The short version Exposed aggregate looks worn for two reasons: a failed sealer that has gone cloudy, white, or flaky, and ground-in grime between the stones. Both are fixable. The work is to strip the old sealer and clean the surface with a method controlled enough to spare the stones, then reseal with the right product for Alberta. High-pressure washing is where most aggregate gets damaged. Controlled dustless blasting is the safer route.
Exposed aggregate is one of the most popular driveway and patio finishes in the Edmonton area, and one of the easiest to ruin with the wrong restoration method. When the surface looks tired, the instinct is to reach for a pressure washer on full power, which is exactly what loosens stones and etches the matrix. This guide explains what is actually going wrong with a faded aggregate surface, and how it is brought back without trading one kind of damage for another.
What is actually wrong: the sealer or the surface
A dull, patchy aggregate surface almost always has one of two problems, and they call for different work. Either the sealer that gives the stones their wet, rich look has failed and gone cloudy, white, or flaky, or the surface itself is carrying ground-in dirt, algae, and tire marks that have built up between the stones. Often it is both, a failing sealer over a dirty surface. Knowing which you are dealing with decides the approach.
The good news is that neither problem means the driveway is finished. The stone and the concrete underneath are usually sound; what has worn out is the finish on top of them, and a finish can be removed and renewed.
Why the sealer turned white or started peeling
Most aggregate is protected with a film-forming sealer that sits on the surface and gives it that glossy, wet appearance. Film sealers fail in a predictable way in our climate. Moisture trapped under the film turns it cloudy or white, a problem called blushing, and the freeze-thaw cycle lifts and flakes it over a few seasons. Sun does the rest, breaking the film down until it looks chalky and uneven.
The mistake that follows is reapplying a fresh sealer straight over the failed one. That traps the old, blushed, flaking layer underneath the new coat and locks the cloudiness in permanently. A surface that has reached this point needs the old sealer stripped off before anything new goes on, not another coat over the problem.
Why high-pressure washing is the usual culprit
Exposed aggregate is nothing more than decorative stones held in a cement matrix, with the top of that matrix washed away when the concrete was placed so the stones stand proud. That is what makes it attractive, and what makes it vulnerable. A pressure washer turned up high enough to strip sealer and grime is also more than enough to pop stones out of the matrix and erode the cement around them. Once stones are gone, they cannot simply be put back, and the surface is permanently pitted.
This is the heart of the problem with restoring aggregate: the surface needs real cleaning power, but it cannot take brute force. The answer is a method whose aggression can be dialled in and matched to the surface rather than a single blunt setting.
Stripping the old sealer the right way
Chemical strippers can remove a film sealer, but on a large driveway they are slow, messy, and leave a residue that has to be rinsed and neutralised, with the runoff to manage. Controlled dustless and abrasive blasting takes a different path. With the pressure dialled down and the right media chosen, it lifts the old sealer and the embedded grime out from between the stones without the gouging of a high-pressure wash, and it does it without flooding the property in chemicals. The aggression is matched to the surface, which is the whole point.
The media matters as much as the pressure, and there is no single correct one for every surface. We choose it for the job, a decision we explain in our guide to the right blasting media for every surface. On aggregate the goal is the gentlest media and pressure that still cleans, and a test spot confirms it before the whole driveway is touched.
The goal on exposed aggregate is to reveal the original colour of the stone, not to cut into the surface. The right method cleans down between the stones and leaves them exactly where they are.
Resealing for an Alberta climate
Once the surface is clean and fully dry, it is resealed, and the choice of sealer matters here more than most homeowners are told. Film-forming sealers give the deepest wet look but are the ones most prone to blushing and peeling through freeze-thaw. Penetrating sealers soak into the concrete and protect from within, with a more natural finish and far less tendency to cloud or flake, which makes them a sound choice for a surface that sits under Alberta snow for months. We will talk through the trade-off so the finish matches what you want and the climate it has to survive.
Timing matters too. Sealer needs a dry surface and a stretch of warm, dry weather to cure, so the work is planned around the forecast rather than forced. A reseal rushed onto a damp slab or ahead of rain is a reseal that blushes.
How we approach an aggregate restoration
We start by assessing the surface and running a test spot to set the gentlest effective media and pressure. The old sealer and ground-in grime are removed with controlled dustless blasting, the surface is rinsed and allowed to dry fully, and then it is resealed with the product suited to your finish and our climate, or handed to you clean and ready if you prefer to seal it yourself. Throughout, the work is contained so the property is left clean.
The same approach restores patios, walkways, pool decks, and steps. Whether the finish is exposed aggregate or a broom-finished slab, the principle holds: clean it with a method matched to the surface, and protect it with a sealer matched to the climate. For driveways that are also spalling or flaking from winter damage rather than just a tired finish, our guide to restoring concrete driveways after Alberta winters covers what blasting can and cannot fix.
When restoration is not enough
Cleaning and resealing renews a sound surface. It does not repair structural damage. If an aggregate driveway has widespread popouts, deep spalling, or sections where the matrix has broken down to the point that stones are loose across whole areas, restoration alone will not bring it back, and the honest answer is repair or replacement of those sections. Part of a proper assessment is telling you which situation you are in rather than selling a clean on a driveway that needs more.
Frequently asked questions
Can you clean exposed aggregate without dislodging the stones?
Yes, with a method whose aggression can be controlled. Dustless and abrasive blasting at a dialled-down pressure with matched media cleans between the stones without the gouging that a high-pressure washer causes. A test spot confirms the setting before the whole surface is done.
Why is my exposed-aggregate sealer white or peeling?
Film-forming sealers go white, called blushing, when moisture is trapped under the film, and they flake as freeze-thaw and UV break them down. The fix is to strip the failed sealer rather than coat over it, then reseal.
Do I have to strip the old sealer before resealing?
Yes, if the old sealer has failed. Applying fresh sealer over a cloudy, flaking layer traps the problem underneath and locks in the cloudiness. The old film has to be removed first.
How often should exposed aggregate be resealed in Alberta?
It varies with exposure and the sealer used, but our freeze-thaw cycle and UV are hard on film sealers in particular. A penetrating sealer generally lasts longer between applications and is less prone to clouding.
Penetrating or film-forming sealer for an Alberta driveway?
Film sealers give the deepest wet look but are most prone to blushing and peeling in freeze-thaw. Penetrating sealers protect from within with a more natural finish and far less clouding, which suits our climate. We will talk through the trade-off for your surface.