Composition and method for obtaining exposed aggregates in surfaces of moulded concrete and other cementitious materials

摘要

Surface retarder coating compositions of the invention are based on the use of at least one non-Ordinary Portland Cement (non-OPC) binder and at least one OPC set retarder agent, which are provided in powder form that can be mixed with water at the construction site. The coating is applied onto the surface of a mould or formwork using roller or spray equipment, and concrete can then be cast within 30-60 minutes against the coating. The OPC set-retarding agent operates to retard setting of the concrete so that it can be de-moulded the next day and its surface can be removed using a high pressure water spray to reveal aggregate embedded beneath the removed surface.