Surface roughness and porosity of hydrated cement pastes

Abstract

3D profile and roughness parameters were used to perform an extensive study of the fracture surfaces of hydrated cement pastes. One hundred and eight specimens were prepared with six different water-to-cement ratios. The surfaces of the fractured specimens are the subject of a study analysing the height irregularities and the roughness. The values of the 3D surface profile parameters and the roughness parameters of the fractured specimens were computed from digital replicas of surface reliefs assembled by means of confocal microscopy in three different magnifications: 5×, 20× and 50×. Seventy-eight graphs were plotted to describe and analyze the dependences of the height and roughness irregularities on the water-to-cement ratio and on the porosity of the cement hydrates. The results showed unambiguously that the water-to-cement ratio or equivalently the porosity of the specimens has a decisive influence on the irregularities of the fracture surfaces of this material. The experimental results indicated the possibility that the porosity or the value of the water-to-cement ratio might be inferred from the height irregularities of the fracture surfaces. It was hypothesized that there may be a similarly strong correlation between porosity and surface irregularity, on the one hand, and some other highly porous solids, on the other, and thus the same possibility to infer porosity from the surfaces of their fracture remnants.