Hey murf right on thats a good point at your last message on your "pics" topic. I know a guy who sets up to pour a wall. Everything was ok. Boom expanded and started pumping. Holly hell, the pump flipped lifting his rear axles up. What happend? Now the weight of concrete is what you should know now imagine a 42m pump stroking and full pipes with concrete. Well bad underground? lets get some answers on "How much weighs 1 cubic meter of concrete" I dont want to piss you guys away but allways when i ask guys i swear you not even 25% know it.

two point two ton

2.2 ton per meter

 So then how many cubic meters is in 42m of pipe and elbows?

question #2, What's the first thing you would do if your pump started to go?!...

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 Put it in reverse and get the mud (weight) out of the boom! It'll make a bigass mess but it might save your tip section or even keep you upright!

Thats a good idea TT, I never thought of sucking the mud back. I'm sure it would help. If if was just teetering. I believe the weight on one outrigger is equal to the total weight of the machine and concrete, in an extreme case.

Fortunatly awareness helped me.I was on a pour downtown Denver with excellent cribbing (heavy 8x8's) 52m.I was boomed flat over right front + 50'.There was a patch of unstable ground below cribbing,what really helped was not to panic.Imediatly cleared crew,boom up 3rd in which reduced the weight on pad as coming in.Was I thankfull? absolutly,move pump continue pour.

An operator that can think 100% on the run is way ahead of the game.I would rather be a live chicken than a dead duck.

For me its always thinking ahead. If yesterday it was raining the mud is soaked beneath surface. To set up the pump. You make the decision before set up. Only driving on jobsite you can see how the site is in shape. If you are not sure stop the truck step out and take a look. Try a set up if the ground dont looks sure. If the pump with all expanded boom moving up and down fast (without stressing hydraulic lines) keeps stable you can give it a try. In the case that starting pumping your outriggers going down only 1 or2 cm(1 or 2 inch)be aware on what can happen. It also can be that the ground will be packed after that, but it hasnt to. Anyhow if you notice while pumping you outriggers are going down try to get the weight opposite. Pump out or back,stop the mixerdriver to unload (Space for pumpback) fold together get a hook on hose and set up again. Or bring over some stuff to build a stable basement for the outriggers. Thats what you can do also before. There are lots of things you can be aware before and while pumping this is only a piece of what is possible.

1 cubic meter of Concrete = 2,400-2,500 Kg/m3 Based on the 45m I operate a 45 meter boom @ 5" will hold approx: 0.570 cubic meters of concrete. 0.570 /m3 = 1,367 kg or 1.506 Ton

 I've seen one sink into an abandoned heating oil tank, I've seen the ground liquify under pressure, I've seen 3'x3' square holes that were five feet deep with an outrigger pad at the bottom of them.    Sometimes they just come down and there's nothing anyone could've done to prevent that.

 Whenever I question the ground conditions at all I start unloading dunnage and bulid a nice big pad that sometimes resembles a small fishing dock. Here in the NW the ground is crap 8 months a year, I've learned that you can set up in a quagmire if you distribute the weight enough. 

I had the 45m balancing of her front axle, flat sticked over the cab on a manure tank job I did last fall, scared the loving piss out me to say the least. Despite having all my dunnage and half of the old barn under the front riggers, it held up fine till I went flat out the 2nd time around, as soon as I got right at center it started to stand up, I threw the pump in reverse and it slowly came back down to earth, went had a smoke changed my shorts, re-rigged and game on, we got it done, but I have never ever been that close to losing a pump nor would I ever wanna try that again, but even with all provisions in place, sometimes things just don't work out the way they are anticipated to and give you a reality check when you least expect it, see if your still paying attention.

Rule 1 if she starts to go: Clear the area!

TT i think your on the money there its all about disributing the weight , im a big fan of 2 sheets of from ply then long timbers follwed by shorts then the pad , build it like an egiptian pyramid , happy days!