Rock breaking

[Don_P]

I had the "opportunity" to break rocks underneath a house using a new to me method, it's been working pretty well. The construction of a full basement under this house stopped 3 decades ago when they hit solid granite in the otherwise decomposed granite. We are now converting that area from a shallow crawlspace to a full basement. We're making good progress using a non explosive demolition agent and an air powered chipping hammer.
http://en.wikipedia.org/wiki/Non-explosive_demolition_agents
We've been using the chipping hammer in the softer decomposed granite until we expose the hard rock. At that point we broke out the percussion drill with a 1.5" x 2' long drill bit and bored holes into the rock.

We then blow out the hole, mix a batch of the high expanding grout, fill the hole and go home for the night. The next morning the rock is fractured.

We then can go back to the chipping hammer. This thing takes a tremendous amount of air, we're hooked to a two stage compressor putting out 17 cfm by a 1/2" line  and it is in continuous run but is doing well. The rock can then be worried away and off to the pile outside.

Hopefully, if my arms don't fall off  , another week and we'll be ready to begin pouring.

[rick91351]

WOW Thanks - that is great stuff if it works as advertised.  I never had stumbled on to that before.  I would guess you don't go to Home Depot or Lowes and their non explosive demo isle.   Classes or read this to mix and set?  It sounds as if it is not all together totally harmless.  For example steam explosions? 

I worked on one about thirty years ago and we had to pop the rock under a house working with a guy I knew.  Existing house that had a crawl space.  They wanted a full basement.  There was a basalt riff under that house.  We bedded the holes real tight and then over that some old  mattresses.  It was so crystalline it really did not need much powder.  We just cleaved it off sort of how your doing it.  We had a small Cat with a bucket rented to pull the muck out from under the house.  I almost quit the railroad and set up my own company I liked that job so well.          

[flyingvan]

How do you plan to construct your walls?

[MountainDon]

 

What does the house now sit on? Concrete on rock?

[Don_P]

It's pretty cool in a sadistic kind of way, but I've never minded digging. The house before this one burned, over the years working for this family I've found remnants of that foundation. This one was built in the '20's basically on the same site using bricks and rocks for the foundation, much of it recycled from the original. 33 years ago the present owners bought it for a song, it was twisting in the wind. He jacked it, excavated a basement under most of it, poured footings and put it on a block foundation. In this area he put it on a block crawlspace. The footings sit on decomposed granite, but as you can see in the last shot it's still got a good bit of composure about it. The hard rock has an allowable bearing capacity of 12,000psf but its' ultimate is quite a bit higher. As an aside the Dexpan puts out 18,000psi when it swells. where you see black tar in the background is a full depth wall then it switches to about a 4' wall. The present idea is that we'll lay back the dig at a 45 from full depth up to the footings under the crawl wall and then remove that 4' at a time pouring footings and stemwalls up to the crawlspace footing. We'll drive rebar into the unexcavated section to tie into as we work our way around. The footing will act as a simple beam for that short span, bearing on the existing work on the left and the virgin "soil" on the right in the pic above. It'll turn a corner and return about 20' back to the basement on our far right, same scenario, we'll meet in the corner. There is a slab outside so we're going to excavate neatly under the existing block wall flush to the outside, mix rich and pour against the bank with a form on the inside. The last bit we will probably mix stiff and pack rather than pour. Then saw and grind the interior projection of the existing footing. Piece of cake  ... and kind of why I stress getting the foundation right to begin with, it ain't cheap or easy to go back under there.

There are warnings but so far no mishaps and a whole lot better than explosives under there. Just following the instructions and youtubes to the letter. I had read about this some years ago but never had the need. We just ordered about 90 more pounds, if there's any left I said I'd buy it, there is a real annoying rock on my driveway that's folded back a number of mirrors.

[flyingvan]

This looks very, very similar to our subterranean guest room under our home......Part of the stemwall footing had washed out before I re-directed surface flashflood drainage, and even a minor rainfall would get the basement damp.   The livingroom floor above was spanned too far and bounced a bit.



    Dunno if any of this would apply in your case...I poured a footing just in from the existing wall, maybe 4' deeper.  Then ripped PT down to 2x2, and drove galvanized screws poking out the back side, and had them rest on the footing and screwed the other ends into the livingroom floor joists.  Then screwed melamine panels into the 2x2's and poured concrete behind them to make slip forms.  When the concrete set I just slid the melamine up to the next level.  It was cool because the 2x2's gave me something to nail the siding into and it decreased the span.

