Geosynthetica has some interesting photos of so called ‘whales’ in geomembranes. These giant bubbles are caused by a variety of things, but are essentially gas trapped underneath the geomembrane that can have significant buoyant force, and as the title of the post implies, even concrete ballast may not be strong enough to weight them down. [Source: geosynthetica.net. Image: FLI via geosynthetica.net]
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Nortex and TerraThane Stabilize Houston Area Highways
Houston’s Highways, Some of Busiest in Nation, Use Innovative TerraThane Polyurethane Foam Technology to Repair Bad Bridge Approaches, Uneven Joints, and Roadway Depressions.
MOUNT AIRY, NC—Highways around Houston, TX, known as one the nation’s worst cities for traffic behind Los Angeles, D.C., and Atlanta, need constant repair, but can’t be closed while the work is done. Nortex Concrete Lift and Stabilization, Inc., a Ft. Worth, TX company, recently completed a whirlwind repair project on one of the city’s busiest corridors in the NE quadrant where I-10, 610 Loop, I-59, and I-69 feed millions of cars daily to, from, and around Harris County.
Normal groundwater erosion beneath the highways causes the concrete highway slabs to drop, roadway depressions, uneven bridge approaches, and uneven joints that make driving bumpy and uncomfortable, dangerous, and causes severe wear and tear on automobiles.
To make the repairs, the Texas Department of Transportation, TXDOT, brought in Nortex. The company carefully planned out the repairs for the half million pound project, and sent out four crews each with it’s own box truck rig to use a relatively new technology called “foamjacking.” Foamjacking uses high-density polyurethane foam to fill the subterranean voids, and lift the concrete slabs to proper level. “We’ve been lifting and stabilizing roadways with polyurethane foam since we got into the business back in 2003,” says Casey Derosa, asst. gen. mgr. of Nortex. “It’s a far superior method versus the old way of mudjacking.” Mudjacking is a ubiquitous term for a mix of mud, sand, cement, crushed limestone, and water hydraulically pumped into large holes drilled into the concrete slabs to fill voids and level the slabs. Mudjacking uses more and much larger equipment, and requires larger holes to be drilled. It typically requires the roadway to be closed much longer than foamjacking, and takes more time to clean up.
[Editor] Click through for the rest of the press release from GeoPrac sponsor NCFI Polyurethanes. [/Editor]
Updates on testing and standards development for geosynthetics
ASTM Updates September 2009
This post contains a summary of geotechnical, materials testing, geosynthetic and related testing standards that were updated by ASTM during the month of September. This month there were not as many updates as the last couple, but a few that caught my eye are a new standard for measuring geosynthetic-soil resilient interface shear stiffness, a revision to the standard practice for laboratories testing concrete and concrete aggregates for use in construction and criteria for laboratory evaluation and a revision to the standard for measuring slump flow of self-consolidating concrete.
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i have seen this kind of problem in my place and i am doing my project on this. the reason was mainly due to the raising water table and lack of gas drainage . kindly suggest me some strong literatures on this .
thank you