what is this filler?

[rh71]

What is this they use to fill the gap between sidewalk concrete? It's a durable rubber-like material. I have a deep chunk missing between my driveway apron and the lip. Is it available to homeowners or are there alternatives? I'm thinking if I don't fill it, water will get in and cause it to start cracking with winter approaching.

 

[monkeydelmagico]

large concrete expansion joints have backer rod then sealer. Small ones, or if you are repairing, will use some form of self-leveling sealer.

 

[edro]

Google "concrete expansion joint" and/or "repair" and you will get all kinds of ideas.
There are tons of products to repair or replace the whole thing or just the missing section.

 

[rh71]

Is their purpose to keep water out (in addition to allowing expansion)? I'm curious how important it is to keep water from getting in these spaces.

For something like stuffing this in, does it need to be sealed in there like I'm reading in the description?

http://m.homedepot.com/p/Reflectix-4-in-x-50-ft-Expansion-Joint-for-Concrete-EXP04050/203151902

 

[skyking]

It is an expansion board worked into the wet concrete. It is not a sealer.
Any water that gets in there is supposed to drain through the gravel below the concrete.