Concrete Driveway Curing Time Chart: Achieving Full Strength
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How Long Before You Can Drive on a New Concrete Driveway?
You can drive & park on a new concrete driveway 7 days after the pour. You could walk on it 48 hours after the pour. However, concrete takes 4 weeks to cure to 99% of its full hardness potential.
Check out the concrete driveway curing time chart in this post for understanding how concrete strength develops.
The concrete mix slurry hardens into rock solid concrete by a process called hydration. The hydration process starts as soon as water is added to the cement and aggregate mix.
This is the reason ACI recommends that concrete mix be placed within 90 minutes of adding water. If the placing is delayed then the concrete mix would have set to a point where it is no longer pliable for proper placement.
Concrete Curing: The Hydration Process
The hydration process is in fact a chemical reaction between water and cement. The reaction results in the water-cement paste to form crystalline structures. The aggregates are enmeshed within this crystalline lattice.
Portland cement used in concrete consists of various natural compounds of calcium. These are mostly silicates with a smaller percentage of aluminates and ferrites. In the hydration process water reacts with these compounds to form hydrates.
An example of the reaction is:
Tricalcium silicate + Water —> Calcium silicate hydrate + Calcium hydroxide + heat
2 Ca3SiO5 + 7 H2O —> 3 CaO.2SiO2.4H2O + 3 Ca(OH)2 + 173.6kJ
The process starts as soon as water is added to cement and never really ends. They say that concrete continues to cure for its entire life.
Having said that, practically speaking, concrete is said to have fully cured four weeks after the pour as it achieves 99% of its potential strength. Any further curing is too small to be of any practical significance.
Concrete Strength Build-up Over Time
What Is the Difference Between Concrete Setting and Curing?
The terms “Concrete Setting”, “Concrete Curing” and “Concrete Drying” often get mixed up when people talk about concrete slabs or driveways.
Concrete Setting
The hydration process starts as soon as water is added to the cement & aggregate mix. Setting and Curing times are just two stages of the hydration process.
The setting time of the concrete itself can be thought of as initial setting time and final setting time. The concrete mix is pliable for the first 3 – 4 hours after water addition.
This is the reason ACI recommends placing the concrete within 90 minutes of water being added to the concrete mix
The final setting time is when the concrete mix has completely lost its plasticity. No work should be done on the concrete after the final setting time, as it will disturb or break the bonds which have already started to form between the aggregates.
Concrete Curing
The hydration process continues beyond the final setting time. The concrete hardens progressively. The concrete is said to have fully cured when it achieves a strength of 99% of its full potential strength.
Under normal weather conditions and correct curing process this will take 28 days. At this point approximately a quarter of the initial water in the concrete mix would have been used for hydration and the balance would have evaporated.
The curing time can vary depending on concrete mix ingredients (especially admixtures), water cement ratio, water evaporation rate, etc.
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Concrete Drying
Concrete drying is not related to the setting or curing of the concrete.
We may consider a concrete slab to be dry when it feels dry to touch. However, in engineering terms, concrete dryness is measured by the moisture content.
Concrete could be dry but may not be fully cured. The opposite could also be true. Concrete may be fully cured but may not be dry if the moisture content is high.
We recommend that a concrete driveway should be sealed once it has fully cured (after 28 days). However, before applying the sealer you have to ensure that the concrete driveway is also dry.
Manufacturers of sealers and coatings generally recommend a concrete moisture content of less than 5% for good adhesion.
How Long Before You Can Walk on a New Concrete Driveway?
I suggest that you wait for 48 hours, after a new concrete driveway is poured before walking on it. In 48 hours the concrete slab should have developed a strength level that is around 25 to 30% of its full potential.
You still need to be careful. Do not let pets with sharp claws on it as yet. Do not walk on it with boots, shoes with spikes or pointed heels.
Concrete Driveway Curing Time Chart
The time at which water is added to the cement & aggregate mix is considered as Time Zero. All times are counted from Time Zero.
| TIME | ACTIVITY |
| 90 Minutes | Time period within which concrete must be poured as recommended by ACI |
| 4 – 5 Hours | Initial Setting Time. Concrete loses its workability after that. |
| 16 – 24 Hours | Final Setting Time. Contraction (Control) Joints should be sawed within this period. Cracks will start forming randomly after that in case control joints are not cut. |
| 48 Hours | Light Foot Traffic is OK, but avoid spiked shoes, scuffing or pets on the concrete driveway. |
| 3 Days | Lightweight vehicles such as bicycles, scooters, skateboards, etc. are OK. |
| 7 Days | Light passenger cars or pickup trucks can be parked on the driveway. However, avoid frequent driving on or off the driveway as well as driving on the edges. |
| 14 Days | Parking & driving of passenger cars or pickup trucks on the driveway is OK. |
| 28 Days | The concrete slab is considered as fully cured. Seal it. |
What Factors Affect Concrete Curing Time?
The curing time depends on the following factors:
Concrete Mix Ingredients & Ratios
The quality of the concrete mix ingredients plays a role in the time taken for concrete to achieve its optimal strengths. Use of admixtures or rapid hardening cement can reduce the curing time considerably.
The water cement ratio also plays an important effect on the ultimate strength of the concrete as well as the curing time. A water cement ratio of 0.5 or slightly lower is ideal.
Water Evaporation Rate
Actually only about ¼ th of the water in the concrete mix is used for hydration of the cement. The remaining water evaporates leaving behind capillaries in the concrete. The rate of evaporation is a very important determinant in both the ultimate strength and the curing time.
Low water evaporation rate in the early stages of the curing process helps in shortening the curing time. Water evaporation rates can be controlled using following techniques:
- Ponding & immersion of the concrete surface under water
- Spraying & fogging of the concrete surface
- Covering the concrete surface with wet blankets
- Covering the concrete surface with wet sand or sawdust
- Covering the concrete surface with a vapor barrier to prevent water loss
- Applying membrane-forming curing compounds
High ambient temperature will increase the rate of water evaporation. Arrange for temporary shade over the concrete slab to maintain cooler temperatures.
Use wind barriers or screens to prevent increased water evaporation rate due to high wind speeds.
Bottom Line
The bottom line is that you can walk on freshly poured concrete driveway after 48 hours and park your car on it after 7 days. However, concrete continues to cure and achieves 99% of its full strength only 28 days after the pour.
Check out this Concrete Driveway Curing Time Chart:
Thank you very much for reading this post. I do hope you found it informative and helpful.
