By Samuel G. Bonasso, PE FASCE*
As we look up at the sky and dream of tomorrow’s new sustainable infrastructure ideas, we must also remember to look at what is under our feet. The answer to many of the problems which drive our sustainable infrastructure concerns today will not be solved by more information technology studies, applications, or measurements. The potholes, ruts and washouts won’t go away unless new techniques for building and maintaining the road are developed. This includes new materials and new ways of using conventional materials.
For example, the true nature of highway-generated waste is all but overlooked by most of the people responsible for sustainable highways. As civil engineers concerned with sustainable infrastructure, shouldn’t we be concerned that globally more than 1.4 billion waste tires are generated annually, of which more than 300 million are generated in the USA. Should we also be concerned that most of these waste tires are burned as hydrocarbon, tire-derived-fuel because they have 25% more BTUs per ton than coal? Should we be concerned that instead of real sustainability the highway is adding to the atmospheric CO2? The only waste that the highway system seems to accept any responsibility for is the old asphalt coated aggregate and the failed concrete, which are part of the roads themselves. And even that responsibility is very limited.
Currently more than 95% of the scrap tires generated in the US are managed by a well-established, mature network of collection and tire-recycling companies. The balance is usually collected by public agencies and stored in special landfills. However, with the current regulation of coal fired power plants and expanding competition from low cost natural gas, the tire-derived-fuel market has seen a 15 to 20% decline since 2015. Similar declines have occurred in other traditional tire-derived product markets, including athletic field infill, molded rubber consumer products, tire-derived-aggregates and other civil engineering use.
Without some creative leadership from the civil engineering profession and highway system management directed at innovations in sustainable highway policy, the future for these existing uses of waste tires is bleak. To become truly sustainable, the US highway system will need to, among other things, accept some recycling and reuse responsibility for the 300 million waste tires generated each year.
In the 21st century the highway system has become an essential public utility. But as long as it is considered a public service, it will be managed with the narrow policies and practices of the earlier age. The surface transportation system is perhaps our most essential utility, since it supports the supply of all the basic necessities required by the human population including; food, shelter, clothing, water, sewer, electricity, education, recreation, health care, law and order, entertainment, etc. It has, in fact become, a meta utility, without which other essential utility services could not be provided.
So, let’s now consider the waste tire from the point of view of a utility waste. If a public electric utility attempted to make a coal company responsible for the coal ash or the CO2 produced by the generating station no one would take them seriously. Certainly, the public service commissions that regulate utilities would not accept such a position. It would be considered totally unsustainable. So how can the highway system continue to dodge its role in the generation of waste tires?
The problem is with highway agencies, particularly the federal agencies. There are no public oversight bodies to regulate their policies, other than the US Congress. So, we are stuck with their rules and regulations as the law of the land, no matter how outdated and ineffective.
At the recent 2017 ASCE Grand Challenge Innovation Contest a discussion with potential investors on the value of innovations revealed that one of the major challenges of getting new ideas into the highway system and Architectural, Engineering, and Construction government construction contracts in general was the fact that patented products were basically prevented from being used. This is particularly true in highways.
For example, to get patented innovations into the highway world of civil engineering would require a policy change that places the responsibility for specifying new ideas on the design engineer and doesn’t limit new uses by an outdated public policy.
One example is the use of tire-derived products to confine aggregate materials promoted internationally by the Australian company Eco Flex. It has a patented system, which confines aggregates in a tire cell created by removing one sidewall from a waste tire. It has been used in road sub-grade stabilization, access roads/pavements, above ground mine and underground mine roads, engineered retaining walls, tailing dams, erosion control, highway embankments, piling platforms, crane platforms, drilling platforms, matrix reinforcement layers, road, rail, national parks, wetlands, creeks, channel protection, storm water erosion, and protection of creek banks.
Recent research at the University of Wollongong, NSW, Australia, Center for Geomechanics and Railway Engineering, has shown that Eco Flex technology used as a capping layer just beneath the rail bed ballast, can be effective in reducing railroad ballast degradation, track settlement, and provide increased stability and resiliency to the track substructure. Eco Flex success has occurred because aggregate confinement is a superior technology and not because public policy has supported its use.
Another patented, aggregate confinement, technology is promoted in the USA by the Reinforced Aggregates Company called Mechanical Concrete® which uses tire-derived-geo-cylinders to confine aggregates. It is an extremely simple technology and has been successfully used for over 10 years on public and private industrial roads. WVDOT Division of Highways recently sponsored research at West Virginia University, College of Engineering has established that tire-derived-cylinder confinement improves the strength and modulus of stone aggregates by 60 to 100% over traditionally compacted aggregates.
Mechanical Concrete® has been used extensively on industrial coal haul road with significant success, reducing maintenance on unpaved and paved sections by 75%. Recent projects also show Mechanical Concrete® offers a permanent solution to the maintenance and repair of potholes. Cylindrical confinement of aggregates eliminates the issue of water weakening the base which is the main cause of rutting, pothole formation, and road edge collapse. These deteriorated road conditions all pose significant safety and economic issues for road users. These aggregate confinement products could also be used for disaster recovery to quickly and effectively get roads back into service.
However, neither of these products can currently be specified on a public road construction project. This means that because of an outdated public procurement policy, two proven, aggregate confinement products that would be significant value to both the highway and waste tire industries, cannot be used.
Another example is highway’s unique potential to use more tire-derived-aggregates, made by chipping the waste tire into small pieces. But they are also prevented by the narrowly defined engineering policies and specifications of the highway system. Even though this tire waste product has been used extensively in California, Minnesota and in other states as a substitute for stone aggregated particularly where drainage is critical.
Until the public and private civil engineers who deal with our infrastructure begin to understand that sustainability means accepting responsibility for the wastes generated by their designs, sustainability will as unreachable as the stars in the sky.
* Samuel G. Bonasso, firstname.lastname@example.org , is an experienced civil engineer and businessman. He has worked and traveled in 48 of the United States, North America, China and Western Europe. His over forty-year construction industry career spans public works, forensics, public service and invention. He is a professional engineer and has been a licensed general contractor. Engineering projects include bridges, ski lifts and cable cars, highways and land use. He is an adjunct professor of civil engineering at WVU College of Engineering. He served publicly as West Virginia Secretary of Transportation and as the Deputy Administrator, Research and Special Programs Administration US DOT, Washington, DC with responsibility for the Office of Pipeline Safety and the Office of Hazardous Materials Safety (PHMSA.) and the Research and Innovative Technology Administration. He is the inventor of Mechanical Concrete® and founder and president of Reinforced Aggregates Company. He lives in Morgantown, WV with his wife Nancy.