In many parts of the South and Midwest, road construction projects use chemical stabilization to deal with weak, wet soils and create an acceptable subgrade. Chemical stabilization is often cost-effective compared to the conventional approach of excavating and replacing poor quality soil, but it has some drawbacks which can affect installation and performance, especially in wet weather. For several communities in Oklahoma, Tensar’s TriAx Geogrids have provided a cost-effective alternative which improves road performance while also reducing construction time.
Communities across the South and Midwest have experienced extreme weather over the past few months, with historic rains resulting in devastating floods. In addition to the immediate dangers and damage that floods bring, construction and maintenance of transportation infrastructure can be affected dramatically. Saturated conditions can cause both delays in construction schedules and structural issues which shorten the life of existing roads.
In Oklahoma, transportation departments in two communities chose Tensar’s TriAx Geogrids over chemical stabilization to address poor subgrade conditions. Chemical stabilization is often used in these areas to prepare subgrades for road construction. Since chemical treatment requires good weather for both application and curing, all the recent precipitation could create havoc with construction schedules. An additional concern in areas where roads can be inundated during floods is the fact that pavement structures are weakened significantly when they are saturated with water. As the flood waters recede, significant damage can be done by traffic which uses the road before the aggregate base and subgrade have dried out. Because chemical treatment reduces the drainability of both aggregate and soil, the potential for permanent road damage is higher unless more severe traffic restrictions are imposed.
Tensar’s TriAx Geogrids solve this problem because they stabilize weak subgrades differently, by interlocking with aggregate to create a stiff, stable layer on which to build. TriAx Geogrids can be installed in just about any weather conditions, and they actually help preserve the ability of the pavement structure to drain, by preventing the loss of granular material into the subgrade and the pumping of fines into the aggregate layer. The triangular geometry of the geogrid creates high stiffness in the aggregate layer and retains that stiffness over time, making for roads that last longer.
In a project for the City of Claremore, Oklahoma, the city’s engineering department decided slightly higher upfront costs of using Tensar’s TriAx Geogrid were worth the long-term improvements in road performance, including reduced maintenance and extended service life. Over the years to come, using TriAx Geogrid for this project will save Claremore taxpayers money, allowing the city to address other needs that would have gone unmet.
A project in Oklahoma City saw TriAx Geogrid reduce overall construction time in addition to increasing pavement life. Switching to Tensar’s TX7 Geogrid shaved off several days of construction time which would have been spent waiting for chemical stabilization treatment to cure. Instead, the contractor was able to place the aggregate and test for compaction in the same day, which meant less time waiting around to install pavement, and less inconvenience for motorists. For a high-traffic intersection in Oklahoma’s most populous city, this was precious time saved without compromising on design life.
Tensar’s TriAx Geogrids may not be able to completely protect roads against extreme weather and flood damage, but for these Oklahoma communities, civil engineers can take pride in high-quality roads that last for decades, and citizens can trust elected officials to spend taxpayer money wisely.
About Tensar International
Headquartered in Atlanta, Tensar International is a full-service provider of specialty products and engineering services that offer innovative and cost-effective alternatives to traditional construction methods. Tensar solutions are based on advanced soil stabilization and reinforcement technologies and incorporate unique, engineered applications for commercial, industrial, municipal, residential and transportation infrastructure site development. The company specializes in solutions for common site development challenges, including grade changes requiring retaining walls and poor soil conditions affecting the cost of roadways, parking lots and building structures. Patented, polymeric Tensar® Geogrids and Tensar’s Geopier® foundation reinforcement piers are the primary components of the company’s systems, offering reliable strength and durability. Contracted services include site evaluation, conceptual engineering, design, value engineering and installation advice. For more information, visit tensarcorp.com.