Reading the surface
Why is my asphalt turning gray?
Asphalt turns gray because sun and oxygen have burned the binder out of the top of the surface, leaving the stone in it exposed.
The numbers
- Gray is the color of the stone. Black is the color of the binder holding it together.
- Gray on its own is not a failure. It is the warning ahead of one.
- The next stage is loose stones coming up under a broom or a tire.
- A sealed surface grays much more slowly, because the coat takes the sun instead.
What the color is telling you
Asphalt is crushed stone glued together with a binder. New, the binder coats every stone and the surface reads black. Sunlight and oxygen break that binder down from the top, and as it goes, more and more bare stone shows through. That is the gray.
It is a surface condition at that stage, not a structural one. The asphalt underneath is still doing its job. What has gone is the protection on top of it.
What comes after gray
Once enough binder is gone the stones at the surface have nothing holding them, and they start letting go. You sweep and get a pile of grit. You walk the drive and hear it under your shoes. The surface goes from smooth to open, which means water now has a thousand small ways in instead of one.
From there it is the ordinary sequence: water in the surface, water in the base, cracks, and areas that flex.
Whether it is too late to seal
Gray by itself is the right time to seal, and it is the point most people wait past. A surface that is gray but solid underfoot takes a coat well, because the open texture gives the sealer something to grip.
The test is not the color. Stand on the worst area and shift your weight. If it holds firm, seal it. If it gives, the base has gone and that area needs repair before anything goes over the top of it.