17. Epoxy Modifications—A Novel Sealing Material for Rehabilitation of Pipe Joints

The main reason for the flexibilisation of this epoxy sealing material is the necessity of the materials ability to compensate relative movements between the pipe segments. Epoxy (EP) modified with ethylene–propylene–diene rubber (EPDM) powder, reactive liquid polymer (ATBN—amine-terminated butadiene–acrylonitrile), and epoxidised modifiers as well as two customised epoxies were analysed. Concerning the dynamic-mechanical analysis, the formulations with reactive liquid polymer (ATBN) or EPDM showed nearly constant mechanical properties in the application temperature range (7–17 ℃). The formulations with epoxidised modifier and the customised proprietary epoxy showed a slope in this temperature range. Generally the glass transition temperature decreased and thus a change of the materials operating temperature range occurred. Thermogravimetric analysis showed that all epoxy modifications absorb water after immersion. Due to the water absorption a plasticisation effect was observed. Further changes in the materials operating temperature ranges have to be considered. A comparison with neat epoxy shows for all formulations a reduction of the mechanical properties like tensile strength and modulus of elasticity. However, no enhancement of strain at break could be achieved by modifying with EPDM powder. The modified epoxy EP/ATBN 2 as well as the customised epoxy C-EP 1 fulfilled the requirement of pressure resistance up to 1 MPa. The measured major strain was negligible. Results of the pressure and inclination test at the fibre concrete test rig show, that the tightness as well as the flexibility (inclination) of the repaired socket can be guaranteed up to a pressure of 1.3 MPa. Finally, a pressure test in a first field application confirmed the suitability of the epoxy based material C-EP 1 for use as a robot processed sealing material.