Behaviors of Repaired Edge Column Slab Connections after Punching Failure Using Normal and Non-Shrinkable (CAH) Concrete

Column slab connections in flat plate structures are critical part of the structure. Punching shear damage to the connections may occur during construction or post moderate earthquakes. To avoid demolishing overall structures with such damage, connections may be repaired to restore the original strength of the structures. This paper presents behavior of repaired edge column slab connections using normal concrete and non-shrinkable (CAH) concrete. Four edge connections of flat plate structure after failure were repaired using normal and non-shrinkable (CAH) concrete respectively for two connections. The connections were re-tested to fail under combined shear and moment. The results show that bonding agent Sika Top Armatec 110 Epocem gave an excellent bond between the old concrete and the repaired concrete in the tests of repaired edge column slab connection as there are no cracks observed along the concrete interface. The edge connections repaired using normal concrete can have similar strength and stiffness as the original connections when good curing is provided The edge connections repaired using an expansive CAH concrete exhibited less strength and stiffness compared to the original edge connections due to lack of surface confinement. The Superplasticizer used in CAH concrete (Mix. B) improves concrete expansion but reduce the strength of the repaired connections Keywords: Repaired connections, punching failure, flat plate, non-shrinkable concrete, reinforced concrete