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During the Pacific Logging Congress, 7th In the Woods event held September 2014 in Molalla, Ore., an aggregate haul road was constructed to demonstrate the difference of an unreinforced section verses a section reinforced with geogrid. The result showed that the reduced use of aggregate with geogrid minimized rutting caused by fully loaded logging trucks.

Port Blakely Tree Farms hosted the logging show. Held every four years, this “live in the woods” event is part of the Pacific Logging Congress and provides a hands-on venue where growers, loggers, and regulators share state-of-the-art practices and technologies on the responsible and economical harvest of timber. Show attendees witness an assortment of live logging activities, all utilizing the latest, most advanced equipment, technology, and environmentally responsible methods.

A typical haul road generally requires about 14 to 16 inches of quality aggregate about 60 cubic yards for every 100 feet of haul road. With just 8 inches of compacted aggregate, the reinforced section proved stronger than the unreinforced section with double the amount of aggregate.

For the haul road demonstration, organized by GSE Environmental and Advanced Drainage Systems, Inc. (ADS), geogrid was used to reinforce portions of a heavily travelled logging road.

“Aggregate surface haul roads are used to expedite transportation of timber as well as to prevent soil loss and minimize erosion,” said Bob Klein, executive vice president, sales for ADS. “A typical haul road generally requires about 14 to 16 inches of quality aggregate about 60 cubic yards for every 100 feet of haul road. Suitable aggregates, however, are often some distance away. The cost of buying and transporting this amount of aggregate can quickly surpass any financial gains brought by expedited transportation of the timber. But with the addition of the proper geogrid, the amount of needed aggregate is greatly reduced, making it economically practical to build a road that will last.”

Half of a 200-foot-long haul road was constructed as a conventional logging road with 16 inches of compacted aggregate over the native subgrade. The other half was constructed with 8 inches of compacted aggregate placed over ADS BX124GG biaxially oriented geogrid. The geogrid was unrolled over the native subgrade, and then 500 gallons of water was pumped over the surface and allowed to saturate. Biaxial geogrids are able to withstand stress in two directions and their apertures are more evenly dimensioned. For the demonstration, a fully loaded tractor trailer logging truck traveled back and forth during several days over both sections of the roadway.

Figure 1: Graph shows how ADS BX124GG geogrid can reduce the amount of needed aggregate and reduce costs.

“The reinforcement benefit of the ADS BX124GG geogrid with its positive mechanical interlock was quickly evident,” Klein said. “Ruts began forming in the unreinforced sections and got deeper and deeper with each pass. Only minimal rutting was witnessed in the reinforced section. With just 8 inches of compacted aggregate, the reinforced sections proved stronger than the unreinforced section that had twice the amount of aggregate. Using the geogrid reduced aggregate use by 50 percent.”

Biaxial geogrids are designed for soil stabilization, base reinforcement, and subgrade improvement. They are used in road reinforcement, parking lots, and even airport runways where stresses are in two directions. The ADS BX Series Biaxial Geogrids are produced from polypropylene using punched and drawn technology and available in six versions. ADS geogrid products come in a variety of widths and lengths.

“The engineered grid pattern of ADS geogrid products is the key to their load-bearing strength and support,” Klein said. “Interlocking this pattern with fill, whether it is soil, gravel, or rock, produces a superior load transfer which provides security for a project, whether it is for a road or for base reinforcement and soil stabilization. Our geogrid products have excellent tensile strength, which makes them ideal for all these applications.”

Information provided by Advanced Drainage Systems, Inc. (ads-pipe.com).

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