al., 2009; and Bennert and Maher, 2008). A great deal of effort has been focused toward the evaluation and improvement of testing and analysis methods to estimate the cracking resistance of AC mixes using the OT (Gu et al., 2015; Walubita et al., 2013; Koohi et al., 2012; Zhou et al., 2007). Garcia et al. (2016) proposed an alternative approach that consists of two performance indices, the critical fracture energy and crack progression rate, to assess the cracking response of AC specimens during the crack initiation and crack propagation stages of the OT test. This study reports the process of selecting the acceptance limits for the proposed performance indices to delineate the well and poor performing AC mixes. The scope of this paper includes a brief description of the proposed OT test method, followed by an evaluation of the consistency of the performance indices from OT and IDT tests, a selection of acceptance limits for the critical fracture energy and crack progression rate, and an assessment of the proposed OT test methodology and acceptance limits. Finally, the paper closes with conclusions, recommendations and future work from this study. OVERLAY TESTER (OT): PRESENTATION OF A NEW APPROACH Traditional OT Test The Texas Department of Transportation (TxDOT), among several other highway agencies, currently employs the OT test to determine the reflective cracking resistance of some of their AC mixes. The TxDOT OT test procedure is outlined in test procedure Tex-248-F, which is similar to the ASTM WK26816 protocol. Figure 1 depicts the setup of the OT device. The OT consists of two plates. One plate is fixed, while the other can slide back and forth. A 4 mm opening gap is set between the two steel plates. The OT specimen is glued on top of the two platens with half of the length of the specimen resting on each plate. The test is conducted in a displacement-controlled mode using a cyclic triangular waveform with a repeated loading rate of one cycle per 10 sec, a constant maximum displacement of 0.025 in. (635 µm) and a test temperature of 77ºF (25ºC). Optionally, a linear variable differential transducer (LVDT) is added to the test setup as described by Garcia and Miramontes (2015). The primary output of this OT test specification is the number of cycles to failure using a 93% reduction on the maximum peak load. Figure 2 shows the typical output data obtained from the OT test. The OT system records the time histories of the actuator displacement, measured load, number of displacement cycles and test temperature. The applied displacement, measured load and cyclic maximum peak load of each cycle are plotted on Figure 2a. The maximum peak load against the number of cycles (a.k.a. load reduction curve) is shown in Figure 2b. Due to the displacement deformation applied with the sliding plate, the formation of a crack occurs at the bottom of the specimen and then © ASCE 2 Airfield and Highway Pavements 2017 Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/03/19. Copyright ASCE. For personal use only; all rights reserved. propagates thru the height of the specimen. A line representing the 93% load reduction limit for this example was also added to the graph. Figure 1. OT schematic layout and specimen setup. Figure 2. Interpretation of OT results: a) Typical OT data and b) Load reduction curve. Description of Proposed Methodology and Performance Indices In the proposed data interpretation approach, the OT test is divided in two stages: a) crack initiation phase that occurs during the first cycle, and b) crack propagation phase that consists of the reduction of the load throughout the number of cycles. An ideal crack resistant mix should be though enough to mitigate the formation of a crack during the crack initiation stage and at the same time, flexible enough so that it would attenuate the propagation of the crack at a gradual © ASCE 3 Airfield and Highway Pavements 2017 4 rate after the crack is initiated. As depicted in Figure 3, the critical fracture energy and crack progression rate were implemented to characterize the crack initiation and crack propagation stages of the OT test respectively (Garcia et al, 2016). Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/03/19. Copyright ASCE. For personal use only; all rights reserved. The critical fracture energy, Gc, is simply the area under the load-displacement response curve up to the maximum peak load from the first cycle as illustrated in Figure 3a. Equation 1 can be used to calculate the critical fracture energy. (1) where W = portion of the work to induce fracture, A = area of the cracked section, which is assumed as the specimen thickness multiplied by its width. The load reduction curve is used to extract the crack progression rate. The load reduction curve is first normalized by the maximum peak load from the first cycle. A power equation is then fitted to the normalized load reduction curve as shown in Figure 3b. The power coefficient (b-coefficient) from the power equation is interpreted as the crack progression rate. Figure 3. Representation of proposed performance indices: a) Critical fracture energy (Crack initiation) and b) Crack progression rate (Crack propagation). RESEARCH METHODOLOGY AC Material Characteristics Table 1 summarizes the characteristics of the AC mixes used in this study to meet the objectives mentioned above. Seven different AC mix types including a thin overlay mix (TOM), a stone mastic asphalt (SMA), dense-graded and dense-graded Superpave (SP) mixes were included in the experimental design plan. The perceived field performance as reported by the local TxDOT engineers (as reported in Table 1) was also considered in the mix selection. © ASCE Airfield and Highway Pavements 2017 5 Table 1. Characteristics of AC mixes Designation Mix-design Characteristics TOM 6.5% PG 76-22 + Sandstone/Limestone/Dolomite (NMAS 4.76 mm) 6.3% PG 70-28 + 0.4% AS + 0.3% FC + Sandstone/Limestone/Dolomite/Gravel (NMAS 9.5 mm) 6.3% PG 64-22 + 30% RAP + 0.5% WMA + Gravel/Limestone/Dolomite (NMAS 9.5 mm) 4.6% PG 64-22 + 20% RAP + 2% WMA + Limestone/Dolomite/Gravel (NMAS 12.7 mm) 5.3% PG 64-22 + 1% AS + 8% RAP + 2% RAS + Limestone/Dolomite (NMAS 9.5 mm) Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/03/19. Copyright ASCE. For personal use only; all rights reserved. SMA-D SP-C Type-C SP-D 1 Perceived Performance Very Good Very Good Good Marginal Poor Type-D 5.1% PG 64-22 + 15% RAP + 2% RAS + Limestone/Dolomite (NMAS 4.76 mm) Poor SP-D 2 5.4% PG 64-22 + 0.4% WMA + 15% RAP + NP (NMAS 9.5 mm) Poor PG = performance grade, NMAS= nominal maximum aggregate size, AS = antistripping, FC = fiber content, WMA= warm mix asphalt additive, CR = crumb rubber, RAP = reclaimed asphalt pavement, RAS = recycled asphalt shingles, NP=not provided Test Procedures and Specimen Fabrication Prior to compaction, the loose AC mixes were heated for two hours at their corresponding compaction temperatures. A Superpave gyratory compactor was used to compact standard 6 in. (150 mm) diameter by 4.5 in. (114 mm) thick laboratory specimens to a target trimmed density of 7±1.0%. The laboratory specimens were cut using a double-blade saw. All specimens were dried using a CoreDryTM device. The specimens were then tested three days after molding. Before testing, the specimens were preconditioned for two hours at a temperature of 77˚F (25˚C). Five replicate specimens were tested for each aspect of the evaluation to account for the repeatability of the measured parameters. The OT specimens were nominally 6 in. (150 mm) long, 3 in. (75 mm) wide and 1.5 in. (38 mm) thick. The specimen preparation process proposed by Garcia et al. (2016) was followed in this study. The OT tests were conducted using a device manufactured by ShedWorks. The cycling loading was continued until reaching either a 93% reduction in load or 1000 cycles. The critical fracture energy and crack progression rate, as well as the traditional number of cycles to failure were reported from the OT tests. As supplementary test (see Figure 4), the testing protocol outlined in ASTM D6931-12 was used to perform the indirect tensile (IDT) tests. The nominally 4 in. (100 mm) diameter and 2 in. (50 mm) thick IDT specimens were trimmed from 4 in. (100 mm) diameter by 4 in. (100 mm) thick laboratory specimens. The IDT tests were performed with a material testing system (MTS) placed inside an environmental controlled chamber. A loading rate of 2 in./min (50 mm/min) was applied to the IDT specimens. The tensile strength was computed using Equation 2. = (2) where σt is the tensile strength and Pmax is the maximum load. Parameters t and D are the thickness and diameter of the IDT