This is an old, backyard concrete patio darkened significantly over time by organic debris from a large, overhead tree canopy. The light-colored area in the middle of the patio is where a large rectangular glass table sat for an extended period of time.
Pressure washing alone is not sufficient to clean outdoor concrete that has been exposed to weathering for such a long period of time. So, first, we shot-blasted the patio concrete (above left), and then ground it smooth (above right), so that we could resurface it with a thin cement overlay.
There were numerous, large settlement cracks throughout the slab (above left and right). We filled and repaired these cracks with a semi-rigid epoxy, and then ground them flush with the existing surface, so that the cracks would not reflect through to the surface of the new cement overlay.
With the surface prep now done, we troweled down a thin, charcoal gray base coat of cement, and then saw-cut the resurfaced concrete patio to add a decorative border and divide the existing, large rectangular concrete slab segments into smaller, equally-sized square tiles (photos above and below).
We then sprayed two "texture coats" of the charcoal gray, integrally-colored cement (below left and right) to provide a uniform color to the surface, and give the final patio a "sandpaper finish" that would ensure adequate slip resistance.
Lastly, we sealed the patio (below left and right) with three coats of a high durability, clear polyurea sealer that would darken the final charcoal gray color, protect the concrete and not have to be re-sealed every couple years.