Dec 9 2009
USGunite of Keller, Texas recently completed an extremely demanding assignment for the foundation of a new 22-story Embassy Suites hotel in downtown Houston. Linbeck Construction is constructing the hotel at the hard corner of Dallas Street and LaBranch Street, and space is extremely tight. Linbeck's team decided that utilizing a pneumatically-applied system of spraying concrete, commonly known as 'shotcrete', would save considerable time and money over the more traditional cast-in-place method for installing concrete retaining walls.
"Considering the exceptionally tight working space in a 30' deep hole," states Linbeck's Project Superintendent Ches Bromley, "we determined that pneumatically-applied concrete was the best solution. Using cast-in-place, we would have had to monopolize the crane operator's time to handle form placement, leaving him no time for other lifting assignments." With pneumatically-applied concrete that required no heavy forms, the crane was able to stay on schedule while serving multiple construction processes simultaneously.
As the excavation advanced to a depth of approximately thirty feet, construction teams installed wood shoring secured with tiebacks into the wall face. Xavier Structures workers installed a double mat of vertical and horizontal reinforcing steel the full height of the shored wall. Shotcrete was sprayed on and around the steel, completely encasing it in concrete 12" to 18" thick. Using scissor lifts and boom lifts, the installation team advanced up the wall at the rate of about 40 -50 yards per day until completion. Using a 1" overspray of gunite (dry process), skilled finishers trowelled a smooth finish on what would become exposed walls for the below-grade parking garage.
Bromley estimated that almost two weeks were saved by using the shotcrete/gunite process. Linbeck estimates a cost of $20K per construction day for large projects, so the savings were considerable, especially since other trades could continue to work during the installation process.
Source: http://www.usgunite.com/prestigegunite/index.aspx