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Sub
03-11-2010, 05:31 PM
Funny story I thought I would share with yall, or at least make you laugh at my great thinking strategy.

Let me start off my saying i'm fairly new to the smoking world, picked it up for a couple months now (this is my defense). I was about to start up my chimney when I had this thought that I didn't want to start the chimney on the actual smoker because I didn't want the paper ash floating around the inside of the smoker as the food was cooking so I figured I would put it on my back patio while the coals warmed up.

I lit the paper under the chimney and set it on my patio, went inside and started rubbing the ribs down, I get done with my first set and and slap down the 2nd slab and then I hear this POP! noise and the first thing that comes to mind is that the chimney blew up somehow; so I run outside and see hot coals ALL OVER my patio, the grass is on fire and the chimney is on it's side...

Immediately I go for the hose and realize I still had the Spigot Covers on for the winter and the hose is just loosely hanging there, I rip that cover off and do my best to attach the damn hose and turn it on. With as fast as my ass could go I put out this fire in my backyard and sit back and listen to the sizzling of the coals as it burns my dry grass.

I try to look at the chimney and it's all bent to **** and I see pieces of concrete all over the place, I now see that the heat had caused the concrete directly underneath the chimney to pop up, causing my chimney to be a rocket showering my yard with coals.

Here was the end result (after I swept up):

http://imgur.com/l8BYG.jpg

http://imgur.com/pD5oU.jpg

So my wife comes home later and I had it cleaned up and she went outside and I didn't say anything and just kept talking to her like there wasn't this divet at her our feet and she yells "what the hell happened!" and I told her "oh that was already there". :twisted: Her look was priceless

lol good times

landarc
03-11-2010, 05:37 PM
Very nice, the darndest things can go wrong when you least expect it.

vr6Cop
03-11-2010, 05:39 PM
That'll buff right out. :wink:

Smokin' D
03-11-2010, 05:51 PM
I've heard of that happening but never saw such a nice picture of the aftermath, or heard such an enjoyable story to go with it. Happy patching.

jonboy
03-11-2010, 06:00 PM
Just set your grill on that spot.
That will fix it. :)
jon

The BBQ QB
03-11-2010, 06:07 PM
Just put your UDS there and move it around, should take about 3 months and everything'll be equal. In fact you could refer to it as a proffessional surface application.

That'll show 'em

Mike D

aztecnology
03-11-2010, 06:21 PM
I did the same thing on the patio at my condo I use to live at. Left the chimney on a pie tin on the cement and had similar results with the cement coming off...

cdollar
03-11-2010, 06:22 PM
I have seen that happen many times. Once I hit my patio surface with a cutting torch. Then I had to go change underwear.

Remember what concrete is made of; cement, aggregate, and water.


Chuck

bbqbull
03-11-2010, 06:26 PM
The technical term of what happened to your concrete is called spalling.
The heat from the fire cause the entrained or trapped air bubbles inside the cement to expand and explode.

I'm glad nobody was injured from the flying fragments of concrete.

I would suggest next time you set your chimney inside another metal vessel or inside the charcoal/wood grate so that doesn't happen again and injure somebody.

Papa Payne
03-11-2010, 06:29 PM
Good thing no one was around the chimney when it happened.

Got any pictures of the chimney?

Papa

Grillman
03-11-2010, 07:39 PM
:eek:

UVaJester
03-11-2010, 10:20 PM
Wow... Glad everyone is ok...!!!

I always set my chimney on the driveway. Guess I'm going to not do that anymore...

Rick's Tropical Delight
03-12-2010, 05:25 AM
the same thing happens under some military aircraft auxiliary power unit exhausts

kickassbbq
03-12-2010, 06:18 AM
I warn people of that in my Class. If you are near that or picking up your chimney when that happens, obviously you could get hurt !!!
Heard of a guy that was blinded by his in same manner.
Be careful and put chimney on charcoal grates instead of concrete.

