How to fill gap between concrete and brick border?

[BrendonL]

Hi, 

In my driveway I have a concrete block and brick border (please see pic), there is no filler between these two except dirt. The gap between the brick and concrete at points is up to 1cm. Could you please advise what products I require to fill the gap.

Thanks 

Brendon

[MitchellMc]

Welcome to the Bunnings Workshop community @BrendonL. It's fantastic to have you join us, and many thanks for your question about filling a gap.

The transition you’ve got between the concrete driveway and the brick border is a classic example of two surfaces that move independently. For this, the best approach is to create a flexible expansion joint rather than using a hard cement-based filler, which will crack over time.

A common method is to push foam backer rod into the gap about 10 mm below the surface. Then, run a bead of Sikaflex 11FC across the top. The backer rod prevents you from using too much sealant and ensures the joint stays flexible, allowing the brick and concrete to move without cracking.

Using a cement-based filler isn’t recommended here. It will almost certainly develop hairline cracks as the two substrates shift, whereas a flexible sealant joint will accommodate movement and last much longer.

Here's a helpful guide: How to fill a joint in a concrete slab.

Please let me know if you have any questions.

Mitchell