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When Can You Remove Formwork on Cast-in-Place Retaining Walls?

05 Nov 2021, Posted by F.A. in Concrete Forms Tips
When Can You Remove Formwork on Cast-in-Place Retaining Walls

One common reason people look for the best possible concrete forms for sale is to create cast-in-place retaining walls. A removable concrete form can be used to create concrete retaining walls in almost any shape that is required for a project, though some special situations require an engineer. These simple yet robust structures are best for applications where flexible walls cannot be used and in free-standing applications. Because they are used in critical functions like stormwater detention ponds, it’s important that a cast-in-place retaining wall maintains its structure, meaning that formwork should be removed only when it’s truly safe.

Constructing a Cast in Place Retaining Wall

A cast in place wall will usually arrive at your worksite in a sort and uncured state, often in a cement truck. A chute that sticks out from the back of the truck is aimed at the form that will be used to cure the concrete. Once the location is confirmed, all debris, plants, and soil should be removed from that area to avoid impacting the integrity of the wall.

The builder can then lay out and excavate for the footings before placing formwork in the ground. Before any concrete is poured, steel reinforcement bars are placed throughout the wall.

Cast-in-place walls are often used for basement walls, parking structures, foundations, beams, columns, and of course, retaining walls. The addition of the steel bars helps these walls to stand up to extra pressure, making them ideal for this use.

Removing Formwork

The removal of formwork is one of the most hazardous jobs possible on a construction site. In addition to the danger of a structure that isn’t done curing, the workers at the site can be in danger if the process is not undertaken carefully. There are a variety of tests that can be used on exposed concrete in order to determine if it is properly hardened before removal begins.

Formwork should never be removed until the concrete is sufficiently hardened so that it can safely bear its own weight as well as any live loads it is subjected to in the future. A major factor in the length of time necessary to reach this state is the type of concrete used, so it is always important to follow manufacturer guidelines specific to your materials. Climate can also have an impact, especially if you are working in cold weather. Admixtures, the size and type of form, and the structure itself are all other factors to consider.

The goal of formwork is to remain in place until the concrete reaches the strength of at least twice the stress to which it may be subjected at the time of striking. It is important that the removal process happens without shock or vibrations that could damage reinforced concrete.

As a rule of thumb, walls can generally have their forms removed in a 24 to 48 hour period provided the cement used allows for this. When possible, leaving the formwork in place for longer is always recommended.

Common Mistakes During Formwork Removal

Whether you are building a retaining wall or another structure, there is always a risk of the concrete not curing properly or ending up damaged. In order to prevent structural issues, it is important to be aware of how each step in the process works and ensure you avoid common mistakes. Some things to look out for include:

•Always make sure you order enough concrete to complete a job.
•Choose the right type of concrete and admixtures for your intended application.
•Never pour on an unprepped site.
•Double-check your water to cement ratio for accuracy before mixing.
•Keep finishing tools nearby and always use them on freshly laid concrete before leaving the site.
•Even when it’s inconvenient, never be impatient and remove formwork before the concrete is fully cured.
•An engineer should always be present during the removal process.

Time is often of the essence on construction projects, which can make it appealing to try and rush the curing process. Unfortunately, this can have dangerous and disastrous consequences. Planning a removal timeline early in your project can help you avoid making decisions like this.