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Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies (2012)

Chapter: Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies

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Suggested Citation:"Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies. Washington, DC: The National Academies Press. doi: 10.17226/14646.
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Suggested Citation:"Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies. Washington, DC: The National Academies Press. doi: 10.17226/14646.
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Suggested Citation:"Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies. Washington, DC: The National Academies Press. doi: 10.17226/14646.
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Suggested Citation:"Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies. Washington, DC: The National Academies Press. doi: 10.17226/14646.
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Suggested Citation:"Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies. Washington, DC: The National Academies Press. doi: 10.17226/14646.
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Suggested Citation:"Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies. Washington, DC: The National Academies Press. doi: 10.17226/14646.
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Suggested Citation:"Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies. Washington, DC: The National Academies Press. doi: 10.17226/14646.
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Suggested Citation:"Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies. Washington, DC: The National Academies Press. doi: 10.17226/14646.
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Suggested Citation:"Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies. Washington, DC: The National Academies Press. doi: 10.17226/14646.
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Suggested Citation:"Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies. Washington, DC: The National Academies Press. doi: 10.17226/14646.
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Suggested Citation:"Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies. Washington, DC: The National Academies Press. doi: 10.17226/14646.
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Suggested Citation:"Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies. Washington, DC: The National Academies Press. doi: 10.17226/14646.
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Suggested Citation:"Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies. Washington, DC: The National Academies Press. doi: 10.17226/14646.
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Suggested Citation:"Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies. Washington, DC: The National Academies Press. doi: 10.17226/14646.
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Suggested Citation:"Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies. Washington, DC: The National Academies Press. doi: 10.17226/14646.
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Suggested Citation:"Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies. Washington, DC: The National Academies Press. doi: 10.17226/14646.
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Suggested Citation:"Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies. Washington, DC: The National Academies Press. doi: 10.17226/14646.
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Suggested Citation:"Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies. Washington, DC: The National Academies Press. doi: 10.17226/14646.
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Suggested Citation:"Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies. Washington, DC: The National Academies Press. doi: 10.17226/14646.
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Suggested Citation:"Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies. Washington, DC: The National Academies Press. doi: 10.17226/14646.
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Suggested Citation:"Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies. Washington, DC: The National Academies Press. doi: 10.17226/14646.
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Suggested Citation:"Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies. Washington, DC: The National Academies Press. doi: 10.17226/14646.
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Suggested Citation:"Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies. Washington, DC: The National Academies Press. doi: 10.17226/14646.
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Suggested Citation:"Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies. Washington, DC: The National Academies Press. doi: 10.17226/14646.
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Suggested Citation:"Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies. Washington, DC: The National Academies Press. doi: 10.17226/14646.
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Suggested Citation:"Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies. Washington, DC: The National Academies Press. doi: 10.17226/14646.
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Suggested Citation:"Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies. Washington, DC: The National Academies Press. doi: 10.17226/14646.
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Suggested Citation:"Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies. Washington, DC: The National Academies Press. doi: 10.17226/14646.
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Suggested Citation:"Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies. Washington, DC: The National Academies Press. doi: 10.17226/14646.
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Suggested Citation:"Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies. Washington, DC: The National Academies Press. doi: 10.17226/14646.
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Suggested Citation:"Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies. Washington, DC: The National Academies Press. doi: 10.17226/14646.
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Suggested Citation:"Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies. Washington, DC: The National Academies Press. doi: 10.17226/14646.
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Suggested Citation:"Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies. Washington, DC: The National Academies Press. doi: 10.17226/14646.
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Suggested Citation:"Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies. Washington, DC: The National Academies Press. doi: 10.17226/14646.
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Suggested Citation:"Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies." National Academies of Sciences, Engineering, and Medicine. 2012. Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies. Washington, DC: The National Academies Press. doi: 10.17226/14646.
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Research Results Digest 370 February 2012 C O N T E N T S Introduction, 1 Workshop Results, 2 References, 14 Appendix A, A-1 Appendix B, B-1 INTRODUCTION Warm mix asphalt (WMA) refers to asphalt mixtures produced at temperatures at least 50°F cooler than those typically used in the production of hot mix asphalt (HMA). The goal of WMA is to produce mixtures with similar strength, durability, and perfor- mance characteristics as HMA using sub- stantially reduced production temperatures. Important environmental and health benefits are associated with reduced production tem- peratures, including lower greenhouse gas emissions, lower mix plant fuel consump- tion, and reduced exposure of workers to asphalt fumes. Lower production tempera- tures also can potentially improve pavement performance by reducing binder aging, pro- viding added time for mixture compaction, and allowing improved compaction during cold weather paving. The first WMA pavements were con- structed in Europe in 1995 and in North America in 2004. Since that time, WMA production has substantially grown in the United States. For example, the FHWA estimates that 10% of the 358 million tons of asphalt mix placed nationwide in 2010 was WMA. As the use of WMA has widened, so have the number of WMA technologies available to the industry. In 2011, 30 or more WMA technologies were available, classified into three broad categories: (1) those using organic additives, including waxes; (2) those using chemical additives; and (3) those using water-based foaming processes. Moreover, as these numbers suggest, WMA has rapidly moved from use in pilot and experimental projects to more routine, large-scale use. At present, at least 30 state departments of transportation (DOTs) have established specifications per- mitting the use of WMA. This rapid growth in use of WMA use naturally raises questions about WMA pavement construction processes and the pavements’ long-term durability and GUIDELINES FOR PROJECT SELECTION AND MATERIALS SAMPLING, CONDITIONING, AND TESTING IN WMA RESEARCH STUDIES This digest summarizes the results of a “Workshop to Coordinate Key WMA Research Projects” sponsored by NCHRP Project Panels 9-43, 9-47, and 9-49 in conjunction with the AASHTO Highway Subcommittee on Materials, the Federal Highway Administration, and the National Asphalt Pavement Association. The workshop was held on May 13, 2011 at the National Academies’ Arnold and Mabel Beckman Center, Irvine, CA. The notes on which this digest is based were prepared by Mr. Tom Baker, Washington State Department of Transportation; Messrs. Matthew Corrigan and John Bukowski, Federal Highway Administration; Dr. Jon Epps, Texas Transportation Institute; Dr. David Newcomb, formerly of the National Asphalt Pavement Association; and Dr. Edward Harrigan, National Cooperative Highway Research Program. Responsible Senior Program Officer: E. T. Harrigan NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM

