Installation - Strengthening Design of Reinforced Concrete with FRP - page 220

(a)

(b)

(c)

FIGURE 8.2 Damage caused by corrosion: (a) before repair, (b) after repair prior to
strengthening, and (c) after strengthening. (Courtesy of Fyfe Inc.)

Sandblasting involves the use of a fine-graded silica sand and a high-
pressure air compressor to remove any dirt or other foreign substance
attached to the concrete surface, leaving a clean, etched surface that FRP
bonds to easily, as seen in Figure 8.4.

The corners in rectangular concrete cross sections should be rounded
to a minimum of 0.5 in. (13 mm) radius when fibers are wrapped around
them to avoid any FRP stress concentrations and possible voids between the
concrete and the FRP system, as seen in Figure 8.5. Putty should be used to
smooth roughened corners. Obstructions need to be removed prior to FRP

FIGURE 8.3 Grinding of concrete substrate surface (left) roughened vs. original concrete

surface (right).