Using a Pionjar & Bentonite to Break Boulders

The big rock you see being drilled in the picture below, was finally broken ---- using bristar! Bristar is a powder that you mix with water and pour in a drilled hole in the rock. It is sometimes called "Chinese Powder" or Bentonite. The material reacts and expands very slowly but with such force that it splits rock. I estimate that the chunk of rock that we split and broke off weighed 40,000 pounds. After pouring the material in the hole it took over two days for the bristar to fully react with enough pressure to break off the rock.

It should be noted that anytime a sizable rock needs to be broken, call the friendly folks here at Dixie U for a price quote. The rock drill pictured below is a newer Pionjar yn 120 and is gas operated and can be taken anywhere to drill holes. I currently have it for sale for $3000.00.

This method of breaking boulders is known as "plugs and feathers" or "shims and feathers". To use this device first a bore hole of a certain diameter is bored -- 1 3/8 ".  I personally use a super heavey weight portable gas powered rockdrill --- a atlas - copco pionjar YN120. This machine can bore a 3 foot deep hole in the hardest granite in 3 minutes! Using the big size wedges requires only one set for a big boulder, or a couple of sets on a big ten thousand pound rock. First you insert the feathers, these are guides or shoe-horns that have been greased to reduce friction, followed by inserting the wedge. you can orient the wedge in the direction you want the crack to run. The use of two or three sets guarantees a straight line fracture which can prove to be important when trimming a high value matrix piece. Upper picture shows the pionjar unit in use and the next picture shows a single wedge breaking a small boulder. I hope to add later some pictures showing a very large boulder that was split by using only two wedge sets (All photos courtesy of Michelle Matthews).