AASHTO/SOM Roundtable Discussion on Superpave

By The American Association of State Highway and Transportation Officials (AASHTO) Subcommittee on Materials Meeting

Held July 27- 31 1997 in San Antonio, Texas

SP1. The Southeast Regional Test Center is developing a protocol to evaluate new SHRP gyratory compactors for superpave. Will states use this protocol to determine acceptability of new compactors? Also, do the states support the need for other protocols to evaluate other equipment, i.e. dynamic shear rheometer, bending beam rhemeter, pressure aging vessel, etc.? (NY)

• Yes. (LA)
• Protocol would aid in accepting equipment. However, results obtained through Round Robin testing would be just as convincing. (WI)
• Yes, provided the results are released to the states. (AL)
• We will use the protocols is available. (TX-BIT)
• part 2: There probably is a need for this for other pieces of Superpave equipment. Does FHWA have any guidance? (TX-Asphalt/Chem)
• Yes. All SHRP Equipment needs evaluation. (TN)
• Michigan - yes. (MI)
• Nebraska believes a protocol for gyratory compactors is needed. (Is FHWA involved in the development of the protocol?) We also believe protocols are needed to evaluate other equipment. (NB)
• We plan to support the protocol for evaluating compaction, and there may well be a need to do the same for other types of equipment. (GA)
• We believe there needs to be a common protocol to accept the new gyratory compactors. We have a consultant who has already purchased one of the new/portable compactors with the understanding from the manufacturer that it will be tested and accepted through the regional center in Texas. We also see a need for protocols to evaluate the binder equipment if it will be used for comparison testing or for QC/QA payments and dispute resolution, etc. (ME)
• Yes. (WA) Yes. (WA)
• Oregon will use this protocol and supports the need for other protocols. (OR)
• It is our intent to use the recently developed protocol. (NC)
• Arkansas may require manufacturers/suppliers to show results from such a protocol in order to determine acceptability of new compactors. This also applies to protocols for other equipment, i.e. dynamic shear rheometer, bending beam rheometer, pressure aging vessel, etc. Data obtained from different instruments or methods will generally have some degree of variance in the results, Arkansas believes that development of precision statements would be useful. (AK)
• Yes. We have specified the protocol as an acceptable alternate. Yes. (MN)
• Yes. (OH)
• Yes, should be standardized. (MD)
• I believe this is a necessary for all Superpave equipment. (RI)
• We certainly see the states needing a way to identify the eligibility of Superpave related equipment, not just the gyratory compactor. If the Superpave Regional Test centers are able to do so, we would like to see them not only develop a protocol but also identify a list of approved equipment. If the Regional Centers do not provide a list, then our state would use the protocol to evaluate new equipment. We can also see the advantage of a protocol when writing up request for bids. (MT)
• Yes. Yes. (NV)
• Kansas will use the protocols. (KS)
• All CDOT's compactors are Troxler SHRP Gyratory Compactors. CDOT would use the protocol to determine the acceptability of another manufacture's compactor. CDOT supports the need for protocols to evaluate other equipment. (CO)
• New York intends to use the Mix ETG "Protocol for Evaluation of SUPERPAVE Gyratory Compactors" to evaluate new gyratory compactors and would support the development of additional protocols for the PGB test equipment. Consideration would have to be given to the time required to develop the binder equipment protocols and the demand for their use, which as we see it is the only negative to this effort. Unlike gyratory compactors which will have a significant demand in the near future, the binder test equipment (being very specialized test equipment) will only see limited demand, primarily from the states and refineries. If these protocols are developed, we would support the development of an "Approved list" of acceptable equipment generated and maintained by one knowledgeable source, possible a SuperPave center (actual testing of equipment could be accomplished by any reputable laboratory). This would assure uniform data review and keep the states abreast of all of the equipment available, centralize the data, ease equipment review, and potentially speed up the purchasing process. Also, generic binder equipment specifications should also be made available. This source could also collect "customer complaints," validate them, and pass them along when requested. (NY)
• Yes. Penn State University is conducting round robin testing for DSR. (CT)
• Indiana fully agrees and hopes we can set up NTPEP to conduct the equipment evaluations. (IN)
• No (NH)
• SC will probably use the protocol to accept new SHRP gyratory compactors. Other protocols are needed for other Superpave testing equipment. (SC)
• Yes, we are willing to accept work on a national basis. (MO)
• Virginia sees the need for protocols on all SHRP equipment. When they are developed we will use them to determine acceptability. (VA)
• Kentucky will use the recommendation of the Superpave Centers in determining those SGC's acceptable to purchase. Protocols for binder equipment are needed. (KY)
• Iowa will not use this protocol directly but look for third party approval of equipment using the AASHTO protocol. For example, NCAT or Superpave Center Validation of equipment using the protocol. I would support the development of protocol for other equipment. There will always be new equipment vendors who want to get in to the market. We need a measuring stick to evaluate this equipment. (IO)
• Will consider it. (AK)
• Protocol has been submitted to AASHTO for consideration as a procedure. Will use procedure. (WY)
• Arizona will probably follow the protocol. Other national protocols would be helpful. (AZ)
• Delaware expects Superpave test centers to develop this. (DE)
• Will use protocol established by ETG. (NM)
• PA DOT is working with the northeast regional Superpave Center in establishing evaluation protocols for new gyratory compactors. PA DOT supports need for evaluation protocols for new binder equipment. (PA)

