Geosynthetic technologies have been part of infrastructure upgrades for many years—yet they still slip beneath the radar
When 9/11 occurred, I was an assistant editor for the magazine GFR (now renamed Geosynthetics). Though the publication had nothing to do with commercial building use of concrete interior wall blocks or panels, though gypsum wall board was not part of the magazine’s content—gypsum heap pad liners were—the editorial desks were inundated for much of a year by releases from those interior wall materials industries. At issue: Which materials would have survived longest in the Twin Towers and, thus, have given the people in the buildings (possibly) a better chance of getting out?
Each industry claimed the other was inferior.
Other industries jumped on board too, of course, to note how their materials would have prevented or survived longer on 9/11.
The geosynthetics industry was also part of the post-9/11 solutions discussion, only in a different way: discussion was offered towards disaster response (e.g., site remediation and pollution containment) and forward-looking infrastructure measures that could mitigate the effects of different types of disasters. Under the latter discussion, coastal defense were included.
Given the major coastal issues that followed, were those ideas prescient? Not a bit. Hurricanes arrive annually, but it was stunning to find four of them strike the Florida coast in less than a month in 2004. Later that year, the earthquake-produced tsunami in the Indian Ocean horrified all of us. And the wide-scale destruction of New Orleans in 2005’s Hurricane Katrina reminded us that even well-developed cities were significantly vulnerable and that we must more stringently evaluate our engineered defenses.
In those instances, could geosynthetics have prevented the disasters? No. Could they have reduced destruction? Certainly, but to an exact degree is speculative—as is the safety in adopting any construction material: brick, concrete, asphalt, wood, etc.
What stands out is this: geosynthetics have consistently been shown to improve infrastructure systems. This includes roads, foundations, massive retaining walls, greenroofs, soil consolidation, hazardous waste containment, and much more.
In nearly every case, geosynthetics do not stand alone. They support the performance of other construction materials, most often by greatly improving the geotechnical conditions in which other materials are installed.
The Importance of an Old Argument
Infrastructure improvement and longevity are not new arguments for the incorporation of geosynthetics in designs. It’s one of the industry’s hallmarks and one of the reasons geosynthetics have entered all major areas of civil and environmental engineering.
An unpaved road experiences significantly less rutting and erosion when its base includes a geosynthetic layer that separates coarse and fine aggregate. Pumping and mixing causes rutting in an unsupported road, but the geosynthetic prevents the migration of those disparate soils. They don’t mix. The road holds up.
In paved roads, geosynthetics substantially reduce reflective cracking.
This reminds me: While attending a county engineers’ conference a number of years ago, I visited with asphalt industry representatives in the exhibit hall. I’d just published an article from a California road engineer about the strong performance of road fabrics in the reduction of reflective cracking with various asphalt road surface treatments. A representative from a southern US asphalt association told me road fabrics performed poorly in the south but he knew they performed well in the north. A representative from a northern US asphalt association told me the exact opposite. That wasn’t surprising. Road fabrics can reduce the amount of asphalt needed up front, you see, and extend service life, thereby reducing the need for resurfacing.
Application by application, similar arguments have been made: geomembranes and geosynthetic clay liners (GCLs) in canals prevent water loss due to seepage; geogrids provide vital reinforcement against creep for retaining walls; on it goes.
It’s unfortunate, though, that it takes a major and rather tragic event, such as the collapse of the I-35W bridge over the Mississippi River in Minneapolis, Minnesota to bring these infrastructure issues to the public (and legislative) eye.
And it’s to be hoped that for once the construction materials industries push not for gaining an edge on their competitor materials but for truly maintainable infrastructure.
The old argument of geosynthetic support bears definite merit here.
What We Need Now
The old saw about “variety is the spice of life” comes to mind, but seems grossly out of place with such a serious issue. Variety is the point, though.
Geosynthetics add much-needed support and material variety to our infrastructure. Just as a forest with too little species variety is at great risk for disease, an infrastructure consisting of too few materials will be at risk of aging at the same rate.
Consider that much of the US road and bridge infrastructure was built (or rebuilt) in the 1950s and 1960s with the massive expansion of the interstate highway system. Many of the country’s older, larger cities rest atop severely outdated sewer and water pipes and tunnels – systems that go back well before the expansion of the road system.
While geosynthetics were not available 100 or 75 or 50 years ago, they are now and have been in steady adoption for the past few decades. Increasingly they are a vital (though often unpublicized) part of new developments. For example, geomembranes engineered specifically for lining new concrete sewer pipes; and geosynthetic clay liners (GCLs) that cap old landfills and enable site reuse (waterless athletic fields, parking lots, hiking trails).
What we need now is to continue sharing engineering information on geosynthetics and how they work with the other common construction materials. Geosynthetics do not compete with concrete or asphalt or steel. They can and do work with these materials in all their various infrastructure designs. And geosynthetics help extend the service life and reduce the necessary maintenance of those constructions.
This argument does not suggest we can get by without maintenance. Geosynthetics do not prevent in perpetuity deterioration; but they significantly reduce it. And that, over time, saves money. And that, over time, gives us time to upgrade sensibly and affordably.
We are faced with a considerable challenge in the United States. There will be fierce competition for public dollars for infrastructure improvements now. The bridge structure that collapsed in Minneapolis resembles greatly so many other bridges in the country. The roads leading to these bridges have their problems. The cities connected by these roads have their problems.
Nothing, really, is a singular problem, and no single material offers an absolute fix, regardless of the spin offered in a press release.
But there will be competition.
We can be smarter about it. It’s to be hoped that the refurbishing and new development that comes of this will give us the time to better monitor and respond to our infrastructure needs in the future.
For those professionals who incorporate geosynthetics
in your designs, please share those strategies with your colleagues. And for those construction professionals on the public and private level who have yet to learn about or adopt geosynthetics, please look into what they offer.
Chris Kelsey is an editorial consultant for geosynthetica.net. He has written about geosynthetic engineering for seven years and is based in Saint Paul, Minnesota.