performance. Newcomb (8) has summarized these questions as follows: • Mix design: What modifications to asphalt mix technology, if any, are required for design- ing WMA? How is the selection of binder per- formance grades impacted by the lower WMA production temperatures? • Long-term performance: How do the short- and long-term performance and durability of pavements constructed with WMA compare with those constructed with HMA? How are these qualities affected by WMA technologies using foaming or chemical additives? Does WMA present an increased potential for dis- tresses such as rutting and moisture damage? • Cost benefits: What are the cost benefits of the reduced fuel consumption and emissions obtained with WMA? • Plant operations: Is WMA compatible with the high production rates needed in the United States? • Control of mixing process: Given that the various WMA mixing processes all differ to a greater or lesser degree from that of conven- tional HMA, are new guidelines needed for proper quality assurance of the mix? • Workability at the paving site: Although the WMA may appear workable and easily com- pactable when produced, does it remain work- able at the paving site? • Quick turnover to traffic: Can WMA pave- ments be opened to traffic as soon as possible after construction, in a time frame similar to or earlier than conventional HMA pavements? Answers to many of these questions are being pursued in WMA research studies informally coordi- nated through the FHWA’s WMA Technical Work- ing Group. For example, more than 15 state DOTs are currently sponsoring WMA research studies, and the 50 state DOTs are collectively sponsoring NCHRP projects investigating WMA mix design, the poten- tial moisture susceptibility of WMA pavements, and whether WMA and HMA pavements provide signifi- cantly different short- and long-term performance. NCHRP projects planned for 2012 and later years will address the short-term laboratory aging of WMA for mix design and performance testing, characterization of foamed asphalt for WMA applications, and the use of recycled asphalt pavement (RAP) and recycled asphalt shingles (RAS) in WMA. A potential shortcoming of such a large, diverse, and dynamic program is the difficulty of comparing results between laboratory and field studies using different experiment designs, conditioning protocols, and test methods to characterize the material proper- ties and performance of WMA. To address this short- coming, the “Workshop to Coordinate Key WMA Research Projects” was organized with the goal of fos- tering cooperation and coordination among research studies. Workshop participants sought to (1) identify the laboratory and field-test methods and sample preparation, curing, and conditioning procedures in use in FHWA-, NCHRP-, state DOT-, and industry- sponsored research projects and (2) agree on a core set of methods and procedures that would be com- monly used, insofar as possible, in all present and future WMA studies. In addition, the workshop participants reviewed new and existing WMA field pavements included in short- and long-term WMA performance studies to facilitate sharing of their field materials and data, and developed selection criteria for future field pavements. The invited participants included researchers and practitioners from the pub- lic sector, academia, and industry, and representatives of the sponsoring organizations. WORKSHOP RESULTS The results of the workshop are presented in tables on the following pages. These tables present a pro- posed core set of criteria, methods, and protocols, including • field project selection criteria (Table 1); • specimen preparation methods (Table 2); • conditioning methods for laboratory-mixed, laboratory-compacted (LMLC) specimens, plant-mixed, laboratory-compacted (PMLC) specimens, and plant-mixed, field-compacted (PMFC) specimens (Table 3); • performance test methods for LMLC, PMLC, and PMFC specimens (Table 4, Table 5, Table 6, and Table 7); and • binder and aggregate test methods (Table 8). These criteria, methods, and protocols were arrived at through a consensus-building activity involving all the workshop participants. They rep- resent the participants’ collective judgment of the minimum complement necessary to enable correla- tion and comparison of results between or among WMA research studies. Use of this core set does not 2 (Text continues on p. 14.)

