Paving Pellet™ Hot Mix Asphalt Production

Paving Pellets can be used just like any liquid asphalt/bitumen in asphalt hot mix concrete, with or without additional bitumen.

The mix design should follow ASTM International Standard WK20240, ASTM D6114, or ASTM D140 for mixing and sampling procedures. To make GTR Paving Pellet laboratory samples, standard procedures should be used with one exception. High sheer mixing imitating the action in the mixing chamber of the asphalt hot mix plant is required. While a Hobart mixer can be used, we recommend a rotating metal cement mixer heated to 375 °F (173 °C) with a 'flame-O' propane torch. The appropriate amount (5,000 g or more) of 350 °F oven-heated aggregate (or aggregate heated in the mixer with the 'Flame-0') should be added, followed by the desired amount of Paving Pellets (approximately 6% by weight for gap-graded mixes and 9% for open-graded friction course mixes). The mixed material should be tested as any asphalt hot mix concrete.

During actual hot mix production, the GTR pellets are metered into the mixing chamber via a RAP feeder or directly into the pug mill as any bitumen. Pellets melt within 30 to 40 seconds with agitation caused by the "ball-mill" effect of the aggregates in the mix-chamber.

To obtain higher production levels at the hot plant and still meet asphalt-rubber specs, 1% of local liquid bitumen may be added to accelerate melting of the pellets and still achieve the preferred ASTM ratio of rubber to bitumen.

If you desire to use the GTR pellets with no additional asphalt oil, add 6% to start with your reference design and make a ladder of 1% increments. You must use a gap-graded or open graded mix design. We typically find that 7% to 9% is standard for most limestone aggregates depending on absorbency and gradation.

We have developed an Excel spreadsheet for determining the various contents and percentages; contact us for more information.

Hot Mix Run