SP2. Aggregate specifications are likely to differ from Superpave requirements. How are the states dealing with this issue? What are the states doing to insure in-place compaction of Superpave mixes? (NY)

• Using same aggregate spec. - checking in place density on sublot and lot basis. (LA)
• Working with the industry to determine, by use of trial Superpave projects and investigations of Superpave sources, Density Acceptance by nuclear gauge verified by cores. (WI)
• If we are to follow Superpave, no requirement should be changed. (WV)
• ALDOT is working with the aggregate producers on Superpave requirements, especially in the flat and elongated areas. Closely monitoring lay down temperatures of the mix along with the temperature of the road surface. Rate of application plays a part. Thin applications have a tendency to cool down very quickly. It is very important that the break down roller stays as close to the spreader as possible. ALDOT is checking frequency of the vibratory rollers.
• We are still investigating aggregates to determine which meet. Have not used any non-complying. (TN)
• Michigan - why? There's no reason to change the aggregate spec. (MI)
• Nebraska is of the opinion that if aggregate specifications differ from Superpave requirements, it's not Superpave. To insure in-place compaction Nebraska will be coring and using nuclear density gauge readings. (NB)
• We are using same aggregate specs as for conventional mix. (GA)
• We are using the consensus properties of Superpave but we have not decreased our previous minimum values (we still require 60% two fractured faces for low volume Superpave mixes even though Superpave does not have a two face requirement). Our OC/QA spec for density on Superpave mixes requires 92% to 97% compaction. We have noticed the need for additional rollers to achieve compaction of the Superpave mixes. (ME)
• We are attempting to evaluate the Superpave mixtures. In-place compaction is based on % maximum theoretical density even with our Superpave specifications. (WA)
• Oregon's aggregate specifications are already equal to or higher quality than the Superpave requirements, therefore we will not be making any changes as a result of Superpave implementation. (OR)
• We are currently using Superpave requirements. We will evaluate and make changes as needed. We are checking volumetrics and controlling density with nuclear gauges based on chores. (NC)
• Arkansas is specifying Superpave aggregate requirements for the Superpave mixes. Arkansas requires that the optimum rolling pattern be established and requires the use of AASHTO T209 for maximum theoretical for density determination. Price adjustments are made on non0complying density up to +/- 1.0% from the minimum and maximum specified limit. Removal is required for densities outside the aforementioned range. (AK)
• We specify our own source properties for Mag Sulfate soundness, insoluble residue, LAR loss, deleferious materials. Inplace compaction is determined strictly by coring. (MN)
• All high-traffic mixes should have density acceptance (for Ndesign of 109 and up). (OH)
• Using SuperPave specifications for aggregate cores and nuclear density gauge for density control. (MD)
• We are starting to look at our aggregates in light of the Superpave specs. We have not dealt with in-place compaction issue. (RI)
• As we learn more about superpave, it's evident that we will need to begin putting more requirements on the volumetric properties of the mix rather than accepting the mix on the basis of the individual components. It should be more up to the contractor to identify and select materials that will assure the mix properties are met. We have compared Superpave requirements with our state aggregate specifications and have ended up slightly altering the Superpave requirements. In all cases, Superpave was not as rigorous or strict as our specs. This occurred with coarse aggregate angularity and sand equivalent. To insure in-place compaction, we continually monitor the mat density with nuclear densometers. We have found that the breakdown rollers need to stay very close to the paver and, in general, more compactive effort needs to be applied. We have found this to be especially true when using polymer modified AC. (MT)
• Kansas is using Superpave aggregate specification now. Kansas uses incentive/disincentive factors on in-place density. We use a calibrated nuclear meter with the contractor option of taking referee cores should he choose. (KS)
• CDOT's aggregate specifications are similar to the Superpave aggregate specifications. CDOT uses QC/QA specifications with incentives/disincentives to ensure in-place compaction. (CO)
• With reference to aggregate specifications New York will follow the recently issued Lead State Guidance which allows states to increase the requirements to levels previously used in the individual state. Specifically, New York is considering adjusting the Flat and Elongated particle requirement from 5:1 to 3:1. With reference to insuring in-place compaction of Superpave mixes, New York will look at increasing the use its performance-related density specification which utilizes a statistical analysis of pavement cores to determine a payment level on controlled access roadways. On non-access controlled roadways, New York will look to make further improvement to its performance-related density specification which utilizes a nuclear density gauge to monitor pavement density. In one form or another, New York will have some level of density monitoring on all of its paving contracts, with the intensity of monitoring related to roadway type. New York believes that density monitoring is important to the performance of all HMA, not just Superpave HMA. (NY)
• Indiana aggregate specs are higher then Superpave, thus we use INDOT aggregate quality specs. We conduct density and air voids test with cores. (IN)
• Cores (NH)
• 1) SC is using Superpave aggregate requirements, and 2) SC is using the bulk in-space specific gravity of roadway cores for acceptance. (SC)
• Superpave requirements supersede our standard specifications. Graduated pay reductions are used for deviations. (MO)
• To the extent possible with Kentucky aggregates, we will adopt the Superpave aggregate requirements. Superpave pavements placed in Kentucky must satisfy the unusual compaction requirements (minimum of 92% of solid density) (KY)
• We will comply with Superpave requirements as much as possible. I believe we will come very close to meeting consensus properties. We will use a percent of N design compaction as standard and comparison to field cores to N design for compliance. (IO)
• No changes to usual procedures. (AK)
• No experience. (WY)
• Arizona typically requires 85% crushed two faces for coarse aggregate and all mechanically crushed fine aggregate. Up to 10% natural fine aggregate can be used provided the fine aggregate angularity (FAA) is a minimum of 45. FAA is monitored on all jobs to ensure a 45 minimum. Ten core densities are compared to the average of four Rice densities per lot (days production typically) to determine in place compaction. Target is cores must be 93% of Rice. (AZ)
• What differences are likely? Compaction checked by calibrated nuclear gauges. (DE)
• Adopting Superpave with minimal changes (some tightening of gradation requirements). In place compaction (density) will be determined by coring. (NM)
• PA DOT is using the most stringent of either it's current aggregate criteria or Superpave's aggregate criteria for our Superpave projects. Construction of test strip on first day of paving. (PA)