3Table 1 Field project selection for short- and long-term performance studies. Project length Project and construction documentation Control section definition Minimum number of WMA technologies Other key features The minimum test section shall be 1⁄2 lane-mile in one travel lane located between inter- sections or interchanges. The plant temperature may be increased to produce the HMA control section. Shorter sections may be allowed if they are well planned and documented. Notes: The ideal production per test section is 800–1000 tons or 1⁄2- to 1 day production or 1 tanker load of binder (400–600 tons of non-foamed WMA); these amounts will vary depending on the nominal maximum aggregate size (NMAS) of the mix. Although 1 day’s production is often possible, test projects with control sections often are difficult to find. Selection of the minimum section length also must consider the type of WMA additive and where it is introduced. NCAT and the University of Minnesota (for cold-climate projects) have developed detailed checklists for documenting field projects (see Appendix A). Notes: Key considerations are (1) a condition survey of the existing pavement, (2) the pavement cross-section, (3) evaluation of pavement structural support, and (4) WMA production and compaction temperatures. The HMA control section must be identical to the WMA sections (including any RAP or RAS content) in all aspects but the presence of WMA, with the exception that the binder content of the control section may differ if necessary to attain identical air void contents in all sections. Minimum two technologies, plus a control. However, this minimum number may be waived, depending on whether the project is a new pavement or an overlay on an existing pavement. (1) WMA and control sections must be surface mixes in the same travel lane and with the same pavement support throughout all sections. (2) The correct mix discharge temperatures for the WMA must be verified throughout the project. (3) New projects are favored, but existing projects may be used if the necessary require- ments are met. It is sometimes feasible to work with the state DOT and contractor to add WMA sections to an HMA project through a change order. (4) Specific and systematic performance monitoring plans are required for new versus exist- ing WMA projects. Both plan types should include the provision for forensic analysis when pavements exhibit significant distress. (5) In the event that a WMA project of interest was constructed without a control section, it may be possible to pair the WMA project with an otherwise unconnected HMA project constructed with similar materials, structure, condition, traffic, and climate (e.g., see Von Quintus, Mallela, and Buncher [1]). (6) Future field projects should consider (a) roadway functional classification (average daily traffic [ADT] and trucks per day [% trucks]); (b) a variety of mix types (e.g., stone mas- tic asphalt and open-graded friction courses); and performance in intersections. (7) RAP and RAS are permitted as long as identical control mixes are available. (8) For overlay projects, the WMA and control sections must have comparable levels of existing distress.

4Table 2 Specimen preparation methods. WMA binders for mix design WMA binder extraction and recovery Laboratory blending with low shear mechanical stirrer or foaming with laboratory- foamed asphalt plant, per the proposed appendix to AASHTO R 35 (2). Notes: (1) Aggregate coating is the key measure of foaming. Use coating to help guide selection of temperature. (2) Mix design may not require production of foamed binder in laboratory. Rather, it may be feasible to add water and binder to a bucket mixer containing aggregate and obtain comparable results. (3) At present, there are three commercial units for producing foamed asphalt. It is not known how these units compare. Further, it is very difficult to test the properties of foamed binder in bucket during production, and the foaming is typically lost during transfer of the binder for mixing with the aggregate. In practice, however, no problems have been identified with foamed WMA. (4) Future research is needed to better define the requirements for laboratory production of foamed asphalt. A procedure such as that of Minnesota DOT is required. In the Minnesota DOT procedure, asphalt binder extractions are performed using AASHTO T 164 Method A (Centrifuge Method). Toluene is used as the extraction solvent for the first two washes with an 85:15 v/v mixture of toluene and 95% ethanol used for the third wash. ASTM D5404—Standard Practice for Recovery of Asphalt from Solution Using Rotary Evaporator—is followed for the binder recovery method with the following modifications: Bath temperature and vacuum settings for toluene distillation (60°C, 100mBar). Fines are removed from the extract by high-speed centrifuging at 2000 RPM for 35 minutes after volume of asphalt extract is reduced to ∼500ml. Notes: (1) The FHWA memorandum Extraction and Recovery Procedures at TFHRC Asphalt Laboratories (Appendix B) provides detailed information on a preferred method of binder extraction and recovery. (2) The use of trichloroethylene (TCE) as the extraction solvent is discouraged. TCE is known to harden recovered binders beyond the in situ level. (3) Western Research Institute has developed an infrared spectroscopy method for detecting residual solvent in the recovered binder. (4) Research indicates that a higher temperature and vacuum than specified in ASTM D5404 may be required to effectively remove the toluene solvent from the recovered binder.

