1、Standard Practice for Sampling Asphalt Mixtures after Compaction (Obtaining Cores) AASHTO Designation: R 67-161 Release: Group 3 (August 2016) American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-2c R 67-1 AASHTO Standa
2、rd Practice for Sampling Asphalt Mixtures after Compaction (Obtaining Cores) AASHTO Designation: R 67-161Release: Group 3 (August 2016) 1. SCOPE 1.1. This method describes the process for removal of a core sample of compacted asphalt mixture from a pavement for laboratory testing. Cores may range in
3、 diameter from 2 in. to 12 in. 1.2. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitati
4、ons prior to use. 2. SIGNIFICANCE 2.1. Samples obtained in accordance with the procedure may be used for measuring asphalt mixture thickness, density, and other testing. 3. APPARATUS 3.1. Core Drilling MachineA power-driven wet-core drilling machine shall be used to obtain the sample. The device sha
5、ll be capable of obtaining a core to the full depth of the asphalt mixture sampled and shall consist of a rigid frame or platform such that the core barrel can be maintained perpendicular to the pavement during the drilling process. The core drilling machine must be of sufficient horsepower and have
6、 the ability to reach a sufficient depth to minimize distortion of the compacted cores of asphalt mixture. 3.2. Core Drill BitThe cutting edge of the core drill bit shall be made of hardened steel or other suitable material with diamond chips embedded in the metal or as recommended by the core drill
7、 bit manufacturer in order to drill through the compacted asphalt mixture cleanly. The inside diameter of the core barrel shall be as specified. 3.3. Separation EquipmentA saw or other method(s) that provides a clean, smooth plane representing the layer to be tested without damaging the specimen. 3.
8、4. Retrieval DeviceA device for removing core samples that will preserve the integrity of the core. Note 1Suitable devices have been made from steel rods, wire, or banding material. 3.5. Cooling AgentSuch as water, ice, dry ice, or liquid nitrogen. 3.6. Sample Marking ToolA lumber crayon, paint stic
9、k, pen, or other suitable marking tool to mark the core sample for labeling, identifying the separation layers, identifying the layer to test, or as otherwise necessary. 2016 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of
10、 applicable law.TS-2c R 67-2 AASHTO 3.7. Package ContainersSuitable packaging containers for securing and transporting the core samples. 4. PROCEDURE 4.1. Freshly compacted asphalt mixtures shall be allowed sufficient time to cool prior to coring in order to prevent damage to the core. 4.1.1. To acc
11、elerate the coring process, compacted asphalt mixtures may be cooled to expedite the removal of the core by the following methods: water, ice, dry ice, or liquid nitrogen. 4.2. Provide a means such as water or air to aid in the removal of cuttings and to minimize the generation of heat caused by fri
12、ction. 4.3. Position the coring machine above the selected location. Engage power and water or air source to coring machine. Slowly advance bit until contact with the compacted asphalt mixture surface. 4.4. Keep the core bit perpendicular to the compacted asphalt mixture surface, applying constant p
13、ressure during the process. Note 2If any portion of the coring machine shifts during the operation, the core may break or distort. Failure to apply constant pressure or applying too much pressure may cause the bit to bind or distort the core. 4.5. Continue the core drilling to the bottom or slightly
14、 below the bottom of the asphalt mixture intended to be samples to allow separation of the core sample at the desired depth from the underlying pavement layers. 4.6. After drilling, separate the core sample from the underlying pavement layers using the retrieval device or other suitable means, witho
15、ut damaging or distorting the sample. Obtain the core sample using the retrieval device. Note 3If the core is damaged to a point that it cannot be used for its intended purpose, a new core shall be obtained within 6 in. of the original location. 4.7. Clearly label the core with a sample marking tool
16、. 4.8. Fill the hole made from the coring operation with asphalt mixture, non-shrink grout, or other suitable material. Consolidate or compact the material in the hole in multiple lifts if necessary. Ensure that the final surface is level with the surrounding surface. 5. PACKAGING AND TRANSPORTING S
17、AMPLES 5.1. Package core samples in suitable protective containers. If multiple core samples are packaged in one container, separate the samples from one another using a suitable separation material. Note 4Concrete cylinder molds and PVC or HDPE pipe have been found to be suitable containers for pro
18、tecting and transporting core samples. Crumpled newspaper has been found to be a suitable separation material when packaging multiple core samples in one container. 5.2. Transport cores in a manner that prevents damage from jarring, rolling, or impact with any object. 5.3. Prevent cores from freezin
19、g or from excessive heat during transport. Note 5In extreme ambient temperature conditions, an insulated container should be used during transport. 2016 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-2c
20、R 67-3 AASHTO 5.4. If the core is damaged in transport to a point it cannot be utilized for its intended purpose, the core will not be used. 6. LAYER SEPARATION 6.1. Using appropriate separation equipment, separate two or more pavement courses, lifts, or layers along the designated lift line. Note 6
21、Lift lines are often more visible by rolling the core on a flat surface. 7. REPORT 7.1. The report shall include the following: 7.1.1. Date the cores were obtained. 7.1.2. Paving date. 7.1.3. Coring location. 7.1.4. The lift/layer being evaluated. 7.1.5. Material type. 7.1.6. Average thickness if re
22、quired. 7.1.7. Core identification information, such as nominal-maximum aggregate size of the mixture, asphalt mixture design identification, performance grade of asphalt binder, etc. 8. KEYWORDS 8.1. Asphalt mixture; core drilling; core sample. APPENDIX (Nonmandatory Information) X1. THICKNESS DETE
23、RMINATION X1.1. Measure the thickness of the designated lift according to ASTM D3549/D3549M to the nearest 0.01 ft, 1/8in., or 3 mm. Calculate an average of three or more measurements taken around the lift. 1This full standard was first published in 2015. 2016 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.