Vince B
03-12-2010, 06:51 AM
I always use a Smokey Joe for that exact reason. When I first got my chimney starter I had a similar experience because I didn't like the paper getting into my wsm. Then I had this idea to use a clay pot base so I would not have the same issue as you with the cement infront of my place. Well the clay pot base lasted about ten minutes and I cracked in half! I now use a Smokey Joe. However I still have the issue with the paper flying around. I think a weed burner or lighter cubes might be in my future. Good to hear that you are alright. Vince B

O-Town
03-12-2010, 06:56 AM
Interesting. I have been sitting my chimney on two brick pavers I had left over from our pool deck redo. Have not had a problem but I wonder if that's safe now?
http://i110.photobucket.com/albums/n101/jcirvin/Lonelytoday-1.jpg

Chef Jim
03-12-2010, 08:39 AM
This makes a good case for buying a weed burner.

1FUNVET
03-12-2010, 08:45 AM
I use a 12" x12" x 1/4" steel plate laid on the ground.

boatnut
03-12-2010, 09:07 AM
Interesting. I have been sitting my chimney on two brick pavers I had left over from our pool deck redo. Have not had a problem but I wonder if that's safe now?
http://i110.photobucket.com/albums/n101/jcirvin/Lonelytoday-1.jpg

I've left mine on precast pavers. I suspect the original problem might of had something to do with the type of aggregate in his patio. Not sure if they use limestone in TX or not. I'm sure Rick can get into more technical analysis :)

rw02kr43
03-12-2010, 09:11 AM
I did the same thing at our old house. I set it down for a min on the asphalt and it melted a hole in it. So then I set it on a slab of granite I had and it split that into a bunch of pieces. Anymore I just sit it on the grate and light it there.

Jason

gsmith
03-12-2010, 09:34 AM
Wow, I never would have thought of that happening. Up until I read this thread I have always put mine on concrete but not anymore.

on a side note - i use sterno to start my chimney, let it get the charcoal going for about 5-6 minutes then put the sterno out and save it until the next time.

ytsejam
03-12-2010, 09:52 AM
i have been using my dutch oven on some acme bricks. putting charcoal on the bricks and setting the d.o. above the coals. I wonder if bricks can explode like that? :eek:

BobBrisket
03-12-2010, 10:21 AM
i have been using my dutch oven on some acme bricks. putting charcoal on the bricks and setting the d.o. above the coals. I wonder if bricks can explode like that? :eek:


Yes, they can. I'm no expert, but Bull's definiton of air bubbles makes sense to me. I always thought it also had to do with water that had seeped into the concrete or bricks as they are somewhat porous, and then the heat created internal steam and pressure. I use some pavers in my kettle, but leave them in there so they don't get wet or absorb moisture. One time, I used some bricks that had set out in rain, and had one of them bust up like that as it heated up. I've continued to use them, but keep em dry and have not had that happend again. Not to say it couldn't, but it hasn't. Even though the top of the crete may look dry, there is still trapped moisture in there at this time of year as snow, etc melts or as it rains. Be careful.
Now it's a weedburner or just put in on dirt or on the grate.

ytsejam
03-12-2010, 10:28 AM
Yes, they can. I'm no expert, but Bull's definiton of air bubbles makes sense to me. I always thought it also had to do with water that had seeped into the concrete or bricks as they are somewhat porous, and then the heat created internal steam and pressure. I use some pavers in my kettle, but leave them in there so they don't get wet or absorb moisture. One time, I used some bricks that had set out in rain, and had one of them bust up like that as it heated up. I've continued to use them, but keep em dry and have not had that happend again. Not to say it couldn't, but it hasn't. Even though the top of the crete may look dry, there is still trapped moisture in there at this time of year as snow, etc melts or as it rains. Be careful.
Now it's a weedburner or just put in on dirt or on the grate.


im gonna have to come up with a new contraption for d.o. cooking:eusa_clap

Harbormaster
03-12-2010, 10:40 AM
I like to be positive about situations like this:

The damage to the concrete is really round!

I use a Smokey Joe to set my chimney on, or light it on the turkey fryer burner.

Divemaster
03-12-2010, 10:56 AM
Glad no one was hurt but a great story and better bluff!

cdollar
03-12-2010, 11:43 AM
I put the charcoal in the pan, then set the chimney on the charcoal to start it. Then, when it's ready, I just turn it out. Simple.

