Concrete Structure Demolition

[andre876]

Hey guys:

Got a demolition job for my cat 430E backhoe. Pics attached.

The building to the left with the exposed masonry blocks is what needs to be removed. It is 27 feet long x 12 feet wide x 9 feet tall. It has concrete stiffeners and a reinforced concrete roof slab.

I'm thinking a water hose to keep down the dust during demolition, a hammer extension to separate the roof slab of building to be demolished from the main building to be untouched.

So my question is, am I missing anything? Could this be done without a demolition hammer extension? How long should the demolition take with and without the hammer?

Thanks in advance.
Andre

 

[skyking1]

I'd be concerned about damaging the roof that will remain. It looks like the target roof overhangs it.

 

[andre876]

It does overhang. In light of this, a man operated demolition hammer to separate the roof slab of building to be demolished from the house to remain, before the backhoe comes in could be a possible solution.

 

[Aarons81]

Is there another bearing wall against the main structure? Is the reinforcing wire mesh or rebar?

 

[andre876]

No other walls that I am aware of. The reinforcement is 1/2" rebar.

 

[CM1995]

Welcome to the Forums Andre!

It does overhang. In light of this, a man operated demolition hammer to separate the roof slab of building to be demolished from the house to remain, before the backhoe comes in could be a possible solution.

I think I would go this route to separate the section being demolished from the main house. Do you have a gas powered demo saw as well?

 

[andre876]

Hey CM1995,

Thanks man! Appreciate it! These forums are GOLD man.

I do not have a gas powered saw but I am making a list of useful tools to buy so I'd be very open to your suggestion on one that has worked well for you.

I'm currently considering buying a jackhammer as an affordable alternative to the hilti 3000:

1: https://www.amazon.com/gp/product/B00IO3Z5MS/ref=ox_sc_saved_title_2?smid=A1Y4RBJHD0SC34&psc=1
or the other slightly more expensive one,

2: https://www.amazon.com/gp/product/B07B4K1CNK/ref=ox_sc_saved_title_1?smid=A1Y4RBJHD0SC34&psc=1

 

[CM1995]

Husqvarna's have been the best for us.

Own 2 K760's, a K770 vacuum saw and just purchased another new K770. The newest K770 was just under $900 USD. Still using one of the K760's daily and the first K760 bought back in 2012 is in a parts box at our shop.

Other folks like Stihl and it's a good brand as well.

My philosophy is to always buy the biggest and best tool you can afford at the time you need it. Your business can always grow into a larger tool but it's hard to grow out of a tool too small for your business. On that note I would suggest the larger demo hammer you posted from Amazon.

 

[andre876]

OK thanks much.
I looked at the Husqvarna and still concrete disc saws as well as some of the chained types and they're really great, only thing is they're in the $2000 price range.
Where do you buy your tools? Any online stores that delivers? If I can get these for under a $1000 then it's something I can get.

 

[treemuncher]

If you want to go a heavier route on the jackhammer and get away from electric power, you might want to check out a Chinese copy of the Pionjar hammer called the YN27. I purchased one from Ebay a couple years back and I've had good luck with it. Gasoline powered beast that both hammers and drills with air pressure to blow out the dust & debris from down the hole. It uses common hollow hex shaft components and replaceable rock bits. Combine this with non-explosive blasting grout and you can remove any rock or concrete you will ever need to. Note: If you ain't a man yet, working this tool will turn you into one or bust your butt!

I carved a fire pit out of granite with one of these and the grout mix up in Maine. I would estimate that most of the drilling at 1.5" diameter ran about 4"-6" per minute in the rock shelf that I was working. Different shaped tools are also available for different medias. Best thing is, it works anywhere.

You will still need a saw or torches to get through the rebar.

 

[CM1995]

OK thanks much.
I looked at the Husqvarna and still concrete disc saws as well as some of the chained types and they're really great, only thing is they're in the $2000 price range.
Where do you buy your tools? Any online stores that delivers? If I can get these for under a $1000 then it's something I can get.

Andre I've bought those saws locally through a construction supply store.

 

[DGODGR]

Just now seeing this. I would imagine that you have done the job already (If so tell us how it went...pictures?) but I fell compelled to reply anyway.
In my opinion the concrete roof is the hardest part here. Even still, the way the concrete/msu building has been built around the components of the parent building requires a bunch of hand demolition in my opinion (I assume you must prevent damage to the parent building). Especially since it looks like space is limited with the fence so close to the side of the building to be demoed. The weight of the falling concrete could easily damage (either the parent building or the fence) when falling from that height, even if the pieces are relatively small. Often times those MSU (masonry standard unit?) walls come down super easy because the cells are not grouted. Something about this scenario has me thinking that this may be the case here but I wouldn't risk bidding it, or demoing it, with that assumption. A hammer (claw hammer or 2# sledge) to the side of the msu would reveal that in short order.
What is a "demolition hammer extension"?
I own a Stihl "demo saw" (I've also heard them called "quick cut", and "cut-off" saws) and have owned it for probably 10 years, or so. If I recall it's a TS 400 or 410 and it cost me about $750 US new. It still works like a champ! The only issue I've ever recall having with it is that the fuel pick up tube sometimes breaks inside the gas tank.
CM1995: What's a vacuum saw?
Keith: Not sure if a Stihl trimmer is germane to this conversation but it sounds like you could simply ask your friend or his worker to get more details.

 

[CM1995]

DG the industry term here is CMU - concrete masonry unit, never heard concrete blocks referred to as masonry standard units but make sense.

This is what I call our "vacuum saw".

https://www.husqvarnacp.com/us/machines/power-cutters/k-770-vac/967860701/

Meets the silica standards when water is not available on the job. It works pretty good. The saw comes with cloth bags to collect the dust then chunk them in the dumpster however we empty ours out at the shop and re-use.