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TECHNICAL PAPER

(a) Initial cracking along the longitudinal rebar

(c) Overhang edge prior to removal of loose concrete

(d) Overhang edge after removal of loose concrete (b) Diagonal crack on edge going below concrete cover
Figure 7: Details of damage to overhang region

116 kN, which corresponds to a 38% greater load. A comparison along both the edges of the slab initiating from the top surface
of the deflection profiles along the center of the specimens at of the deck at this load level. At a load level of 196 kN per
these loading levels, as shown in Figures 9(a) and (b), shows the hydraulic jack, the ultimate tensile strength of the top concrete
clearly evident stiffening and strengthening effect of the NSM cover layer was exceeded and the bond between the FRP and
FRP strips. the concrete was lost. This damage was quickly followed by the

At a level of 184 kN per jack, hair-line cracking was observed on opening and propagation of a large diagonal crack along the
the top of the overhang surface following the top longitudinal strut formed, as shown in Figure 8(a), indicating attainment of
steel reinforcement bars. Minor diagonal cracks were noted ultimate capacity of the overhang for resisting vertical loads.

Figure 8: Damage at ultimate capacity showing concrete cracking and local debonding of the NSM FRP adhesive from the concrete in the right figure

THE INDIAN CONCRETE JOURNAL | JUNE 2021 15