Conventional excavation technology for repairing and replacing worn-out underground buried pipes, such as drainpipes, water supply pipes, gas pipes, communication cables and electric power lines, induces traffic congestion and large amount of waste. To overcome the disadvantages of conventional excavation technology, various trenchless (or excavation free, or no-dig) repair-reinforcement technologies have been developed and tried. But trenchless technologies so far developed have some drawbacks such as high cost and inconvenience of operation.
In this study, a repairing-reinforcing process for underground buried pipes with glass fiber fabric polymer composites using VARTM (Vacuum Assisted Resin Transfer Molding) which overcomes the disadvantages of present trenchless technologies has been developed. The developed process requires shorter operation time and lower cost with smaller and simpler operating equipments than those of the conventional trenchless technologies.
For the reliable operation of the developed method, a simple method to apply pressure and vacuum to the reinforcement was devised and flexible mold technology was tried. Also, resin filling and cure status during RTM process were monitored with a commercial dielectrometry cure monitoring system, LACOMCURE.
The resin flow was analyzed to determine the appropriate process parameters, and the resin wetting and void removal during RTM process for very large and long composite pipes were experimentally investigated. Also efficient void removal methods were suggested and evaluated through the real construction experiments.
From the investigation, it has been found that the developed repairing-reinforcing technology with appropriate process variables and on-line cure monitoring has many advantages over conventional methods.
