Expansive Demolition Agents

The expansive demolition agent is a cementitious powder. Using a drill with a mixing attachment, the powder is mixed in a bucket and poured or tamped into drilled holes. As the mix hardens and expands, the concrete cracks between the drilled holes. As the hairline cracks develop over the slab, they run outward into each other and grow wider, until the slab literally falls apart under an expansive force that can exceed 12,000 psi.

Used correctly, expansive demolition agents produce little dust or debris. The only labor involved is in drilling the holes, mixing and applying the agent, and then hauling the broken up pieces of concrete away.

One cautionary note: With expansive demolition agents involves a phenomenon known as "blow- out." This happens if the powder mix gets too hot and reacts with the water too quickly for the material to expand laterally. The result can range from a puff of smoke to a loud gunshot-like sound that can send hardened mix 30 feet into the air. Since blow-outs are unpredictable, safety procedures require workers to stay well away from the drilled holes once the mix has been poured into them. If a blow-out does occur, however, it usually has little effect on the project, since the remaining mix in the hole is usually still effective enough to crack the concrete.

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