WATER MAIN CLEANING AND LINING: A UTILITY AND CONTRACTOR PARTNERSHIP

摘要

The history of cement-mortar lining has followed rather closely the development of ferrous-based metal pipes for the transmission of water. The first cast iron water pipe was neither coated nor lined but was installed in the same condition in which it came from the casting molds. As its use increased, oxidation of the iron became recognized as perhaps the most serious problem in the use of ferrous based metal water pipes. The use of cement-mortar as a protective lining for water mains was reported by the French Academy of Science in 1836. Early experiments had shown that alkaline water in contact with iron inhibits oxidation. The development of Portland cement in 1842, produced a dependable binder for cementing aggregates together. As Portland cement and sand mortar is to some degree porous, it allows water to penetrate through to the pipe wall where it becomes trapped and static. In the process of filtering through the mortar, the water becomes alkaline due to the composition of the Portland cement. This forms the alkaline environment which inhibits the oxidation and tuberculation of iron. Cement-lined and coated sheet-metal pipe was introduced in the United States around 1850. In 1922, in Charleston, South Carolina, an effort was made to apply an in-plant lining in cast iron pipe. In 1936, an American Standards Association specification established the thickness of plant-applied cement-mortar lining.