Whereas reconstructed stone finishes are typically achieved by acid etching, removing surface laitance to reveal the natural colour of the fine aggregate or sand, our exposed aggregate finishes additionally reveal its coarser aggregate.
This may be done by a variety of techniques with each requiring specialist expertise and experience in order to achieve a consistent appearance, both within and between each individual precast panel.
Grinding the surface of a concrete panel by machine, typically to a depth of 3 mm, produces a smooth terrazzo-like appearance. This may be honed to a dull eggshell polished finish or progressively ground using a sequence of finer abrasive wheels to achieve a high-gloss finish.
Exposed aggregate finishes may otherwise be achieved by removing that cement matrix that surrounds the coarse aggregate at the face of the concrete panel. Depending on the concrete mix, the shape of the panel and the degree of aggregate exposure we use the following techniques: