Polymer Materials for Structural Retrofit

One of the greatest threats from a terrorist bomb attack comes from fragmentation – pieces of walls, windows, fixtures, and equipment flying at high speeds can result in extensive injury and death. A key tactic to defeating this threat is to ensure the exterior wall of a building can survive the bomb blast without breaking apart and contributing to the fragment problem. To address this need, the Air Force Research Laboratory at Tyndall Air Force Base, Florida began a series of tests to investigate the use of an elastomeric polymer coating to prevent fragmentation from lightweight structural elements such as concrete block walls and temporary lightweight buildings. The elastomer material is a highly ductile polymer that can be sprayed onto building surfaces. Recent tests indicate the coating applied to the interior surfaces of a lightweight portable building can offer protection for occupants against an explosive charge at a relatively close distance. The polymer bonds to the wall forming a tough elastic skin. Although structural failure of the supporting walls does occur, the elastomer material remains intact and contains the debris. During full-scale explosive tests, the retrofitted building experienced significant deflections but no wall fragments were observed entering the room. Post-test observations indicate the ductile response of the polymer membrane can effectively contain the splintered wall components and can prevent serious injury to persons inside a room. The polymer retrofit technique can reduce the standoffs required to limit damage and casualties by approximately 50%, and is an effective tool in providing military commanders in the field with an expedient method to protect deployed forces from terrorist and enemy bomb attacks.