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Nov 22, 2004 Rehabilitation and Maintenance of Drains and Sewers Restoration of Concrete, Reinforced Concrete and Pre-stressed Concrete Sewers Concrete surfaces that are to be the foundation for a repair measure must always consist of undamaged concrete, i.e. they must be free from dirt, old paints that cannot carry loads, floury fine grout layers and all other substances that can reduce a bonding effects (e.g. damaging salts such as sulphates, nitrates). The concrete foundation must be prepared such that a tight and durable bond can be achieved between the repair grout to be applied and … |
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Feb 16, 2011 Rehabilitation and Maintenance of Drains and Sewers Restoration of Concrete, Reinforced Concrete and Pre-stressed Concrete Sewers (Image: Corrosion protection sealing of the de-rusted reinforcement [BDZ89]) The required preparation of reinforcement rods depends on their condition, on the extent of the corrosion and the type of repair measures. For limited repairs of concrete spalling due to corroding reinforcement, the recommended method is conservation by means of anti-corrosion paints (Bild 5.2.1.3.2) in accordance with the rules for steel construction. An anti-corrosion paint … |
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Nov 22, 2004 Rehabilitation and Maintenance of Drains and Sewers Restoration of Concrete, Reinforced Concrete and Pre-stressed Concrete Sewers For a durable bond between old concrete and repair grout, and with reference to the repair process, the concrete foundation must possess the following properties [Grube90] :
For most of the measures, a certain degree … |
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Feb 16, 2011 Rehabilitation and Maintenance of Drains and Sewers Restoration of Concrete, Reinforced Concrete and Pre-stressed Concrete Sewers (Image: Applying the repair grout by hand [BDZ89]) The application of the repair grout (Bild 5.2.1.3.4) must be carried out before the bonding bridge is fully hardened (working "fresh on fresh"), otherwise there is the danger that the bonding bridge becomes a separating layer. When preparing and applying, as well as during the finishing process of the repair grout, the preparation instructions of the manufacturer must be carried out. Detailed information … |
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Measures for the restoration of defective regions in the inside of sewers of concrete, reinforced concrete and pre-stressed concrete have the aim, depending on the selected repair grout, among others of [DAfStBb] :
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Although sewer clinkers in masonry sewers are generally resistant to acids (for exceptions (Abschnitt 2.6.4), the cement-bound grout joints are destroyed with corresponding loading (Abschnitt 2.6.4). If these masonry joints are not filled in with an appropriate grout again (pointing), then the result can be leaks, the falling out of one or more sewer bricks from the walls up to collapse of the arching. In this type of damage in the wetted cross section, … |
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Processes have been developed especially for the cases where the static bearing strength of individual pipes is endangered, that permit these to be secured for a certain period of time and thus to delay the time of replacement or for a time until the start of other, more comprehensive measures of damage elimination. The steel tension rings for man-accessible sewers belong to these processes. In this process, and depending on the type of damage and … |
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Feb 16, 2011 The core of this robot system is a self-propelled carrier apparatus that can be equipped with milling, drilling and injection heads, a trowel arrangement or shell with grout supply (Bild 5.2.1.6.1).
The system is suitable for carrying out repairs in concrete and reinforced concrete, … |
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Feb 16, 2011 (Image: SikaRobot system [FI-Sika] - Lowering the Sika robot into the manhole) The SikaRobot system [FI-Sika] consists of three hinged-together machine units for ease of introduction into the sewers via a manhole (Bild 5.2.1.6.2) (Bild 5.2.1.6.2) (Bild 5.2.1.6.2) (Bild 5.2.1.6.2). In the base version it consists of a drive unit, a control unit and a working head with tool holders as well as a TV camera for visual control of the repair works. The applicability … |
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Remote controlled robot processes are available for eliminating points of damage such as leaks, flow obstacles, cracks, pipe breaks and projecting or unprofessionally installed nozzles in non-man-accessible sewers. The following are some of the commercially available robot processes:
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Restoration processes are used for local or sectional rectifications or for the replacement of pipes or structural components in order to restore the functionality, the static load bearing capacity as well as the leaktightness. |
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Nov 22, 2004 All injection media based on cement suspensions and plastics solvents are suitable for crack widths of ≥ 3 mm. The further injection limits are given in [Verkehra] for the following injection media and crack widths:
When high pressure injection pumps with pressures above 20 bar are used, then the injection limit for plastics … |
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Nov 22, 2004 A differentiation must be made here between cracks that have come to rest or those that are still moving (working). In the former case, no further condition requirements are placed on the injection medium. For correspondingly large crack widths here, cement based injection media can be applied that have a natural modulus of elasticity that is relatively high for injection media and thus permit no movement. In the case of movement, tears and renewed … |
