Can You Leave Concrete Forms on Too Long?

When it comes to any concrete construction project, understanding the role of concrete forms is crucial.

These forms provide essential support during the curing process, ensuring the finished product is strong and durable.

But do you know when it's time to remove those concrete forms, and what happens if they're left on too long?

Keep reading to find the answers!

What are Concrete Forms and How Do They Work?

Concrete forms are an essential part of any construction project that involves pouring concrete.

These structures provide a temporary framework for freshly poured concrete to set and cure, ensuring it has the desired shape and strength.

Concrete in steel form poured concrete in the building construction area on the mountain

When you pour concrete, it starts as a semi-liquid mixture that needs support during curing.

Concrete forms come in various materials, such as wood, metal, and plastic, and serve as a mold to hold the concrete in place while it sets.

The forms you choose depend on factors like the dimensions, pressure, weight requirements, and your project's specific needs.

Continue reading: Deck Blocks Vs Concrete Footings: What’s The Difference?

Can I Leave Concrete Forms on Too Long?

In general, leaving concrete forms on for an extended period will not cause any significant issues.

However, there are some factors you should consider for the entire curing process.

It's essential to know the appropriate time to remove concrete forms, as this plays a vital role in successfully curing your concrete project.

Pouring concrete onto wooden concrete forms

Typical concrete forms can be removed after 24-48 hours of pouring and finishing the concrete.

However, specific large structures may require forms to be left on for over a week to ensure proper curing and hardening.

The curing method used for your concrete project can also impact when the forms can be removed.

If your concrete mix includes an accelerant, it will cure quicker, but the final product may not be as strong.

On the other hand, if you use water curing or curing compounds, the concrete will need longer to achieve its desired strength and durability.

The process may take about 7 days to reach 80% of its strength.

What Factors Affect the Drying Time of Concrete Forms?

When working with concrete, it's important to understand the various factors affecting its drying time.

Red colored reinforcement bars along with Styrofoam concrete forms

In this section, we'll explore the influence of concrete grade, cement grade and type, and temperature on the drying process.

Concrete Grade

The grade of concrete you're using can impact the drying time.

Higher-strength concrete typically dries slower than lower-strength concrete, as it contains a higher cement content.

When choosing the appropriate concrete grade for your project, consider how long it takes to dry and plan accordingly.

Cement Grade and Type

The type and grade of cement used in the concrete mix can also significantly affect drying time.

Different types of cement have varying hydration rates, which can either speed up or slow down the drying process.

For example, rapid-hardening cement can shorten the drying time, while using a lower-grade cement may result in slower drying.

When selecting cement for your project, consider its grade and type in relation to its drying time and how it may impact your overall timeline.

Temperature

Temperature affects the curing process of concrete forms.

Higher temperatures can accelerate the drying process, while colder temperatures can slow it down.

In cold weather, concrete can take much longer to dry, potentially causing delays in your project's completion.

You might also like: When To Apply Concrete Cure And Seal?

What Happens If I Remove the Concrete Forms Too Early?

Slumping Concrete

If you remove concrete forms too early, the concrete may not have gained enough strength yet.

It can lead to a phenomenon called "slumping," where the concrete loses its shape and can't support itself.

You could have a lumpy, uneven surface requiring additional repairs and resources.

Large Cracks

Another issue that could arise from removing forms prematurely is the development of large cracks.

A huge crack on the wall

The concrete may not be strong enough to support the weight of itself, resulting in these cracks.

Cracks not only look unsightly, but they can also compromise the structural integrity of the concrete surface.

Related content: How To Fix Hairline Cracks In A Concrete Driveway

Collapse

In the worst-case scenario, removing concrete forms too soon could lead to the collapse of the entire structure.

Without adequate support and strength, the concrete may not be able to withstand the forces placed upon it, causing it to break or collapse.

It would waste time, resources, and potentially significant repair costs.

To avoid any of these issues, make sure to follow proper curing guidelines and wait for the appropriate amount of time before removing the forms.

When Should I Remove the Concrete Forms?

As explained earlier, you can remove concrete forms between 24 to 48 hours after the concrete has been poured and finished.

The time frame allows the concrete to harden and develop sufficient strength to support itself.

However, this isn't a one-size-fits-all rule - below, we've outlined the curing time for specific concretes.

Concrete Type Curing Time
Walls and Columns 24-48 hours
Soffits with Props 1 week
Slabs With Props 3-4 days
Props Supporting Slabs (< 15 feet) 1 week
Props Supporting Slabs (>15 feet) 2 weeks
Props Supporting slabs (< 20 feet) 2 weeks
Props Supporting Beams and Arches  (> 20 feet) 3 weeks

How Do I Properly Strip Concrete Forms?

In this section, we've listed essential considerations when stripping concrete forms.

Test the Concrete Strength

Before removing concrete forms, it's important to test the concrete strength first to ensure it has reached sufficient strength to be stripped.

Use a penetrometer or a rebound hammer to assess the concrete's strength accurately.

Keep a check on the recommended strength levels from the concrete manufacturer.

Monitoring the concrete while it cures can help avoid early stripping and maintain proper strength.

Begin at the Top

When stripping concrete forms, always start from the top of the structure.

Following this process ensures that the lower sections are still supported as you work your way down.

Additionally, it prevents accidental damage to the newly formed concrete and allows for easier access to upper formwork components.

Strip the Ground and Sides

The final steps in stripping concrete forms involve removing the ground and side supports.

To do this correctly, first, detach the vertical supports and braces.

Then, carefully remove the side forms, ensuring not to damage the newly formed concrete edges.

Always remember to prioritize safety by wearing proper protective gear and using appropriate tools.

Continue reading: How Close To The Edge Of Concrete Can I Drill?

Tips to Avoid Damage When Removing Forms

Ensure Concrete Strength

To prevent any damage when removing concrete forms, you should first ensure the concrete has reached sufficient strength.

construction worker pouring cement or concrete with pump tube

Make sure to examine the concrete's appearance and texture and curing time before removing the forms.

Do Not Use Too Much Force

When it's time to remove the concrete forms, avoid using excessive force.

Over-aggressive removal techniques can cause cracks or damage to the concrete surface.

Instead, you should gradually and gently release the forms, taking care not to apply too much pressure.

You might consider using specialized tools, such as pry bars or form release agents, to help make the process smoother and less risky.

Refer to an Engineer

If you're uncertain about removing forms or worried about damaging the concrete, consulting with a civil or structural engineer is a good idea.

These professionals can provide valuable advice on the best practices for form removal while ensuring the integrity of your structure.

So, don't hesitate to reach out for guidance, as it could save you from costly mistakes and potential problems down the line.

Putting it All Together

While there isn't a strict rule for how long you can leave your concrete forms on, you should always consider your specific circumstances.

Remember to follow best practices to ensure a successful outcome.

And as always, consult with professionals if in doubt to ensure you make the right choices for your concrete needs.

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