[TowerTalk] breaking up boulder

[John Lyles]

In addition to exothermic chemical reactions that expand in holes to crack rocks, there are some more proven techniques that 
cave explorers use when opening passages and moving rocks. Get a decent SDS+ bit and hammer/drill and put a number of 5/16 to 3/8 inch holes about 6 inches deep in a line. Then use Bull Pins, they are used
by steel workers to line up bolt holes on beams. These tapered steel pins cost a few bucks, and you tap a line of them into the holes, and as they go deeper they expand each hole, until the rock cracks. I have done this 
dozens of times with boulders weighing many hundreds of pounds with success. The more expensive way is feathers and wedges, small metal parts that use 5/16 inch diam holes about 3 inches deep. But they don't 
crack rocks that are very large, so you end up shaving off flakes at a time. They are about $5 a set, so if you need a line of them to crack a big rock, it may cost $50. The next level up in fun is called microblasting (also rock shaving), 
there are commercial products you can investigate on your own for this. You still need the SDS drill for all of these techniquies. The bull pins are by far the easiest and cheapest method to reduce a large boulder into many smaller ones. 
Eventually you use a comealone or pry bar steel to move them out of your way. Most of these tricks require that you excavate around the sides enough for expansion and removal. 

73
John 
K5PRO