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Nov 22, 2004 Cracks situated in the compression region of the structure should be pressed with an injection medium that possesses at least the strength of the component and has a similar modulus of elasticity in order to recreate the effect of the cogging or the force locking and to make lateral displacement impossible. For cracks in the tension region of the structure, highly elastic, possibly foaming and well bonding injection media should be utilised as already … |
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Nov 22, 2004 Important criteria for the flanks of the cracks are their moisture content and surface properties. In the application case under consideration, moist and dirty crack flanks must usually be assumed. Injection media utilised here should be able to bond moist crack flanks and be able to penetrate in fine hairline cracks in the crack flanks. An overview of the allocation of suitable injection media to parameters of unconsolidated soil and to cracks to … |
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(Image: Limits of injection for injection media with reference to the granulate distribution [Maidl83a]) The utilisation of the above-mentioned injection media depends upon the chemical and mechanical requirements with reference to the respective application case (type of damage, purpose and aims of the injection measure) and/or, with linking the embedment into the injection measure according to the geological and hydro-geological conditions of the … |
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Injection grouts are mixtures of cement, water, additive of small granulation and, if required, additional substances (e.g. stone flour, fly ash, bentonite) and additive media (fluidisers, thickeners, hardening retarders, hardening accelerators, stabilisers, among others) [Stein81]. Injection pastes are mixtures of cement, water and, if required, additive substances and additive media. Characteristic of grouts and pastes that can be injected are their … |
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Suspensions are mixtures that consist of a carrier fluid containing evenly distributed, non-dissolved solids. In contrast to the pastes, they contain a substantially smaller proportion of solids. Depending on the properties of the mixtures, they can be utilised for fixing and/or sealing purposes as well in strongly porous as well as in less porous unconsolidated soils (water porosity coefficient k > 10-3 m/s) and for cracks with widths from > 3 mm. |
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Feb 16, 2011 Water glass is understood to be sodium or potash salts whereby the relationship alkali/silicon in the water glass can vary widely. Starting materials for the injection technology are fluid water glasses that can mix very quickly and in any relationship with water. Added to the fluid water glasses are reactive substances that cause the formation of silica gel by means of chemical conversion and poly-condensation of the silicates under water separation (… |
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Nov 22, 2004 These media, which are commercially available under various names, are used for sealing purposes (see section 5.2.2.3). The water-soluble acrylic resin is thinned with a polymerisation accelerator or retarder and water, mixed with a catalyst that is necessary for the polymerisation and then injected. The solution with a viscosity between 1 and 4 MPas polymerises to a transparent and elastic gel. The gel swells under the influence of the water or shrinks … |
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Nov 22, 2004 Commercially available epoxy resins are mostly low viscosity to glassy but seldom crystalline substances. Before their application, they are modified with the corresponding hardeners and, if required, also with solvents, reactive thinners (low viscosity epoxy resins), softeners, fillers or pigments [Batze81]. Epoxy resins can be applied up to the coarse poor clay region (Bild 5.2.2.1.1), whereby relatively high strength is obtained. Disadvantageous … |
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Nov 22, 2004 Both gels and two-component polyurethane systems are available. NCO pre-polymers (poly-functional) based on ethylene-oxide rich polyethers are used for the creation of gels. Through mixing with surplus water there are first created emulsions or solvents, which harden by means of water and, if required, added di- or poly- amin under lattice polymerisation. Insofar as in the carbon dioxide created by the water reaction, is not dissolved in the watery … |
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Nov 22, 2004 A relatively new injection medium is silicate resin that has been used for some years in mining. This consists of the reaction of inorganic alkali silicate with organic iso-cyanate. The component A is a modified water glass; component B is a poly-functional iso-cyanate [FI-Webac]. To create the resin, the two components are mixed in a ratio of 1:1 of volume. Depending on the recipe, the end product thus created is either a foamed or an un-foamed … |
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Nov 22, 2004 The plastics and synthetic resins solvents utilised for injection purposes possess the following advantages:
Depending on type and dosage of the components used, there occurs a polymerisation, poly-condensation or a poly-addition that leads to an … |
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A chemical solvent is understood as the dissolving of fixed particles in a solvent medium. Of all the injection media under review, they posses the best penetration as they possess no visible floating particles. The most important injection media in this respect are solvents based on water glass and synthetic resins. Synthetic resins are fluids containing solvents or are free- flowing fluids that transform into a gel or solid condition due to chemical … |
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