Preparation of ultrastable oil-in-water emulsion as a robust superwettable and sustainable concrete release agent

Release agents are compounds that are applied on the surface of moulds to create a thin film that acts as a barrier to prevent adhesion. Water-based release agents are especially preferred during the formulation due to their eco-friendly nature and less toxicity. In this work, we present a facile fabrication of a novel wax-free oil-in-water (O/W) emulsion-based release agent as a sustainable and efficient commercial product for the proficient removal of concrete from mould. The newly formulated O/W release agent was synergistically stabilized by the combination of Sorbitan monostearate (span-60) and Sodium dodecylbenzene sulfonate (SDBS) from 0.6% to 4.0% surfactant concentrations. The surfactant ratio (1:1) was optimized as best based on the hydrophilic-lipophilic balance (HLB). Firstly, physical parameters such as high/shear speed (12000 rpm), oil/water ratio (60:40), temperature (55 °C), and high/shear time (10 min) were optimized. Afterward, the performance and chemical properties of the O/W release agent were investigated by monitoring surface morphology, density, viscosity, contact angle, droplet size, and pH. The new O/W release agent achieved excellent results during on-site trials on iron mould surfaces indicating the promising potential in the construction industry.