# Breaking Rocks



## velvetfoot (Jun 29, 2012)

I have some big (who knows how big) rocks embedded in a couple of places, like in the lawn.  I've tried breaking them up with a sledge and a bunch of protective stuff on, but no luck.  Would an electric jackhammer, like the kind you rent, work on something like that?  I've never used one.  Thanks.


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## peakbagger (Jun 29, 2012)

"Slow dynamite" works pretty well. http://www.demolitiontechnologies.com/expanding-grout-technical-info You still need to rent something to drill holes in the rock but once the holes are in you pour it in and wait 36 hours. It does require a "leap of faith" the first time you use it, but it works as long as you follow the instructions on hole placement I used to work in a papermill with a lot of old foundations and ledge and this was highly preferable to blasting. http://www.concreteconstruction.net/repair/demolition-the-easy-way.aspx

The alternative is feathering and wedging like masons do but the slow dynamite is a lot easier.


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## ScotO (Jun 29, 2012)

Dig a trench around the rock and rent a small jackhammer.  Our local tool rental place has two-cycle jackhammers and I rented one last year to remove old steps and some large boulders from our front yard.  Took some time, but word really well.


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## velvetfoot (Jun 29, 2012)

Thanks. I'll look into both.


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## Vic99 (Jun 29, 2012)

Dang.  Could have used this thread 2 weeks ago when I was building stone stairs down a slope to a river.  Good luck.


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## begreen (Jun 29, 2012)

Ha! We had this little outcropping of rocks that I always had to mow around. It was just a little 18" by 12" patch. I tried digging them out, but never succeeded. Then, when we had the garden and greenhouse area leveled and terraformed we needed rock for the retaining wall. I told the excavator guy about the little outcropping and he dug them up.

This is what he found! It makes a great seat and table. I could not have found a rock that flat.


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## velvetfoot (Jun 29, 2012)

I'm sure mine are similar in iceberg type dimensions.


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## MasterMech (Jun 30, 2012)

If those rocks turn out to be large, look into a day or half day rental of a mini-excavator with a hydraulic breaker.  Usually runs you less than $300 but will break a lot more rock than any hand-held hammer.  Easier on the body too.


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## MasterMech (Jun 30, 2012)

begreen said:


> Ha! We had this little outcropping of rocks that I always had to mow around. It was just a little 18" by 12" patch. I tried digging them out, but never succeeded. Then, when we had the garden and greenhouse area leveled and terraformed we needed rock for the retaining wall. I told the excavator guy about the little outcropping and he dug them up.
> 
> This is what he found! It makes a great seat and table. I could not have found a rock that flat.
> 
> View attachment 69380


Looks like it may have been even bigger at one time and sheared a chunk off creating your "table". Many a time farmers have gone after a stubborn rock in their fields and gotten more than they bargained for.


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## begreen (Jun 30, 2012)

I suspect you're right. In the background you can see another big rock that he found buried while he was poking around. This one came out of the driveway. Again it was just a little nuisance bump that I couldn't remove.


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## velvetfoot (Jun 30, 2012)

I'd prefer to just "take a little off the top".


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## Gary_602z (Jun 30, 2012)

I was told my Great Grandfather would build a fire around big boulders (How hot or long I don't know) and then throw water on them.

Gary


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## Ehouse (Jul 1, 2012)

Examine the rock.  if it is sedimentary, (layered) try wedge and sledge.

Ehouse


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## homebrewz (Jul 1, 2012)

Any or all of the suggestions listed here will probably work. Based on your location, I'm guessing its argillite, which is sort of a shale/mudstone that has undergone low grade metamorphism. That's what they're mining in the quarry at West Sand Lake. It might break up easy enough. Definitely use the proper protection if you're going to out there and start whacking it with hand tools. Good luck.


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## MasterMech (Jul 2, 2012)

Did I mention that if you have a mini (or not so mini, ) excavator, even temporarily, your friends/neighbors will _bring you beer?!   _It's incredible.   Usually the good stuff too.


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## btuser (Jul 2, 2012)

Here in NH we've got a lot of granite, and it's hard stuff.  Really difficult to break up a boulder when it's supported on all sides by compacted earth.  I just recently tried the Dexpan stuff and have to say I was impressed.  It took longer than we thought but we were able to blow (slow-blow) a wedge out of a large boulder made of some of the hardest rock I've ever drilled.  1 1/2" x 16" hole with a good bit and a Hitatchi hammer drill (you know, the ugly one) was close to 1 hr per hole and I had to drill 6 of them.  Thank God for books on tape.

I drilled in at a 45 degree angle in a v-pattern, filled the holes and 2 days later the wedge had split.  Another 2 hours to completely break it free but I'd say we pulled a 400lb piece of rock out of the way, enough to burry the electrical conduit another 2 feet to meet code.

Wedges/feathers can work wonders, but if you're going to split big rocks you need big wedges/feathers and that can get pricey real quick.  If we'd been able to move the rock at all (we had a full sized backhoe on site) it would have made more sense to burry it but it was right up against an electrical pole.  If we'd dug it up the pole would have fallen in the hole.  If I did it again I would get a bigger drill.  I'm getting tired of fighting with rocks.


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## thewoodlands (Jul 2, 2012)

velvetfoot said:


> I have some big (who knows how big) rocks embedded in a couple of places, like in the lawn. I've tried breaking them up with a sledge and a bunch of protective stuff on, but no luck. Would an electric jackhammer, like the kind you rent, work on something like that? I've never used one. Thanks.


https://trowandholden.com/store/agora.cgi?product=cat5


zap


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## btuser (Jul 2, 2012)

Wedges/feathers work better the harder the stone. They don't work as great when trying to split a burried rock. You can dig a trench around it and drill horizontal to "pop the top" but I've not always had the best luck trying that. Then again I had little wedges for doing granite like curb stone and slabs, not the right size for the job. 