SP3. Superpave Gyratory Compactors: More and more gyratory compactors are coming into the marketplace. AASHTO SOM must take action to develop a process to establish evaluation standards for this equipment since FHWA is not in the business of approving the compactors. What is the status of a possible NCHRP study to come up with evaluation standards? (Iowa)

• Use AASHTO evaluation standards performed by Superpave Center. (LA)
• Good idea. (WI)
• Evaluation should establish physical characteristics and compactive effort or energy. (WV)
• See question SP1. (AL)
• Refer to SP1. FHWA has the evaluation method developed already. (TX-BIT)
• Don't know. (TN)
• Both NCAT and the University of Texas are doing this now. Why reinvent? (MI)
• An NCHRP study should be considered. Should the regional Superpave Centers be involved with this? (NB)
• Use Superpave center protocol. (See question SP1 above)
• See SP1 above. Perhaps this function could be taken care of by a NCHRP study but a Regional Center may be able to expedite the process. (ME)
• The ETG on mix has come up with a protocol and is suggesting that the Superpave centers do the work at the manufacturers' cost. (WA)
• Oregon is not aware of the status but agrees that such a study appears to be necessary. (OR)
• Arkansas thought that new compactors were to be evaluated by one or more of the Superpave centers against samples that were run with the original machines (Pine and Troxler) to determine if comparable results could be obtained. Upon completion of the evaluation the information would be sent to FHWA. (AK)
• MnDOT has received the FHWA protocol from the gyratory TWG. (MN)
• Suggest that the NCHRP process would take too long. Suggest SP1 spec be looked at. (OH)
• Not needed. Being developed by MIXETG and Superpave centers. (MD)
• Kansas has no information. (KS)
• See SP1 above. There is an evaluation protocol at each Superpave Center. (CO)
• The Mix ETG recently completed work on a "Protocol for Evaluation for SUPERPAVE Gyratory Compactors" which should address this question. Also, the comments under SP1 are applicable. (NY)
• Recommended NTPEP and the equipment manufacturers pay for the evaluation/comparison. (IN)
• SC will probably use the protocol developed by the Southeast Regional Test Center for evaluating and accepting gyratory compactors. (SC)
• MoDOT would be agreeable to a study. (MO)
• The Asphalt Mix ETG has developed a protocol for evaluating new SGC models. This procedure involves evaluation by one or more of the Superpave Centers. (KY)
• AASHTO has developed a protocol that is being used on a trial basis at NCAT. (IO)
• Standard has been submitted to AASHTO. (WY)
• It is our understanding that standards have been released by FHWA and then the Superpave Centers may do the evaluations. (PA)

SP4. What have been other states' experiences with Superpave? How are they controlling and accepting these mixes in the field? What modifications have other states made to the recommended Superpave procedures? (SC)

