Equipment World Digital Magazine
Issue link: http://read.dmtmag.com/i/536721
EquipmentWorld.com | July 2015 69 performance problems because of contractor misuse. "The confusion always is that almost all geosynthetics are black, so geogrids and geotextiles all look alike, so sometimes they don't know," he says. "There are a lot of different products and they all are made a little bit differently and have different strengths and weights. Some of the stronger products are typically used for reinforcement, others for erosion control." As a hypothetical example, Odgers describes a scenario in which an engineer may favor one product over another, and then design a project requiring rein- forcement with that specific geo- synthetic matched to the project. This makes perfect sense to the engineer, but that message might not make it to the contractor. "The contractor might not really un- derstand the differences between this product and other products he's used in the past. Sometimes you'll see the contractor end up using a lesser product thinking it can work as a substitute. Then it doesn't work properly." And why would a contractor not use the designated product? The common answer might be cost, but Odgers says it could just be convenience. "Maybe it's a small project and a contractor has some- thing sitting in his yard left over from a past job and he says, 'Oh I've got some geogrid or geotex- tile already, I'll just use this.'" But another scenario could just be inattention to the precise specifications needed. "An engi- neer will design the thickness of the aggregate, for instance, for the pavement, and it's very specific on how much you can reduce that aggregate to the geosynthetic that they specify," he says. "If you trade it out with something else, that's when you're going to see possible failures of your road- way." Contractors are becoming more interested in educating themselves about geosynthetics, Odgers says. "The biggest thing is (for contrac- tors) just to contact the differ- ent companies to make sure that whatever they're using is going to meet the specification." And as the use of geosynthet- ics becomes more widespread, manufacturers are also produc- ing better performing materials. "The old woven geotextiles came from the carpet backing industry," Odgers says. "They really weren't designed for roadways. So now we're designing products around those applications so that you get better performance – longer last- ing and cheaper roads."