When to remove shuttering from concrete shed base

  • How Long Should Concrete Cure Before Removing Forms
  • What Is Formwork?
  • What Is Removal of Formwork
  • Factors Affecting Concrete Formwork Striking Times
    • Grade of concrete:
    • Grade of cement:
    • Temperature:
    • Size of the concrete member:
  • When to Remove Concrete Form
    • Time of Removing Formwork as per ASTM
  • Formwork Removal Time Period | Deshuttering Time
  • How to Properly Remove Formwork
  • FAQs:
    • What is the Curing of Concrete?
    • What Is Formwork?
    • How many days is the curing of concrete?
    • When to Remove Forms From Concrete Slab?
    • When to Remove Forms from Quikrete?
    • What do you mean by Deshuttering Time?
    • When strip concrete forms?
    • How long before removing concrete forms?

Concrete is one of the important building materials used in construction. For making good concrete that lasts a long decade, it has to be properly produced, placed, and most importantly cured after casting.

So, In this article, we will cover When to Remove Concrete Forms or How Long Should Concrete Cure Before Removing Forms from them.

What Is Formwork?

Formwork is a type of casting mold or box, like a container into which fresh concrete is poured and compacted. When the concrete is hardened, the formwork is removed and a solid mass is produced in the shape of the inner face of the formwork.

Removal of Formwork

How Long Should Concrete Cure Before Removing Forms

What Is Removal of Formwork

The removal of formwork is also called a strikeoff of forms in which concrete is poured. The formwork should be removed only after when concrete component achieves its sufficient strength.

Care should be taken during the removal of formwork to ensure the stability of the remaining formwork.

Read More: Building Construction Step By Step Process

Factors Affecting Concrete Formwork Striking Times

The time of removal of formwork depends on how quickly concrete members gain sufficient strength and it depends on the following factors.

Grade of concrete:

As the rich grade of concrete, the rate of development of strength is higher, and thus concrete gains strength in a shorter time.

Grade of cement:

A Higher grade of cement offers a quick setting and it gains strength in a shorter time. Type of Cement – The cement type used in concrete also affects the strength development of concrete.

For example, Compare to ordinary Portland cement rapid hardening cement has higher strength gain in shorter. Low heat cement requires more time for setting compared to OPC.

Temperature:

A high temperature of concrete and surrounding at the time of placing concrete makes it achieve higher strength in shorter times. During winter, the strength-gaining process becomes slower.

Size of the concrete member:

The size of the concrete member also matters in the strength-gaining process. Largesized concrete section members gain strength in a shorter time than smaller sections.

Read More: Methods Of Damp Proofing House Construction

When to Remove Concrete Form

Time of Removing Formwork as per ASTM

Sr.
No
Type of Cement Time of De-shuttering
1 Type I cement 7 days
2 Type II cement 10 days
3 Type III cement 3 days
4 Type IV or V cement 14 days
5 ASTM  C 1157 C 595, C 845 cements Varies  

Generally, the American Concrete Institute recommends the following

Sr.
No.
Type of Formwork Minimum Period Before Striking Formwork
1 Walls and columns vertical Supports 24-48 hours
2 Slabs, with their props left under them 3-4 days
3 Soffits, with their props left under them 7 days
4 Props supporting slabs under 15 feet 7 days
5 Props supporting slabs under 15 feet 14 days
6 Props  supporting arches& beams over 20 feet 21 days

Formwork Removal Time Period | Deshuttering Time

Sr. No. Type of Formwork Minimum Period Before Striking Formwork
1 Vertical formwork to columns, walls, beams 16-24 h
2 Soffit formwork to slabs (Props must be re-fix immediately after removal of formwork) 3 days
3 Soffit formwork to beams (Props must be re-fix immediately after removal of formwork) 7 days
4 Props to slabs: 1) Spanning up to 4.5 m 2) Spanning over 4.5 m 7 days & 4 days
5 Props to beams and arches: 1) Spanning up to 6 m 2) Spanning over 6 m 14 days &21days

Read More: ACC Block – Manufacturing And Comparison With Red Clay Brick

How to Properly Remove Formwork

  • Formwork removal is one of the most hazardous jobs on the site. If not properly done it not only affects the structure but also can result in high risk for the laborers working at the site.
  • Therefore following important points should be kept in mind while removing the formwork.
  • Conduct proper tests (mostly NDT) on concrete to ensure its strength is developed.
  • Removal of formwork should be started from vertical members are removed first.
  • The supports of the slab or soffits should not remove until it is ensured to bear their self-weight and external stresses effectively.
  • The crowbars should not fix on the side to remove the formworks as it can damage the edges of the concrete.
  • Loose concrete or any other material found in the edges and corners is to be removed.
  • The safety engineers should inspect the site before the removal of formworks to ensure suitable conditions.
  • For workman safety, inspect the formwork position so that sufficient bracings and work platforms are provided to remove the formwork at higher elevations.
  • The team removing formwork should know about risk and rule regulation of safety on the construction site.

FAQs:

What is the Curing of Concrete?

The method of shielding concrete against the steady loss of moisture in order to retain it for carrying out hydration is maintained within the required temperature range, this process is called Curing of Concrete. It is a practice to keep concrete moist until the end of hydration.

What Is Formwork?

Formwork is a type of casting mold or box, like a container into which fresh concrete is poured and compacted. It is kept for several days until concrete acquires its strength and stability.

How many days is the curing of concrete?

Min. 7 days are required for curing concrete at a temperature above 5oC. However, a greater time might be required for curing for some concerts with Higher Strength. 70% of compressive or flexural strength must be acquired by concrete in its curing span.

When to Remove Forms From Concrete Slab?

Slabs, with their props left under them, can typically be removed after 3-4 days. Props supporting slabs under 15 feet can be removed after 1 week.

When to Remove Forms from Quikrete?

Formwork of cover can be removed after its achieved sufficient strength of taking load or it is usually safe to remove after 24 hrs of curing.

What do you mean by Deshuttering Time?

Deshuttering is also called a strike-off of forms in which concrete is poured. The formwork should be removed only after when concrete component achieves its sufficient strength. This process is called de shuttering Time. Care should be taken during the removal of formwork to ensure the stability of the remaining formwork.

When strip concrete forms?

1. For Concrete Forms, Concrete walls and concrete columns can be removed after about 24 to 48 hours.
2. Slabs, with their support left under them, can be normally removed after 3 to 4 days.
3. The Soffits, with their remaining supports under them, can be removed after 1 week.

How long before removing concrete forms?

Walls and columns can be removed after about 24-48 hours. Slabs, with their props left under them, can typically be removed after 3-4 days. Soffits, with their props left under them, can be removed after one week. Props supporting slabs under 15 feet can be removed after one week.

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How long do you leave concrete before removing shuttering?

The forms or “molding” that holds the concrete in place until it dries should be left alone for at least two days to ensure that the concrete is completely dry. If the forms are removed too soon, the concrete can begin to sag, crack and collapse, especially if conditions like temperature affected its strength.

When can I remove frame from concrete slab?

Walls and columns can be removed after about 24-48 hours Slabs, with their props left under them, can typically be removed after 3-4 days.

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