SECTION 401
The complete sampie(s) (unseparated) shall be protected against damage, transported and delivered by the Contractor within
one working day to NHDOT testing technicians at the testing lab location. Sublots where the core becomes lost or damaged will
be resampled at the direction of the Engineer at the Contractor’s expense.
The specification limits in Table 401-7 will be used for calculating pay factors for in place air voids for each lot:
Table 401-7 - In Place Air Voids Acceptance Limits
TARGET (%) LSL USL
~~ AverageofSamples 2.0%) —s—~=CS~S HE
' But not less than 2.5%
? But not more than 9%
When a core is less than 80% of the nominal thickness, a new core will be taken in the same sublot at a random location for
the determination of in place air voids.
A sublot with a test result less than 2.0% for in place air voids will be rejected and subject to removal and replacement.
3.17.3.2.1 Maximum Theoretical Density (MTD). MTD shall be determined in conformance with AASHTO T 209
once per sublot from the core obtained for determining in place air voids.
3.17.3.2.2 Disputed Cores. If a Contractor believes that a core result is invalid for whatever reason, the Contractor shall
notify the Engineer of this in writing within 24 hrs. of being informed of the test result. After being informed of the disputed core
result, the Engineer will select three random core locations, one in each three sections of the disputed sublot at the same offset
as the disputed core. The Contractor shall cut the cores at the selected locations in the presence of the Engineer who shall place
them in secured containers for delivery and testing at the Bureau of Materials and Research laboratory in Concord, NH. If there
are 10 or more cores already tested to date, the pay factor for voids in the lot will be calculated (without using the result of the
disputed core). If less than ten cores have been tested in the disputed lot, the three cores shall be held until ten cores have been
tested or the lot is complete, whichever comes first, at which time the pay factor will be calculated.
If the pay factor for the lot that contains the disputed result is 0.95 or greater, and the disputed test result is outside three
standard deviations from the mean value of the lot (calculated without using the result of the disputed core), the three cores shall
be tested and the average value of the three will be calculated.
If any of these three cores falls outside three standard deviations from the mean value for the lot (calculated without using
the result of the disputed core), the original core test value will stand. If the three cores fall within three standard deviations of
the mean value the average of the three cores will be used as the core result for the disputed sublot.
If the three cores are not used, the Contractor shall pay for the cost of testing.
3.17.3.3 Pavement Thickness. The thickness requirements contained herein shall apply only when each pavement layer
is specified to be a uniform thickness greater than 3/4” The thickness of each layer of hot asphalt mix will be measured in
conformance to ASTM D 3549 to determine compliance with the acceptance tolerance. Measurements shall be obtained from
cores taken for determining in place air voids of each pavement layer. A leveling course, or the first layer over a gravel or stone
base, a milled surface or an existing surface, shall be excluded from thickness measurement.
3.17.3.3.1 Once each thickness measurement has been taken, a thickness index will be calculated. The thickness index is
the actual deviation from target divided by the allowable tolerance. This will allow statistical comparisons to be made among
measurements based on varying specified thickness. Thickness indexes will be established for the sole purpose of calculating
pay factors. Thickness index shal! be calculated under the following equation using the specification limits in Table 401-8.
TI =(M -ST)VT
where: TI = Thickness Index
ST = Specified Thickness
M = Measured Layer Thickness From Core
T=15% x ST, but no less than 1/4”
Table 401-8 -Thickness Index Acceptance Limits
_. ___-TARGET ESE USL
Thickness Index 0.00 -1.00 +1.00
2016 NHDOT
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