Combination of mechanical and optical profilometry techniques for concrete surface roughness characterisation

Abstract

Achieving durable bond between new and old concrete still represents a challenge in concrete repair technology. It has been the subject of a number of investigations, but in most cases, only adhesion strength was addressed. To better understand bond mechanisms, in particular those related to surface roughness, two complementary surface characterisation techniques were implemented, providing a multiscale roughness characterisation by means of specific filtering calculations: mechanical profilometry for low-scale roughness and optical profilometry for the upscale roughness. Using these complementary approaches, different types of concrete surface preparation were characterised. The resulting description highlights the complexity of concrete surface topography. Moreover, it shows that the type of surface preparation essentially affects the meso-and macro-roughness levels, microroughness being practically insensitive. Such results will be useful for better understanding the interlocking potential and bond performance of concrete repairs.

Near-to-surface properties affecting bond strength in concrete repair

“…Results obtained for laser profilometry and optomorphology are different in values while the same SRI: this is due to the fact that the filtration of the signal was not applied in case of optomorphology. This was already observed in previous research [23]. However, conclusions remain the same: the higher SRI increases, the higher Pa.…”

“…Optomorphology, a technique of relief identification is based on the deformation's measurement of a parallel fringes pattern projected on a surface [24] and allows for a digitalization of the surface, as presented in Garbacz et al [11] showed that the surface geometry of the substrates tested is discriminated by similar parameters, whatever the filtration level is. Authors' investigations [16,23,24] show similar relationship for C40-A when comparing results of SRI and mean arithmetic deviation of total profile (Pa) obtained by optomorphology. Relation between Pa vs. SRI is presented in Figure 4.…”

“…EN 1504 [10] recommends visual observation, the use of a profile meter or sand test for this purpose. An original visual surface quantification is also proposed by ICRI (ACI) [17]: nine reference rough plates are placed near to actual concrete and compared to the surface roughness [19,20]. These Concrete Surface Profile (CSP) chips allow a classification from 1 to 9 but are really limited to surface preparation suited for coatings: maximum proposed roughness is smooth and do not represent more aggressive surface preparation like water jetting or jack hammering.…”

“…Profile can be obtained by means of profilometers (mechanical and laser) or digitalization of the cross-section image [6,16]. A combination of profiles can be also extended onto surfometry, resulting in a 3D image of the real surface [23]. More recently, a new way of surfometry quantification has been developed.…”

Multi-technique investigation of calcium hydroxide crystals at the concrete surface

“…This is why the observations were completed with profilometry of the surface. Mechanical and optical profilometry are sometimes used on concrete to assess its roughness and evaluate its behavior regarding adhesion problems [3][4][5].…”