AASHTO R67-16 pdf free download
AASHTO R67-16 pdf free download.Sampling Asphalt Mixtures after Compaction (Obtaining Cores).
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 Machine- A power-driven wet-core drilling machine shall be used to obtain the sample. The device shall 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 the ability to reach a sufficient depth to minimize distortion of the compacted cores of asphalt mixture. 3.2. Core Drill Bi- -The 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 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 Equipment- A saw or other method(s) that provides a clean, smooth plane representing the layer to be tested without damaging the specimen. 3.4. Retrieval Device- A device for removing core samples that will preserve the integrity of the core. Note 1- Suitable devices have been made from steel rods, wire, or banding material. 3.5. Cooling Agent- Such as water, ice, dry ice, or liquid nitrogen. 3.6. Sample Marking Tool- A lumber crayon, paint stick, 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.
3.7. Package Containers- Suitable 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 accelerate 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 friction. 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 pressure during the process. Note 2- -If 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 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.
4.5. Continue the core drilling to the bottom or slightly 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, without damaging or distorting the sample. Obtain the core sample using the retrieval device. Note 3- -If 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. 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. AASHTO R67-16 pdf download.
