The density of bitumen, also called asphalt, is an important indicator of its mass and is used to determine its commercial value. In addition, following distillation, density is used to assess bitumen quality for classification purposes and indicates the range of applications different bitumen grades can accommodate.
As bitumen mainly consists of high molecular weight hydrocarbons, it is extremely viscous or solid at ambient temperature, remaining so even after heating. This makes determination of bitumen density, or related units such as API gravity or specific gravity, not only cumbersome but dependent on the use of toxic solvents. METTLER TOLEDO offers a solution for the trouble-free and secure determination of the density of bitumen for quality control.
The standards EN15326 and ASTM D70 are commonly used to measure the density of bitumen/asphalt. Each stipulates the use of a manual pycnometer for this purpose. However, the manual technique is both difficult and time-consuming, requiring cleaning steps involving high temperatures and organic solvents in order to pour out the bitumen.
ASTM D8188 is a more recent standard test method to determine the density of bitumen/asphalt and is based on the use of a digital density meter. Consuming approximately 3 mL of sample, the digital method automatically undertakes heating, completes measurements in a few minutes with integrated calculation of API number, and includes an automatic cleaning procedure.
METTLER TOLEDO's intuitive Excellence Density Meters, along with the powerful and reliable SC1H and SC30H heated automation units, are ideally suited to carry out determination of the density of bitumen in accordance with ASTM D8188. Designed to keep samples at elevated temperatures of up to 90°C and completely automate the measurement of required parameters, the heated automation units support the measurement of 1–30 samples fully automatically. The unheated versions, SC1 and SC30, can be used for other petrochemical products that are viscous (up to 30’000 mPa) but liquid at room temperature, such as lubricants.
Convenient health protection and increased efficiency
Hexane and toluene are reliable cleaning solvents during the measurement of petroleum products, but prolonged exposure can be harmful to operators. By including a cleaning step in each measuring program, METTLER TOLEDO's automated systems protect operators from direct contact with toxic solvents or vapors. In fact, measurements can be started completely hands-free: Simply wave a hand over the ErgoSens™ infrared sensor to launch a method.
After the density of bitumen is determined, the required measurement units (e.g. API gravity) are calculated, and printed if need be, before the whole system is thoroughly cleaned without operator intervention. Waste is collected in a separate container, which can be equipped with the LevelSens™ Level Sensor to eliminate the risk of overfilling.
Automatic error detection securely excludes the presence of bubbles – which are impossible to see in such dark, opaque samples – therefore ensuring that reliable results are consistently obtained.
