TRB Committee AFK10, General Issues in Asphalt Technology



TRB Committee AFK10, General Issues in Asphalt Technology

Minutes of the Meeting

April 20-21, 2005

I. Chairman Joe Button opened the meeting and introduced special guests Jeff Seiders, Dale Rand, Darren Hazlett, TxDOT; Harold Mullins, Gary Dolph, Texas Asphalt Pavement Association; and Dennis Christiansen, Deputy Director of TTI. (The agenda is shown as Attachment 1 Agenda.)

II. Members and guests introduced themselves. The members present included:

Joe Button, Scott Shuler, Dave Newcomb, Gary Fitts, Gayle King, Skip Paul, Jack Weigel, Ron Collins, Jim Scherocman, Tim Aschenbrener, Don Watson, Frank Fee, Becky McDaniel, Fred Hejl (staff).

Guests included: Jack Youcheff (for Tom Harman); Jim Moulthrop, chair of the TRB Bituminous Section; Ramon Bonaquist, chair of TRB Committee AFK50; Dennis Christiansen, Cindy Estakhri, Tom Scullion, Emmanuel Fernando, and Sandy Tucker, TTI; Jeff Seiders, Dale Rand, Darren Hazlett, TxDOT; Harold Mullin and Gary Dolph, Texas Asphalt Pavement Association.

III. Minutes of the last meeting in Nashville were approved as written.

IV. Dennis Christiansen, Deputy Director, gave an overview of the Texas Transportation Institute. (Attachment 2 Christiansen) He welcomed everyone to campus and to the TTI facility. TTI was established in 1950 as a cooperative agreement between Texas A&M and the Texas Department of Highways. Now all state universities in Texas are involved. TTI is unique in that it is a state agency. TTI works in all areas of transportation and has nine centers of excellence including the AAR Rail Lab, International Center for Aggregate Research, Superpave Center, and more. In FY2004, over 70 sponsors funded over 300 projects at TTI.

VI. Presentations on topics of interest to the committee followed.

Joe Button introduced Jeff Seiders, who gave a presentation on one of the hottest projects in Texas right now, the Trans Texas Corridor. (Attachment 3 Seiders)

The Trans Texas Corridor is the Governor’s initiative to incorporate dedicated truck lanes, rail (freight and commuter), utilities, etc., all together. The first project is essentially parallel to I35. Last year a 15-year development contract was signed to design, build, operate and maintain this system. A Spanish company (Cintra) and a Texas company formed a joint venture on this contract. A 1200 foot wide right-of-way will be typical. This will spawn a lot of other work with connections to other systems. Contracts on the Trans Texas corridor will be design-build or design-bid-build projects. Some projects will include warranties.

One major incentive for this is to accelerate construction of planned facilities through alternate funding. Discussion of funding options and the pavement selection process ensued.

Sandy Tucker, Head Librarian for TTI, briefly explained how to get TTI reports. For the last few years, everything that TTI is publishing for the DOT is now available as full-text documents from the TTI website. The website address is: .

Dale Rand, TxDOT, spoke next about rewriting the TxDOT specs. (Attachment 4 Rand) TxDOT has four different hot mixes – SMA, Permeable Friction Specs, Performance Design Mixtures (Superpave) and Dense Graded Hot Mix Asphalt (QC/QA). They also have DG HMA (Method) for miscellaneous work. Currently TxDOT only uses about 10% Superpave and about 60% DG HMA (QC/QA). PFC and SMA are increasingly being used.

Many of the specification changes came about to alleviate problems they had observed on some projects. For example, Texas has had problems with diluted tack coats. One year they had four projects with distresses that could be tracked back to poor tack coats and excessive dilution. Now the specifications disallow diluting emulsified tack coats and require sampling the tack from the distributor immediately before use. The tack coat rate is between 0.04 and 0.10 gal of residual asphalt per square yard.

PG76-22 is the typical binder grade in TX. Now TxDOT has Hamburg Wheel test requirements ranging from 20,000 passes at 50(C for PG76 down to 10,000 passes for PG64 (some districts allow 5000).

Texas has had debonding problems too, which they thought could be related to paving on a cold surface. The specifications now allow placing mix when the roadway surface temperature (not air temp) is 60(F or higher.

