Bustin' Up Boulders

[3RRL]

I've read a lot about guys dealing with large rocks and boulders lately. In most of those threads, there is a reference to a liquid solution which you pour into drilled holes and it splits the rocks. Well, I got to experience it first hand with some boulders I had to split this weekend.

Some of you may remember earlier this year where I had to repair a tricky turn on my dirt road. I had to cut down one side and build up the other in order to bank it correctly. I got the job done, but in doing so, I exposed the tops of 2 rocks which I could not shave down with the boxblade or FEL. They stuck up about 5 or 6 inches, so every time we made that turn it was a real good bump. I decided to get rid of them by trying to dig them out at first, but soon realized in order to get around them, I'd have a huge area dug out on that turn. Plus the road was rock hard.
So I decided to go another route.

 

[tommu56]

Rob I feel your pain!

The dexpan needs some place to displace rock too.

I though about using it but would have to drill horozonally then figure how to get it in and keep it there.

I used pins and feathers to get my rock out of the way.

tommu

 

[3RRL]

Even though it was hot in the mid-nineties, I decided to drill a bunch of holes into the rocks and try to bust them up with a 20 pound sledge hammer. About 2 years ago I bought a 1" hammer drill at Harbor Freight for 49 bucks, but have never used it. I figured it was a really good deal and could come in handy someday... for that price anyway.
So I broke it out and used the largest masonry drill, a 3/4" by 8" long. There was a longer one, about 12" long, but I wanted to save it for later. Man, it is harder than heck to drill into solid stone like that. Where I hit quartzite in the granite boulders, it took up to 10 minutes to drill some of the holes. I was whooped after drilling about 20 of them in various places, trying to get them so when I whacked the rock, parts of it would split off. All I wanted to do was knock off the tops.
But no luck as the sledge hammer just bounced off the rock when I struck it.
This was really hard work drilling them holes and then swinging that sledge. I was already tired after toting all that other stuff up to the jobsite.

 

[3RRL]

Tom, PAIN, you got that right!

Realizing I wasn't making a dent swinging that sledge, I first decided to go at it with the backhoe again, but my small backhoe had a real problem getting past the smaller granite rocks that surrounded the larger ones... when that didn't work, I almost gave up right then. It was getting hotter and hotter too.

But then I remembered the Dexpan or Bustar or Bentonomit ...all different name brands for basically the same thing. I called the local Mercantile and they knew that only in Fresno could it be found. That's a 2 hour drive for me, so I asked the to ask others in their store to see if anybody else knew about this stuff. Well, lucky for me one guy in the store said a place in Visalia carried stuff like that, 45 minutes away. However, my contractor was meeting me at the property in a couple hours, so I called him and asked if he could swing by and pick some up for me and he obliged. That was great.

Knowing that, I started drilling more holes into the rock at about 45 degree angles so when the rock cracked, it would pop the tops off ...that's all I wanted. I ended up drilling about 20 more holes at least 6" to 8" deep. As a matter of fact, I busted the 8" drill bit and used the 12" long one hoping it would last. I ended up with 15 to 20 holes in each of the big rocks. Whew!
You can see the enormity of the rocks, that part which was exposed.
This is the stuff we got which is much like Bustar, but a product made in Spain.

 

[3RRL]

So after we met the contractor for our preliminary walk through, I started back to work on the rocks. There were limited instruction on that 10kg pail. One thing for sure was to use it in temperatures below 90 degrees and to use chilled water (around 55 degrees) to mix it. Otherwise a "blowout" or violent eruption" would occur. Also, don't put your face by the the hole you are pouring it into in case of the latter.

I had Loretta try to find more instructions on line but the ones for this product were mostly in Spanish, which didn't help me at all. Other instuctions however, were more helpful and encouraging, and some were not. One site said to have 1-1/2" holes up to 2" diameter holes ...hahaha who in the heck was going to do that? King Kong? Then there was hole spacing etc and finally one that said 3/4" holes (which I had) were OK. As long as the depth of the hole was a minimum of 4x the diameter. Others said to blow out all the dust or it would absorb the moisture causing a premature blowout or not enough down deep in the hole. Last was it would take somewhere between 12 to 32 hours for it to work, and I was pressed for time since the fire truck would be up on Monday to inspect the road and the homesite.

So I decided to wait until it cooled down below ninety degrees to mix the stuff up and then try it. I mixed it up and poured in about 7pm and got there the next morning to see if it worked ... and it did!!
Man, was I happy!

 

[3RRL]

Now to get to work with the tractor to backfill and compact the hole.
Here is a view showing how the tops of those boulders stuck out above the grade, and then after I backfilled and graded the turn.
I also made the turn a little wider by cutting the left side back.
Next time up I'll fill and compact some more to get an even better finish on the turn.

 

[GuglioLS]

Rob,

Nothing like breaking rocks in the hot sun huh?. Sheesh what a PITA. Interesting stuff that Bustar, what is it made out of anyway? It must first dry at the end exposed to air, then expand internally? Is that how it works? I noticed it's not cheap either, I suppose it was worth it for what you were faced with. Would that H/F hammer drill go to 1.5" dia? I need to do something similar with some "expanding material" that has a velocity of about 36K FPS.

Larry

 

[RedDirt]

Your normal thorough job with beautiful results...what else would we expect? I'll bet hanging on to that drill you'd just be thinking about the next batch of photos you needed to take for the documentation so you could rest . Just reading your story make my arms ache.

That HF drill goes on the "A" list if it lasted the job!

I'm curious too about the compound you used. Does it work on the expansion principle? Do you know the key ingredient? I'm lucky here not to have any rocks here to speak of but I have broken boulders in the past and will likely meet a few more in the future.

 

[Egon]

That is a job well done and documented.

 

[3RRL]

Yeah, that was pretty hard work.
It was surprisingly tough to hold onto that heavy hammer drill for that long. Loretta wanted to try so she started one hole and gave up after getting about 2" deep. But it was worth it to me. I take a lot of pride grading and keeping my dirt roads smooth, and those rocks popping out like that drove me crazy. Every time I dragged my boxblade over them it would jump up and I'd lose all the little rocks I'd collected. Then I'd have to get off the tractor to pick them up and toss them off the road. Now I feel better about it.

I'm not sure what the active ingredient(s) are in that compound? I presume it get solid pretty quick and it keeps expanding for a long time. The instructions on the Internet were all pretty specific about that though. It was almost like cement when mixed up. The hammer drill worked good enough to do that job and I was happy about that. I don't know how large of a bit it can swing though. I imagine 1" is the limit?

We saved the rest of the stuff in a sealed plastic bag in a cool, dry place as instructed. I'm sure now there will be some other applications for it around the property. I'm glad I read about here on TBN, or I would still be up there trying something different or maybe have to live with the rocks? One video I wanted to post was when I was blowing out all the residual dust out of the drilled holes. It was pretty cool, but Loretta left her camera at camp. So when she gets it back, I'll post it. I made a long tube for the air gun to get to the bottom of the holes, and when I blew out the dust it looked like a geyser!