Monthly Archives

April 2019

New and improved MD3+

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More accurate than ever  — just in time for the asphalt season

MD3+ dosing system for asphaltLast July, Surface Tech introduced the MD3+, the latest version of its Micro Doser system that can handle both 19mm or 38mm sizes of ACE XP polymer fibers. This year, the MD3+ comes with added improvements to the computer interface, which tracks the total weight used and average dosage rate right on the home screen to ensure the accurate dosing of 4.2 ounces of ACE XP into each ton of produced asphalt.

“We are proud to announce that we’ve succeeded in making some programming enhancements that improve the dosing accuracy even more —MD3+ can now dose to within 2 percent of the dosage rate. This is well under Surface Tech’s suggested 5 percent in our product and dosage specifications,” said Joe Dennis, vice president & chief technical officer.

Additionally, Surface Tech has ramped up the availability of the MD3+. The company will be stocking a fleet of more than 20  MD3+ systems strategically around the country and making them available just in time for the spring asphalt season.

To find out how to add the MD3+ and Surface Tech’s revolutionary ACE XP polymer fibers to your next asphalt project, Contact Surface Tech today. We make asphalt stronger than steel, with a life cycle that can go the distance.

Technical review of Indirect Tensile Strength testing advises caution in relying on results

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ACE XP Polymer Fiber
Alternative tests, plus a balanced mix design, can improve predictions of asphalt performance

The indirect tensile strength (ITS) test has been utilized for more than 40 years as a definitive method for predicting the performance of asphalt mixtures. But the test, at 25°C, can render misleading results, according to a recently released technical brief by Phil Blankenship, P.E.

indirect tensile strength (ITS) test“While the indirect tensile strength test at 25°C is sensitive to changes in mixture properties such as air voids, asphalt binder content, binder grade, aggregate properties (angularity, texture, etc.), the resulting indirect tensile strength does not always equate to positive field results,” he writes. “In other words, high tensile strength alone does not always relate to improved cracking resistance.”

The author discusses various developments taken over the past 10 to 15 years in ITS testing to achieve more predictive results for top down cracking. However, differences in testing temperatures and loading rates may not, in reality, conform to ASTM D 6931 standards.

Blankenship presents data from various experiments that show a weak correlation between strength (at 25° C) and ALF cycles to failure. Various results of other tests also show that indirect tensile strength testing alone (at 25°C) can be misleading.

Instead, Blankenship advises that other cracking tests produce good correlations to field performance, and the types of tests and standards are provided within the paper. The author further explores taking a “balanced mix design” approach, or performance-based testing.

To explore the various testing methods for yourself, click here.