Concrete is a composite material comprising a cement matrix mixed with water and aggregates like gravel and sand. Strengthening it involves adding metallic reinforcements such as bars to the mixture. The bond between these reinforcements and the concrete is crucial for its static and dynamic performance. One method to enhance this bond is by changing the concrete mixture, though this can alter the mechanical properties noticeably. An alternative approach involves modifying the surface topography of the metallic reinforcements to create mechanical interlocking between the asperities artificially formed on the metal surface and the cement matrix. Various techniques have been explored to create effective interlocking surfaces, including sandblasting [1] and, more recently, laser surface nanostructuring [2]. Both methods were applied to increase the surface roughness of reinforcing metallic bars, resulting in an enhancement of their adhesion with concrete. However, a comprehensive investigation into the correlation between surface texture topography and the strength of the bonding with hardened concrete has not been conducted.

In this study, ultrafast laser technology was employed to texture steel surfaces through Direct Laser Writing (DLW) and with Laser-Induced Periodic Surface Structures (LIPSS), aiming to enhance adhesion between stainless-steel flat samples and a standard cement mixture (see figure 1). Customized pull-out tests were conducted to measure the adhesion strength in comparison with untreated and sandblasted surfaces. Results demonstrated that laser surface texturing significantly boosts adhesion between steel and concrete, surpassing sandblasting due to mechanical interlocking and improved wettability of the treated surfaces.

References

[1] J. Hou, X. Fu, and D. D. L. Chung, Cement and Concrete Research, 1997, 27 (5), 679–684.

[2] N. V. Makarova, and S. V. Makarov, Journal of Physics: Conference Series, 2018, 012082.