EFFECT OF NANO SILICA ON CONCRETE BOND STRENGTH MODES OF FAILURE

Abstract

Steel bars are required in order to provide the concrete with the tensile strength that is needed in structural concrete. Bond means the interaction between reinforcing steel and the surrounding concrete, which allows transferring of tensile stress from the steel into the concrete and vice versa. The best ways to enhance the concrete bond strength are by improving the ITZ between aggregates and the mortar between aggregates and the steel re-bars. Recently, those ways were achieved by using pozzolanic materials. The presented research aims to study the effect of adding nano silica (up to 4.5%) on the concrete-steel bond modes of failure. The results revealed that by the addition of 3% nano silica as partial replacement of cement (wt.%), the compressive, splitting tensile, splitting bond and pull out bond strengths increased by 43.5, 12, 16 and 38.5% respectively as compared to normal concrete. It was also concluded that Nano silica enhanced the bond strength for both modes of failure, Pullout and splitting, due to the improvement in the mechanical
properties.