Chuck

CBQ
03-12-2010, 01:52 PM
Get a few firebricks and put the chimney on that. http://www.nakedwhiz.com/firebricks.htm

I use a weedburner myself because it's more fun to set stuff on fire :P

Hofy
03-12-2010, 02:17 PM
I have an area of concrete that looks similar. I was lighting my chimney on the patio also but never had it explode. I now use a concrete block and set the chimney on the open side of the block.

Kevin_Texas
03-12-2010, 02:38 PM
That's just crazy. I will for sure pass this own to friends and family

howy61
03-12-2010, 02:50 PM
go to HD or lowes, spend $1.50 on an concrete paver as a chimney trivet.

DUN!

pomah25
03-12-2010, 03:04 PM
Would love to see the pics of the chimney!

thomasjurisd
03-12-2010, 03:54 PM
I'll go ahead and put my head out on the chopping block so ya'll can kick it around a bit - but could it be that the aggregate contained flint rock, which reacts violently to heat?

Rick's Tropical Delight
03-12-2010, 05:12 PM
i'm willing to bet the DIRECTIONS say not to put chimney starters on concrete. the virtual weber bullet site (http://www.virtualweberbullet.com/chimney.html) does.

this is from a concrete design manual:
Heat Effects on Portland-Cement Concrete. Rapid heating of moist concrete can vaporize
water in the concrete capillaries and cause explosive spalling. As the concrete temperature begins to
rise above about 149 oC (300 oF), the progressive cement paste dehydration, thermal incompatibilities
between paste and aggregate, and aggregate deterioration lead to irreversible damage and progressive
loss of strength that is more pronounced as the temperature rises. Aggregates have a major impact on
the thermal behavior of concrete and in decreasing order of desirability for thermal resistance they are
lightweight aggregates (e.g., expanded slags, clays, and shales or natural pumice or scoria), finegrained
igneous rocks such as basalt or diabase, calcareous aggregates, and siliceous aggregates.
Including slag cements in the concrete mixture also seems to enhance thermal resistance. Heat
resistant conventional concrete can be achieved by proper mixture proportioning, use of appropriate
aggregates, inclusion of slag cement, and high-quality concrete placement, finishing, and curing.
However, if the concrete temperature will reach 204 oC (400 oF), conventional concrete probably will not
be sufficient, and thermal cycling at lower temperatures can cause damage.

jestridge
03-12-2010, 05:24 PM
Never cut metal against a _____________ floor. A question on our welding safety test.

txschutte
03-12-2010, 06:35 PM
4 parts silica sand
1 part gray cement
1 part white cement

mix to a thick, smooth consistency with water.

apply a liberal amount of concrete patch adhesive (also known as concrete milk)
after the "milk has dried or turned a bluish hue, use a rubber trowel to spread the concrete patch mixture into the spall. finish as surrounding concrete. Allow to dry/cure for 7 days.

Who said this was just a BBQ site?

Rich Parker
03-12-2010, 06:57 PM
Thanks Bull for explanation!

I light my on the driveway all the time. I guess I should say used to.

I'M OFF
03-12-2010, 07:26 PM
Never cut metal against a _____________ floor. A question on our welding safety test.


concrete



I learned the hard way!

Rick's Tropical Delight
03-12-2010, 07:37 PM
4 parts silica sand
1 part gray cement
1 part white cement

mix to a thick, smooth consistency with water.

apply a liberal amount of concrete patch adhesive (also known as concrete milk)
after the "milk has dried or turned a bluish hue, use a rubber trowel to spread the concrete patch mixture into the spall. finish as surrounding concrete. Allow to dry/cure for 7 days.

Who said this was just a BBQ site?

that wouldn't work up here in freeze/thaw land. i wouldn't attempt patching that spall because it's too shallow and whatever you put in there will come tight out in no time.

thomasjurisd
03-12-2010, 07:45 PM
Never cut metal against a _____________ floor. A question on our welding safety test.

