Shear capacity of 50 years old reinforced concrete bridge deck without shear reinforcement

A relatively low direct tensile strength is observed in cores drilled from old bridges in the Netherlands. To check whether this will influence the shear capacity of the bridges, beams sawn from a bridge deck built in 1961 were tested under shear loading in the Stevin laboratory at TU Delft. The flexural capacity of the beams was increased by means of carbon laminates glued to the bottom side. New beams with the same concrete compressive strength and reinforcement arrangement were casted and tested as reference. Six tests on old concrete beams and six tests on new concrete beams with a shear slenderness ratio between 2.2 to 4.1, and a cube compressive strength of about 80 MPa have been performed. In these tests no difference was found between the shear capacity of old and new beams with the same compressive strength, although the lower direct tensile strength of the old concrete compared to the new concrete