• Use Superpave on only two projects. (LA)
• Good experience on a limited number of projects. Mixes are controlled and accepted using our standard QMP with modifications for the gyratory. No other modifications. (WI)
• The short term aging should be changed to one (1) hour at compacting temperature. (AL)
• Have encountered numerous problems controlling/accepting by Marshall using GSE. (TN)
• Using QC/QA procedures. No changes to recommended procedures. (MI)
• Nebraska will control with the gyratory compactor. We are not making any modification to the recommended Superpave procedures. (NB)
• Acceptance is same as for conventional mixes - gradation, AC, and density gyratory levels appear to be higher than necessary (or practical), and we have modified these. VMA is based on effective specific gravity rather than bulk gravity. (GA)
• We have placed two experimental Superpave mixes with minimal problems. One project did have lower density than desired and extra effort was required for compaction. We plan to construct 10 to 12 Superpave projects with QC/QA this season. We have requirements for gradation, air voids, asphalt content, VMA, and density for these initial projects. One design went over the restricted zone and we did notice some segregation. (ME)
• This year percent AC gradation. (WA)
• Oregon has not done any Superpave projects yet. This year will be our first experience. (OR)
• Acceptance is based on volumetrics and density. No significant changes have been made to the Superpave procedures. We have no factual reason to do so yet. (NC)
• Arkansas has had good success with Superpave mixes so far. Percent compaction is hard to achieve. Paving contractors have to work to achieve minimum percent compaction. Mix is accepted by asphalt content, volumetrics (gyratory) and roadway density. (AK)
• MnDOT has constructed 2 state projects and assisted with 4 county projects. In 1997 we will construct 5 state jobs. We will be using Standard QM control practices. With density incentive and disicention for VMA, voids, gradation, and AC Content. (MN)
• Contact Dave Powers, Ohio DOT at 614-275-1387. (OH)
• Progressing. (RI)
• Vermont is just starting with Superpave. The field control for Superpave mixes will be based on gradation and volumetrics. Asphalt content will be monitored by printed weight on contractor slips. (VT)
• We have laid down two Superpave projects and, outside of a little difficulty with the contractor obtaining compaction incentive, they have been positive for all parties involved. On further thought, some of our state engineers had a difficult time accepting the criteria of 4% design air voids, they felt the mix would be too open and the potential for water damage may be high. We are controlling the mix in the field by air voids and VMA taken from gyratory specimens. However, the only provisions we currently have for accepting the mix is by mat density and aggregate gradation of the cold feed. So far we have tried to closely adhere to the recommended Superpave mix procedures. However, there is one part of the process that we are looking at altering. We are studying the effects of shortening the oven aging times on mix samples from 4 hours to 2 hours. Aggregate absorption is playing a big part in this study, we hope to have some conclusions by the end of the summer. (MT)
• We have placed one test section to date. Nuclear density gauge, cores, AC content, gradation. None. (NV)
• Kansas has adopted Superpave with minimal changes. We think that the compactive effort is too great for low volume roads and shoulders and thus are researching this issue. We also specify mix designs by using the Superpave gradations but also specify whether we want the mix to be either above or below the forbidden zone. (KS)
• Some of Colorado DOT's experiences with Superpave:
  • mixes on the fine side of the forbidden zone are easier to construct and are expected to perform better
  • some mixes are extremely tender and difficult or impossible to compact at reasonable temperatures
  • a lack of bond between the surface course and the underlying HBP has been encountered when highly modified binders are used. (CO)
• CDOT has used both gradation and volumetric specifications to control and accept Superpave mixes. CDOT intends to implement the use of volumetric specifications. CDOT has modified the following recommended Superpave procedures:
  • the forbidden zone is only used as an advisory
  • four inch specimens are used instead of the recommended six
• New York has constructed several SuperPave projects with no reported problems. These projects are less than one year old so evaluation of field performance is not applicable. Major problems were encountered on one Superpave project, which was eventually converted back to a Marshall project. It should be stressed that while our evaluation is continuing, at this time we do not believe the problems encountered were related to the use of Superpave. New York has established a detailed mixture verification procedure that relies on laboratory verification of the mixture design (when appropriate) as well as plant verification. Once a mixture design has been accepted, production monitoring becomes the responsibility of the producer, under New York's performance-related QC/QA specification. While the QC/QA specification still being phased in, New York is confident of its ultimate success. The only changes to the recommended Superpave procedures that will be considered by New York will be those suggested in the recently issued Lead Status Guidance. (NY)
• Routes 1 and 77 were somewhat successful. Volumetric criteria and field compaction requirements. None. (CT)
• We have had a few compaction problems. Indiana follows Superpave to the letter and we are conducting PURWHEEL rut testing on Interstate projects for intermediate and surface mixes. (IN)
• SC has had compaction problems with the 12.5 mm mix. Superpave mixes are controlled and accepted on Asphalt Binder content, VMA, air voids and gradation. Probably will go to volumetric acceptance in the future. (SC)
• We have had problems with low VMA and density. Mixes are controlled in the field by volumetrics and density. No modifications to Superpave criteria have been made. (MO)
• Kentucky's experience with Superpave has been generally positive, with a few minor difficulties (FAA, in-place density, high binder contents). Kentucky accepts Superpave mixes based on air voids, VMA, binder content, and in-place density. We have implemented no major modifications to the Superpave procedures. (KY)
• Iowa's trial Superpave projects have been positive. Previous years 1995, 1996, and 1997 have been and will be controlled with a combination of Marshall Compactor and Gyratory results. The Gyratory results are used as a guide to Marshall adjustments. In 1998, Iowa will require contractors to field control with gyratory compactors. Iowa has not made any modification to Superpave procedures (procedures or specifications)? We will construct 6 pilot projects in 1997 that will comply with Superpave specifications. Data from those projects will be used as basis for reviewing any possible recommended specification changes. (IO)
• Constructed 3 projects. (AK)
• No experience. (WY)
• Arizona's experience with Superpave test section projects (11 projects) has been good with little rutting and no cracking to date. An end product specification with incentives/disincentives is used. Present specification is 32 pages long. If additional information needed please call. (AZ)
• Delaware has good experience. Standard acceptance procedures. No modifications. (DE)
• First project currently under construction. Control and acceptance based on field compacted gyratory specimens. (NM)
• PA DOT experience has been relatively good on two completed Superpave projects. Approximately three more currently under construction. PA DOT controlling and accepting Superpave mixes based on current procedures and tolerances for Marshall mixes, until more experience is gained. No recommendations at this time. (PA)