    The one massive boulder that would never have made it out the window, I just dug a deeper hole and tipped it in.

[Don_P]

  Thanks, excellent plan, a little modification around the existing crawlspace footing, I love it!

[flyingvan]

Lemme know if you want more pictures...That 'little modification' also involved digging out 14 yards of dirt and carrying out the little hole that's now the window, with two 5 gallon buckets.   I thought getting all the concrete poured before cutting the doorway into the existing basement was a good idea.

[Don_P]

Happily we can walk across the existing basement to a truck backed up to the door. we can get 22 buckets in the back of the truck then drive down to where we're dumping. I haven't bothered to measure the quantity we're moving yet... maybe I shouldn't  Took a lighter day yesterday, a friend dropped off a load of 30 logs, we had to drop them at a neighbors place, the mud at the mill probably would have eaten a log truck, so I shuttled all day yesterday. Unfortunately the tractor starter made a horrible noise and the back is knocked loose so I left it running all day while we worked. Just got part of the garden limed and tilled before the rain... off to remove a starter. Looks like $167 online... I'm hoping I can get it rebuilt and converted to 12 volt if it isn't totally trashed. Always something!

[rick91351]

I did 12 yard in two buckets from our house in town to make it a full basement.  I was young and dumb.......    I kept those two buckets around for a long time as a reminder so if I had another hair brained idea I just had to walk out to the little one car detached garage and pick one of them up.....  You know that was before plastic five gallon buckets kids.  Yep they were made out of metal..........

[Don_P]

TGIF! 42 yards... boy am I pooped. My helper was off at the end of the day to go climb up on a roof to work on a chimney cap, he'll do well, ah to be half my age again  . Made the mistake today of looking up. They didn't support one end of the floor girder on enough bearing for the weight above, it's crushing. We'll need to get a better support under it. Happily my new tractor starter was here when I got home and she fired right up with no ominous sounds. I'm paid up for a conference tomorrow but it's going to be pretty and those logs, they've just sat there like logs on a bump...

[MountainDon]

Did the new starter come in 12 volts?


What's the plan for a new and better girder support?

[Don_P]

The new starter is a 6 Volt and I am running 12 volts now. The high tension lines run through a ballast resistor. When I converted it I was told it was no big deal to run the starter on 12 volts because the starter is used in such short bursts, I dunno. I had jumped the old one using 12V vehicles for over 20 years before converting it. I'm assuming the failure was just metal fatigue but again, not sure.

We're going to jack the girder just a little and slip in a 6x8 or 8x8 oak post to support the girder and also act as a block wall end cap for the exposed end of the block wall that the girder rests on. Mowers and a Gravely do manuever around under there. we'll probably put steel caps on the oak to isolate it from the floor and to form a saddle for the girder. We live much heavier than our ancestors... well, and we are heavier ourselves. We're going to remove the spongy undesized, overnotched and powderpost eaten floor joists, build frame walls on the new basement floor over spread footings, the slightly shorter frame walls will allow us to replace the floor in 2x10's on tight centers vs the 2x8's on wide spacing. The building is balloon framed so the studs are on the sills which allows us to remove the floor without disturbing the rest of the structure. I'll probably do it in phases to preserve lateral support on the basement walls as we go. The real load paths in these old beasts can be difficult to really nail down.

[rick91351]

I converted over a IH Super C to 12 volt.  But was warned also convert over the lights as well.  I never did.  Shortly after that the clutch went out and I so did not want to 'breaker in to'.  Now about fifteen years later that might make a good winter project.   

I talked to my miner friend about your rock breaking experience.  He says he has some in his powder house but never has used it yet.  But your experience has him wondering again.  He and his pardner are going back under ground this year.  Says last year for that.  Too labor intensive for old guys.         

[MountainDon]

The new starter is a 6 Volt and I am running 12 volts now. The high tension lines run through a ballast resistor. When I converted it I was told it was no big deal to run the starter on 12 volts because the starter is used in such short bursts, I dunno. I had jumped the old one using 12V vehicles for over 20 years before converting it. I'm assuming the failure was just metal fatigue but again, not sure.

