Bond of nanoinclusions reinforced concrete with old concrete: strength, reinforcing mechanisms and prediction model

Abstract

This paper investigated the bond strength of eight nanoinclusions reinforced concrete with old concrete through a splitting tensile test. The reinforcing mechanisms of bond due to nanoinclusion was also explored by means of scanning electron microscope and energy dispersive spectrometer. A prediction model for the bond strength between nanoinclusion reinforced concrete with old concrete substrate was developed and calibrated against the experimental results obtained. The experimental results indicated that bond strength between nanoinclusions reinforced concrete and old concrete can reach 2.85 MPa, which is 0.8 MPa/39.0% higher than that between new concrete without nanoinclusions and old concrete. The reinforcing mechanisms can be attributed to the enrichment of nanoinclusions in the new-to-old concrete interface, compacting the interfacial microstructures and connecting hydration products in micropores of old concrete with that in bulk new concrete. In addition, the prediction model proposed on the basis of reinforcing mechanisms can accurately describe the relationship of the nanoinclusion content and the bond strength of nanoinclusions reinforced concrete with old concrete.