Texas requires thermal profiling of each sublot using an infrared thermometer to look for thermal segregation, defined as anything with temperature differential of more than 25(F. Those areas identified as having thermal segregation are then inspected through a density profile. Density is checked by comparing between high and low density readings and between the average and low for different mix types and sizes. If the temperature differential is greater than 50(F, the contractor must cease operations and correct the problem. No bonuses will be paid on sublots that do not pass the density profile.

Darren Hazlett spoke about the status of a draft ASTM standard for PG grading of hot applied surface treatments. (Attachment 5 Hazlett) This standard came about after TxDOT adopted the PG binder grading system for hot mix in 1997. They wanted to be able to eliminate penetration and viscosity specs for surface treatments, tacks, chip seals, etc. Amy Epps Martin did a project for TxDOT to address binder properties and how they contributed to distresses. That lead to a framework of tests and grade selection. Binder evaluation is based on initial stiffness in the DSR and later stiffness after PAV aging. No RTFO aging is used since nothing like that occurs for a chip seal. TxDOT also uses a minimum phase angle to get elasticity of certain grades.

The first draft standard received several negatives. A revised standard was submitted April 19, 2005, for subcommittee ballot. This will also be submitted to AASHTO. If it is not favorably received nationally, it will be implemented as a TxDOT specification.

Harold Mullin, Director of the Texas Asphalt Pavement Association (TxAPA), updated the group on current asphalt related issues. He also addressed the need for educated, trained personnel on every level.

Dealing with the highway 130 project has been challenging. The asphalt industry has learned a lot in the process and hopes that future projects will go to asphalt. Texas has more full-depth perpetual asphalt projects than any state in the union. TxDOT alone laid 15 million tons of hot mix last year. As an industry we need to educate the decision makers and others on the benefits of asphalt. Speed of construction, ease of construction, ease of maintenance, quiet pavements all play towards hot mix.

TxDOT allowed the industry to provide significant input into the new specifications. These specifications will help get the quality they want. The agency and industry sponsored 25 seminars to over 2000 people about the new specs. They distributed 2500 reference CDs on the new specifications.

TxAPA has run the Texas certification center since 1993. They train about 900-1000 people per year. All courses are currently taught in English, since the spec book and test methods are in English. They are considering doing soils and aggregate training as well, since we need a good foundation to build the pavement. TxAPA is also concerned about the background of engineers coming out of school. They are trying to work with Jon Epps to sponsor a professorship program (chaired position) like Mississippi and other states have done.

Tim Aschenbrener then reported on Colorado’s End Result (PWL) Joint Density Spec. Last year was the first full year of implementation. The specification requires taking a 6” diameter core centered over the joint. The target density at the joint is 92% of the max. Within the mat, the target is 94%. The allowable range is +/- 4%.

Pilot projects were evaluated in Summer 2003. Of 30 processes evaluated, 19 received a bonus, and 10 received full bonus. The specification was used on 32 processes in 2004 and 18 received a bonus, with 10 receiving full bonuses.

The processes that have been successful include:

• Paving in echelon has been excellent.

• Changing the roller pattern also helps.

• Building a notched wedge joint has helped too – 1” vertical notch then 12:1 taper formed with a shoe and rolled with a small parking lot roller.

• Another contractor makes a small windrow or hump with a shoe then pinches in with rubber tire mounted on a steel wheel roller.

• Hamm compactor (German) has been used successfully too – the front roller is normal, rear one is oscillatory (shear) roller.

• Cutting the joint is most effective.

• Enforcing the specification has been most important to get everyone to do their best.

Colorado used to see 82-83% joint density; now the lowest they can do is 88%.

Tom Scullion spoke about the process used in Texas for Designing Overlays for Concrete Pavement (Attachment 6 Scullion). A condition survey and non-destructive testing are used to guide the pavement design by identifying where joint repair is needed, then an overlay test is used to help design a crack resistant mixture.

A rolling deflectometer, with three rolling geophones, measures deflection every two feet. The device is essentially a rolling Dynaflect. TTI has recommended tentative criteria to identify bad joints and areas where an overlay will not work without joint repair. The current device only goes 1.5 miles per hour, so more development work is needed to speed it up. They have now added a digital video camera and GPR to supplement the deflection data.