Back in the days before cars were simpler and did not have any computers, etc., I worked in a service station part time in high school. The guy had a multi voltage booster setup for starting cars in winter. 6, 12 and 24 volts were available at the click of a switch. Old 6 volt cars that were stubborn started real quick on 12 volts at minus 30 F; ditto 12 volt cars on 24 volts. They just needed a second or two to spin 'em up. The short term use never caused any problems that could be seen at the time. But like you say over the long term who knows. I suspect you will get many years out of it.

[Patrick]

I did something like that 2 5 gallon buckets at a time 60 yards total I would dump it outside then get a dumpster when I had enough to fill the dumpster I excavated half the area then started at the house tying into the footing and pouring 3 foot sections and I kept the forms about 6" proud and 6" higher than the existing stem wall to deter water intrusion been perfect last 6 years. I ran the wall from the house until 3 feet from the corner and then started at the center of the back wall until I was 3 feet from the corner and then poured the corner in one shot then I repeated on the other side worked perfect. Wife never thought I would finish it. Took me under 8 months start to a finished play room for the kids.

[Don_P]

I was pm'ing with Rick the other night and he asked for a pic of what I was up to... well about 35 feet 
we're out of the basement on the job, the new bedroom and laundry room should be moved back into this week and we've been working on the roof. It is terne metal shingles in an irreplaceable size and pattern, about 95 years old. We rented a 65' articulated lift and called in a sandblaster to remove the old flaking paint and get down to a sound base. Many of the shingles were in bad shape. A friend of mine did the last repaint 12 years ago and fiberglassed many bad places. We did the same, repairing or replacing any of his patches that had let go and doing many, many more as the rust worms have not slept. We then primed and are in the process of repainting. The top coat is about half done, I should finish up midweek and we'll then drop down and begin repainting the house, using the lift to hit the high work until they come for it at the end of next week. If the site allows these are very handy machines. I had done the terracing around this house some years ago and it has good access pretty much all around. With a bit of jockeying around we are able to reach the entire roof. Expensive but much faster and safer than trying to scaffold the whole thing.



I visited the next job last night, supporting a 100 year old farmhouse and installing a basement underneath, the existing foundation is crumbling under it, part of the house is on the ground and rotting ... back to the dungeon 

[rick91351]

WOW wished I was around for your next venture.  I use to sort of do that on the side or help put or reput basements under existing houses after I went to work for the railroad.

BTW it is a good idea to have someone on the ground when you have a man lift or such.  In underground mining some times they are called him a shifter.  Just in case something goes haywire.  I was up nailing battens one time and went to move the basket only thing it would respond to was up.  NO NO Rick does not like up send Rick down....  Nope Rick was up.  Had to wait for Ellen to get in ear shot.  Then try and tell her on the main control panel what to do as if I could remember it all.   AND FOR GOD SAKE DO NOT HIT THE STIFF LEG TOGGLE SWITCH BY MISTAKE!!!.

Okay but what is the stiff leg toggle switch.

OH MY GOD I'M GOING TO DIE......

She was able to get control down there, and brought me down.  I think I fell at her feet crying.            

[rick91351]

Were terne metal shingles popular in your area?  I know of only one building and it is the old Forestry Offices in Boise that used them.  The state engineers a while back inspected it and said pretty much no problems in the hundred plus year old roof.  Looks like to me you would have a lot of electrolysis going on.     

[Don_P]

There are some terne metal roofs locally but I wouldn't say it was popular. I imagine the coating over the steel probably finished landing in the flower bed decades ago. I worked on an old log home several years ago that had the roof that came off one of the old courthouses when it was torn down at the turn of the 20th century. It was solid zinc shingles and finally failing a century later. It was at least a half century old when they were removed from the old courthouse. I've seen zinc shingles on the net so they are still available in some patterns, a good material. I think this was the last time we can kick the can down the road on this roof, or rather I lost the discussion on replacing it this time. The guys I'm working with that have been doing the heavy lifting on the job are about the same age as the next generation that will inherit the home. I've told them to start researching and find appropriate replacements. With any luck it will be their job next time. 

[DaveOrr]

Up where I live we use explosives for the job of rock breaking.   

http://www.youtube.com/watch?v=PJbrD5OuUe8