Experimental investigation of RC footings resting on sand strengthened with concrete jacketing

Abstract

An experimental study regarding structural strengthening of existing reinforced concrete footing was conducted on six full scale reinforced concrete footings, strengthened with concrete jacketing under concentric and eccentric loads. The footings had constant dimensions and flexural steel reinforcement which was designed to prevent brittle failure due to crushing of concrete before steel yielding. Concrete jacketing was installed on all sides and top of existing concrete for footings subjected to concentric loading, while concrete jacketing was installed on three sides and top of existing concrete for footings under eccentric loading. The bonding between the existing and the new concrete was done either by applying epoxy bonding with dowels or by using an epoxy bonding agent on all sides only. This was to investigate the effect of each strengthening technique on the stress distribution beneath reinforced concrete footings rested on cohesionless soil. The dowels were used and designed to prevent any premature shear failure. The experimental results showed that the stress distribution beneath the center of footings subjected to concentric loading was higher than that beneath the control specimen by approximately 10%. The results also showed that the contact stress distribution beneath control and strengthened footings were not consistent with the available theoretical solutions. The effect of using dowels, in connecting old and new concrete, on stress distribution under strengthened footings and load-carrying are presented.