- 975 - SECTION 1081 -- ASPHALT DENSITY GAUGE
1081.01 Description
1.An Asphalt Density Gauge may be used for Quality Control when determining the in-place density of asphaltic concrete.
1081.02 Material Requirements
1.The device must be approved by the Engineer. 1081.03 -- Testing Method
1.The Contractor shall establish the method of testing in the preconstruction conference. All testing shall be in accordance with AASHTO T-343 and as directed in this provision.
2.The first 3 (three) density locati ons of the project shall be cored in accordance with AASHTO T166 to calibrate the asphalt density gauge. Prior to coring, the Contractor shall calibra te the device at each core location.
3.Calibration: A correction factor shall be established for the first 3 (three) cores by calculating the difference between the average density measurement of the asphalt density gau ge and the roadway core density. All readings taken with the gauge shall ha ve the correction factor set at zero. The necessary corrections will be adju sted in the Department Superpave Software. The correction factor shall be verified with another core for every 15 density readings that are to be recorded.
4.Density Reading Procedure: Place the asphalt density gauge on the asphalt mat over the area to be tested. Record the density reading, and repeat this process for a total of 5 (fiv e) readings, as detailed in Figure 1. An average of the 5 (five) readings will be used as the density reading for each location. For densities taken less than 6 (six) inches from the edge of the lift, density readings shall be taken as shown in Figure 2. The span between density reading locations in each direction shall be no greater than 12”.
1081.03 Asphalt Density Gauge
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5.If any density measured by the asphalt density gauge is below 90%, a density core shall be cut at that location and used for density measurement for that sublot. Density readings below 90% shall not be used to calculate a correction factor. All disputed values determined using the asphalt density gauge will be resolved using AASHTO T 166. - 977 - SECTION 1082 -- ASPHALT CONCRETE LONGITUDINAL JOINT DENSITY TESTING
1082.01 Description
1.One sample for determination of joint density will be taken randomly from each lot. This joint dens ity sample stands independent of the required standard density per sublot used for determining the average of 5 (five) density pay factor.
1082.02 Equipment
1.Testing shall be conducted in accordance with the AASHTO T 166, NDOT T 587, or an approved Asphalt De nsity Gauge. The Contractor shall insure that the proper adjustment bias and/or correction factors are used and accessible to Department personnel, along with all other inputs when NDOT T 587 or the Asphalt Density Gauge is selected. All correlation factors and test results shall be generated and reported on the Department Superpave Software.
1082.03 Testing
1.The Contractor shall estab lish the method of testing in the preconstruction conference.
2.One sample for determination of joint density will be taken randomly from each lot, as determined by the Engineer. The location of the edge density samples are identified by the Random Sampling Schedule.
3.The joint density core shall be cut 1 (one) inch away (laterally) from the identified edge of the top of the mat.
4.The Contractor shall cut core s the first day of work following placement of the mixtur e. The core samples shall be a minimum of a 3 (three) inch (75mm) diameter.
5.The Department will observe t he Contractor taking, transporting, and testing the cores (as applicable). The Department will take immediate custody of the cores at the completion of the testing. All disputed values determined using NDOT T 587 or the Asphalt Density Gauge will be resolved using AASHTO T166.
6.The Contractor shall determine the density of samples by comparing the specific gravity of the core sample to the Maximum Specific Gravity (Rice). The individual QC test value of the Maximum Mix Specific Gravity (Rice), determined by AASHTO T 209, will be used to calculate the density of each corresponding core.
7.Exceptions to the sampling and testing of joint density core samples for the determination of density are as follows:
a.When the nominal layer thickness is 1 (one) inch (25 mm) or less, the sampling and testing of density for this layer will be waived.
b.When the average thickness for the standard lot is 1 (one) inch (25 mm) or less, the testing of joint density samples for this lot will be waived.
Source: Nebraska Standard Specifications for Highway Construction, 2017 Edition. Pages 1009–1010 of 1,048.