Influence of the formwork removal by polarization on the facing aesthetics in reinforced concrete

Abstract

Formwork removal by means of polarization offers an alternative solution to compensate for some of the disadvantages and risks of using mineral-based oil due to its petrochemical origin. This technique consists of applying an electrical current between the steel reinforcing bars and the metal formwork wall in order to obtain a thin water film at the concrete/formwork interface and allow for formwork removal. This paper focuses on the facing quality of the reinforced concrete and formwork surface at various temperatures for both conventional and self-compacting concretes. A series of experimental tests have been conducted in the laboratory to determine the optimal polarization parameters (voltage value, time and duration of its application). On-site tests were then performed to observe the scaling effect. Results indicate that the proposed polarization technique can indeed provide an effective means to separate the concrete from its formwork without requiring demoulding oil. Concrete mixtures implemented both in the laboratory and on-site display high-quality facing without the presence of any attachment points. A chromatographic analysis of the concrete pore solution and water transported by electro-osmosis shows that ion concentrations remain unaffected. This polarization approach can thus be used as an alternative to avoid the use of oils of a chemical or petrochemical origin.