What Is the Best Time to Seal Concrete Driveway?
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Should You Seal a Concrete Driveway?
You should certainly seal a concrete driveway.
The best time to seal concrete driveway is four weeks after pouring. Sealing should only be done after concrete has fully cured.
The best time to seal concrete driveway that is old is in fall. Sealing will protect the driveway from the winter snow and rain.
What Happens If Concrete Is Not Sealed?
Concrete appears to be rock hard and it is. But concrete is also quite porous with tiny capillaries within it. Concrete readily absorbs water which is highly detrimental to its structural strength..
“The most destructive agent of concrete structures and components is probably water”.
Quote from Wikipedia
Water, essential for concrete curing, becomes its mortal enemy after curing. Water ingress into concrete hurts it in more ways than one.
Acidic Chemical Corrosion
Rain and groundwater is almost never free of chemicals. The composition and concentrations depend on where you live. Coastal areas will have higher chlorides, whereas industrial areas may have higher sulfates.
But they are all acidic and acid corrodes both the aggregates and the steel reinforcement. The concrete loses its strength over time.
Alkali Silica Reaction (ASR)
In addition to acidic chemicals, rain and groundwater also contains several alkaline chemicals, such sodium and potassium oxides. In the presence of water they form alkalis such as sodium hydroxide and potassium hydroxide.
Once alkaline solutions permeate into the concrete they react with silica in the aggregates to form a hygroscopic gel. The gel expands, stressing the aggregates and even cracking them.
Freeze Thaw Cycle
Freeze thaw cycle is a serious threat to concrete strength in cold climates. Water within the concrete pores freezes when temperatures fall and thaws when temperatures rise.
Ice has more volume than water and hence exerts an outward pressure on the concrete structure. The freeze thaw cycle creates a cyclical stress on concrete. Even relatively low levels of cyclical stress can ultimately lead to failure over a period of time.
The only effective way of protecting a concrete driveway from water ingress is to seal it. As sealants deplete over time, you also need to reseal a concrete driveway when required.
When Should You Seal a New Concrete Driveway?
The best time to seal a concrete driveway, after it has been poured, is when it has fully cured. Full curing of concrete usually takes 28 days under normal curing conditions.
Do not try to apply a sealer before the concrete has fully cured. The sealer will interfere in the curing process. Waiting too long, after the concrete has fully cured, leave the concrete vulnerable to water penetration and deterioration.
Concrete cures by a process called hydration. In hydration, water in the concrete mix reacts with the cement to form a crystalline web like structure. This mesh encapsulates the aggregates and gives concrete its impressive strength.
The curing process begins as soon as water is added to the cement & aggregate mix and actually continues forever. Having said that, concrete is considered fully cured when it attains 99% of its compressive strength potential. This takes 28 days under normal curing conditions.
The excess water from the hydration process evaporates, leaving behind pores (aka capillaries). It is these pores you need to seal. You do not want water to get into these pores once the concrete has fully cured.
When Should You Seal an Old Concrete Driveway?
The effectiveness of concrete sealer depletes over time. You should reseal an existing concrete driveway whenever the existing sealer has become ineffective.
There is a very simple test to find out whether the existing sealer is still effective or not. Wipe the sealed concrete surface with a damp rag to remove dust. Place a few drops of water on the surface.
If the water beads up the way it would on a sheet of glass or a lotus leaf, then the sealer is still effective. Do not reseal the concrete driveway.
If the water does not bead up and flattens out or gets absorbed by the concrete, then the existing sealer is no longer effective. It is time to reseal the concrete driveway.
A concrete driveway is subjected to a fair amount of abrasion from vehicular traffic. Abrasion gradually removes the sealer coat. Pressure washing can also deplete the sealer coat.
The best time to reseal an old concrete driveway is
- Immediately after pressure washing
- In fall. Your concrete driveway will be well protected against snow and rain during winter months.
RECOMMENDED PRODUCTS
The Best Sealers for Your Concrete Driveway or Patio
A topical sealer is essential for protecting concrete surfaces from water permeation that can damage the concrete from within and compromise its lifespan.
I highly recommend Foundation Armor Concrete Sealers. Pick the one that best meets your aesthetic and application preference.
At What Temperature Should You Seal a Concrete Driveway?
You should apply the sealer on your concrete driveway only when the temperature is within the range specified on the packaging or the data sheet. For most brands the range is between 50° F and 90° F.
NOTE: Both the concrete temperature and the ambient temperature should be within the range.
Topical concrete sealers form a film when they dry. An important characteristic of a sealer (or paint or coating) is the minimum film formation temperature (MFFT).
It is the temperature below which the sealer will not form a film with strong bonds. The film may have a hazy or powdery appearance. Such sealer films get abraded in no time, exposing the concrete surface to water impregnation.
It is the best to apply sealer coats on concrete driveways in fall as the ambient temperature is pretty much within the recommended range.
The best time of the day to apply sealer on concrete driveway, during fall, is in the morning.
Avoid sealer application in the afternoon. In summer the concrete may be too hot. In winter the ambient temperature may drop later in the evening to maybe even below dew point.
Thank you very much for reading this post. I do hope you found it informative and helpful.