The mixture design includes a test method for designing mixes to resist reflection cracking. Gyratory samples are trimmed, then glued onto plates with SuperGlue. One plate is fixed, the other moves to produce a fixed displacement of 0.025 inch. Cycles of five second opening and five second closing are applied until the overlay cracks. The target varies from a minimum of 200 cycles up to 750 cycles depending on mix type. (Some of their SMAs are getting over 350 cycles.) The designed mix must also meet Hamburg rutting test limits to help ensure that cracking resistance is not obtained at the cost of rutting.

Scullion also described the thermal detection detector they have been working with. Sensors mounted on a bar behind the paver allow temperature measurement across the mat, so that thermally segregated areas can be easily identified. (Attachment 7 Scullion)

Emmanuel Fernando described the Ride Rut Facility at TTI that is used to certify inertial profilers and operators according to Texas test Method Tex-1001-S. A ride/rut facility (a 2000 foot long asphalt lane) was constructed for this purpose in 1999. A reference profile is measured with a rod and level survey. The profilers are run over 0.1 mile test sections with ten repeat runs on each test section. The repeatability of the ten profiles and of the IRI results from those profiles are checked using the averages and standard deviation point to point. They also check the accuracy of the profile measurements by comparison to the reference (rod and level) profiles. A decal is put on certified profilers.

The facility has also been used for evaluations for FHWA and other state agencies (CO, DE, OH).

There is more info at the website .

IX. In the interest of time, the committee reluctantly passed on the opportunity to tour the TTI facilities and turned to completing the committee business. Agency/organization reports were also deferred. Some presentations were provided by members for information. (Attachment 8 FHWA, Attachment 9 NCAT)

Membership Joe Button updated the group on the membership status. We currently have 18 members and one emeritus member. Four members had informed Button that they would be unable to attend the meeting: Barry Takallou, Julie Nodes, Gerry Huber and Gary Hicks. In addition, New Jersey travel restrictions prevented Eileen Sheehy from attending.

Triennial Self-Evaluation The committee’s Triennial Self-Evaluation Report is due in a month. The format is somewhat different this year. It is now a triennial strategic plan, with short and long term plans. The committee needs to consider what the technical issues are that this committee may be addressing in the short (three year) and long term (greater than three years) and how the committee might address them – working with other committees, sessions, etc. Goals, plans and objectives need to be stressed. At the next meeting, the committee will get feedback on the TER, so we can then review our plans and goals and revise as needed. Skip Paul commented that the long form of the meeting notes will help identify long term goals. Education is certainly a long term goal. We will include time in next meeting for long range planning.

Action Item: Joe Button to draft the TER and distribute to committee members for review. Final version submitted to Fred by mid-May.

2005 Sessions This committee sponsored a workshop on “Factors Affecting Compaction of HMA.” Gayle King noted we had really good cooperation from the authors who were invited. King and Jim Scherocman are now trying to get papers from the authors to combine in an e-circular that Fred Hejl has agreed to publish. King asked the committee about the required quality of the papers that would be needed for an e-circular. Some authors submitted short write-ups, others are research quality. After some discussion, the committee agreed that it would be best to take some time and request revisions to ensure that all of the papers are of equal, high quality that will reflect well on the authors and committee.

Action Item: Gayle King and Jim Scherocman will review the papers and determine which need more work, then work with the authors to get needed revisions by end of May and will submit to Fred Hejl for publication as an e-circular in mid-July.

Other sessions on “Rubblization of Concrete Pavements” (Dave Newcomb), “Improved Testing of HMA for Construction Control” (cosponsored with AFH60, Ray Brown) and “Permeability and Moisture Issues in HMA” (Scott Shuler) reportedly all went well and were well-attended.

