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Durability, in the strict sense, refers to the resistance of the CIPP liner to external, foreseeable influences throughout its service life. Evidence of durability can be demonstrated through performance tests or derived from practical experience and long-term observations. Important: The economically reasonable service life for a CIPP liner is currently set at 50 years, during which no repair costs should arise. This assumes that all required tests … |
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The CIPP liner is a composite system consisting of:
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1. Internal membrane (foil or coating): The separating layer that forms the inner wall of the CIPP liner after installation. 2. External membrane (foil or coating): The separating layer that forms the outer wall of the CIPP liner after installation. Inner and outer membranes usually consist of:
During installation, … |
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The resins used for the CIPP are classified as duromers, as they consist of closely cross-linked polymers (macromolecules). These resins are considered insoluble, slightly swellable, and chemically very resistant. They therefore meet the fundamental requirements for use in sewer rehabilitation. The cured resin has a decisive influence on the deformation resistance and load-bearing capacity of the CIPP product. Duromers (also called thermosets), are … |
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For the lining tube, unsaturated polyester resins (UP), epoxy resins (EP), or vinyl ester resins (VE) are generally used. The resistance of the resin systems must be proven by their suitability for use in the municipal sewage sector. Only resin systems that are hydrolysis-resistant and insensitive to moisture in the cured state are to be used [DWAA143-3:2014]. Pigmentation to control mixing and/or resin impregnation is permissible. When selecting the … |
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EP resins are primarily used for lining tubes in the field of house connection renovation and are often coloured (e.g., blue, purple). Lining tubes for house connection renovation are not the subject of this module. (Image: Lining tube for house connection renovation with dyed EP resin (pink)) (Image: Lining tube for house connection renovation with dyed EP resin (blue)) |
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(Table: Resin systems used for cured-in-place lining [Steinb]) |
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The polyester resins (UP), epoxy resins (EP) or vinyl ester resins (VE) listed in the table are preferably used. The composition of the resin systems used must be described in the suitability certificate. (Table: Preferred resin types [DWA-A143-3]) |
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For all resins except epoxy resins, curing is triggered by different types of initiators, which can be categorized into two main types: 1. Thermal Initiators
2. Photoinitiators
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UP and VE Resins: Composition and Curing Unsaturated polyester (UP) and vinylester (VE) resins are typically dissolved in a reactive diluent, most commonly styrene. To enable curing, initiators are added to these resins, which differ based on the curing method:
[ZKS-Hein] How the Curing Process Works When exposed to a specific temperature range or ultraviolet (UV) light |
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The curing process of epoxy (EP) resins differs fundamentally from that of UP and VE resins. It is not a polymerization, but rather a polyaddition reaction. In this process, special hardener systems are used, consisting of two components:
These systems can cure even at ambient temperature. However, the curing process can be accelerated or controlled by applying heat. On-Site Impregnation Because the EP resin reacts directly upon contact … |
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(Image: Carrier material neu) Carrier materials are processed into tubes, and after impregnation with the appropriate resin system, they form the lining tube. These materials are divided into two groups:
In some cases, combinations of these materials are also used. (Table: Carrier materials based on [Siebe03]) |
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Carrier materials often consist of polymeric fibres, also referred to as synthetic fibre felt or polyester needle felt. These materials are typically made from:
When combined with resin, polymeric fibres can have a weakening effect due to their high flexibility. This flexibility results in a lower achievable modulus of elasticity |
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Carrier materials often include glass fibres, which can be of the following types: Types "E", "C", "R", "E-CR". In combination with the resin, glass fibres have a reinforcing effect because:
Glass fibres are typically available in the following forms:
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Only textile fibres free of softeners may be used. The seam or overlap areas of the carrier material must not impair the properties of the lining tube. For lining tubes with a multi-layer structure, any joints or overlaps must be arranged in an offset (staggered) pattern. (Image: Carrier material - Test sample of a polymeric fibre CIPP (ohne metadata)) (Image: Carrier material - Test sample of a glass fibre CIPP (ohne metadata)) |
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Important: The carrier materials must be impregnated with the resin as thoroughly as possible. The resin must be homogeneously distributed, without any visible air inclusions or defects. The impregnation of the lining tube is carried out either at the factory or on site. Factory Impregnation The lining tube is impregnated in the factory under controlled conditions, ensuring the highest quality standards. Depending on the resin used, the impregnated … |
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Impregnation of the lining tube at the construction site should only be carried out in mobile facilities that meet the following requirements or contain equipment:
The impregnation should be reproducible, factory-set, and independent of weather conditions. Impregnation on site (Image: Impregnation on site - Stacked … |
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The following table lists the quality influences during the manufacture of the lining tube on its load-bearing capacity, leak tightness, and functionality. (Table: Manufacturer-related quality influences during the assembly and impregnation of the lining tube [MUNLV05]) |
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The mechanical properties of lining tubes are influenced by the combination of carrier materials, wall structure, and resin matrix. Literature references to material characteristics of different types of lining tubes highlight these influences. For example, the expected flexural modulus of lining tubes with a wall structure made of glass fibres is approximately four times higher than that of those made from polymeric fibres. This demonstrates the … |
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Polymeric fibres felt tube also called needle felt liner 1. Internal membrane
2. Supporting laminate
3. External membrane or preliner
Glass fibre tube … |
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