Development of a laser roughness analyser to predict in situ the bond strength of concrete-to-concrete interfaces

Abstract

The bond strength at the interface between concrete layers cast at different times is important to ensure the monolithic behaviour of reinforced concrete composite elements, for example precast beams with cast-in-place slabs and bridge decks strengthened with a new concrete layer. Previous studies by the current authors stated that the bond strength is highly influenced by the surface roughness of the concrete substrate. Further studies proved that it is possible to quantify the surface roughness and to correlate this with the bond strength of the interface. Nevertheless, the adopted methodology is work intensive and partially destructive. This paper describes a subsequent study using a laser roughness analyser that was specifically developed to characterise the roughness of the concrete substrate. The proposed new method presents four major advantages: (a) increased accuracy; (b) it is simple and fast to execute; (c) it implies a really non-destructive procedure; and (d) results can be assessed in situ.