I'm on a job at the moment operating a 12 meter placement boom on a creeping shutter. It is going up 20 floors in all, at 4 above ground at moment. Blowing out in evening is getting messy. I was wondering if it was possible to push the concrete out with water from boom into skip. is there a high risk of blocking due to segregation ? The scissors on the shutter is my main concern.

If you have "good" contact with the ground you won't have many problems just with air (tip to ground).As for what you propose the old adage,ya ain't seen nothin yet applies.Your talking a biblical fiasco.

When you get within xxx yards have the ground loosen the mix a bit.I have no idea if your blowing back into a mixer,candy cane,diverter valve.By this time at #4 you should already be dialed in,I can't wait till #20.Perhaps you have someone already within your organization that is familar with blowdown.I know there are some good pic's on this list somewhere.

paddy,

get your pipeline organised with a shut off valve and t/y piece so you can blow backwards into a skip or a truck mixer. you shouldnt get much mess at all. Wouldnt recomend water washin if you are try to save on mess.

LOL. If you think you have a mess now! Try water washing.

Can you send me video and film of what your doing, i wont post them if you dont want me to. send them to todd@concretepumpimping.com

please i would really like to see what your doing.

Thanks for your help. I've only been operating mobiles until now, new to placement booms. First few floors we blew up with boom into concrete skip but its getting too high for that. Pump is on side of street so was trying to avoid blowing down. Got 4m3 steel skip and welded pipe coupling to side for blowing into.

  Hey paddy, you can blow that little boom out with water "pressure" without having to actually having "pump" any water?

 I did it once with a 32m placing boom on a Saturday with no back up to call for help, the air compressor ran out of fuel just as we started blow down! I considered water washing as a last resort just to save the pipe but it would've rocked off down in the basement. There was great water pressure so I strung some hose up to the boom and pushed 2 sponges through the system with water pressure. But afterwards the pipe is full of water, but its clean water?

For blowing downwards get yourself one of them fully enclosed skips, like they use for asbestos etc, weld the pipe to the side then you have no worries,

Thanks again but the problem is not cleaning out the boom,it's the pipes that run down 3 floors onto basement slab across then up and the amount of pressure involved when your working with people who don't comprehend the danger. The new skip with the pipe fitting and lid works fine but my workmates are disappointed they would rather make as loud a bang, scatter concrete as wide and send a sponge ball as far as possible. I knew suggesting water washing would sound stupid to some of you but if it would work having lots of water around afterwards would be a small price.

Get the site agent , ganger and crew etc and have yourself a tool box talk on what you are doing ,use your method statement and risk assesment, then maybe they will have an idea.

or alternatively get sponge bob on the case.........