specimen, respectively. © ASCE Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/03/19. Copyright ASCE. For personal use only; all rights reserved. Airfield and Highway Pavements 2017 6 Figure 4. IDT specimen setup. DATA ANALYSIS AND DISCUSSION OF RESULTS Consistency of Measured Performance Parameters for OT and IDT Tests The consistency of the proposed parameters was evaluated from OT test results obtained from replicate specimens. The average, standard deviation and coefficient of variation (COV) of the reported parameters are presented in Table 2. The COVs of the critical fracture energy and crack progression rate were less or equal to 20% except for the results from Type-D mix for the crack progression rate. The crack progression rate for Type-D mix presented a higher COV because the curvature of the load reduction curve was difficult to estimate with a few load repetitions necessary for the specimens’ failure. The number of cycles to failure presented COVs that ranged between 27% and 85%. The measured parameters with IDT tests presented COVs of less than 5%. Preliminary Acceptance Limit for Crack Progression Rate To properly establish an acceptance limit for the crack progression rate, the behaviors of the load reduction curves were investigated. The average normalized load reduction curves for each mix is presented in Figure 5. Three additional curves representing the 100, 300 and 1000 cycles to reach a 93% load reduction are added to the figure. The load reduction curves for the TOM and SMA-D mixes are way above the curve associated with the 300 and 1000 cycles meaning that these two mixes will easily resist more than 1000 cycles. The load reduction curve for the SP-C follows the ideal curve for 1000 cycles to failure. The load reduction curve for the Type-C mix is slightly above the ideal curve representing 300 cycles. Conversely, the load reduction curves for the Type-D and SP-D 2 mixes are significantly below the curve for 300 cycles. © ASCE Airfield and Highway Pavements 2017 7 Table 2. Summary of Parameters from OT and IDT Tests OT Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/03/19. Copyright ASCE. For personal use only; all rights reserved. Mix Type TOM SMA-D SP-C Type-C SP-D 1 Type-D SP-D 2 Parameter Average Std. Dev. COV Average Std. Dev. COV Average Std. Dev. COV Average Std. Dev. COV Average Std. Dev. COV Average Std. Dev. COV Average Std. Dev. COV IDT Critical Fracture Energy, in.-lbs/in.2 Crack Progression Rate Number of Cycles to Failure Max Load, lbs Tensile Strength, psi 2.7 0.2 7% 1.7 0.2 9% 1.7 0.1 8% 1.1 0.1 9% 3.5 0.2 5% 3.1 0.3 10% 1.9 0.2 10% 0.33 0.01 3% 0.32 0.01 4% 0.37 0.03 8% 0.45 0.03 6% 0.60 0.04 7% 1.10 0.36 33% 1.31 0.26 20% 1000 0 NA 1000 0 NA 653 326 50% 350 94 27% 73 26 35% 21 18 85% 14 6 40% 2007 73 4% 1108 24 2% 1736 64 4% 1720 48 3% 2641 68 3% 2580 47 2% 1743 62 4% 160 6 4% 88 2 2% 138 5 4% 137 4 3% 210 5 3% 205 4 2% 139 5 4% Figure 5. Comparison of load reduction curves. The three representative load reduction curves for 100, 300 and 1000 cycles with the associated crack progression rate are shown in Figure 6. The corresponding crack progression © ASCE Airfield and Highway Pavements 2017 Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/03/19. Copyright ASCE. For personal use only; all rights reserved. rates for the curves representing 100, 300 and 1000 cycles to failure are 0.577, 0.466 and 0.385, respectively. The curve corresponding to 300 cycles can be interpreted as the curve associated to the current pass/fail criteria. As a preliminary acceptance limit, a crack progression rate of 0.50 is proposed to delineate the AC mixes with well and poor cracking resistance using the proposed OT methodology and associated performance indices. Figure 6. Representative load reduction curves for 100, 300 and 1000 cycles. Correlation between Fracture and Tensile Properties of AC Mixes Some of the current TxDOT AC mix design specifications contain limits for the IDT strength as a surrogate for cracking performance in the field. The maximum and minimum allowable IDT tensile strengths are 200 psi (~1.4 MPa) and 85 psi (~600 kPa), respectively. The IDT strengths from the seven mixes are compared with their corresponding critical fracture energy values from OT in Figure 7. A good correlation is observed between the two parameters with a coefficient of determination (R2 value) of 0.80. Based on this correlation, the preliminary upper limit (UL) of three and the lower limit (LL) of unity were selected for the acceptable critical energy range. Figure 7. Correlation between IDT and OT tests performance indices. Characterization of AC Mixes using Proposed OT Methodology To better interpret the cracking properties of the AC mixes using the proposed performance indices from the OT test, the design interaction plot presented in Figure 8 is recommended. The critical fracture energy (crack initiation property) and crack progression rate (crack propagation property) are plotted against one another. The design interaction plot can be subjectively divided into the following four categories: © ASCE 8 Airfield and Highway Pavements 2017   Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/03/19. Copyright ASCE. For personal use only; all rights reserved.   9 Tough-Crack Resistant: AC mixes with good resistance during crack initiation (tough) and propagation (flexible). Ideal mixes should be in this quadrant. Tough-Crack Susceptible: AC mixes with good resistance to crack initiation (tough) and susceptible to crack propagation (brittle). Soft-Crack Resistant: AC mixes susceptible to crack initiation (soft) but good resistance to attenuate the propagation of the crack (flexible) Soft-Crack Susceptible: AC mixes with poor resistance to crack initiation and propagation. These mixes should be definitely avoided. Figure 8. Design interaction plot The distributions of the critical fracture energy and crack progression rate for all mixes are presented in Figure 9. According to the proposed methodology, the best mixes are the SMAD and TOM mixes since they are flexible after the crack has initiated (the lowest crack progression rates). The high critical fracture energy of TOM is desire since more energy will be required to initiate the crack. The SP-C mix should satisfactorily resist the initiation and propagation of the crack. The Type-C mix will satisfactorily resist the propagation of the crack, but the crack will initiate easily due to the low critical fracture energy. Conversely, the critical fracture energy and crack progression rate for the SP-D 1 mix are out of the acceptable limits. This mix will require more energy to initiate the crack, but the crack will abruptly propagate due to its brittleness. Similarly, the results for the Type-D mix are not within the acceptable limits with a poor crack progression rate and high critical fracture energy. The SP-D2 mix can be ranked as the worst of the AC mixes with the highest crack progression rate. Figure 9 - Cracking performance of AC mixes. © ASCE Downloaded from ascelibrary.org by RMIT UNIVERSITY LIBRARY on 01/03/19. Copyright ASCE. For personal use only; all rights reserved. Airfield and Highway Pavements 2017 SUMMARY AND CONCLUSIONS The main goal of this paper was to present the process of selecting acceptance limits for the performance indices proposed on a new data interpretation method for the OT tests. The proposed data interpretation method, performance indices and corresponding acceptance limits were used to determine the cracking resistance of several AC mixes commonly use in Texas. The cracking resistance of the AC mixes can be ranked more consistently using the proposed cracking methodology. From the findings of this study, the following conclusions can be drawn: 1. The current pass/fail criteria for the number of cycles to failure was implemented to select the acceptance limit for the crack progression rate. A crack progression rate of 0.50 is proposed as an acceptance limit to discriminate the well and poor crack resistant mixes. 2. The good correlation between the OT critical fracture energy and IDT tensile strength parameters was used to establish preliminary acceptance limits for the critical fracture energy. 3. The design interaction plot and proposed acceptance limits for the performance indices seem to be consistent in assessing the cracking properties of the AC mixes. Further work is on the way to evaluate the fracture and tensile strength properties of a greater number of AC mixes and increase the data points of the correlation between the IDT and OT test parameters. AKNOWNLEDGEMENTS The authors are grateful to the Texas Department of Transportation for the continuous support they provide. 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