EFFECT OF AGGREGATE SIZE ON BOND STRENGTH OF CAST-IN-PLACE AND POST-INSTALLED REINFORCEMENT BAR

This research investigated the effect of aggregate size on the bond strength of cast-in-place (CI) and post-installed (PI) reinforcement bars on 112 specimens (60 CI and 52 PI) under a pull-out test. The PI reinforcements were inserted to center of the concrete specimen using FIS EM plus 390 S epoxy mortar. Different coarse aggregate sizes (4.75 mm, 12.5 mm, 25 mm and 37.5 mm) were considered to study the influence of aggregate size. Reinforcement bars with diameters of 8 mm, 10 mm, and 12 mm were used. The experimental result showed that the influence of aggregate size on the bond strength of CI specimens with smaller bar diameters (8 mm and 12 mm) is insignificant. In the post-peak range, the residual bond of CI specimens with larger aggregate size is greater than that of CI samples with smaller aggregate size. All PI specimens failed in rebar rupture mode, regardless of the bar diameter, embedment length (even with a smaller embedment length of 5 times the diameter of the bar), aggregate size, and drilling technique. The epoxy mortar used was effective, enabling the utilization of 100% of the reinforcement bar capacity. Splitting failure mode was not observed in PI specimens, which is a good implication for the effectiveness of PI bars. In addition, comparisons between experimental and analytical models from codes and researchers were made, and it was found that the experimental results of the current study for CI specimens are in good agreement with the CEB-FIP 2010 model code predictions.