Hillsborough County Florida is using a mix of expanding polyurethane foam and conventional cement grout as a more cost effective means of filling sinkholes. Officials say the mix uses 30 to 40% less grout adding up to a 30% cost savings. The article in the Tampa Tribune did not indicate the contractor or product name that they are using but apparently several agencies in California and other states are using the same material. Story via ASCE SmartBrief.
Press Releases
Minnesota Company Transforming Highway and Bridge Repair by Using NCFI Engineered Polyurethane Foam
August 11, 2011 MOUNT AIRY, NC—Gary Molstre, owner of Mudpumpers Mudjacking, Moorehead, MN, says there is no chance they are changing the company name, but they are definitely changing the material they use to repair highways and bridges to an engineered polyurethane foam system and they’ve coined a term for it: “foamjacking”.
Mudjacking, also called slab jacking, concrete lifting, concrete raising, and slab leveling, is the traditional method of fixing damaged concrete highways and bridge approach panels. The process was developed in the 1930s and involves pumping “mud” (everything from clay, sand, and loam, to Portland cement, fly ash, lime, casting plaster, and hot asphalt have been used) beneath concrete slabs that have become uneven, sunken, and/or pulled away from bridge approaches due to soil erosion and/or the soil being compacted or compressed from the sheer weight of the slab. Mudjacking involves drilling holes in the concrete and pumping “mud” and pressure beneath to lift the slab to its original place and keep it there. [Editor] Click th rough for the rest of the press release. [/Editor]
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Failures
Johannasburg Sinkhole Opens after Tunnel Collapse
A 12m long sinkhole opened up on Oxford Road in northern Johannesburg South Africa after a partial tunnel collapse in the Gautrain rail tunnel being constructed underneath the road. Eyewitness accounts say there was a broken water pipe flooding the sinkhole, but no word on which occurred first. The road is expected to be closed for 2 weeks. Gautrain representatives said the tunneling would resume after geotechnical/geological investigations into the collapse are completed, which could take "several weeks". (Photo credit: Werner Beukes, Sapa via News24.com)
Via The Star (Zambia) and News24.com (Johannesburg?)
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Geologic Hazards
40 Foot Sinkhole in Tenn. Stadium Endzone
A large 40 foot wide by 40 foot deep sinkhole opened up just outside the endzone of Austin Peay State University’s Governors Stadium in Tennessee. The stadium is currently undergoing upgrades for next year’s football season. Sinkholes are not unexpected on Austin Peay campus, and the video below shows one example of how the University has actually incorporated the remediated sinkholes into the landscaping. Representatives from the University and the contractor expect the sinkhole will be filled without any problems.
[Updated 1/19/2015] Click through for the video since I can’t figure out how to turn off the auto-play on this one. [/Updated]