Experimental investigation on the bond strength between Ultra high strength Fiber Reinforced Cementitious Mortar & conventional concrete

•Bond properties between UHSFRCM and conventional concrete were investigated.•The bond strength is highly dependent on the substrate surface preparation method.•Sandblasting indicated the best performance as a surface preparation method.•An appropriate bond strength can be reached in the early days.•Efforts were made to pave the way for analyzing the composite structures. Nowadays, there is an increasing desire to use Ultra High Strength Fiber Reinforced Cementitious Mortar (UHSFRCM) in the rehabilitation of existing concrete structures. Although excellent mechanical improvements are reported in literature, the performance of the bond to provide a monolithic composite structure is still open to question. In this study, the bond has been investigated using three pull off, slant shear, and direct shear tests. The substrate surface of corresponding specimens had been prepared by sandblasting, grooving, wire brushing, and as-cast methods. Sandblasting indicates the best results, satisfying specified limits presented by ACI.