ASTM D8673/D8673M-26

1.1 This method covers the proper use of handheld digital, bimetal, and infrared thermometers for monitoring the temperature of asphalt mixtures during production, placement, and compaction, and with temperatures typically 50 °C to 220 °C [122 °F to 428 °F]. Each type of thermometer has different characteristics which need to be considered for proper usage.

1.2 Units—The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with the standard.

1.3 The text of this standard references notes and footnotes which provide explanatory material. These notes and footnotes (excluding those in tables and figures) shall not be considered as requirements of the standard.

1.4 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

4.1 The temperature of an asphalt mixture during production, placement, and compaction is one of the primary factors that affect the long-term performance of an asphalt pavement due to temperature’s effect on the ability to compact an asphalt mixture. In general, the higher the temperature of an asphalt mixture during the compaction operation, the easier it is for the compaction equipment to achieve the desired level of density. Some asphalt mixtures, however, exhibit tenderness during the compaction operation and shove in front of the steel wheel rollers when being compacted. Depending on the properties of the asphalt mixture, the tenderness can occur at very high temperatures or at intermediate temperatures. Further, if the mixture temperature is too low, the stiffness of the asphalt binder can prevent the desired level of density from being obtained. Thus, it is important to monitor the temperature of asphalt mixture during production, placement, and compaction operations. The proper use of each type of handheld thermometer minimizes variability that can be introduced by the operator.

4.2 Field measurements of the temperature of asphalt mixtures can be made on the surface of or internal to a sample of asphalt mixture. Do not compare the surface and internal temperatures for acceptance because the cooling rate may be different.