Nondestructive repair and rehabilitation of structural elements using high strength inorganic polymer composites.

摘要

Results reported in this dissertation focus on the development of an inorganic polymer composite for rapid, nondestructive repair and rehabilitation of physical infrastructure. The composite consisting of an alkali-aluminosilicate made of nano/micro size particles and high strength fibers was evaluated for repair and strengthening of concrete structural elements. In the area of repairs, the focus was to repair small width voids such as delaminations and cracks developed due to restrained shrinkage and long-term distress in concrete bridge decks and other similar structural elements. A strengthening study was done to increase the capacity of reinforced concrete beams with carbon fibers. Uniqueness of the strengthening system with inorganic matrix is its fire resistance.;For the repair system, the matrix composition was evaluated for flowability using plexiglass models and concrete slabs, bond strength using slant shear and bending specimens, and durability studies using wet/dry and freeze/thaw conditions. Delivery of the composite to cracks and delaminations was also investigated using equipment that is currently used with organic polymers. The temperature resistant repair system with carbon fibers was evaluated using strengthened concrete beams heated to over 1,000°F at the maximum bending moment location.;The following are all the major findings of the investigation: The inorganic nano/micro composite flows well into cracks -- even cracks that are between 0.03 and 0.04 inches wide. Commercially available equipment can be used for the inorganic matrix. The hardened matrix bonds well with concrete and provides a structurally integral repair. Strength tests showed that the strength at the repaired locations is higher than the strength of the parent material. In addition, since the modulus of elasticity of the inorganic system is comparable to concrete, the repaired structural components regain full structural integrity as compared to mere cosmetic repairs provided by organic polymers. The system is durable under wetting/drying and freezing/thawing conditions. For both, strength and durability increases with the nano-size material content and improves performance. The heat tests showed that the repaired beams can be heated up to 1,385°F repeatedly with minimum loss of strength.