Demolition explanation?

Question

So: two horrible old tower blocks are scheduled for demolition. They have been picking at them for months and all that's left is the concrete skeleton.

Today I noticed that round each pillar or load bearing bit of wall are wrapped things like black plastic bin liners. There are bits of blue string attached to some of them.

Are they setting it up for a big bang?

It seems odd because there's no special security, just the normal halfarsed perimeter fencing with pictures of non-existent dogs. Can they leave the place full of explosives like that? or is this some earlier, intermediate non-bangy step?

Answer 1

It sounds like you've got a bang coming your way.  

Normally, they'll drill holes in the concrete columns, insert the explosives and detonator cord (the 'blue string' you noticed) and wrap the column to contain the debris (the 'plastic bin liners').

Usually they'll mortar over the explosive charge to keep it in the hole, so it's unlikely anyone could remove it.

Security doesn't have to be too tight - mainly they'll just want to make sure no one has monkeyed with the explosives or cord and no on is in the building when they blow it.    

Answer 2

Sounds like they are almost ready to blow them down.  It can take weeks to drill all the holes for explosive charges, then a few days to load the explosives and connect the blasting cords.

I guess your bin bags are pieces of material to reduce the distance that pieces will fly and the blue cord is blasting cord.