Surface issues of profiled cementitious composites

Abstract

The paper provides a topography analysis performed on samples of hardened cement paste, mortar and concrete profiled by grit blasting. Macro-topography (profile) is evaluated by three-dimensional co-ordinate measurements, and microtopography (roughness) is investigated via contact angle measurements. The topography of the generated surface depends on the properties of the matrixaggregate-interface. The lower the bond, the rougher the surface. The microroughness of the aggregate surfaces increases due to grit blasting, but the adhesion properties, in terms of contact angle, do not necessarily improve. The contact angles depend on a balance between frictional force and capillary force and, therefore, are not a simple expression of the surface roughness.

Surface Modification of Cured Cement Pastes by Silane Coupling Agents

“…Momber directly examined the contact angle of cement paste and concrete and found a decrease in the contact angle with gritblasting and sawing, but also acknowledged that more investigations are necessary to determine a relationship between contact angle and the location of measurement. 20 Our study avoids these issues by polishing samples to a uniform surface roughness and avoiding measurements on areas with grooves or areas with irregular surfaces.…”