SP5. What LA requirements are other states specifying for aggregates used in Superpave binder and surface courses? (SC)

• Maximum Louisiana of 40. (LA)
• 45% max for upper and lower layers. (WI)
• 40 (WV)
• LA<48 except for sand stone and slag where the requirements are <55. (AL)
• LA wear is 30 max for all hot mix paving. (ID)
• Min. LA: 35. (TX-BIT)
• Asphalt: 9% soundness, 40% wear. (TN)
• Exactly what is recommended for the traffic loading. (MI)
• Nebraska specifies a maximum loss of 40 per cent on the LA Abrasion test. (NB)
• Max 50% loss for Class A and 60% for Class B; same as for conventional mix. (GA)
• We do not have any LA Abrasion requirements for Superpave mixes at this time. We do not have requirements for our Hveem mixes, either. (ME)
• We specify 30 maximum for all aggregate for ACP. (WA)
• Oregon allows a maximum of loss of 30%. (OR)
• We are using our existing specification requirement of 55 Max. (NC)
• Arkansas maintains the same LA Abrasion requirements (not greater than 40) and Sodium Sulfate Soundness requirement (loss shall exceed 12% after 5 cycles) as for Marshall designs. (AK)
• Maximum loss on LAR = 40%. (MN)
• Standard spec of 40. (OH)
• Maximum loss 45. (MD)
• Probably the same as presently used. 40 in surface mixes and 50 in base mixes. (RI)
• Specifying an LA Abrasion maximum loss at 40%. Asphalt Institute suggests setting a value between 35 and 45%. (MT)
• 45% max for dense-grade. (NV)
• Kansas uses 40% for the LA value. (KS)
• CDOT specifications require an LA of 45 or less. (CO)
• New York currently specifies a LA requirement of 45 for binder and surface courses. Further, we would not support the addition of an LA requirement to the Superpave aggregate consensus property requirements because we feel this test is a measure of an aggregates brittleness not a measure of it's abrasion resistance. (NY)
• Same as conventional mixes 40 percent maximum wear. (CT)
• Intermediate LA = 45% max; Surface LA = 40% max (IN)
• 45% (NH)
• SC LA requirements for Superpave: riding course 45, intermediate course 50. (SC)
• As in our standard mixes, LA equal to or less than 50. (MO)
• Kentucky has no special LA requirements for Superpave mixtures. Our regular LA requirement is 40. (KY)
• We will use our present standard Specifications for LA abrasion (not exceeding 45%). (IO)
• Texas has no plans to deviate from standard specification which requires 40% maximum for LA. (Soils and Aggregates-TxDOT)
• No changes. (AK)
• Will follow guidelines. (WY)
• Arizona uses AASHTO T96 and calls for max. abrasion at 100 rev. to be no more than 9%, at 500 rev. no more than 40%. (AZ)
• 45% max. (AASHTO M80). (DE)
• An LA Wear of 40 or less at 500 revolutions. (NM)
• PA DOT using Superpave recommendation of 35% max. (PA)

SP6. Are States verifying Superpave mix designs submitted by the Contractor?

• Where? Central/District lab.
  
• When? Trial batch
• immediately before production / as soon as material available/etc.
  
• Who? DOT personnel/Consultant/etc. (Maine)

