To develop a matched sealing material for socket rehabilitation of grey cast iron pipes, an epoxy resin is modified by the addition of different components to improve the flexibility. Three different modifications are made by adding ethylene-propylene diene monomer (EPDM) rubber powder, reactive liquid polymer (ATBN) and epoxidized modifier. In this paper the effect of the modification method as well as the influence of absorption of water on the mechanical and physical properties are analyzed in terms of: tensile strength, modulus of elasticity, adhesion performance, pressure resistance, glass transition temperature and water content. A comparison with neat epoxy shows for all materials that the modulus of elasticity and strength decrease. Unlike other tested modification methods, the modification with rubber powder did not enhance the flexibility. All materials absorb water and a plasticization effect arises with further changes of mechanical and physical properties. The application of the sealant on the grey cast iron leads to a reduction of the strain at break (in comparison to the common tensile test of the pure materials) and has to be evaluated. The main requirement of pressure resistance up to 1 MPa was tested on two chosen materials. Both materials fulfill this requirement.

The project DeWaLoP, led by Vienna Water, aims to develop a robot that is able to apply a sealing system to repair the joint sockets of pressure operating water pipes measuring about 1 m in diameter. To do this, a modification of the sealing material for inner surface application will be developed and a complex robot system will be designed to perform various tasks, such as inspecting, cleaning and restoring. Seven commercial sealing materials with a broad spectrum of mechanical and physical properties were tested. For this purpose, a series of tests was carried out to measure tensile strength, bending and adhesion; in addition, dynamic mechanical analyses, differential scanning calorimetry and thermogravimetric analyses were also conducted. A change in the mechanical and physical properties of these materials after water exposure could be observed. Furthermore, the surface preparation and remaining contaminants, e.g. rust, can affect the adhesion properties of the sealant. The plan is to develop a formulation of a matched material based on the results of these tests and the existing knowledge about the behaviour of sealing materials. The proposed in-pipe robot consists of three main subsystems: a control station, a mobile robot (similar to a vehicle) and a maintenance unit with a redevelopment system. An operator controls the movement of the cable-tethered robot system remotely from outside the construction side.

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