PSI - Issue 64

Eric Williams et al. / Procedia Structural Integrity 64 (2024) 1573–1580 Williams, Annooz, and Myers / Structural Integrity Procedia 00 (2024) 000 – 000

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Figure 3. Average bar bond strength for (a) 13 mm rebar and (b) 19 mm rebar.

3. Discussion 3.1 Pull-out result discussion

For the 19 mm bars, MKPC-coated rebar performed on par with steel rebar and epoxy-coated steel rebar. This was not the case for the 13 mm bars. This is thought to be largely due to the larger thickness of the MKPC coating. The thickness of the coating between the lugs is 154% thicker than on the lugs for the 13 mm rebar, while it is only 38% thicker on the 19 mm rebar. As mentioned previously, this is due to the surface tension of the fluid MKPC not settling as much due to the nominally smaller spacing between lugs on the 13 mm rebar. This difference in thickness means the rebar begins to lose the mechanical advantage of the lugs, reducing the bond performance. This loss of mechanical advantage is clear when comparing the MKPC coatings of 13 mm bars to 19 mm bars in Figure 4.

Figure 4. MKPC coating on (a) 13 mm rebar and (b) 19 mm rebar.

Notice the definition of the 19 mm rebar’s lugs compared to the definition of the 13 mm rebar’s lugs in Figure 4. The difference in performance may also be due to the difference in lug pattern between the two sizes, as each size came from different manufacturers. On going studies are currently examining both the mil thickness of the MKPC coating and lug pattern on the mild steel bars to gain an improved understanding of the role both of these play on the