Improvement of the Serviceability of Damaged Concrete and Reinforced-Concrete Structures by Sealing Hardening Injections
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IMPROVEMENT OF THE SERVICEABILITY OF DAMAGED CONCRETE AND REINFORCED-CONCRETE STRUCTURES BY SEALING HARDENING INJECTIONS V. І. Marukha
UDC 539.421: 624.012:666.96
We consider main approaches to the analysis of the engineering state of concrete and reinforced-concrete structures with in-service defects and evaluate the efficiency of improvement of their serviceability by injection technologies. We compute the parameters of these technologies and propose numerous injection composite materials with high technological characteristics based on polyurethane and polyepoxide. The efficiency of these materials is confirmed by the results of testing of laboratory specimens with filled stress concentrators. Additional possibilities of corrosion protection of uncoated steel reinforcement by adding corrosion inhibitors to the injection compositions are discovered and the technological features of hardening of damaged structures by filling detected defects are revealed. Keywords: concrete, reinforced concrete, crack, strength recovery, injection material, inhibitor protection, technology of hardening.
At present, much attention in the building industry is given to the recovery of strength and serviceability of damaged concrete and reinforced-concrete structures intended for long-term operation [1]. This problem concerns both the commercial objects and the municipal buildings, which often have high historical and architectural value. For reinforced-concrete structures, the situation is worsened due to their cracking as a result of corrosion of steel reinforcement, which leads to the increase in the total volume of the metal and corrosion products and, hence, to the formation of tensile stresses in concrete matrices [2, 3]. The formation of cracklike defects in concrete is the main hazard for the characteristics of strength and durability of these structures. Thus, it is possible to improve the indicated characteristics by “healing” (removing) these defects. The increase in the residual life of damaged concrete (reinforced-concrete) structures by using the injection technologies is a complex problem covering the concepts of the physicochemical mechanics of materials and required certain engineering and technological solutions. In what follows, we focus our attention on the key aspects contributing to the efficiency of the proposed approach. These are the evaluation of the stress-corrosion state of structures containing defects filled with sealing materials, the determination of the force modes of injection, the development of new injection materials and corrosion inhibitors with an aim to combine the recovery of strength with the inhibitor protection of reinforcement, and the development of the processes of injection recovery of strength. Determinations of the Force Modes of Injection To inject materials into defects, it is necessary to analyze the mechanical state of damaged structures and, first of all, of the structures containing cracks, which are especially dangerous for concrete. In this case, one “Tekhnoresurs Engineering
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