Circulars, State-of-the-Art Reports and TR News Articles. Warm Mix Asphalt was suggested as a possible topic. Matt Corrigan wrote a nice article for FHWA on warm mix asphalt; Dave Newcomb is willing to do another with a different approach. Fred Hejl will talk to the editorial board and let Newcomb know whether to pursue this topic. This also might be a good topic for a session next time. The problem is that every product is proprietary. Dave suggested having each company that is currently marketing in the US get before an audience and talk about it. The representatives would have to be warned about not doing a sales job and not bashing any other products. With pending research on cancer and hazardous effects of high temp asphalt, there may be a place for this technology, which could be used in any non-attainment area. There are also some findings from NCAT related to what warm mix asphalt does in terms of aging of the binder and effects on rutting and cracking. The proprietary nature of this might make it more appropriate for a circular than a record. Hejl noted that a circular also gives the committee the ability to make sure all the papers get published together. If peer-reviewed, some or all of the papers might get rejected. Dave Newcomb will organize the session. Gayle King and perhaps Matt Corrigan will moderate.

Action Items: Fred Hejl will check with editorial board regarding interest in an article on warm mix asphalt and inform Dave Newcomb. Newcomb will organize a session for 2005 with ultimate goal of preparing an e-circular. Gayle King and Matt Corrigan will moderate.

Fred Hejl will also check with Dale Decker on whether he was going to pursue papers from his rubblization session to put in a circular.

Action Item: Fred Hejl to follow up with Dale Decker.

Joe Button then asked Don Watson about the status of a state of the practice report on SMA’s that Allen Cooley was supposed to be working on. Watson indicated that Cooley had not finished this, but there may be work in progress at ICAR and elsewhere that would make this topic a good one to follow-up on. Jim Scherocman commented that there are many states now using SMA extensively and many other states are looking into it. This would be a good time to do the report before new people make the mistakes that others have done. Scherocman would be glad to help with it. Watson will contact Cooley to see if he will take this up again. Scherocman and Button will help.

Dave Newcomb commented that there are problems with some of the test methods specified for fibers. In fact, the fibers that have been used successfully do not meet the specs. One spec deals with sieve analysis using an obsolete piece of equipment, so that has been changed, but others still need to be addressed. Scherocman noted that some SMA’s do not need fibers anyway. If you use polymers and watch temperatures, you should be OK.

Tim Aschenbrener added another thing that might be of interest in SMAs is the use of grit. Newcomb explained that grit is blotting sand that is used in Britain due to skid resistance concerns. Grit is not needed unless there is a concern about skid resistance.

Aschenbrener said he is also hearing about loosening up the mineral filler specifications. Don Watson thinks this is a good research issue. Some states use fly ash, some use kiln dust, etc. Jim Scherocman agreed that is an item that needs to be addressed. Skip Paul added that if you don’t use fibers, you need at least 8% P200. Scherocman commented that the problem is on conventional plants in states that don’t do a lot of SMA’s because they are not set up to blow in fibers or add high quantities of mineral filler. He added that he thinks there is enough information out there, but there is a need for a synthesis and/or session leading to a circular. Scherocman will put together a session, working with Don Watson. Dave Newcomb will try to get a contractor to help. Fred Hejl suggested that the work to put together a session on SMA’s, may help to identify what needs to be synthesized. The deadline for submittal of a synthesis topic is January 31, 2006. The consensus was to submit it as a synthesis by January 31, 2006. Watson will also write a research need statement on mineral filler for SMA.

Action Items: Don Watson will contact Allen Cooley about completing state of the practice report on SMA. Jim Scherocman and Joe Button will help Cooley.

Don Watson will prepare research need statement on mineral filler for SMA.

Jim Scherocman will work with Don Watson to put together a session on SMA’s. A synthesis need statement may be prepared after putting together the session for submittal prior to January 31, 2006 by Watson and Scherocman. This may lead to a circular as well.

Both the warm mix and SMA sessions will be invited talks. Both may lead to circulars. Since TRB conflicts with NAPA in 2006, Scherocman suggested that scheduling the SMA session later in the week would be better for some people who may be trying to get to part of NAPA and still get to TRB. (NAPA committees meet on the weekend.)

Moisture Susceptibility Jim Moulthrop noted that the proceedings of the California conference have been published. Carl Monismith is doing training around California. In NCHRP studies, PennState is looking at the Environmental Conditioning System and surface energy research is on-going at TTI.

