Deterioration of integrity of concrete structures due to exposure to aggressive environments, poor construction quality, time dependent degradation and extension of operating life far above the intended design life have been reported in many reinforced concrete structures. Although all minimum durability requirements stated by existing design may be met, more and more owners are willing to invest somewhat more in order to obtain an increased and more controlled durability and service life beyond what is possible when only meeting durability requirement based on current standards. Asset Life Extension Management (ALEM) program can be developed for improvement of durability, service life and service life prediction and to plan for appropriate periodic or ad-hoc intervention, maintenance, improvement, repair and rehabilitation of concrete structures during intended operation life.
This paper presents a practical methodology to assess the concrete resistance to environmental and time dependent degradations such as freeze thaw, alkali-aggregate reaction, sulphate attack, carbonation, chlorides, etc., and concrete cover. The paper also discusses the additional measures and mitigation options to address the degradation mechanism and to extend the life of a structure. This resulted in development of life extension options and in combination with the prevention strategy to develop an asset life extension management program. A case study of life extension of a gas processing plant in coastal area is presented assessing remnant life of 370 concrete structures. The outcome of the study and the developed ALEM program demonstrated the practicality of the proposed methodology and to ensure safe and reliable operation of a 46 years old facility for an addition 20 years of service.