NCAT invites your comments and questions, which may be submitted to Christine Hall. Questions and responses are published with editing for consistency and space limitations.
Zane Hartzog, Alabama DOT
What experiences have other states had with balanced mix design? What were the challenges of BMD and performance testing, and how have you dealt with them? If using a bonus/penalty system for pay with volumetrics, how did you use the same system for performance testing?
Michael Stanford, Colorado DOT
We are still at the beginning stages of IDEAL-CT Testing and are looking into a balanced mix design approach for Colorado.
Tony Collins, North Carolina DOT
What type of mix design programs are being used by contractors in your state? How does your state track or record binder source changes on a job mix formula (JMF)? Do you require a revision to the JMF or notification from the contractor when a source changes?
Sungho Kim, Virginia DOT
What is the minimum and maximum lift thickness allowed in the specifications in terms of nominal maximum aggregate size (NMAS)? Virginia currently has a minimum two-and-a-half times and a maximum four times of NMAS. Are you satisfied with outcomes if you implement five or even six times?
The following responses have been received to questions shared in the previous issue.
How is density handled for portions of intersecting side streets that may be part of the scope of work for the mainline project? Are they included in density testing or are they exempted? -Greg Sholar, Florida DOT
Nathan Morian, Nevada DOT
In short, they are included, but with a different tolerance than would be considered for the mainline. We essentially consider them as requirements for acceptance testing but make allowances for non-typical placement, compaction, etc. Please see our 2014 NDOT Standard Specifications Section 402.03.03 Compaction for details (https://www.nevadadot.com/doing-business/about-ndot/ndot-divisions/engineering/design/standard-specifications-and-plans).
Eric Biehl, Ohio DOT
In Ohio, we would not do density checks if the contractor uses the same compaction effort as the mainline. Longer side streets could get density checks.
Kevin Suitor, Oklahoma DOT
Yes, all asphalt falls under density requirements.
Cliff Selkinghaus, South Carolina DOT
If the tie ends to the intersections are less than 1500 feet in length, we do not require a gauge shot or cores. The contractor is required to maintain the same roller pattern and compact the same as their mainline section.
Matthew Chandler, Tennessee DOT
It would really depend on the scope of the side road. Theoretically, it should always be included in the potential random sample, but for very small tie ins, the inspector is unlikely to ever include those as possible locations. If there is a thousand or more feet of the side road included, the side road would almost certainly get tested for density.
Howard Anderson, Utah DOT
In Utah, we typically don't take cores for density in the intersections although we reserve the right to check density in those places. We expect to see the same effort given to density in those locations and our inspectors are aware that they need to observe the same compaction efforts.
Sungho Kim, Virginia DOT
Yes, if it is within the main pull (on the mainline). It’s hard to imagine density testing if it is within the side streets unless it is big enough (I assume it is just around the entrance/intersecting area on the side streets).
Shawn Jack, West Virginia DOH
West Virginia Division of Highways tries to be reasonable whenever possible. For this situation, it is typically on a case-by-case basis. If there are large enough quantities of side streets/non-mainline work, then they may fall under a separate specification. Otherwise, in certain small cases, the method of acceptance for density testing is determined by the project engineer.