There are many different methods for demolishing buildings. Sometimes, it may be safer to deconstruct your building manually, but if you need it done quickly, then a controlled explosion may well be the way forward. Once you've settled on a controlled explosion, however, the next question follows. Which explosive? The specific demolition contractor you hire will likely make a recommendation, but here's a quick guide to show you what to expect.
Overground, Underground or Underwater?
The location of your project will obviously have a huge impact on which explosive is most suitable. For general overground demolitions, no specialist qualities are necessary. However, if you're working underwater, then thermite and thermate-based concoctions may be a good option; they need little oxygen to ignite. For damp overground conditions, slurry explosives and any mixtures that are nitramine-based would work, as these are both reasonably water-resistant.
If the site you're demolishing is large or made of extremely dense material, you will likely need a very high-pressure, high-brisance explosion. Nitramine-based mixtures are suitable in this case; equally, gelatinous explosives often have good bulk strength, which could be helpful in increasing a detonation's effect.
Size and Strength of Explosion
While most explosive mixtures are designed to be far-reaching and powerful, this may not be suitable for your project. If that's the case and you're looking for a smaller, more focused explosion, then emulsion-based explosives may suit. These can be weakened and strengthened to generate a wide range of strengths and pressures.
If you're running your project on a budget, then choosing something that's widely available may work for you. Of course, it will need to be safe for use in the conditions you're working with, but something like ANFO, or ammonium nitrate/fuel oil, is quite versatile, as well as cheap. It is not water-resistant and doesn't have a very high pressure—nor is it very fast, nor does it have a big radius. However, if you're willing to take the time and conduct several smaller explosions instead of one big one, this may be a good option for you.
Again, you'll want to speak to the contractor that you're hiring before making any purchases of materials, and indeed many of them may be unavailable to you—but it's good to be conversant in what kind of qualities and functions you'll be looking for in your explosive material, and what kind of limitations your specific site and project may cause. To learn more, contact an explosive supplier.