• Yes, first day of production - DOT and contractor personnel. (LA)
• Yes, in DOT Central Lab before project, when mix design is completed and submitted by the contractor. (WI)
• Require field verification at beginning of production. (WV)
• Yes, by department personnel in the Central laboratory. (AL)
• In FY 97 TxDOT will do the mix designs to allow contractors time to gear up. (TX-BIT)
• Tennessee DOT has furnished designs to date. (TN)
• Michigan - yes. (MI)
• Nebraska will verify Superpave mix designs when into "full" Superpave. Verification will be done initially in the Central Lab using Department personnel. (NB)
• GDOT currently does the design. In the future when contractors do their own, we would verify at the District Lab Level. (GA)
• 1. Contractor doing aggregate structure evaluation. 2. WSDOT verifying their work. 3. WSDOT doing percent of AC, stripping, and calibration for percent. (WA)
• Oregon is not using Superpave designs yet, so we have not developed these procedures. (OR)
• We are verifying Contractor's Superpave mix designs in our central laboratory. Mix designs are to be submitted at least 30 days prior to anticipated commencement of production. (NC)
• Prior to acceptance Arkansas verifies the initial mix design that is submitted and also verifies other mix designs as well as necessary by utilizing actual materials to be used in production. This work is done in the central laboratory. (AK)
• MnDOT does verify Superpave mixes. We have in past verified these in our central laboratory. This year "97" 4 outstate districts will conduct their own verification. We have options for both current production and trial mix option. Aggregates submitted 30 days prior for testing and mixture 15 days; production mixes must accompany full QM test results. (MN)
• Central lab approves and design is field verified. (OH)
• Yes, at regional laboratory. Design is checked by SHA before the mix is approved by SHA personnel. (MD)
• Probably will verify in central lab. (RI)
• Vermont is verifying Superpave mix designs submitted by the contractors. This process is carried out at the Materials and Research Central Laboratory by a state employed technician. Material samples from a trial drop are submitted with the mix design. (VT)
• We will verify all Superpave mix designs submitted by contractors. We will do this in our central lab. In Montana's spec. it stated that the DOT has 20 days from receipt of the contractor furnished mix materials to verify the design. (MT)
• Yes, central lab. We verify mix design with samples before production behind the paver samples after production begins. (NV)
• Kansas verifies the mix design in the district lab. We use trial batch prepared by the contractor prior to production. (KS)
• CDOT's central lab verifies Superpave mix design before paving commences. (CO)
• New York's mixture verification procedure is a multiple step process designed to work in association with the state's QC/QA specification for HMA production monitoring. The verification procedure consists of the following: 1) Paper review of the submitted mix design to ensure accuracy and completeness, 2) Regional laboratory verification of the submitted mixture design before Verification Status is granted (when specified criteria are met the laboratory verification can be waived), 3) Production of Verification Status mixture design is allowed to be utilized on department projects, Verification Status mixture designs are closely monitored for quality by the producer under the State's QC/QA specification except that the contractor is paid at a Quantity Adjustment Factor of 1 as long as the material is of "reasonable" quality, bonus payments are available for exceptional quality, if material supplied during Verification Status production is not of reasonable quality it will be evaluated to determine if it should be removed, if it is left in-place it is paid at a Quantity Adjustment Factor of 0.85, 4) After 3 production days the mixture is assigned Production Status and the full disincentive portion of the QC/QA specification applies. (NY)
• Yes, at our Central Laboratory by DOT personnel. Route 2 project verified by trial batches and test strips. (CT)
• Yes, we check calculations in the district labs and allow mixture adjustments in the first lots. (IN)
• Yes - central lab trial batch - DOT personnel (NH)
• Superpave mixes are designed by the Research and Materials Laboratory in SC. Mix designs are verified and adjusted in the field by Central Lab inspectors. Mobile labs are being set up on projects. (SC)
• MoDOT designs mixes in our Central Laboratory. We plan to move toward contractor initiated designs. Designs are by trial batch using agency personnel. (MO)
• Kentucky verifies the contractor's Superpave mix design at the District Laboratory (or at the plant site) as soon as material is available. DOT personnel verify the contractors acceptance tests at a frequency of one verification per 4000 tons. (KY)
• Iowa will verify Superpave Mix Designs completed by contractors. This will follow our present QM-A (Quality Management-Asphalt) program. Design are and will be required to be approved prior to plant production. Contractor mixed and individual component materials are required to be submitted under our present program. (IO)
• Verification by consultant lab before production. (AK)
• No experience. (WY)
• Arizona test section projects the consultant did the design and ADOT Central Lab performed verification tests before mix production. In the present end products pilot projects the consultant does the mix design and ADOT Central Lab checks the calculations and approves or disapproves. Specification allows ADOT to perform one design check in the lab if the design is questionable. (AZ)
• Delaware DOT verifies contractor designs at central (only) lab prior to production; must take into account changes that occur in plants. (DE)
• State currently performs mix design. (NM)
• Yes, central lab, as soon as material is available, DOT personnel. PA DOT has contracted with Northeast Superpave Center to perform mix verification and mixture analysis on selected projects. (PA)

SP7. Of those states who have constructed Superpave Mixture projects: (Nevada)

1. Who performs the mixture design
2. Did you specify the Superpave aggregate specifications as is
3. Did the contractor have difficulties meeting these requirements during construction.

