STUDY ON DEFLECTION CONTROL OF COMPOSITE SLABS STRENGTHENED WITH BONDED STEEL PLATES

Abstract

This paper demonstrates how long-term deflection of reinforced concrete slabs can be controlled by creating composite slabs. Three similar reinforced concrete slabs, 1,000 mm wide x 150 mm thick, reinforced with five high-strength (fy – 450 MPa) 12 mm diameter bars, spanning 4,500 mm, were constructed for this research study. The compressive strength of the concrete (fcu) was 25 MPa, with an elastic modulus of 33.6 GPa. One control slab, without bonded plates, formed the baseline for the deflection and was compared with the performance of two composite slabs strengthened with steel plates, one with a 110 mm x 6 mm plate (Comp1) and the other with 2 x two 110 mm x 6 mm plates (Comp 2). The bonding surfaces were prepared by scabbling the concrete to expose the well-bonded large aggregate, and the steel plates were dry grit blasted to a white metal finish to obtain a 100-140 µm blast profile. The steel plates were bonded to the concrete surfaces by means of Pro-Struct 618LV primer and Pro-Struct 617NS epoxy. All the slabs were loaded with a UDL of 1.0 kN/m. The experimental deflection results showed deflections of 20.18mm for the control slab, 16.67 mm for SP1and 16.31mm for SP2. The percentage difference between the theoretically calculated and experimentally measured deflections was 20.54% for the control slab, and-34.85% and-37.58% for SP1 and SP2, respectively.