Experimental study of the effectiveness of retrofitting RC cylindrical columns using self-compacting concrete jackets

• Effectiveness of retrofitting rc cylindrical columns using SCC jackets.
• Comparison of experimental and analytical results to evaluate retrofit technique.
• The ultimate strain of the confined concrete increases.
• Strong jacket on weak core system surges the post peak ductility due to confinement.
• Weak jacket on weak core decreases the strength gain factor and ductility factor.

External confinement using jackets can suitably increase the strength and ductility of the reinforced concrete cylindrical columns. This paper encompasses an experimental investigation for studying the effectiveness and suitability of self compacting concrete (SCC) mixes as a retrofitting material and its use as jacket for cylindrical columns. The experimental programme included development of SCC mix and its use in retrofitting of cylindrical column specimens which were either intact or distressed earlier to certain level. The experimental programme consisted of testing 6 control specimens, and 36 primary specimens initially distressed to 80–85% of theoretical stress level, repairing, and retrofitting prior to testing. The control specimens were of diameter 160 mm and height 600 mm, cast in M20 conventionally vibrated concrete, reinforced longitudinally with six bars of 12 mm diameter and five lateral ties of 8 mm diameter as transverse reinforcement. Two different SCC mixes, were used for jacketing around the columns. The jacket was reinforced with mild steel welded wire mesh (WWM) 25 mm × 25 mm made of 3 mm diameter wire. The retrofitted specimens were tested after 28 days, 56 days and 90 days of curing. The test results revealed the effective use of SCC as retrofitting material. The SCC jacket with WWM as reinforcement increases the ultimate load carrying capacity of column specimen. The ductility factor is also calculated after the retrofitting with SCC mixes.