Prestressed Concrete Cylinder Pipes Exposed Internally to Aggressive Water


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Title: Prestressed Concrete Cylinder Pipes Exposed Internally to Aggressive Water

Author(s): A. A. Ibrahim, 0. A. Abuazza and F. A. Tarrani

Publication: Special Publication

Volume: 170


Appears on pages(s): 437-450

Keywords: Adhesion; carbonation; electrical properties; hardness; permeability; polyurethane resins; weathering.

Date: 7/1/1997

Thousands of huge pipes 7.5 m long and 4 m inner diameter are requi red in thi s project for transferring water hundreds of kilometers from the south to the north of Libya. This water from the wellfields is considered to be aggressive to the internal concrete core of the pipeline. Dissolved carbon dioxide is the most aggressive factor in the water. The acid produced by the excess carbon dioxide in the water reacts with constituents of cement paste, causing leaching of the cement binder with a consequential loss in both mechanical strength and section. Such levels of carbon dioxide decrease the design life of the PCC pipes, and many possible solutions have been studied to overcome this problem. Finally it was decided to treat the water at a central water treatment faci 1 i ty and to provide an internal Iining tc the wellfield pipes upstream of the treatment facility. It is necessary for the lining to be durable for 50 years in line with the design life of the project and the prestressed concrete cyl inder pipes. This paper describes the laboratory tests which were performed on both weathered and unweathered samples, supported with compar i sons between the two coating systems which are polyurea and polyurethane. By studying all the test results as presented in Tabl e 1-5 s the conclusion that can be drawn is that f the pol yurea coat i ng sat i sf i es the acceptance criteria for the i nternal lining application for prestressed concrete cylinder pipe (PCCP) to prevent a, i cid attack due to free carbon dioxide.