Benefits of Rubberized Asphalt

Asphalt Rubber Technology Service

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Benefits of Rubberized Asphalt

Reduces Reflective Cracking in Asphalt Overlays Reduces Maintenance Costs Improves Resistance to Cracking in New Pavements Improves Resistance to Rutting in New Pavements Increases Pavement Life Improves Skid Resistance Decreases Noise Levels Beneficially Uses 500-2,000 scrap tires per lane mile

Reduces Reflective Cracking in Asphalt Overlays

Reflection cracks occur in asphalt overlays and relfect the crack pattern in the pavement structure underneath. They are most frequestly found in asphalt overlays over portland cement concrete (PCC) and cement-treated bases. These cracks are caused by vertical or horizontal movements in the pavement beneath the overlay resulting from traffic loads, temperature, and earth movements. Rubber-modified asphalt, specifically when used in Stress Absorbing Membranes (SAM) or Stress Absorbing Membrane Interlayers (SAMI), greatly reduces the occurrence of reflective cracking because of its elastic properties. The SAM or SAMI can effectively stretch and move with the underlying pavements rather than cracking from the stresses.

Before and after shots of I-40, 1998 - Appearance after 8 years

On left, conventional overlay exhibiting reflective cracking

On right, rubber overlay with no reflective cracking

Reduces Maintenance Costs

Generally, roads paved with conventional asphalt require some sort of maintenance every few years. Because of the resistance to cracking and aging exhibited by rubber-modified asphalt, roads paved with rubber-modified asphalt applications generally experience longer service lives before maintenance is required.

Patch on a conventional asphalt pavement

Alligator cracking in a conventional asphalt pavement

Improves Resistance to Cracking in New Pavement

Pavements made from Rubber-modified Hot Mix Asphalt resist cracking better than pavements made from conventional hot mix asphalt.

Rubberized asphalt pavement (10% Crumb Rubber Modified Test Section) without cracking

Conventional asphalt pavement (Control Section) exhibiting cracking

Improves Resistance to Rutting in New Pavement

Like SBS polymer-modified asphalt binder, rubber-modified asphalt binder is stiffer than conventional asphalt binder. Pavements made with modified binders resist rutting better than pavements made with conventional binders.

Hot mix asphalt sample after testing for
rut resistance using the Asphalt Pavement Analyzer

Increases Pavement Life

After years of exposure to the elements, apshalt may lose some elasticity or resiliency through oxidation. During this process, the pavement materials are also subjected to repeated stresses from expansion and contraction due to temperature changes, and cracks begin to appear. Rubberized hot mix asphalt (HMA) generally resists the formation of these cracks better than conventional HMA. Not only does rubber-modified asphalt exhibit more elasticity than unmodified asphalt, but it also shows a greater resistance to aging. This anti-aging effect is the result of anti-oxidants contained in the scrap tires, which are processed into the crumb rubber modifier used in rubber-modified asphalt.

Highway 395 - before rubberized asphalt overlay (SAMI)

Highway 395 - rubberized asphalt overlay (SAMI) after 16 years of performance

Improves Skid Resistance

Rubberized hot mix asphalt (HMA) can also improve the safety of highways. Pavements made from rubberized HMA exhibit greater skid resistance than those made from conventional HMA.

Decreases Noise Levels

Noise levels on highways and interstates continue to increase as traffic levels increase. However, rubberized hot mix asphalt (HMA) has been proven to reduce noise levels by up to 5 decibels.

Beneficially Uses 500-2,000 Scrap Tires per Lane Mile

Over 280 million scrap tires are generated each year in the United States. Of these, over 60 million are unused and being placed in stockpiles. Rubber-modified asphalt offers a beneficial solution to this problem. Depending on the application selected, between 500 and 2,000 scrap tires can be used in each lane mile of pavement. This means that for a one-mile section of a four-lane highway, anywhere between 2,000 and 8,000 tires can be used in creating a safer, quieter, longer-lasting road!

Between 500 and 2,000 scrap tires can be used in each lane mile of pavement with rubber-modified asphalt applications.

2002 HUGO DRIVE • CLEMSON UNIVERSITY • CLEMSON, SC 29634
PHONE: (864) 656-6799 • FAX: (864) 656-6186 • EMAIL: arts@ces.clemson.edu