If you only need to go down a few inches for loam you could cut/score the rock a few inches deep with a diamond saw/grinder, then break it down with a sledge. It would be slow but I've done this to even out the face of stone when I'm stacking I just need to take a corner off. Not really that effective or efficient but it might be an option if it's only a little bit and you've already got the tools.


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## lukem (Jul 2, 2012)

We don't have to deal with too many rocks in these parts, but had a nasty one on a landscape job once....right where we wanted to put a retaining wall.  The only tools we had available were a Stihl concrete saw a sledge.

We cut the rock as deep as we could go about 4" from the edge...and gave it a couple whacks to slab off some...and repeat...and repeat...and repeat.  It took a lot of cutting, but eventually we got enough of the rock out of the way.  Not saying this is the best way, but it did work.  I'm not sure what type of rock this was but it was kind soft (as far as rock goes)...def not granite....about the same hardness as the pavers we cut with it...not sure if it would be to hard on it cutting "real rock"...so be advised.

If you are just trying to get the rock below grade this might let you take the top off the rock and leave the rest lay.

The smaller electric or gas hammers work best on concrete slabs because there is enough "give"  under the slab...makes for a little bit of a soft spot....I think they would have a hard time with compacted earth on all sides....but I've never tried it either.


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## woodgeek (Jul 2, 2012)

peakbagger said:


> "Slow dynamite" works pretty well. http://www.demolitiontechnologies.com/expanding-grout-technical-info You still need to rent something to drill holes in the rock but once the holes are in you pour it in and wait 36 hours. It does require a "leap of faith" the first time you use it, but it works as long as you follow the instructions on hole placement I used to work in a papermill with a lot of old foundations and ledge and this was highly preferable to blasting. http://www.concreteconstruction.net/repair/demolition-the-easy-way.aspx
> 
> The alternative is feathering and wedging like masons do but the slow dynamite is a lot easier.


 
My rock is ledge that ties into a bedrock slab that underlies my entire property....that stretches halfway to the mantle....and that my foundation was blasted out of.  Where can I get the slow dynamite stuff??


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## backpack09 (Jul 3, 2012)

Hoe Ram.
That is all.


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## velvetfoot (Jul 3, 2012)

I might try those wedges - have to buy them first. 
Not sure about bringing in any heavy equipment though.
Might just cover them with some more dirt.


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## btuser (Jul 5, 2012)

I split a 2-3' boulder one time into a few pieces so I could move it around.  My little wedges did little good so I drilled some 3/4" holes about 16" deep and about 8-12" apart, the got some $2 round point (a little over 1" at their thickest point)chissels form the local china tool shop.  I pounded them in with a sledge and the rock split up just as you'd expect, but a lot more work than wedges/feathers.  A good set of large wedges can get pretty pricey and they're almost non-existent in the used market, but they will out live you and you're grand kids.  My guess is they either get lost in the debris or thrown away by people who don't know what they're for.


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## save$ (Jul 5, 2012)

Sometimes it is easier to dig a bigger hole next to the rock and push it over into the hole.   Let it rest a little further down in the ground.  The last battle I had with big rocks  was when I was prepping my yard for hot top.  There was a crew working on the street.  I gave them a few buks.  In 15 minutes, they removed 6 rocks about the size of ice chests that had been a problem for years.   Should I ever want another big rock moved, I'll hire it done!


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## MasterMech (Jul 5, 2012)

save$ said:


> ... The last battle I had with big rocks was when I was prepping my yard for hot top....


 

Keep talking like that and the rest of the country is going to think you black-topped your lawn. 

My wife's family is from the Boston area. They pahk dah cah in dah yahd too. 

My family is from southern IN and I reckon y'all never heard of a driveway.


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## peakbagger (Jul 5, 2012)

Amazing what you can buy on Amazon

http://www.amazon.com/Dexpan-Controlled-Demolition-Excavating-Alternative/dp/B000BRPHQ4

I used to use something called Brightstar? but I cant locate it with quick search.

Old timers used to drill the holes, fill them with water and wait for a really cold night. A lot of the really old logging roads that are used for hiking trails will have boulders that had thier top split off. I expect most of the time they used blasting powder.

I recently saw some photos of the results of this at this link https://plus.google.com/photos/113614445036278454829/albums/5760750473132962129?banner=pwa

By the way check out the later pages of this photo album and check out the interesting natural rock formations ( and the fools who climb them  !)


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## Thistle (Jul 5, 2012)

lukem said:


> We don't have to deal with too many rocks in these parts, but had a nasty one on a landscape job once....right where we wanted to put a retaining wall. The only tools we had available were a Stihl concrete saw a sledge.
> 
> We cut the rock as deep as we could go about 4" from the edge...and gave it a couple whacks to slab off some...and repeat...and repeat...and repeat. It took a lot of cutting, but eventually we got enough of the rock out of the way. Not saying this is the best way, but it did work. I'm not sure what type of rock this was but it was kind soft (as far as rock goes)...def not granite....about the same hardness as the pavers we cut with it...not sure if it would be to hard on it cutting "real rock"...so be advised.
> 
> ...


 
Probably Bedford Limestone,very plentiful in most of your state,shipped to all states & several countries for over 150 yrs.


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## lukem (Jul 5, 2012)

Thistle said:


> Probably Bedford Limestone,very plentiful in most of your state,shipped to all states & several countries for over 150 yrs.



Not bedford stone....although we are filthy with that a little south of me.


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