The roughness of the substrate surface plays an important role in the behaviour of multi-layer reinforced concrete members. Methods like sand-blasting, hydrodemolition and raking are usually adopted to increase it before placing the new concrete layer. Afterwards, a visual inspection is usually conducted to verify if an adequate roughness degree is achieved. However, this type of assessment is highly subjective and therefore it can lead to inaccurate conclusions. Since no standard method exists to verify the roughness of the substrate surface, current concrete design codes implicitly propose a qualitative assessment. To overcome the drawbacks of this current practice, the authors developed a method and measuring device that can be used in situ to more accurately predict the bond strength of concrete-to-concrete interfaces.