ASTM WK25108 to Outline Rotational Viscotester Used in Road Building
October 26, 2009 // Published as a news service by IHS
ASTM International is developing ASTM WK25108 - Test Method for Measurement of Apparent Viscosity of Asphalt-Rubber or Other High Viscosity Binders by Using a Rotational Viscotester (Field Method).
ASTM WK25108 is a standard for rotational viscotesters, which are used in road building for quality control of asphalt-rubber binders.
Subcommittee D04.44 on Rheological Tests, part of ASTM Committee D04 on Road and Paving Materials, is developing the standard.
According to George Way, a D04 member, the increase in use of asphalt-rubber can be traced to 1994, when ASTM D6114/D6114M - Specification for Asphalt-Rubber Binder was first approved.
"Asphalt-rubber is a mixture of a maximum 85% asphalt binder and a minimum of 15% crumb rubber derived from recycled waste tires," said Way.
"Because of the unique nature of asphalt-rubber, it must be manufactured to proper consistency (viscosity range) at the project site to ensure its benefits," Way said. "The most practical way to check the consistency at the project site is with the handheld viscotester."
Way said that from both the supplier and user perspectives, if the consistency of asphalt-rubber is too low, the asphalt-rubber will be too low in viscosity, too watery and will run off the stone.
However, if the consistency is too high, asphalt-rubber will be too stiff and will not be able to pump through the hot plant or, if pumped, will be too viscose in the pavement, hard to compact and prone to ravel off the road.
"The routine use of the handheld viscotester for checking and controlling the quality of the product at a production site in real time is somewhat unique," Way said. "Other asphalt materials are typically not routinely checked or tested at the project or at time of construction, but often after the paving is complete."
Source: ASTM International.