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New types of explosives changing the demolition game

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At first blush, the concept of finesse and demolition using explosive forces may not sound like a workable marriage but it's proving to be a match made in heaven for some jobs.

At first blush, the concept of finesse and demolition using explosive forces may not sound like a workable marriage but it's proving to be a match made in heaven for some jobs.

The demolition industry isn’t about to give up the heavy equipment — or the more recent addition of walk-beside robots — to tear, shear and smack down structures but as with all tools they have their limitations.

Using explosives is another option, of course, but handling dynamite requires special skills, certification, permits, careful handling and specific storage. Then there’s the problem of working in confined spaces or densely populated urban settings.

There are other solutions, however, which are a happy medium and an alternative like materials that have a slower burn rate and thus aren’t classified like dynamite and require no permits or certification or are based on gases which expand rapidly.

There is even a grout-like material which expands rapidly and forces concrete or stone to shear.

Microblaster by EZbreak is a product distributed in Canada by geologist Brad Wilson out of Kingston, Ont., whose main business is selling gemstone.

Microblaster takes just a 5/16th of an inch hole, usually 2.5 inches deep though the maximum working depth is up to 12 inches, and is also classified as a “propellant” rather than an explosive, so no special permits or certificates are required.

“My friend in West Virginia developed it and I helped get the bugs out of it. I use it in my prospecting for gems and I sell it in Canada,” said Wilson.

“It’s a gas producing cartridge which is similar to ammunition except it just has paper and no projectile.”

Each cartridge has about a gram of material with a detonator system which is either actuated with a string pull or by compressed air.

He said there’s no hard and fast rule for set up, though the harder the rock , like granite, the more effective it is. Porous material like concrete tends to absorb some of the energy released.

Still, he said, he’s used it to break up concrete sidewalk within a couple of feet of windows with no adverse effect while one client used it to take out a concrete support column in the basement of a house.

“They shored it up either side, took out the column, moved it and then installed a new one,” he said. “There’s virtually no fly rock produced.”

Getting the attention of the construction industry, which tends to do things the way its always done them has been somewhat frustrating, he explained.

“They will go at it with a backhoe and a jackhammer with all that noise and dust for hours where as I could just do it in half and hour,” he said though he is building a word of mouth business in the sector.

“They don’t seem to want to try something new. I guess they’ve already invested in all that heavy equipment.”

Similarly, Malcolm Reading whose Black Rock Trading distributed Boulder Blaster in Canada and parts of the U.S. says his product is neither an expanding epoxy nor an explosive.

“It’s not blasting and not expanding. You drill a hole in the rock or concrete fill it with water then put in the cartridge,” he said. “It goes bang and sets up a pressure wave which splits the rock but there’s no vibration passed along.”

The cartridge shoots off a high pressure pocket of air and the energy passes to the water. Since a liquid cannot be compressed, that energy then expands against the stone which accordingly cracks and splits.

A line of holes with sequenced “bangs” will cause stone — concrete or granite — to crack and shear along that line and it makes for a highly controlled event.

“You don’t need any special certificates and you can be using Boulder Blaster after a couple of hours of training,” he said.

Reading imports the cartridges from South Africa where they were created as part of a diversification strategy of a small arms maker.

It’s ideal for confined spaces because there are no issues with toxic fumes and no need for ventilation.

He also offers another line or products under the AutoStem line which is for larger projects.

“It’s not an explosive either though it goes bang and breaks rocks,” he said. AutoStem is also a cartridge which reacts in a process of deflagration as opposed to detonation, he said, the difference being that it has a slow burn rate compared to TNT or other high explosives.

They’ve just been launched in Canada and the cartridges have up to 500 or 600 grams of powder each which can be triggered by a simple pull cord.

They can also be configured for a simultaneous explosion.

“You can use them in mining, quarrying and construction and in Europe they took down a chimney stack,” he said. “Again, there’s little ventilation required.”

The size of the hole is dependent on the size of the cartridge. Boulder Buster takes a 1.5 inch hole while AutoStem goes up to 2.5 inches. Boulder Buster needs to penetrate about 75 per cent of the stone while AutoStem needs about a 67 per cent penetration.

“The advantage of AutoStem over dynamite is also that you don’t have to stem it in,” he said referring to the practice of inserting the explosive then adding sand or aggregate and then tamping it down which is labour intensive.

“As the name suggests it stems automatically so that saves you time and money.”

The product can also be used underwater, he said.

by Ian Harvey

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