This item includes placing a surface or intermediate course asphalt concrete that is accepted based on the level of density obtained. This type of specification is based on performance and not on method. Under this specification a Contractor can be rewarded for providing a better product than required by the minimum specification, or can be penalized for not meeting the minimum requirements. The requirements of 401 apply unless noted.
Item 446 is accepted by density testing and the roller selection is at the discretion of the Contractor and not governed by 401.13. Additionally the requirements of 401.16 that detail compaction operations are waived except the last four paragraphs. These last four paragraphs describe how requirements for the rolling pattern to obtain compaction. The Inspector should observe the rolling pattern for conformance.
Density of the asphalt concrete is based on cores that are cut from the completed mat (asphalt pavement placed at the design thickness). The core locations are determined by the Engineer as detailed in 446.05. Ten cores are required to be cut per lot. A lot is considered one day of production with provisions for combining a small production day (<400 tons) with the next day. Each lot is divided into five equal sublots and 2 cores are cut from each sublot. Core locations are determined on a random basis using a random number selection process. That process will be used for all lots.
Cores are required to be cut within 48 hours of placement. To allow the contractor to core the same day determine core locations prior to the end of work by estimating production based on production rate and contractor expectations. However these locations are not be given to the Contractor before the end of the day’s production. The Department does not intend to bias the Contractor’s operations by specifying where the cores will be taken.
If a cold longitudinal joint is made between the mainline and shoulder, include the shoulder in the lot for coring. If a hot joint is made, be sure the same equipment and rolling pattern is used on the shoulder. If the contractor does not adhere to this requirement, include the shoulder in the lot for coring.
There are additional specific requirements for cold longitudinal joint cores. In each lot three cores are to taken from the cold longitudinal joint in the first and last lots and randomly from one of the middle three lots. Joint cores are to be 3, 4 or 6 inches from the cold joint depending on its construction type. All other cores are to be located at least 12 inches from the edge of pavement.
Form TE-217 provides a standardized method for sublot lay out and random selection of core locations (transversely and longitudinally). The form is located on ODOT’s Construction website and is available as either an Excel spreadsheet that automatically calculates core sample locations or as a manual-use (non-electronic) form.
If using the Electronic TE-217 form enter all required information as indicated by the yellow highlighting. After entering the beginning and ending stations for the lot, press key F9 and the computer automatically generates the random numbers. The form automatically calculates the core sample locations as shown in the orange highlighted boxes. Use these locations to lay out the cores on the completed asphalt mat.
For the Non-electronic TE-217 form all calculations are done manually. The selection of random numbers must come from a table. This table is included with the Non-electronic TE-217 on the ODOT website as well as instructions for selecting random numbers. The same method should be used consistently on the form. When this form is completed use the calculated locations to lay out the cores on the completed asphalt mat.
The Engineer will physically mark the core locations on the mat using aerosol paint. Be sure coring takes place where marked. This can be ensured by observing each coring operation or by painting the core location with a small diameter circle with an “X” or other marking. The Contractor must be instructed to cut the core within this circle. The cut core should be examined to verify there is paint on the surface which indicates the core was cut at the selected location. If the Contractor takes “sister” cores make sure they are cut within 4 inches longitudinally of the Department’s cores. For joint cores, use a different paint color than for the mainline cores. This provides assurance that joint cores are cut from the locations selected by the project.
There have been isolated incidents where cut cores have been “switched out” with other cores that presumably would provide better density test values. Project personnel must provide thorough oversight of the core cutting operation such that the cores being testing for payment are from the locations selected by the project through the random selection process. Substitution of cores by cutting in other locations or by replacing cut cores with others is absolutely prohibited and cannot be tolerated.
Core holes are required to be filled by the next workday using the same asphalt mixture used to place the mat. The holes must be dry and coated with tack meeting the requirements of 707.02. The asphalt must be compacted adequately and finished flush with the completed asphalt mat.
After core samples are obtained, package and identify in accordance with current District or Laboratory policy. The District test lab may have specific requirements for labeling the core samples. The samples should be shipped to the District lab as soon as possible. Care should be taken not to damage the core by dropping it, throwing it, or exposing it to excessive heat. Cores should not be stacked in any way.
1. Obtain JMF for the project.
2. Determine and document if paver is on approved list.
3. Document the number and types of rollers being used.
4. Document pavement surface condition, preparation, and surface and air temperatures.
5. Document tack or prime used along with source and quantity used versus required.
6. Document lift thickness, mat width, weather conditions, surface tolerance checks, equipment problems, mat problems (segregation, tearing, tenderness, etc), spreading rate, roller coverage, and any other issue or observations made during paving operations.
7. Observe and document trucks hauling material:
a. Check for secured waterproof cover.
b. Check for insulated truck beds for temperatures below 50° F (10° C) and/or if the haul exceeds 20 miles (32 km).
c. Observe the asphalt mix in the truck and note any slumping, drain down, or blue smoke.
8. Determine compliance with compaction requirements as per 401.16.
9. Record asphalt mixture temperatures in the paver hopper and on the mat at the time of compaction.
10. Determine and record required and actual placement rates and variance.
11. Write location (station), date, and time on asphalt plant tickets. Tickets should be totaled daily, initialed, with the calculator tape attached.
12. Record luminance readings for night paving operations
13. Determine plan quantity for payment
14. Determine and mark core locations for each day of production using Form TE-217