• a) contractor, b) yes, c) no (WI)
• a) contractor, b) yes, c) (WV)
• a) contractor, b) no, c) at times. This is the norm of any mix. (AL)
• a) TxDOT, b) yes, c) borderline on FAA (TX-BIT)
• a) TnDOT, b) yes, c) yes, compaction (TN)
• a) contractor, b) yes, c) no (MI)
• Nebraska, at this point, is only getting started with Superpave. The contractor will perform the mixture design and the state will specify the Superpave aggregates. (NB)
• a) GDOT until July 1998, b) No, c) Yes, air voids @ N design and N max were lower than recommended due to need to add more asphalt in the field to obtain desired density. (GA)
• We require the contractor to perform the Superpave design and MeDOT verifies the criteria at the aim asphalt with the submitted aggregate design. We have tried to follow the Superpave aggregate specs as much as possible. Coarse aggregate angularity spec slightly modified for low volumes so that we did not decrease our existing specs (see item SP2 above). The contractor has had to revise his past practices to meet the Superpave requirements for some projects - less natural sand allowed, etc. We should have much more data available after our pilot projects are built this year. (ME)
• a) see SP4, b) no, changed coarse fracture LA abrasion, c)nothing yet for the first two projects. Had no problem meeting the aggregate specifications. (WA)
• Oregon has not used Superpave mixtures yet. (OR)
• a) Arkansas requires the contractor to develop the mix designs. (AK) b) yes, c) generally, no; however, for mixes containing PG 70-22 and PG 76-22 asphalt binders, the contractor had to start and finish their rolling soon after laydown in order to obtain minimum percent compaction. (AK)
• a) past - MnDOT, current/future - contractors; b)yes, c)some were OK. Only project had to be abandoned because the contractor had difficulty with FAA and Gmm @ Ni. (MN)
• a) contractor, b)use lower FAA, c)not FAA
• a) SHA/contractor, b) yes, c) no
• a) Montana has constructed two Superpave mixes, one mix design was supplied by the contractor, the other was performed by the DOT. b) Superpave aggregate specifications were adhered to except as noted in above. Traffic levels were 3-10 million ESALs, CAA: 85/80, SE 45%; c)no (MT)
• a) Kansas uses contractor mix design; b) Kansas: see SP4; c) Kansas: contractors experienced problems obtaining minimum VMA values with local available aggregate sources. (KS)
• a) Contractors and consultants provide the mix design which is verified by the CDOT Central Lab before production starts. B) CDOT uses the forbidden zone only as an advisory. C) CDOT partnered with the Colorado asphalt paving industry to implement Superpave specifications and the contractors have not had trouble meeting the specification requirements. (CO)
• New York feels strongly that mixture design is the responsibility of the producer. In New York, many producers perform their own mixture designs, however, a significant number of producers elect to use an independent laboratory for this purpose. All Superpave aggregate requirements are specified on New York projects. Typically, there are no problems meeting the specified aggregate requirements. However, in some cases the use of both a manufactured and natural sand (in areas where only a natural sand was typically used previously) has been necessary to meet the Fine Aggregate Angularity requirement and in one case locally available aggregate could not meet the Course Aggregate Angularity requirement and another aggregate source was shipped in by rail. (NY)
• Route 2 by the University of Connecticut; Routes 1 and 77 by the ConnDOT. Yes. Routes 1 and 77, no; Route 2, do not know as yet. (CT)
• a) contractor; b) Indiana uses SP criteria and INDOT quality; c) we check asphalt content, gradation, and volumetrics in constructions (IN)
• In SC the DOT performs the mix design. Superpave aggregate specs are used in SC. Contractors are having compaction problems with the 12.5 mm mix. (SC)
• a) MoDOT; b) yes; c) limited problems meeting VMA and Va due to breakdown in drum (MO)
• a) original design by contractor, verification by Central Lab; b) yes; c) on Kentucky's few Superpave projects, the troublesome properties encountered during construction included low in-place density, air voids, and VMA. (KY)
• 1) for the 1997 pilot projects it is the contractor's option of completing and submitting a Superpave design for verification, or working on cooperative design with the Iowa DOT. 1998 and future projects will require contractors to submit gyratory designs for verification; b) yes, only made slight modification to have our sieves comply). We do not at this time contemplate any changes to Primary and Interstate mixes. We will review aggregate specifications for lower traffic, local and secondary, in the coming years; c) no, aggregate suppliers and contractors are learning how to produce what is required more economically, we have not had any problems to date. (IO)
• a) consultant lab, b) yes, c) no
• No experience. (WY)
• a) an accredited lab which may be the contractor or contractors mix consultant; b) Arizona tried Superpave Spec first but adopted a very similar spec in order to reduce disputes about % crushed and angularity; c) there were problems at first since high crushing requirements hard to make from rounded gravel sources. Contractors have changed operations and specs have been rewritten to be more technician sensible and practical to apply. (AZ)
• a) contractor [DelDOT provided each producer in the state with an initial design of one level of traffic mixture using materials available to the producer]; b) yes; c) none known (DE)
• a) state; b) No. Specified coarse side mix and tightened requirements. c) project still on-going, but no significant gradation problems to date. (NM)
• a) contractor does for acceptable commercial laboratory; b) more stringent of PA DOT specs or Superpave specs; c) no problems, so far (PA)

SP8. What programs have been established for approving Superpave Mix Design Labs?(Arkansas)