Submarine? :thumb: It's submarine right?

timmy7649
03-12-2010, 08:27 PM
thats why i built this out of an old propaine bbq with side burner. the propaine burner works great to start the coals and fast. fuuuuunnnnnnyyyyyyy story. glad everyone and things are safe.http://i786.photobucket.com/albums/yy150/timmy7649/DSCF1512.jpg
http://i786.photobucket.com/albums/yy150/timmy7649/DSCF1513.jpg
http://i786.photobucket.com/albums/yy150/timmy7649/DSCF1514.jpg
http://i786.photobucket.com/albums/yy150/timmy7649/DSCF1516.jpg
http://i786.photobucket.com/albums/yy150/timmy7649/DSCF1515.jpg

Redwingsfn31
03-12-2010, 10:17 PM
the same thing happens under some military aircraft auxiliary power unit exhausts




I am gonna go out on a limb here and guess you are or were in the airforce.

Rick's Tropical Delight
03-13-2010, 08:31 AM
I am gonna go out on a limb here and guess you are or were in the airforce.

nope, but i like concrete and really fast aircraft :becky:

that looks like a crop circle in the driveway. maybe the wife would have believed that. people pay big bucks for the exposed aggregate finish :thumb:

CajunSmoker
03-13-2010, 09:53 AM
that wouldn't work up here in freeze/thaw land. i wouldn't attempt patching that spall because it's too shallow and whatever you put in there will come tight out in no time.


How about if you bored some holes into the area so the patch ccould have deep support areas kinda like bridge pilings?

nope, but i like concrete and really fast aircraft :becky:

that looks like a crop circle in the driveway. maybe the wife would have believed that. people pay big bucks for the exposed aggregate finish :thumb:

My nephew is an engineer for an aircraft manufacturer that was working on the joint force's fighter project. That was his job, to figure a design that wouldn't blow the tarmack on the runways to pieces. Last I heard he's still working on it:-D

Rick's Tropical Delight
03-13-2010, 10:42 AM
How about if you bored some holes into the area so the patch ccould have deep support areas kinda like bridge pilings?

My nephew is an engineer for an aircraft manufacturer that was working on the joint force's fighter project. That was his job, to figure a design that wouldn't blow the tarmack on the runways to pieces. Last I heard he's still working on it:-D

it would be better to remove more concrete to make a thicker repair, but hey, a skim coat of that texas mortar might work in the south. ohio is the absolutely worse weather for pavement due to the number of freeze/thaw cycles. thin layers have so much more surface area compared to their thickness they crack when they shrink.



click this (http://www.wbdg.org/ccb/AF/AFETL/etl_02_7.pdf) for airplanes :plane:

Smokey-T
03-13-2010, 10:54 AM
Similar to the crop circle, the crete circle is thought to be a by-product of alien thermal experimentation. Often, select pieces of animals parts can be found in proximity of a crete circle covered with dry particles or lathered with celestial sauces. While infrequent, danger of alien - human cavity probes are possible. Proceed with caution! :heh:


http://imgur.com/pD5oU.jpg

CajunSmoker
03-13-2010, 11:09 AM
Similar to the crop circle, the crete circle is thought to be a by-product of alien thermal experimentation. Often, select pieces of animals parts can be found in proximity of a crete circle covered with dry particles or lathered with celestial sauces. While infrequent, danger of alien - human cavity probes are possible. Proceed with caution! :heh:


http://imgur.com/pD5oU.jpg


kinda like a alien reach around thing:sorry:

Odin the Dog
03-13-2010, 11:33 AM
I light my chimney inside my wife's pyrex baking dish. I'm hardcore that way.

brown dog
03-13-2010, 01:43 PM
Exterior concrete has chemicals added to the mix to cause the air bubbles. Concrete= sand, portland cement and (stone, slag etc.) This gives the product the ability to expand and contract , therefore less likely to crack or spall in the extreme conditions. The concrete by nature is very porous. This is why you waterproof a basement before you back fill , add drain tiles etc to get the water away. Add heat and the trapped air pockets expand=kaboom! Never use any concrete product near heat.

expatpig
03-13-2010, 01:54 PM
Good thing I saw this, lol, On my next UDS build,I was going to put a thin layer of concrete in the bottom as an experiment.

leanza
03-13-2010, 02:34 PM
:doh: :idea: :mod::boom:

Rick's Tropical Delight
03-13-2010, 02:43 PM
Good thing I saw this, lol, On my next UDS build,I was going to put a thin layer of concrete in the bottom as an experiment.

use fire brick splits