What must be done for each mixture being tested using the ESCD?

For each mixture being tested using the ESCD (Electronic Specific Gravity and Density Tester), calibration is a crucial step. Calibration ensures that the device provides accurate and reliable readings of the specific gravity and density of the hot mix asphalt. This process involves comparing the readings of the ESCD to a known standard or reference, thus allowing any variations to be accounted for which can affect the results of the tests.

Without proper calibration, the measurements taken could lead to inaccurate assessments of the asphalt mixture's properties, which are essential for quality control and compliance with specifications. Thus, ensuring the device is calibrated appropriately before use is fundamental to obtaining valid and reproducible results.

Other actions, while also important for overall quality assurance and testing integrity, do not specifically address the requirement for the ESCD testing process. Thorough mixing may impact the uniformity of samples but is not specific to the ESCD functionality, visual inspection pertains to the quality and appearance of the mixture rather than the data gathering process, and documentation is vital for tracking results but does not directly relate to the ESCD's calibration requirement.