Since the bond behavior analysis is a requirement for understanding
the stress transfer process between concrete and CFRP, the study
conducted also included a pull-out test for assessing the bond
characteristics of a CFRP strip. Using the same slit size and epoxy
adhesive, the bond behavior was analyzed in order to determine the
effect of the anchorage’s length.
The pull-out test of the laminate strip inserted in a groove in
a concrete fragment specimen was done in order to determine
the anchorage’s length (Fig.6). The specimens were composed of
concrete cubes with dimensions of 150 mm with a continuous slit
of 3x15 mm, where the CFRP strips were placed. The embedded
lengths were 50, 100 and 150 mm.
A concrete cube was situated in a tension testing machine where the
tension force was continuously increased up to failure. Two alternative
failure modes were observed in these experiments, namely, either the
pullout at the interface between the CFRP laminate strip and epoxy
paste or the rupture of the CFRP strip. A displacement transducer
was used to control the test and measure the slip at the free end.