Fixing concrete

Cheesefood · 03-20-2007, 08:31 PM

OK, non brew related.

My folks got me a firepit for christmas. It's a huge concrete bowl that I just found out has a big crack in it. Any ideas on what's a good fireproof patch for concrete?

**the_bird** · 03-20-2007, 08:40 PM

Is it still structurally solid? Not going to break?

You can buy a concrete mix that's designed for patching at the Depot. It's more expensive, about $10 a bag. No stones in the aggregate, it's just sand. I've been using it to fix where the basement walls are spalling, it's been holding like a mofo for a couple of years now (the outer half-inch to an inch in sections of the basement has crumbled, it's still structurally sound but messy. I take out the loose stuff and go over it with the patching 'crete).

It's a LOT smoother than regular concrete.

Brewsmith · 03-20-2007, 09:29 PM

That Rapid Set stuff is great. We use it at work to patch concrete. I don't know how it holds up under high heat though.

**Chairman Cheyco** · 03-20-2007, 09:51 PM

More concrete.

Shockerengr · 03-20-2007, 10:09 PM

I've used hydraulic waterstop cement (comes in a small bucket) to patch leaks in foundations, but i don't know how well it will hold up to heat.

**Orfy** · 03-20-2007, 10:30 PM

2 ways of fixing a crack in most objects.
Drill an hole at the end of the crack, this will stop the crack spreading.
Enlage the crack and fill it to a reasonable depth. This allows penetration and better bonding of the material. You can get fire cement that is designed for bonding fire surrounds.

When you use it do not set a massively hot fire going. Allow it to temper first with a smaller fire.

**BierMuncher** · 03-20-2007, 10:34 PM

Patch it with heat rated fireplace mortar and then layer about 4-5 inches of sand on top when burning wood.

Monster Mash · 03-20-2007, 11:23 PM

I find it hard to believe they made a firepit out of concrete. My nieghbor had a fire on her driveway (long story) and the heat make the concrete explode. I have also had coworkers use a torch to cut a steel pipe full of concrete and it exploded.

If the whole thing heats evenly I guess it would work but when concrete heats up it expands. If the concrete around the heated area is cool it has nowhere to go but out. BOOM!!!

Quote:

Originally Posted by BierMuncher

Patch it with heat rated fireplace mortar and then layer about 4-5 inches of sand on top when burning wood.

That is good advice!!!

**kladue** · 03-20-2007, 11:26 PM

As mentioned above a nonshrink grout would fix the concrete, but if the bowl is concrete burning a hot fire at the start would probably be quite interesting as the trapped water turns to steam and bits of concrete pop like firecrackers. If you want to make a lower cost liner for the fire area mix perlite with Sairset refactory cement and build up about 1 inch layer in fire zone. Thin the sairset and mix with perlite to get a mixture that is mostly perlite and enough sairset to make it bind together, coat top of perlite mix with sairset cement to protect the softer perlite. This should reduce the heat flowing to the concrete to a level it could endure for a while, start with small fires to cure coating and dry concrete first.