Rehabilitation of manhole covers

The rehabilitation of manhole top sections forms part of drain maintenance work. In order to adjust and replace manhole top sections, considerable eff orts are more necessary than ever because, in comparison with former times, especially high demands are placed on the evenness of the road surface whi ch, as a result of the heavy traffic, is subjected to increased strains and stresses. This paper shows the results of a research programme. The target of the project was to evaluate substantial examinations of different rehab ilitation methods of manhole covers. The large number of damages to manhole covers shows that there are weak points in rehabilitation methods. To find these weak points was an additional point of the research programme. The e xaminations demonstrated the principal failures of a lot of rehabilitation methods. On the whole the mistakes were found to be the use of inappropriat e materials and the methods used on site. Recommendations are made for impr ovement of the rehabilitation methods and to heighten the duration of the u se of rehabilitated manhole covers. (C) 2000 Institute for Underground Infr astructure. Published by Elsevier Science Ltd. All rights reserved.