ASTM D7741/D7741M-18 PDF Download

ASTM D7741/D7741M-18 is a standard test method used to measure the apparent viscosity of asphalt-rubber (A-R) or other high-viscosity binders. The test can be conducted in both field and laboratory settings.

In the test, a handheld rotational viscometer is used to measure the apparent viscosity of the completed A-R or high-viscosity binder blend. This is done by inserting a rotor (spindle) into the binder and measuring the resistance to movement (torque) caused by the viscosity of the liquid. The measurements are obtained in either Pascal-seconds (Pa·s) or centipoise (cP).

The measured apparent viscosity is used for controlling the production of A-R or high-viscosity binder, assessing the uniformity of the produced binder, or other related purposes. It is important to note that as the spindle turns in the A-R or high-viscosity binder, it tends to drill into the sample, causing the rubber particles to be spun out of the measurement area. Therefore, the peak viscosity measurement value is recorded to reflect the viscosity of the blended material.

The use of high-viscosity asphalt binders like A-R is becoming more common, and specifications such as ASTM D6114 highlight the need for field control of the apparent viscosity. This test provides a portable and practical solution for measuring the apparent viscosity of A-R and other high-viscosity binders in both field and laboratory environments. The test is essential for ensuring consistent mix properties and good performance of materials like asphalt-rubber hot mix and asphalt-rubber membrane. The standard acknowledges the use of different units (SI and inch-pound) and emphasizes that they should be used independently of each other.