Rebonding of Prestressed Tendons in Concrete by Internally Released Adhesives

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Demolishing of prestressed concrete is difficult due to the energy storedin the prestressing metal tendons which is usually up to 125,000 pounds. Inunbonded tendons the energy may be catastrophically released, threateningthe safety of people, workers and buildings. Most of all flat plateconstruction and bridge girders produced utilize tensioning of metaltendons; so the problem is large and it most improtantly it is unresolved. The objectives of this research are to develop and to test means ofrestraining or rebonding the tendons under stress for continued effectiveload transfer during use and for safe demolition. The proposed researchapproach consists of four activities. 1) We will develop information on theforces available in prestressed members and calculate the countervailingforces needed to be supplied by the release mechanism and materials. 2)Large scale laboratory testing will be done on the proposed systems.Strucutral tie downs and tensioning devices will be used. 3) Full scaleprestressed girders will be tested using the rebonding system. 4) the datawill be evaluated and disseminated.The impact on education should be large. This project should employ anestimated 25-30 different students from both undergraduate and graduatelevels. They will be active in all aspects of the project. The proportionof women gaining that experience should be high, approximately half or more.