Types of Concrete Forms
Concrete forms can be divided into two main categories: permanent and temporary forms. Permanent forms are usually made from metal, timber, or plastic and are used for large projects that require a long life. Temporary forms are typically made from plywood and are designed for short-term use. Both types of forms have different characteristics that should be taken into consideration when selecting a form for a particular project.
Selection Criteria for Concrete Forms
When selecting a form for a concrete project, several factors must be taken into consideration. These factors include the size, shape, and weight of the form; the type of concrete being used; the environmental conditions; the cost; and the desired finish. The form should also be designed to provide stability and minimize leakage. In addition, it should be easy to install and remove, and it should be compatible with the concrete mix being used.
Following are different types of concrete forms.
- Wooden Forms
- Insulated Concrete Forms
- Foam Concrete Forms
- Concrete Wall forms
- Steel Forms
1. Wooden Forms
Wooden forms are the most traditional type of concrete form and are mainly used when the concrete casting does not exceed 6 inches in height. These forms are constructed using wooden boards that are either nailed or screwed together to form the desired shape. Special leveling devices are used to ensure that the form is properly leveled or sloped as needed. For curved or free-form designs, thinner cross-sections are employed to achieve the desired form. Before pouring the concrete, the inner surfaces are treated with a low-grade oil or form release agent to ensure that the concrete doesn’t stick to the surfaces. With proper maintenance, these forms can be used multiple times.
2. Insulated Concrete Forms
Insulated Concrete Forms: Overview: Insulated concrete forms (ICFs) are hollow blocks made of an insulating material that are fitted together like building blocks, forming part of the foundation and wall systems. Reinforcement is placed within the blocks and filled with concrete of the necessary slump and cast. This system acts as a sandwich, providing high energy efficiency and eliminating the need for removal of the forms once the concrete is filled.
Benefits of Insulated Concrete Forms: Insulated concrete forms offer multiple benefits to builders, including improved energy efficiency due to the sandwich-like construction and the elimination of the need for removal of the forms once the concrete is filled. Additionally, ICFs are more durable than traditional masonry building materials, and provide increased protection against fire, wind, and insects.
3. Foam Concrete Forms
Non-Traditional Method: Foam concrete forms are a non-traditional method for pouring concrete. Instead of pouring the concrete directly into the form, the concrete is poured upside down, allowing the desired finish to be achieved. Materials used to create the forms include melamine, acrylic glass, and laminated board. These form create negative spaces that add an artistic touch to the final concrete cast.
4. Concrete Wall Forms
Concrete Wall Forms: An Overview
Concrete wall forms are pre-manufactured forming systems designed to cast large area walls, foundations, and piers. These systems are typically constructed with engineered wood and steel framing, or made entirely with steel. The individual elements are connected using pins, latches, and ties to hold the reinforcement in place when the concrete is poured. Wall forms come in a variety of sizes and shapes; some manufacturers even offer custom sizes to meet specific project requirements.
5.Steel Concrete Forms
Steel forms offer a number of advantages over wooden forms in the construction industry. They are more durable and capable of withstanding up to 2000 work cycles when properly maintained. This is significantly higher than the life span of wooden forms, which tend to deteriorate quickly. Additionally, steel forms do not absorb moisture from the concrete, creating a more precise surface finish. This makes steel forms the ideal choice for a wide range of construction projects.
What to Consider When Selecting Concrete Forms
What to Consider When Selecting Concrete Forms:
When selecting concrete forms, several key elements must be taken into account. These include the pour size, pressure on the form, weight on the form, type of compaction, and how much concrete needs to be retained.
Own or Rent Concrete Forms
The cost of owning and long-term use must be weighed against the cost of renting. If renting is the better option, it is important to choose a form type that is easily available and economical.
Familiarity of Form Type
A form system that is familiar to the workers should be chosen to minimize production loss. Training on a new form system may be necessary, and this should be taken into account.
Aesthetics and Tolerances
Steel forms provide a clean finish with fewer bug holes on the cast concrete surface compared with wooden forms. Steel forms also provide better tolerances.
Height of Structure
For low height structures, wooden forms are the best choice. Taller forms, such as those over 20ft, should use steel forms with extra bracing and supports.
Straight, Curved and Offset Forms
For casting concrete with straight, curved, or several offsets, or abrupt turns, steel forms are the most efficient choice. Thin wooden forms can be used if cost is a factor.