Jim Scherocman stated that he has observed that in states requiring use of an antistrip, most contractors do not use it in private/commercial work. It would be interesting to compare the “same” pavement with and without the additive. He added that there is a problem with trying to add lime to low VMA mixes. Different methods for adding the lime need to be explored. Moulthrop noted that the moisture sensitivity workshop in California included a best practices document. Gary Fitts asked for clarification on the focus of the proposed research; is it to address moisture sensitivity or methods to add lime to hot mix asphalt? Becky McDaniel noted that Indiana has a similar need statement on lime addition in their long range plan. Tim Aschenbrener said that Colorado has ten years of experience with using lime and no premature distresses now that they use it. Don Watson said that Georgia requires a minimum wet strength of 60 psi as well as ratio. Watson will write up a research need statement on moisture sensitivity for us to keep on our list. It may need updating after the two current NCHRP studies are completed.

Aschenbrener suggested that is a need for a Forensic Investigation Guide for Moisture Damage. The tests out there focus on different mechanisms. This guide could help you find out which mechanism (adhesion, cohesion, constructability, etc.) is in play on any particular project. Gayle King added that there are tests like Methylene Blue that show if clay is the problem. Re-emulsification with acid amine blends can be identified. Jim Moulthrop commented that there were a lot of good papers in the California workshop, but other than those who attended, few people have delved into it.

Gary Fitts added that he has seen projects where things are fine until the top is sealed off through some pavement preservation method. When the underlying layers could breathe, they did not strip, but once closed off they did. He said there is a need for a way to test a pavement to determine if it can be sealed or if it needs to be milled off before sealing. Ron Collins said that in the mid 80s many states put a moratorium on use of some mixes, like open graded friction courses, because of stripping. Ray Bonaquist noted that Maryland checks underlying layers using T283 before determining depth of milling. This concept will be added to need statement that Watson is writing.

Discussion ensued on Hamburg testing and variables, other test methods, etc.

Action Item: Don Watson will prepare a research need statement on moisture sensitivity for the committee to keep on the books and possibly revise based on findings from two on-going NCHRP projects.

Pavement Preservation. Jim Moulthrop reported on the Task Force on Roadway Preservation at TRB. The group was given four products to take charge of, including a pavement preservation workshop, developing an owners’ manual on pavement preservation, developing a pamphlet for politicians and appointed officers and one other. The workshop will be on October 31-November 1, 2005, in Kansas City, at the Westin Crown Center, in conjunction with an asset management workshop.

Center for Pavement Preservation – there has been discussion of having regional centers for pavement preservation working cooperatively with the national center. California, Louisiana and Texas centers are in process of being formed. The Midwest Pavement Preservation Partnership is composed of 13 states.

There has been quite an emphasis on pavement preservation related research lately. CalTrans has a microsurfacing study, and there is an NCHRP project on chip seals scheduled for 2006. Joe Button noted that about 80% of the TxDOT budget is spent on maintenance, however only about 2% of TTI’s budget is on maintenance and construction. Less than 5% of the TxDOT research budget is spent on maintenance. The emphasis may be shifting, though since Button helped TxDOT write some strategic maintenance research needs. In addition UT and TAMU jointly submitted a proposal to TxDOT to establish a Texas Pavement Preservation Center, which may become a regional center. The funding will be for operation of the center, but not for research. California is also starting a pavement preservation center (Shakir Shatnawi) that they hope will be regional. That center may be able to do research.

Button asked if there is anything this committee should be doing in the area of pavement preservation. Moulthrop recommended we keep working together and looking for opportunities.

Fitts suggested a state of the practice report focusing on thin hot mix overlays such as small aggregate mixes for less than 1 inch thickness. Scott Shuler added that Colorado is planning to place test sections. Gayle King stated that now is the time that someone should be looking at the SPS-3 projects before they are all gone. Discussion ensued on how this study of the SPS-3 sites could be initiated. The group finally decided that it might be best and most timely to pursue 20-7 (SCOH) funding. States represented on this committee should talk to their chief engineers, maintenance engineers, materials engineers, and others stressing the importance of this study. The urgency is that the remaining projects will not be there much longer. Moulthrop and Button will work with Larry Galehouse to write a letter endorsing the need. This will take the form of a research need statement with a cover letter and endorsements from California, Texas, and other states.

Action Item: Jim Moulthrop and Joe Button will work with Larry Galehouse and others, especially state committee members, to get endorsements on cover letter. Letter will request SCOH support for this research.

