Foamed Asphalt Expands From Coast-to-Coast

From coast-to-coast, road agencies and road builders in North America are waking up to the tremendous benefits base recycling with foamed asphalt can bring to their taxpaying customers. From the pine forests of New England, to the scenic Lake Superior shore in Ontario, to the bayous of Louisiana, to California's fertile Central Valley, foamed asphalt base recycling using the powerful and versatile Wirtgen WR 2500 S is proving its benefits and utility to a growing crowd of stakeholders. Why is base recycling with foamed asphalt getting so much attention these days in North America? Because Wirtgen's WR 2500 S is demonstrating that foamed asphalt is a process whose time has come, and Wirtgen America is putting the "pedal to the metal" to get the word out.

Foamed asphalt is the future
"Foamed" or "expanded" asphalt is created by carefully injecting a predetermined amount of cold water into hot penetration-grade asphalt in the mixing chamber of a pavement remixing unit, and offers a cost-effective alternate for road base stabilization.

Since the end of the 1980s, Wirtgen has been a major player in development of foamed asphalt (bitumen) technology, in which foamed hot asphalt is used to stabilize and improve existing road materials, producing highest quality base courses and cold mixes at lowest cost.

These materials can be processed in-place by milling and crushing the existing pavement structure -- while incorporating foamed asphalt -- using the WR 2500 S Recycler from Wirtgen. Precise addition of water allows control of the rate of asphalt expansion and the amount of expansion. Foamed asphalt technology is built into the WR 2500 S, not tacked on as an aftermarket add-on.

The expanded asphalt has a resulting high surface area available for bonding with the aggregate, leading to a stable road base using the existing in-place materials. The benefit is substantial cost savings over use of asphalt emulsions for base stabilization, and complete elimination of the cure or "break" period. The foamed base then is graded and compacted, and can permit traffic -- including heavy trucks -- almost immediately. Bringing experience to bear Wirtgen America is bringing some of the best minds in the world in foamed asphalt to North America because we want to make foamed asphalt work for everyone and dispel any myths that may be floating around.

We're taking the concept to a high technical level with people who have years and years of experience. They can tell how well an application is working just by looking at it or smelling it. We can put that experience to work for you as we bring foamed asphalt technology to every corner of this continent.

And foamed asphalt is applicable to every climate we have. We've done it the desert, in the high mountains, in the boreal forests of Canada and the humid bayous of Louisiana. Foamed asphalt will benefit you whether you're a road owner or a road contractor.

Preserves environment Foamed Asphalt base recycling using the WR 2500 S also saves valuable aggregate resources. We all know in most areas of North America there are plenty of aggregates resources in situ. What we're running out of is aggregate that is permitted for extraction. Existing aggregate sites once on the outskirts of town now are surrounded by new neighbors who are not only opposed to existing mining operations and truck traffic, but any kind of expansion of the quarry or pit in the future. In the meantime, due to environmental opposition, aggregate operations are finding it hard to get approval for new extraction sites, even way out in the country, far away from the cities where most of the aggregate is consumed. Little wonder that base recycling using foamed asphalt is so desirable, because it reuses existing aggregates resources that already have been acquired, permitted, shot, loaded, crushed, screened, stockpiled, reloaded and hauled. The existing investment in processed aggregate is optimized, because the material is just lying there in the roadbed waiting to be reused.

For example, in September, a report released by the Construction Materials Association of California found state policymakers and planners had failed to consider whether local supplies of construction aggregates will be available to meet the state's urgent need of upgrading, maintaining and building new infrastructure.

But reuse of existing aggregates through techniques such as base recycling with foamed asphalt -- as described in California on pages 12-13 -- can prolong those resources until new extractive sites can be permitted.

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