MODERN HYDROACTIVE POLYURETHANE FOR RESTORATION OF WATERPROOFING CAPABILITY OF HYDROTECHNICAL STRUCTURES
The main material of the hydrotechnical structures of the water management and reclamation complex is concrete. Its durability is the main indicator of reliability of building operation. The high density of hydraulic concrete, which determines the water resistance, is a guarantee of its durability. At the same time, in hydraulic concrete during the operation under the influence of aggressive environmental factors various defects (cracks, dissected zones)develop, which reduce its waterproofing capability. These defectsare the main centers of water filtration through building structures.
At first, drip filtration develops in buildings, which in the course of time increases into active jet filtration. That can lead to the complete destruction of the building. In this connection, the issue of restoration of monolithicity and waterproofing of concrete hydro-technical constructions is relevant. The solution of the problem may be the use of injection waterproofing of the structures when using hydroactive polyurethane resins. Due to the presence in the chain of macromolecules the final isocyanate (-NCO) groups, polyurethanes are capable for interacting with water molecules with the release of carbon dioxide, which leads to foaming. As a result, water blockage occurs in the concrete body and its waterproofing is restored.
The analysis of the modern construction market shows that there is currently a sufficiently wide range of single- and two-component hydroactive polyurethane resins capable of reacting with water with foam formation. As the study has shown, the rate of polymerization, the beginning and the end of polyurethane compositionsfoaming substantially depend on the rate of catalyst or polymerization accelerator in the composition, as well as on the environmental temperature. So,when increasing the rate of catalyst in the mixture from 2 to 9%, the rate of polymerization reaction increases by 3,3-3,9 times, and when increasing the environmental temperature from 10 to 25 °C, the polymerization rate increases in 1,3-1,4 times. The foaming time of polyurethane compositions varies within 0,8 ... 16 minutes. Depending on the polyurethane formulations, the resins can be slow- reactive, fast-reactive and ultrafast-reactive, which opens a prospect for their application in the conditions of the filtration of different intensity: from drip to jet.
Two-component polyurethane resins are the most promising for application in the technology of injection waterproofing on hydraulic engineering structures of water management and reclamation area, which enable to eliminate water leakage through the structures of different intensity: from drip to active jet filtration. Two-component polyurethane resins such as CarboPur, Tunnelinjekt, PenePurFoam, when contacting with water, form a rigid elastic foam with high physical and mechanical properties: bending strength up to 80 MPa, adhesion to water-saturated concrete to 2, 8 MPa.
Field study proved the high efficiency of injecting waterproofing with the use of hydroactive polyurethane resins in the conditions of water filtration through the structures of docking facilities of pumping stations. In the course of implementation of the projects on the restoration of waterproofing of reinforced concrete structures, the following types of work were performed: eliminating leaks through the isolation joints of concrete, as well as through shrinkage and structural cracks; eliminating leaks in the adjacent zones of "wall-floor", "wall-ceiling"; sealing leaks through the places of engineering communications laying(pipelines); arrangement of shut-off and veal waterproofing in the walls (injection of resins into dilapidated zones of the structure).
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