Frank Fee commented on the need to get various disciplines involved in working together. He added that this committee may be uniquely positioned to get collaboration with other committees, including those involved with maintenance, construction, materials, pavement management, traffic, pavement design, environment and noise. He suggested soliciting for friends of the committee who are actively involved in these groups. Dave Newcomb thinks we already have those people here. Fred Hejl agreed that in many cases we do have those groups represented, but not in every case. Becky McDaniel pointed out that the committee is not at its membership limit, so we could consider adding members from under-represented disciplines. Discussion followed on how to get these people together. One suggestion was to host a two-hour organizational meeting at TRB, perhaps over dinner or lunch. Fee said we would need a position paper explaining what we want to accomplish ahead of time. The idea is to get committee chairs or very active people to participate with us. Hejl will schedule a committee meeting at a mealtime. Frank Fee asked Dave Newcomb and Jim Moulthrop for help drafting a letter. Hejl will help to identify who the liaisons should be.

Action Item: Frank Fee will work with Dave Newcomb and Jim Moulthrop to draft a letter inviting TRB committee chairs or other active members to come to organizational meeting at next TRB meeting with the goal of fostering more collaboration between this committee and all the other players. Fred Hejl will help to identify who to send it to and will schedule a meeting during TRB.

Upcoming Meetings Joe Button passed out a calendar of upcoming meetings from ISAP. Other members noted some other meetings including CILA, Congresso Ibero Latino Americano del Asfalto, to be held November 2005 in San Juan, Costa Rica. More information is available at .

A conference on pavement noise called Quiet Asphalt Pavement 2005 is being sponsored by the Asphalt Pavement Alliance and FHWA and will be hosted by the Institute for Safe, Quiet and Durable Highways. It will be held November 1-3, 2005, in Lafayette, Indiana. More information will be posted on the SQDH website at when it becomes available.

The Second Rubber Modified Asphalt Conference will be held May 18-19, 2005, in San Antonio in conjunction with the American Chemical Society. More information is available at .

The World of Asphalt will be held in Orlando, Florida, March 13-16, 2006. See for details.

Sessions or Workshops for 2006 Session topics for next year include “Warm Mix Asphalt” and “SMA: Don’t Screw It Up” as discussed earlier. Tim Aschenbrener suggested a session on “Segregation: Point/Counterpoint.” He envisioned a different format including a few introductory presentations followed by a debate and rebuttal period. Potential speakers and topics include: Introduction on state of the practice with specifications; end results specs (Dale Rand TxDOT, WashDOT, Lon Ingram, Erv Dukatz); Method Specifications (Skip Paul, Roadtec – Richmond or Heddrich); The Real World of Claims and Performance – relative weaknesses of both method and end result (Devil’s Advocate Scott Shuler, Dale Decker or Al Palmer). This session would be good to tie in with Ray Brown’s segregation paper sessions. Aschenbrener will moderate with Jim Moulthrop as back-up.

Don Watson also suggested the topic of the Bailey Method and Locking Point might be of interest. Ray Bonaquist said that his committee gets 50 unsolicited papers, which they review then group them based on what they get. If he gets several papers on these topics, he will group them into a podium session. He did get about three related papers last year. Alabama, Georgia and Louay Mohammad are working on locking point. After some discussion, the committee decided to co-sponsor a workshop with Ray Bonaquist’s committee. “Practical Approaches to Hot Mix Asphalt Mix Design” could be modeled on last year’s compaction workshop, where there were three presentations on each of four topics. Topics here could include State of the Practice, Tools for Mix Design (Bailey), Use of the Gyratory to Assess Performance and the Locking Point. The state of the practice could include a summary of changes made to mix designs based on the findings of the NAPA/FHWA meetings by Becky McDaniel. This should be planned with the goal of producing an e-circular after the workshop. Skip Paul noted that some LTRC work incorporates the Bailey method and locking point and would make a good concluding paper. The workshop could be one or one-half day, though one-half day seems most appropriate. Frank Fee, Ray Bonaquist, Don Watson and Becky McDaniel will put together a workshop on this topic. Fred Hejl needs a one paragraph description and time (one day or one-half day) before June 1.

