What is this material between our concrete and bricks (lining our pool)?

[TFP_Addict]

Wasn't sure where to post this, since there isn't a general forums section.

The material lines our pool between the brick (edge) and the concrete. This material is only near our pool. It feels rubbery and bendable.
And The material is over 30 years old is has been breaking apart in certain areas and needs to be replaced.

 

[Rocket J Squirrel]

It is called "mastic". It provides a flexible buffer space between the pool and the deck while sealing that gap. It does wear out over time and need to be replaced.
Pool Mastic: Everything You Need to Know | Willsha Pools

Everything You Need to Know About Pool Mastic - Platinum Pools

Learn what pool mastic is and why it's important to maintain. Pool mastic will help maintain the large investment you made purchasing your swimming pool.

platinumpools.com

 

[ajw22]

That is an expansion joint that needs to have flexible material.

DECK-O-SEAL - Polysulfide-Based Joint Sealant

Seal all cracks and joints with DECK-O-SEAL two-part, elastomeric, polysulfide-based joint sealant. DECK-O-SEAL is used for caulking and sealing joints subject to concrete movement to provide a firm, flexible, weather-tight seal. It is ideal for sealing joints around swimming pools, and for...

www.deckoseal.com

Is often used.

Pool Expansion Joint

• ajw22
• Jan 25, 2019

Expansion Joint Caulking Around Inground Swimming Pools

Information about pool caulking, how and why to caulk the expansion joint around the pool, between the coping stone and pool deck.

www.poolcenter.com