Journal de génie civil et environnemental

Effect of Formwork Surface Texture Features on Surface Morphology, Roughness Parameters, and the Demolding Force of Cementitious Materials

Abstract

S. Hashim Mohseni, Sifatullah Bahij, Safiullah Omary*, Françoise Feugeas and Fahri Birinci

Concrete is the commonly used building material. It has to be poured into the formwork to take the appropriate shape of a structural element. Therefore, the used formwork affects the surface parameters and final properties of cementitious materials. This paper aims to study the effect of formwork surface texture parameters and release agents on the surface of cementitious materials. Including a reference formwork (F17-Ref), mineral oil (F17-MO), vegetable oil (F17-VO), polyethylene terephthalate coated (PET), and polymeric coated (C20C27) formworks were prepared. For this purpose, pre-crack demolding tests on cement paste samples and pull-off demolding tests on concrete samples were conducted to analyze the adhesion between cement paste/concrete and formwork. The results highlight that the specimens with polymeric-coated plates had the lowest surface roughness values, but all of the coated formworks had almost similar surface energy. In addition, the experimental tests confirmed that samples subjected to PET and F17-VO formworks presented lower adhesive force. As a comparison vegetable oil showed better demolding behavior compared to mineral oil. On the other hand, the visual aspect reveals that the cementitious surfaces subjected to polymeric- coated formworks are shiny and smooth compared to the opaque surface of oil-coated formworks. Finally, based on the outcomes, the PET-coated formwork could be recommended as an alternative solution to release agentss.