Repair or Replace? No Brai By Drew Robb


It seems a no-brainer on the surface – repairing cracked or spalled concrete in a parking deck, sta-


dium, bridge, tunnel or runway is an obvious solution to keep ownership costs down. But if the underlying dam- age is severe, it may be cheaper over the long term to tear everything down and rebuild. The missing element, in many cases, is an assess-


ment of overall life-cycle costs. This is the time-honored method to determine the best course of action with regard to structural concrete repairs. By considering all aspects of the financial equation, an owner can achieve a fuller understanding of available options. Spending a little more today to fix an immediate


problem correctly may considerably reduce the total cost of the structure over its lifespan. “Life-cycle costs (LCC) are cradle-to-grave costs


summarized as an economic model of evaluating alterna- tives for equipment and projects,” said H. Paul Barringer, P.E., of Barringer & Associates. “The objective of LCC analysis is to choose the most cost-effective approach from a series of alternatives…to achieve the lowest long- term cost of ownership.”


Consider the age of the entire facility. The answer might not be obvious.


Concrete Condition Survey Identifying unseen conditions and the extent of damage is a


key element in any LCC evaluation. Nondestructive Testing (NDT) is often used by engineers to obtain detailed structural information. NDT techniques include sounding, galvanic pulse testing, ground-penetrating radar and in-situ load tests. When more upfront condition detail is available, the engi-


neer can prepare a more accurate remedial cost estimate, and it is less likely the owner will face costly change-order surprises should he elect a repair option. Ahuge repair bill may tilt the balance toward replacement –


as is the case with some older hospitals in California, where regu- lations require emergency buildings to meet current, more stringent earthquake codes. Amajor healthcare provider in


Los Angeles, for example, recently demolished two large buildings erected about 30 years ago and is rebuilding. The high cost of improv- ing the structural elements of these facilities to meet current seismic standards was one of several fac- tors that led management to select the replacement path. “In some instances, replacement may prove to be the better


concrete structures. When the concrete collars for these lights began to fail, airport officials tried a quick-setting repair material, which failed to eliminate the problem. Faced with a live and important aircraft taxi lane , they con-


sidered all options – further repair or complete replacement. In this case, they chose a proven solution capable of being


injected in harsh loading conditions – a customized epoxy formu- lated specifically to cope with difficult working conditions and without compromising concrete integrity. “The epoxy stabilized our taxiway lights and eliminated fur-


Parking decks have been transformed into computer server farms in Beijing.


option for an older structure with a few years left before the design life ends,” said John Bors, Vice President of ChemCo Systems. “In all cases, it is prudent to hire an engineer for a structural life-cycle evaluation and condition survey. If the damage is not disruptive to the entire structure, often the best option is to repair.”


Further Repair or Complete Replacement? Take the case of San Francisco International Airport (SFO),


located on the Bay, which had some taxiway lights embedded in 22


ther deterioration,” said Charlie Freas, a consulting engineer at SFO. “This proved to be the right decision in the long term, both financially and structurally.” The airport has since used simi-


lar epoxy formulations to repair cracking in parking structures, serv- ice tunnels below groundwater lev- el, and its light-rail system, as well as for concrete spalling on taxiway aprons and ramps. “Groundwater infiltration is a


constant challenge as it increases pumping costs and wear,” Freas said. “With regards to pavement spalling, the airport is constantly inspecting its runways, aprons and the surrounding concrete infrastructure for any signs of degradation in order to avoid flying object damage, which can cause catastrophic dam- age to jet engines. “As concrete spalling can be substantial at times and the con-


sequences so significant, we would rather replace an entire con- crete section than be faced with the possibility of having to buy a new engine,” Freas said. “However, we have confidence that effective epoxy repairs provide the flexibility and strength to sup- port our planes without further spalling.”


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