Action Item: In addition to the sessions on Warm Mix Asphalt (Newcomb) and SMAs (Scherocman and Watson), Tim Aschenbrener will put together a session on “Segregation: Point/Counterpoint.”

Frank Fee, Ray Bonaquist, Don Watson and Becky McDaniel will put together a workshop on “Practical Approaches to HMA Mix Design.”

Research Need Statements The committee currently has six need statements on the website. The fourth topic on the list, dealing with tack coats, has been funded, so it will come off. Two new needs are being written following on yesterday’s discussions; these are on Mineral Filler in SMA and Moisture Sensitivity (including forensics). Joe Button had also distributed another possible need statement prior to the meeting on designing mixes at other than 4% air voids. Discussion ensued on the priorities. NCHRP 9-33 will address design air voids, so that need statement may be premature. The committee decided, however, that the air void project will be put on the list at a low priority to be moved up later as needed based on findings from on-going projects.

Jim Scherocman suggested two additional need statements. The first he titled “Tender Mixes, Their Causes and Solutions” looking at all causes of tender mixes and how to resolve them. Scherocman will write a need statement.

The second need suggested was “Measurement of Moisture Content in an Asphalt Mix.” Scherocman said that current ASTM and AASHTO test methods do not sufficiently dry the aggregate in hot mix, so the moisture content is underestimated. The moisture left in the mix slows the absorption of asphalt during production, making the mix act over-asphalted. A microwave oven heats the water, but not the binder, so the water cannot escape from the aggregate. Putting a sample of mix in a mason jar in the sun slowly heats the mix and allows the water to evaporate, but this technique is slow. The ignition oven curve flattens out a bit as you burn off the water, but it has not been possible yet to identify a definitive test. Scherocman thinks that as little as 0.4-0.5% water may be a problem, so any test needs to be pretty sensitive. Frank Fee noted that this will also depend on the binder; work at WRI has shown that different binders change stiffness with the addition of small amounts of water. Fee recommends the use of lower temperature and vacuum since heat alone will eventually start to volatilize the binder. Frank Fee, Skip Paul and Jim Scherocman will write a need statement.

Ron Collins suggested the need to increase the use of RAP. He feels that we are starting to waste our RAP, at least in some areas of the country. Research is needed to use higher percentages of RAP, including RAP processing as well as design. By screening the RAP, contractors are using more of the coarse fraction but more of the binder is held in the fine fraction. Gayle King stated you need to consider the percentage of binder in the RAP fraction. Ron Collins, Frank Fee and Gayle King will take the lead in writing a need tentatively titled “New RAP Mix Design Based on Improved Processing Equipment.” Jim Scherocman noted that Washington State has used 85% RAP, and Wyoming has used 70%.

Ron Collins also suggested another need statement on the effects of mix temperature on performance. What are the effects of thermal segregation? Also, Collins said he has seen differences in rutting and fatigue performance (especially cracking) of mixes compacted at different temperatures. There is work going on in this area, so the study will need focus. Ron Collins, Scott Shuler and Tim Aschenbrener will write a need statement on “Impact of Temperature Differential on Pavement Performance.” Don Watson asked if we might sponsor a session on this topic. It was pointed out, however, that Rita Leahy’s committee is co-sponsoring a session that will likely cover this; it is entitled “Effect of Construction Variability on Pavement Performance.”

Collins also asked why roads perform better in some states than others, even if they use similar materials. We are penalizing some contractors and making them remove mix that may be acceptable, but are leaving some bad mix in place. Skip Paul said NCHRP put in a line item (20-36, $750,000) for internal US scanning tours. That might be the way to do an evaluation quickly. Button asked about including some of those states that were very different from neighboring states twenty years or so ago, but are now doing better. Jim Moulthrop added that there would need to be a very tight work plan because there are so many variables, including specifications, inspection, maintenance, pavement preservation and management, organization, funding, climate, etc. Skip Paul, Jack Youcheff and Tom Harman will submit this topic for a possible scanning tour with endorsement of this committee. Paul will write a draft and send to Ron Collins, Tom Harman and Jack Youcheff. Mid-May is when the group deciding on scans will meet.