5Table 2 (Continued) LMLC specimens for mix design PMLC specimens for quality assurance PMFC specimens for quality assurance and long-term performance testing 1. Mix design: 150-mm diameter × 115-mm high at Ndesign. 2. Moisture sensitivity: 150-mm diameter × 95-mm high at 7.0±0.5% air voids. Note: Some researchers may also use complementary lower and higher air voids, e.g., 4.0% and 9.0%. 3. Dynamic modulus and flow number with AMPT: 100-mm diameter × 150-mm high cored and sawn from 150-mm diameter × 175-mm high specimens at 7.0±0.5% air voids (per appendix to AASHTO R 35 and 2011 change to AASHTO TP 79). 4. IDT creep and strength: 150-mm diameter × 50-mm high prepared from gyratory specimen. Note: It is recommended to cut only one specimen from the center of each 115-mm high gyratory specimen. 5. Hamburg Test: 150-mm diameter × 62-mm high prepared from gyratory specimen. 6. Beam Fatigue Test: 380-mm long × 63-mm wide × 50-mm high beams cut from rolling- wheel compacted slabs. 7. Overlay Test: 150-mm diameter × 115-mm high. 1. Verify mix design: 150-mm diameter × 115-mm high at Ndesign. 2. Moisture sensitivity and resilient modulus: 150-mm diameter × 95-mm high at 7.0±0.5% air voids. 3. Dynamic modulus, flow number, and AMPT fatigue: 100-mm diameter × 150-mm high cored and sawn from 150-mm diameter × 175-mm high specimens; 7.0±0.5% or field air voids. 4. Indirect Tensile Test (IDT) creep and strength: 150-mm diameter × 50-mm high. 5. Hamburg Test: 150-mm diameter × 62-mm high. 1. 150-mm diameter cores: generally suitable for (a) bond strength, (b) in-place density and thickness, (c) air voids analysis, (d) IDT creep compliance and strength, (e) IDT dynamic modulus, (f) Hamburg Test, (g) Overlay Test, and (h) moisture sensitivity. Notes: (1) Some low-temperature IDT testing may be done with 4-in. diameter specimens due to load requirements for 150-mm diameter specimens. (2) A core barrel with a 150-mm inside diameter should be used. (3) Due to lift thickness limitations, 150-mm pavement cores are generally not suitable for (a) dynamic modulus and (b) flow number.

6Table 3 Required conditioning methods. 2 hours at WMA construction compaction temperature. 2 hrs at WMA construction compaction temperature, then 16 hours at 140°F (per AASHTO T 283), then 2 to 2.5 hours at compaction temperature. Long-term aging (per AASHTO R 30), 5 days at 85°C (after conditioning for rutting tests). 16 hours at 140°F (per AASHTO T 283), then 2 to 2.5 hours at compaction temperature. For WMA mix design and volumetric analysis, moisture sensitivity (AASHTO T 283 and T 324), and flow number (AASHTO TP 79). Notes: (1) This is the short-term conditioning recommended by NCHRP Project 9-43 as the best representation of aging at construction (see [2]). (2) This recommendation leads to decreased flow number requirements for WMA compared to HMA and possibly lower binder contents compared to an equivalent HMA mixture, and was based on data from mixtures with aggre- gate absorptions of 1.0% or less. (3) The flow number measured under these conditions may be indicative of a propensity of the mixture to early rutting. (4) For WMA mixtures containing RAP or RAS, the compaction temperature is that for the virgin binder. For WMA and HMA dynamic modulus (AASHTO TP 79), flow number (AASHTO TP 79), and moisture sensitivity (AASHTO T 283 and T 324) Notes: (1) This conditioning is intended to simulate aging after approximately 1 to 2 years in service. (2) Measurement of Gmm after conditioning provides an indication of extended binder absorption. For WMA and HMA fatigue testing (AASHTO T 321 and TX-248-F) and low- temperature cracking testing (AASHTO T 322). Note: This conditioning is generally done on bulk specimens, but may be done on cored and sawn specimens if desired. For WMA and HMA dynamic modulus (AASHTO TP 79), flow number (AASHTO TP 79), and moisture sensitivity (AASHTO T 283 and T 324). Notes: (1) This conditioning is intended to simulate aging after approximately 1-2 years in service. (2) The flow number measured before this conditioning may be indicative of the propensity of the mixture to early rutting. LMLC SPECIMENS PMLC SPECIMENS

