Influence Of A Bioadmixture On Adhesion Between Cement And Formwork - Analysis Of The Roughness Of Formwork Surfaces.

The objective of this work is to understand how adhesion between cement and formwork is influenced by the morphology of the formwork's surface and the addition of a bioadmixture. Indeed, mechanical anchoring of the cement paste is related to the roughness of the formwork's surface. A procedure using interferometry is developped in order to characterise the morphology of the surfaces which were in contact during formwork process: formwork and cement. It allows to determine a scale observation to which the surface texture parameters Sa, Sq, Sdr, Vvc et Vvv are representative of the surface shape features. The surface of the formwork is polished in order to get three different types of surface texture which are characterised at the scale observation. The surface parameters are correlated with the demoulding performance. Three ratios of bioadmixture are studied in order to assess if the bioadmixurte can be determinant to minimise the demouling effort while preventing the development of biofilms and guaranteeing the requirements of aesthetic. The results highlight that a specific polishing degree combined with a minimum ratio of bioadmixture in cement paste allow to achieve equivalent performances as with classical demoulding agent.