3 min read

How Interbloc's Interlocking Shear Key Works

Interbloc is a precast wall system with a unique interlocking concrete block sitting at its heart. These blocks make it fast to install, incredibly durable, and able to be non-destructively dismantled at end of life. The blocks also carry an industry-leading buyback guarantee. All of these benefits are possible thanks to Interbloc’s shear key.

Why is the shear key important to you?

We all want to build faster and stronger without compromising quality and safety. We also want reasonably priced solutions. Precast modular construction systems fit this to a “T”. That’s not to say that all precast solutions offer the same benefits - Interbloc is unique because of the approach we take to design.

We believe great design has people at its core. We think about how you will use the blocks and where you will use them. We think about what will happen at the end of the structure's life, and how we can maximize the use and value of each block. Most of all we think about the safety and stability of the structure. All of this comes together in Interbloc’s shear key.

Shear Key, an Introduction:

Before we get into the specific benefits of shear keys, it's important to cover some terminology first.

Shear Force  A force acting in a direction that's parallel to (over the top of) a surface or cross-section of a structure.
Lateral Forces A force acting in a generally horizontal direction, such as wind, earthquake, or soil pressure against a retaining wall.
Overturning Forces Overturning moments seek to cause the footing of the structure to become unstable and turn over.

What is a Shear Key?

Shear keys are used in structures to maintain integrity and improve the strength. Its purpose is to transfer the shear force caused by lateral forces between the structure and the shear key. It doesn’t resist overturning forces. Overturning forces are resisted by the weight of the concrete block itself.

Shear Key

Ranging from bridges to masonry and retaining walls, you may see shear keys in many structures in your life. They all have the same purpose no matter the application - to improve the strength of the structure.

The benefits of a shear key

  • Creates a modular solution
  • Allows you to non-destructively dismantle one structure and build another
  • Faster installation 
  • Provides resistance against earthquakes
  • Resists lateral forces

How Interbloc’s Interlocking Shear Key Works

Interbloc’s shear key uses a cruciform tongue and groove interlocking design, providing an interlocking key in both horizontal directions.

 Annotated Shear Key

(On the left image is the shear key in blue, on the right is the shear key on Interbloc)

When you're installing a layer on top of your base layer, you'll find the blocks positively locate. By having the shear key in both horizontal directions, installation is easy - much like the popular childhood toy LEGO.

Interlocking Concrete Blocks
Interbloc’s use of a shear key means you can use it across multiple applications. These include:

The safety standards that the shear key meets

The main safety standard that our shear key follows is the NZS3101 code Part 1 2006 Section 7.5. This standard relates to the shear strength of members. The members, in this case, are the interlocking concrete blocks.

Read NZS3101 code Part 1 2006 Section 7.5 in this link

If you're wanting a solution that is easy and fast to build, get in touch with us.

Leave a comment

Comments will be approved before showing up.