Any project involving concrete construction must include expansion joints. To reduce stresses, fractures or cracking, contractors utilise expansion joints to create a cushion between adjacent concrete sections. This cushion stops structural damage caused by movements brought on by weight, wind, or temperature changes.
Foam joints are also commonly used alongside structural steel, primarily for installing steel lintels into masonry walls. The expansion joints allow the steel and concrete to move freely without causing damage.
Learn how to prevent stresses, cracking or fractures caused by moving concrete, and discover how to use expanding foam to fill gaps with some general advice from Steelbuilders.
Construction varies from project to project, making it difficult to define the movement characteristics of different materials accurately. However, because of the diversity of materials, it is necessary to provide for differential movement of the materials, otherwise known as movement provisions.
Movement provisions typically involve using expansion joints in brick masonry to prevent unnecessary and unwanted cracking. Expansion joints can be used for both horizontal and vertically installed lintels.
Vertical Expansion Joints: permits horizontal movement of brick masonry.
Horizontal Expansion Joints: permit vertical movement in multi-story walls where the lintels support masonry panels.
When To Use Expansion Foam
Three main applications for expansion foam joints in construction:
- To create a gap in new concrete, preventing concrete from sticking to existing structures; or,
- To allow concrete to expand and shrink freely without applying pressure to adjacent structures.
- To allow steel lintels to move to expand and contract independently.
Because steel expands more than masonry, a pocket of space should be left at each end of the lintel to allow for movement of the steel angle.
Other uses for expansion foam include covering pipes to prevent them from cracking or breaking due to movements in the concrete.
Locating Expansion Joints
Properly locating expansion joints can help you avoid stair-step masonry cracks at the corners of windows and doors. To find expansion joints when steel angle lintels above an opening are supported by brick, the designer can:
- Align the joints with the jambs of the opening
- Place the joints at the ends of the steel angle
- Locate the expansion joints between openings
Expansion Joint Materials
Filing materials for expansion joints are made from a variety of materials, including:
Because it is so flexible and can be moulded to fit a variety of gaps, foam filler is the most prefered material for expansion joints because it prevents dust and water seepage.
For instance, Steelbuilders carries Ableflex Expansion Foam, a cross-linked, closed-cell, flexible and lightweight polyethylene foam.
Available in an easy-to-install roll of tape, modern expansion joint foam like Ableflex can even be installed on-site, thanks to the detachable “zipper” sections.
Adhesive vs Non-Adhesive
Expansion joints are split between two varieties, adhesive and non-adhesive. Adhesive expansion joints, as the name suggests, feature an adhesive edge on one side of the foam, which sticks to the concrete, making it easier to install before pouring concrete.
Non-Adhesive expansion joints, on the other hand, require manual adhesion applications and are not self-adhering. These expansion joints are used when a particular type of bond is needed for the structural application, i.e. coastal environments. You must install the adhesive before concrete pouring.
Abelflex / Foamjoints
Abelflex Expansion Foam Joints are a unique one-piece extruded foam with no laminations. The foam is a closed cell, making it non-absorbent and impervious to most liquids, for excellent weather ability and resistance to ultraviolet light. Moreover, its cross-linked construction gives the foam joint superior compression and recovery properties, which are vital to ensure an excellent joint filler. Abelflex Expansion Foam Joints are also highly resistant to temperature, acids, alkalis, oils and solvents.
Abelflex is essentially plastic foam filled with a series of independent bubbles, similar to pool noodles, making it spongy and compressible enough for close-up spaces between concrete.
Abelflex Expansion Foam Joint is available in rolls of 25 metres long at the following widths:
Thicker sizes include:
- 15mm to 100mm
- 15mm to 30mm in rolls
- 40mm to 100mm in 2400mm sheets
How To Use Expanding Foam Tape With Sealant
Abelflex / Foamjoints are also available in pre-cut zip-top expansion joint materials for installations that require sealant. These Abelflex / Foamjoints are designed for easy on-site tear-off for sealant applications, thanks to the zipping feature (all Foamjoint is zipped approximately 10mm from the edge), which gives a clean tear every time.
If the project does not require sealant, Foamjoint should be installed upside down, with the zipped top down to avoid unwanted removal.
Creating Smarter Solutions with Steel Builders
No matter what project you undertake, you want to avoid structural damage. Expansion joint foam protects adjacent concrete structures and their structural steel supports, like lintels.
Whether installed vertically or horizontally, expansion foam joints in construction allow concrete and structural steel to expand and shrink freely without applying pressure to adjacent structures.