7Table 3 (Continued) From ambient temperature, reheat to compaction temperature for a target period of 2.5 hours. For samples not at ambient temperature, note the temperature and reheat to compaction temperature, noting the time. Long-term aging (AASHTO R 30), 5 days at 85°C (after conditioning for rutting tests). Recommended minimum time between fabrication and testing. Recommended maximum time between fabrication and testing. Drying as needed. For volumetric analysis. For volumetric analysis. For WMA and HMA fatigue testing (AASHTO T 321 and TX-248-F) and low-temperature cracking testing (AASHTO T 322). Note: This conditioning is generally done on bulk specimens, but may be done on cored and sawn specimens if desired. 5 days. 20 to 30 days unless specimens are properly vacuum sealed and stored. Record times and temperatures of storage. Take precautions when drying PMFC specimens at elevated temperatures to avoid damaging them. PMLC SPECIMENS (continued) PMFC SPECIMENS

8Table 4 LMLC specimens: required performance testing for mix design. Flow number Hamburg Test Dynamic modulus Beam Fatigue Test Overlay Test IDT creep compliance and strength Moisture sensitivity Hamburg Test Volumetric mix design Compactibility Coating AASHTO TP 79. Note: Follow the procedure in Section 8.5 of the draft appendix to AASHTO R 35 (2). AASHTO T 324 performed for moisture sensitivity. Note: Prepare specimens at air voids content of 7±1% and conduct test at standard conditions: 50°C under water. AASHTO TP 79. Note: Provides necessary input data for pavement analysis with DARWin-ME. ASTM D7460 in strain control. Strong alternative: Tex-248-F, Test Procedure for Overlay Test, January 2009. AASHTO T 322. Note: Provides necessary input data for pavement analysis with DARWin-ME. AASHTO T 283. Note: 1 freeze/thaw cycle. AASHTO T 324. Note: Prepare specimens at air voids content of 7±1% and conduct test at standard conditions: 50°C under water. Per the procedure in the draft appendix to AASHTO R 35 (2). Per the procedure in section 8.3 of the draft appendix to AASHTO R 35 (2). AASHTO T 195, in accordance with the guidance in section 8.2 of the draft appendix to AASHTO R 35 (2). Note: Be aware of the inherent variability of the method and potential variability in results between different types of mixers. RUTTING MODULUS FATIGUE CRACKING THERMAL (LOW-TEMPERATURE) CRACKING DURABILITY OTHER

9Table 5 PMLC specimens: required performance testing for quality assurance. Flow number Hamburg Test Dynamic modulus Beam Fatigue Test Overlay Test IDT creep compliance and strength Semi-Circular Bending Test Moisture sensitivity Hamburg Test Gmm (AASHTO T 209) Volumetric properties Gyratory compaction to Ndesign AASHTO TP 79. AASHTO T 324 performed for moisture sensitivity. Note: Prepare specimens at air voids content of 7±1% and conduct test at standard conditions: 50°C under water. AASHTO TP 79. Note: Provides necessary input data for pavement analysis with DARWin-ME. ASTM D7460 in strain control. Strong alternative: Tex-248-F, Test Procedure for Overlay Test, January 2009. AASHTO T 322. Note: Provides necessary input data for pavement analysis with DARWin-ME. Strong alternative: Per Li and Marasteanu (4). AASHTO T 283. Note: 1 freeze/thaw cycle. AASHTO T 324. Note: Prepare specimens at air voids content of 7±1% and conduct test at standard conditions: 50°C under water. AASHTO T 209. AASHTO R 35. AASHTO T 312. RUTTING MODULUS FATIGUE CRACKING THERMAL (LOW-TEMPERATURE) CRACKING DURABILITY OTHER

