Synthesis and characterization of release agent from used cooking oil at the concrete/formwork interface

Abstract

For this preliminary study, the lubricating properties of six formulations containing used cooking oils were tested. The physicochemical properties involved were determined by measuring viscosities at temperatures between 0° and 40°C as well as by calculating adhesion energies. The formwork/concrete interface was then studied on the steel surface by means of both tribological measurements and analysis of facing quality at 1 day and 7 days after stripping. The results obtained were compared with a marketed vegetable-based oil. The physicochemical results revealed attractive parameters despite a viscosity that remained high. The liquid/vapor surface tensions and wettabilities measured satisfied the recommendations, i.e. greater than 30 mN/m and less than 30°. The selected formulation offered the best compromise between composition and the physicochemical recommendations. At the formwork/concrete interface and for a scraped application, satisfactory criteria were derived, with a 35% reduction in friction and an acceptable facing quality for this initial study.