Flexural performance of plain concrete beams strengthened with vibrated conventional concrete and non‐vibrated SCC / FR ‐ SCC overlays

Abstract This study investigates the flexural strengthening of plain concrete beams using tensile‐face overlays of vibrated conventional concrete (CC), non‐vibrated self‐compacting concrete (SCC), and non‐vibrated fiber‐reinforced self‐compacting concrete (FR‐SCC). Locally developed SCC and FR‐SCC mixtures were used, with the FR‐SCC containing 0.5% by volume of 6 mm polypropylene fibers. Four‐point bending tests were performed on beams with overlay thicknesses of 25, 35, and 45 mm. All strengthened specimens exceeded their corresponding batch controls. FR‐SCC produced the highest mean ultimate load at every thickness, with batch‐normalized increases of 55.79%, 64.34%, and 85.78%. Two‐way ANOVA showed that overlay thickness significantly affected ultimate load, peak deflection, and energy absorption, while material type significantly affected ultimate load. No premature delamination was visually observed. FR‐SCC also exhibited the lowest sorptivity, approximately 47.73% lower than that of CC. The results indicate that locally developed, vibration‐free FR‐SCC overlays offer a promising strengthening option where conventional compaction is difficult or not feasible.