10 Table 6 PMFC specimens: required performance testing for quality assurance and long-term performance. Hamburg Test Dynamic modulus by IDT method Spectral analysis of seismic waves (SASW) Overlay Test IDT creep compliance and strength Semi-Circular Bending Test Hamburg Test Moisture sensitivity Bond strength between layers Visual distress survey Rut depth profile In-place thickness and density Smoothness (IRI) FWD Permeability Gmb Gmm Air voids analysis Absorption (by calculation) DSR torsion bar AASHTO T 324 performed for moisture sensitivity. Note: Prepare specimens at air voids content of 7±1% and conduct test at standard conditions: 50°C under water. Per the procedure in Kim, Seo, et al. (5). Strong alternative. Strong alternative: Tex-248-F, Test Procedure for Overlay Test, January 2009. AASHTO T 322. Note: Provides necessary input data for pavement analysis with DARWin-ME. Strong alternative: Per Li and Marasteanu (4). AASHTO T 324 performed for moisture sensitivity. Note: Prepare specimens at air voids content of 7±1% and conduct test at standard conditions: 50°C under water. AASHTO T 283. Note: 1 freeze/thaw cycle. For forensic analysis, as necessary. Per the procedure in West, Zhang, and Moore (7). Per the FHWA LTPP Protocol. Core or SASW measurements. With cooperation of state DOT. As needed for forensic analysis. Per the FHWA LTPP Protocol. As needed for forensic analysis. Per the method in Cooley (6). AASHTO T 166 or T 331. AASHTO T 209. AASHTO T 269. RUTTING MODULUS FATIGUE CRACKING THERMAL (LOW-TEMPERATURE) CRACKING DURABILITY PAVEMENT CONDITION

Table 7 Summary of performance testing and specimen conditioning. Performance Testing Sample Type Modulus Rutting Fatigue Cracking Low-Temperature Cracking Durability LMLC PMLC PMFC Specimen Conditioning Conditioning Sample Type LMLC Mix design/volumetric analysis X Modulus X Rutting X X Fatigue cracking X Low-temperature cracking X Durability X X • Dynamic modulus (AMPT) • IDT • SASW • Flow number (AMPT) • Hamburg Test • Hamburg Test • Beam Fatigue Test • Overlay Test • Overlay Test • IDT • Semi-Circular Bending Test • IDT • Semi-Circular Bending Test • Lottman Test • Hamburg Test • Lottman Test • Hamburg Test Test For 2 hrs @ WMA compaction temperature 2 hrs @ WMA compaction temperature 16 hrs @ 140°F + 2 hrs @ WMA compaction temperature + 5 days @ 85°C 2 hrs @ WMA compaction temperature 16 hrs @ 140°F + 2 hrs @ WMA compaction temperature (continued on next page)

Table 7 (Continued) Conditioning Sample Type PMLC1 Volumetric analysis X Modulus X Rutting X Fatigue cracking X Low-temperature cracking X Durability X Sample Type Test For Conditioning PMFC Volumetric analysis Dry and test Modulus Rutting Fatigue cracking Low-temperature cracking Durability 1For samples of mix at ambient temperature, reheat at WMA compaction temperature for 2.5 hrs. For samples of mix not at ambient temperature, reheat at WMA compaction temperature and note time. Test For 2 hrs @ WMA compaction temperature 2 hrs @ WMA compaction temperature 16 hrs @ 140°F + 2 hrs @ WMA compaction temperature + 5 days @ 85°C 16 hrs @ 140°F + 2 hrs @ WMA compaction temperature

13 Table 8 Binder and aggregate testing. Continuous performance grade of extracted WMA binder Continuous performance grade of original WMA binder, to include modifiers added at the plant Aging Index Multiple Stress Creep Recovery Test Linear Amplitude Sweep Test Frequency sweep to develop master curve Gradation Bulk specific gravity and absorption Flat and elongated or AIMS method Sand equivalent Fine aggregate, uncompacted voids Coarse aggregate angularity Stockpile moisture content Geologic type LA Abrasion Test or Micro Deval Test Soundness AASHTO R 29 without RTFO aging. Note: Done before and after PAV aging. Use a DSR capable of handling stiff binders. AASHTO R 29. Note: Use a DSR capable of handling stiff binders. AASHTO TP 70. Per Hintz, Velasquez, et al. (3). AASHTO T 27. AASHTO T 84 and T 85. ASTM D 4791 or use state or contractor data. AASHTO T 176 or use state or contractor data. AASHTO T 304 or use state or contractor data. AASHTO T 335 or use state or contractor data. AASHTO T 255 or use state or contractor data. Yes or use state or contractor data. AASHTO T 96 or T 327 or use state or contractor data. AASHTO T 104 or use state or contractor data. BINDERS AGGREGATES

