A client's perspective on the implementation of rehabilitation procedures and durability specifications for structures on national roads in South Africa

摘要

This paper highlights the importance of a client having a rehabilitation procedure for repair of national road structures in South Africa to supplement the output of a successful bridge management system (BMS) adopted by the South African National Roads Agency Limited (SANRAL). The various levels of input incorporating structural inspections, procuring and specifying diagnostic testing, contract documentation that incorporates a set of rehabilitation specifications and finally procuring and implementing repairs is highlighted. Of specific importance are the rehabilitation specifications adopted for structural repair of concrete. The method on how the rehabilitation procedure adopted was incorporated into a series of projects is demonstrated. The different types of repairs undertaken are outlined, as is the importance for the client to be clear in what is required from the consulting engineer including documentation and drawing requirements. The danger of engineers striving for perfection in repairs and the consequent cost thereof is discussed. The problems encountered and lessons learnt from the various levels of the rehabilitation process are also highlighted. The paper also discusses the approach to structural design, detailing and a set of performance based specifications for specifying durability that will help to prevent repairs to structures very early in their design life. A new set of environmental exposure conditions that the structure is located in is defined in terms cf exposure to the harmful effects of the environment on the structure. A new set of testing methods that classifies material selection and characterization and workmanship on site is highlighted. Changes to specifications and testing procedures and results thereof of projects undertaken nationally are also reviewed.