Page 128 - Trenchless Technology Piping Installation and Inspection

94 Cha pte r T h ree

FIGURE 3.1 Excessive tuberculation in water pipes. (Source: 3M Water
Infrastructure.)

Coatings and linings for renewal
of potable water pipes

Cement- Epoxy Polyurea Polyurethane
mortar

FIGURE 3.2 Basic coatings and linings materials for renewal of potable water
pipes. †

further degradation and, if needed, can structurally enhance and
renew severely damaged pipelines.
The primary materials used for coatings and linings fall into four
broad categories of cementitious materials and polymers which include
cement-mortar, epoxy, polyurea and polyurethane (see Fig. 3.2). These
methods are sometimes used in conjunction with one another. For
chemical resistance and monolithic coverage, adhesion is generally
regarded as a required attribute of coatings and linings. For structural
enhancement, adhesion may or may not be a desired property.∗ Other
attributes of coatings and linings vary greatly between polymers and
cementitious. Some coatings and lining materials may be excellent
for bridging cracks and holes, but may have low chemical resistance
owing to inherently higher porosity; others may exhibit excellent
long-term strength, but poor adhesion in damp environments. As for

∗Research is ongoing in this area. For more information, please refer to applicable
ASTM, AWWA, and ASCE standards and practice guidelines (currently under
preparation) as well manufacturers of these products.
†Carbon fiber is another renewal method which is mainly used for large diameter
transmission pressure pipe applications.