ABSTRACT
High performance concretes (HPC) with higher compressive strength are particularly suitable for subsequently generating reinforcing overlays on existing structures. The aim of the herein presented research was to experimentally demonstrate the suitability of such approach and verify an improved bond at the interface between HPC overlay and normal strength concrete (NSC) as substrate. For this purpose, small and large scale tests with different specimen geometries and setups were performed, investigating the interface shear transfer between high strength overlay and normal strength substrate. In general, the small scale tests provided consistent results with rather low scatter for same test-setups and roughness categories. The bond strength values with HPC were significantly higher than observed with normal strength overlay. While the NSC overlays showed, based on visualization of the crack pattern via digital image correlation, some slight signs of delamination in the member tests, the HPC overlays lead to a monolithic behavior of the tested composite slabs.