Problem statements shall be submitted to Joe Button by May 13. Committee members will rank the needs and return to Button. Paul suggests choosing about three top needs then doing TRIS and other searches to determine how much work has been/is being done in the area. Only a one-stage NCHRP submittal process is used now, so it is important to do the groundwork.

Summary of Action Items:

Jim Scherocman will write a need statement on “Tender Mixes: Their Causes and Solutions.”

Frank Fee, Skip Paul and Jim Scherocman will write a need statement on “Measurement of Moisture Content in HMA.”

Ron Collins, Frank Fee and Gayle King will take the lead in writing a need tentatively titled “New RAP Mix Design Based on Improved Processing Equipment.”

Ron Collins, Scott Shuler and Tim Aschenbrener will write a need statement on “Impact of Temperature Differential on Pavement Performance.”

Skip Paul, Jack Youcheff and Tom Harman will submit the topic of why roads are performing better in some states than in others for a possible scanning tour with endorsement of this committee. Paul will write a draft and send to Ron Collins, Tom Harman and Jack Youcheff.

All problem statements will be submitted to Joe Button by May 13. Button will distribute them to the committee members for ranking.

Next Meeting

Possible locations considered for the next meeting included New Orleans or Orlando (during World of Asphalt). New Orleans was selected as the next site. Debate ensued on how long the meeting should last and when it should start. The current plans are to run from noon on April 24 to noon on April 26. (Paul will also check the preceding and following weeks.) It is possible that the schedule may change to delete the half day on Monday to accommodate travel. Joe Button will check on whether Julie Nodes and other people from the West can get into New Orleans in the morning.

The group also discussed meeting logistics such as local speakers and tours. Local speakers are interesting, but the number and time should be limited. Tours are also of interest if there is something unique to see and if time allows, but we do not absolutely need a tour. Some of the more successful tours have been those that rolled into dinner at the end of the first day.

The group will also make a bigger push to get other committee chairs to come. Consideration will be given to expanding the committee membership. The possibility of adding a young member was discussed briefly. If someone qualified can be identified they could be added, however, this committee has been viewed as a more senior committee requiring more experience to really contribute, so a young member may not have the experience needed.

Jim Scherocman commented that there is a real gap in education in this industry. There are courses, seminars, workshops, etc., going on, but it is hard to find out what is going on. Gary Fitts added that there is also not enough being done at the universities to train engineers about asphalt and pavements in general. Graduates need a more well-rounded background. Agencies and contractors lack knowledgeable people. At universities, Scott Shuler said, when an asphalt person retires, the position is typically not filled unless endowed. There is often not enough funding for asphalt research to compel deans to keep an asphalt person. Jim Moulthrop asked if there is a perception that this is so simple there is not a need for training in this area. The committee will take this topic on as a long term area of emphasis. Jim Moulthrop asked if TRB has committees on education or training with which we could collaborate. Fred Hejl said there is a committee on education and training, and Skip Paul added that there is something coming out on Workforce Development.

Action Item: The committee will consider education as a long term objective in our strategic plan. Opportunities to collaborate with other TRB committees on training, education and workforce development will be sought.

Other possible topics for consideration by this committee were suggested by Gary Fitts (IARC classification of asphalt fumes) and Jim Scherocman (acid modification).

Committee Support Fred Hejl announced that in the past the Asphalt Institute has supported this committee with funding to allow us to meet outside the annual meeting, however, they have found it necessary to substantially reduce their support. The funding was used to support travel to the meeting. Support is needed for the committee so that we can get the people here that we need to be here. If there is no support, the committee will not be able to continue meeting like this or attendance may suffer. We have a couple of years of funding before this affects us. Jim Moulthrop asked if it is possible that NAPA or the State Execs might fill the void. Jim Scherocman said there are some individual oil companies or contractors that would be willing to support the committee, and he offered to secure the funding. Frank Fee offered to help. It would be more convenient to get one sponsor rather than a handful.

Action Item: Jim Scherocman and Frank Fee will work on securing funding of about $5000 per year.

Joe Button thanked the Asphalt Institute for their continued long support of this committee. He apologized to those who offered to make presentations about their organizations, but time did not allow them. Becky McDaniel also asked Button to thank those who were going to give us tours. Finally, Button acknowledged the support of the Texas Asphalt Pavement Association and TTI. The meeting was adjourned at noon.

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