The potential of concrete: textures (140)
Here is a really interesting concrete solution.
As HEARING indicates on their own website "they used triangular fillets as profiled shuttering and were thus able to cause the grain to protrude evenly from the surface after surface treatment, washing in this case, thus providing the desired structure."
Applying colour only to a superficial layer of concrete stone aggregate allows the opening to be highlighted with this separate, nearly white enclosing element.
But attention must be paid to the extremely precise moulding process, that permits precast concrete panel openings to be fitted perfectly in the exact position where the windows are placed in the concrete wall!!