14 preclude the use of additional criteria, methods, and protocols that may be dictated by the specific objec- tives of a particular study. Also, the objectives of a particular research study will dictate which methods and protocols of this core set are used. For example, an experiment design for a study of WMA fatigue cracking potential would not likely require the inclu- sion of methods for rutting, moisture sensitivity, or low-temperature cracking from the core set. Appendix A contains templates for documenta- tion of field projects as referenced in Table 1. The templates are used with permission of the National Center for Asphalt Technology (NCAT) and the Uni- versity of Minnesota. The NCAT template is appli- cable to any field project, whereas the University of Minnesota template is specialized to projects that are primarily focused on low-temperature cracking behavior. Appendix B provides information on extraction and recovery procedures for asphalt binders refer- enced in Table 2. This information was prepared in the asphalt laboratories of the FHWA’s Turner- Fairbank Highway Research Center (TFHRC). REFERENCES 1. Von Quintus, H.L., J. Mallela, and M. Buncher, “Quantification of Effect of Polymer-Modified Asphalt on Flexible Pavement Performance,” Transportation Research Record: Journal of the Transportation Research Board, No. 2001, Transportation Research Board of the National Academies, Washington, D.C., 2007; pp. 141–54. 2. Bonaquist, R. NCHRP Report 691: Mix Design Prac- tices for Warm-Mix Asphalt. Transportation Research Board of the National Academies, Washington, D.C., 2011. 3. Hintz, C.S., R. Velasquez, C. Johnson, and H. Bahia. Modification and Validation of the Linear Amplitude Sweep Test for Binder Fatigue Specification. Pre- sented at the 90th Annual Meeting of the Transporta- tion Research Board, Washington, D.C., 2011. 4. Li, X.-J. and M.O. Marasteanu, “Using Semi-Circular Bending Test to Evaluate Low-Temperature Fracture Resistance for Asphalt Concrete,” Experimental Mechanics, Vol. 50 No. 7, 2010, pp. 867–76. 5. Kim, Y.R., Y. Seo, et al., “Dynamic Modulus Testing of Asphalt Concrete in Indirect Tension Mode,” Transportation Research Record: Journal of the Transportation Research Board, No. 1891, Trans- portation Research Board of the National Academies, Washington, D.C., 2004, pp. 163–73. 6. Cooley, L.A. NCAT Report 99-01: Permeability of Superpave Mixtures: Evaluation of Field Permea- meters. National Center for Asphalt Technology, Auburn University, Auburn AL, 1999. 7. West, R.C., J. Zhang, and J. Moore. NCAT Report 05-08: Evaluation of Bond Strength Between Pave- ment Layers. National Center for Asphalt Technology, Auburn University, Auburn AL, 2005. 8. Newcomb, D., An Introduction to Warm-mix Asphalt. National Asphalt Pavement Association, at fs1.hotmix. org/mbc/Introduction_to_Warm-mix_Asphalt.pdf. Accessed 18 November 2011.

A-1 APPENDIX A: FIELD PROJECT DOCUMENTATION TEMPLATES FROM THE NATIONAL CENTER FOR ASPHALT TECHNOLOGY AND UNIVERSITY OF MINNESOTA

