EVALUATION AND REHABILITATION OF A REINFORCED CONCRETE WATER DUCT AFTER 90 YEARS IN SERVICE

摘要

This paper presents the evaluation results of a square duct of six square meter section exposed to an aggressive environment. Contact soil water contains chlorides and industrial sewage has flown through the duct. According to present criteria, this is a case of severe aggressive conditions. The assessment of the structure includes: the observation of macroscopic defects, concrete compressive strength, chemical analysis, chloride profile, depth of carbonation and evaluation of steel reinforcement (corrosion potentials, direct observations, metallography and chemical analyses). Reinforced concrete structures are known to be a living system, their structure and physical characteristics changing with time. The constituent materials, mix proportioning, method of preparation and subsequent treatment determine the properties of concrete at the inception of a structure. The continuous change in the microstructure of concrete due to its response to the service environment may increase or decrease structural performance. Hence, the structure-environment system needs careful consideration rather than simplistic approaches currently used. The results indicate that the structure is safe and still has a significant service life.