• Contractors' lab and personnel certification. (LA)
• None at this point but we don't foresee any problems. (WI)
• Same as other mix designs (for level 1). (WV)
• ALDOT uses all Marshall design laboratory requirements minus the hammer, and adds all requirements for gyratory compaction. (AL)
• None (TN)
• Same procedure you would use to approve Marshall mix design labs. (MI)
• Nebraska has not established a formal program, but will most likely specify "approved equipment" and certified mix design personnel. (NB)
• Certification procedures are under development at this time. We expect implementation late this year. (GA)
• We are using our past practices of inspecting the contractor testing facilities but we have not addressed this issue with a "program" at this time. (ME)
• Nothing that we know of yet. We have set up and followed AASHTO R-18. (WA)
• Oregon has not developed such procedures yet. (OR)
• None at present. (NC)
• We use the same trial mix process with QM Quality indicators to verify submitted mixes. (MN)
• None. (MD)
• None to date. (NV)
• During initial implementation Kansas central lab approves. In the future contractor's field labs must be inspected and approved by and AASHTO accredited private laboratory. (KS)
• CDOT in cooperation with the Colorado Asphalt Paving Association (CAPA) has implemented a training and certification program for asphalt testing techniques. CDOT's specifications require all testing technicians (both CDOT and Contractor) doing QC/QA testing to be certified. (CO)
• New York does not have a specific program for "approving" mix design laboratories. We feel that this is unnecessary if a detailed complete mixture verification process is being followed. The mixture verification process used in New York includes "shortcuts" in the process for those producers and laboratories who have demonstrated their capability to perform a quality mixture design. (NY)
• Personnel are required to attend an Asphalt Institute Course, or its equivalent. (CT)
• AMRL inspected (IN)
• SC DOT designs all Superpave mixes. (SC)
• MoDOT designs in Central Lab and has no criteria for approving outside labs. (MO)
• Kentucky has no special program for approving Superpave Mix Design labs at present. (KY)
• Does this questions address the AMRL Certification of agency approval of contractor's labs? As an agency we do not approve Superpave Mix Design Labs per se. We do certify technicians and require that laboratory equipment meet certain standards. If the question addresses AMRL Certification, AMRL has begun round robin of binder and mixture samples. I see this being an extension of existing certifications which will encompass Superpave binder and mixture procedures. (IO)
• None (AK)
• None. (WY)
• All labs that do mix design must be AASHTO accredited. In addition ADOT's Quality Assurance Section approves labs for Arizona test methods. The Superpave test procedures (i.e. TP-4, Gyratory compaction) and criteria form the Superpave design manual for new construction and overlays SHRP-A-407 or the Asphalt Institutes Superpave Level 1 Mix design SP-2 will be incorporated into the existing program. (AZ)
• None. (DE)
• At present, state develops mix design and does not approve private testing labs for this purpose. (NM)
• PA DOT has no criteria, but lab must be reputable. (PA)

SP9. How are the "yet" unknown a)test variabilities, b)production variablities, etc., etc., going to affect the implementation and enforcement of the new Superpave specifications. (RI) *

• Will add markedly to the uncertainties. Existing equipment and procedures produce results more variable than 50 blow Marshall. Unless these variables are measured and mitigated these procedures are no better than guess work. (WV)
• We are using the same tolerances as we use on our regular mixes, it worked on our SPS9 project last year. (MI)
• As a result of these unknown variabilities, Nebraska is allowing a "tolerance" from the PG graded MP2 specification. We feel that with the results of testing this year, the variabilities will be better known and the specifications, testing tolerances, and enforcement will be refined. (NB)
• Good question. I guess we will need to adjust tolerances as we gain more experience with Superpave mixes.
• Oregon has initiated a research effort to quantify the production variabilities associated with Superpave. We plan to eventually develop appropriate tolerances for production specifications. (OR)
• Have not impacted implementation to date. (NC)
• Arkansas is tentatively scheduled to implement Superpave as the standard mix design during 1998. Jobs are currently being let to contract so that experience can be gained during 1997 by both the contractors and AHTD. Arkansas' standard specifications (1996) implemented many of the Superpave criteria (such as volumetric acceptance) in the current Marshall mixes. Some contractors are requesting to change to Superpave because of difficulty in producing mix meeting acceptance requirements of the 1996 specifications utilizing Marshall procedures. (AK)
• Some modifications of the specifications will probably be necessary. (NV)
• Kansas has negotiated several test projects to evaluate the variability and adjusted our specifications accordingly. (KS)
• With respect to PGB, New York has reviewed its laboratory testing history (data generated after we became proficient in the test procedures) and established substantial conformance limits for evaluating out-of-tolerance material. These limits will continue to be used and revised until other limits are included in the applicable AASHTO standards. With respect to monitoring mixture design and mixture production, the previously used tolerances for mixture maximum specific gravity and specimen bulk specific gravity will continue to be used. We have not encountered any problems to date relating to acceptance tolerances, and the lack of "official" tolerances should not hinder implementation as long as consistent sound engineering judgment is applied. (NY)
• We will work out problems as they arise with input from other states and hopefully cooperation from contractors. (CT)
• We are getting smarter every day. The more test results we have, the better understanding we have of the variables. (IN)
• South Carolina has implemented the Superpave Binder Spec on all projects starting with the January 1997 letting. Superpave mixtures are being placed on interstate projects. Test and production variables will be reviewed and specs will be revised to account for variables. (SC)
• We are following the current Superpave specifications, however, maintaining VMA, voids, etc., in the field has been a problem. Also obtaining a mix meeting requirements can not be achieved with many aggregates without addition of special hard angular aggregate. (MO)
• Unknown variables will not affect the implementation in Alabama. However, several areas need to be addressed (test variability, etc.) before pay factors can be established. (KY)
• Binder Testing - Iowa set up a program in 1997 to evaluate testing and production variabilities. Superpave Mix - Iowa has not evaluated this as of yet. (IO)