A-2

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A-5

A-6

A-7

A-8

A-10

A-11

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A-13

A-14

A-15

A-16

A-17

A-18

A-19

B-1 APPENDIX B: EXTRACTION AND RECOVERY PROCEDURES AT TFHRC ASPHALT LABORATORIES There are three standard methods related to extrac- tion and recovery of asphalt binders from asphalt mixtures: 1. AASHTO T 164-06/ASTM D2172-01, Standard Method of Test for Quantitative Extraction of Asphalt Binder from Hot-Mix Asphalt (HMA) 2. ASTM D 5404-97, Standard Practice for Recovery of Asphalt from Solution using the Rotary Evaporator 3. AASHTO T 319-03, Standard Method of Test for Quantitative Extraction and Recovery of Asphalt Binder from Asphalt Mixtures For extraction and recovery of asphalt binders, a combination of AASHTO T 164 and ASTM D 5404 or AASHTO T 319 may be used. In AASHTO T 164, centrifuge extraction (Method A) is preferred to the reflux (Method B) because it minimizes heat hard- ening of the asphalt binder. For routine extraction and recovery of asphalt binders, it is recom- mended to use AASHTO T 319 since this method was designed to minimize solvent hardening of the binder, provide complete removal of the solvent, and more completely extract the asphalt binder from the aggregate. Several different solvents may be used such as n-Propyl bromide; trichloroethylene (TCE), reagent grade; or toluene, reagent grade. There is large variability associated with determining recov- ered binder properties; however, the type of solvent used between TCE, toluene, and n-Propyl bromide does not produce statistically significant differences in the results for Superpave Binder Tests. For routine extraction and recovery of asphalt binders, Turner Fairbank laboratories will use toluene, reagent grade, as the solvent and, accord- ing to AASHTO T 319, after the third wash toluene, reagent grade, combined with ethanol, absolute, in proportions of 85% toluene and 15% ethanol will be used. Ethanol is typically added to remove more asphalt from the aggregate. It is not recommended to use n-Propyl bromide due to its short shelf life and there may be product-specific prob- lems with polymer modified asphalts and polyphos- phoric acid (PPA) modified asphalts. TCE with 15% ethanol has been shown to be a superior solvent for removing most of the asphalt binder from aggregate1; however, this is not so much a concern as is the con- cern for maintaining the bulk binder properties. Unfortunately, the effects of TCE on the chemistry of the recovered binder are not understood. Further, it has been shown that TCE solvent produces higher (i.e., stiffer)3 and hardened2 recovered binders. Finally, TCE and related solvents were phased out for environmental reasons.3 Due to the nature of research, other solvents may be used on a case-by-case basis for specialized extractions. For example, tetrahydrofuran (THF) may be necessary for use with some polymer-modified binders or rubber-modified binders. THF should not be used on a regular basis (i.e., substituted for toluene) and must be used with care due to its high flammability. PPA-modified asphalt binders should be extracted by other solvents (other than lab-grade TCE and n-Propyl bromide, toluene, toluene/ethanol, and THF) that do not contain stabilizers that react with the acid in the binder.4 1Cipione, C.A., R.R. Davison, B.L. Burr, C.J. Glover, and J.A. Bullin. Evaluation of Solvents for Extraction of Residual Asphalt from Aggregates. Transportation Research Record: Journal of the Transportation Research Board, No. 1323, Transportation Research Board of the National Academies, Washington, D.C., 1991, pp. 47–52. 2Abu-Elgheit, M.A., M.J. Ijam. Change in Consistency and Composition of Trichloroethylene- and Trichloroethane-Treated Asphalts (Annotation). Talanta, Vol. 29, pp. 1131–4, 1982. 3Stroup-Gardiner, M., J.W. Nelson. Use of Normal Propyl Bro- mide Solvents for Extraction and Recovery of Asphalt Cements. NCAT Report 00-06, November 2000. 4Important Note When Recovering Binders Containing PPA. The Asphalt Institute. http://www.asphaltinstitute.org/ai_pages/ Technical_Focus_Areas/Important_Note_Recovering_Binders _Containing_PPA.pdf. Accessed on October 20, 2009.

Transportation Research Board 500 Fifth Street, NW Washington, DC 20001 These digests are issued in order to increase awareness of research results emanating from projects in the Cooperative Research Programs (CRP). Persons wanting to pursue the project subject matter in greater depth should contact the CRP Staff, Transportation Research Board of the National Academies, 500 Fifth Street, NW, Washington, DC 20001. COPYRIGHT INFORMATION Authors herein are responsible for the authenticity of their materials and for obtaining written permissions from publishers or persons who own the copyright to any previously published or copyrighted material used herein. Cooperative Research Programs (CRP) grants permission to reproduce material in this publication for classroom and not-for-profit purposes. Permission is given with the understanding that none of the material will be used to imply TRB, AASHTO, FAA, FHWA, FMCSA, FTA, or Transit Development Corporation endorsement of a particular product, method, or practice. It is expected that those reproducing the material in this document for educational and not-for-profit uses will give appropriate acknowledgment of the source of any reprinted or reproduced material. For other uses of the material, request permission from CRP. Subscriber Categories: Highways • Materials ISBN 978-0-309-21386-8 9 780309 213868 9 0 0 0 0

Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies Get This Book
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TRB’s National Cooperative Highway Research Program (NCHRP) Research Results Digest 370: Guidelines for Project Selection and Materials Sampling, Conditioning, and Testing in WMA Research Studies summarizes a May 2011 workshop designed to help foster cooperation and coordination among warm-mix asphalt (WMA) research studies.

The goals of the workshop were to help identify the laboratory and field-test methods and sample preparation, curing, and conditioning procedures in use in Federal Highway Administration-, National Cooperative Highway Research Program-, state departments of transportation-, and industry-sponsored research projects and to agree on a core set of methods and procedures that would be commonly used, insofar as possible, in all present and future WMA studies.

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