Concrete Pump?

[dfkrug]

I owned and operated a concrete pump for a few years. A Schwing 36M boom pump truck.
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A Very Brief History of Concrete Pumps and What Monolithic Recommends

SPEEDY:

Good info. Interesting link.

Don't most of the boom-truck pumps (like your Schwing) and grout pumps
use dual (or more) hydraulic cylinders to pump concrete? Or are some
of them squeeze pumps (peristaltic)?

In my brief stint in the ICF biz, I met many pump operators or
owner/operators....most knew little about their pumps. Around here many
have been spoiled by the common use of 3/8" aggregate mixes, so it is
hard to find those willing to pump the 3/4-rock mixes. The argument is
the latter is harder on the pumps. They were mostly using 3" hoses, so I
have been skeptical. Any truth in that, in your opinion?

 

[speedy67]

Yes, all 'concrete' pumps use twin cylinder 'positive displacement' pumps. Altough here are some boom pumps that have a peristaltic squeeze pump, but they are far from common in North America: Concrete Squeeze Pumps - Keep on Pumpin... Concrete Pumps, Chelsea PTO, CIFA, concrete pumps for sale, CIFA USA, CIFA Boom Pumps, Concrete Pumping, Squeeze Pumps, Concrete Pumps for Sale

Like I said before, the main reason to use 3/4" aggregate is to cut down on the expense of the cement powder. This also reduces the water demand and therefore the shrinkage cracking problem. Did you realize that simply increasing the cement content, therefore increasing the ultimate (compressive) strength of a mix will tend to result in more shrinkage cracks? Contrary to popular belief, concrete doesn't need expansion joints, it needs control joints, which allow you to introduce a point of weakness where the crack will 'tend' to appear.

With a 3/8" mix a 3" hose is a great safety factor, but it's also overkill. A wise pumper once told me 3" hose is too big for small mix and too small for big mix. 2 1/2" is best for 3/8 and 1/2" mix, lighter, much easier to handle. 25' lengths are easily carried by one man. (empty of course) You can pull it around much easier and, in fact, hold it on your shoulder without undo strain.

As for whether a 3/4" mix is harder on a pump than 3/8"...I'd tend to think that if they were both crushed stone, that the 3/8" would tend to wear more, owing to the fact that there would be more individual sharp edges of stones to scrape on all the wear surfaces....Just my own personal theory....

 

[dfkrug]

Like I said before, the main reason to use 3/4" aggregate is to cut down on the expense of the cement powder. This also reduces the water demand and therefore the shrinkage cracking problem. Did you realize that simply increasing the cement content, therefore increasing the ultimate (compressive) strength of a mix will tend to result in more shrinkage cracks? Contrary to popular belief, concrete doesn't need expansion joints, it needs control joints, which allow you to introduce a point of weakness where the crack will 'tend' to appear.

With a 3/8" mix a 3" hose is a great safety factor, but it's also overkill. A wise pumper once told me 3" hose is too big for small mix and too small for big mix. 2 1/2" is best for 3/8 and 1/2" mix, lighter, much easier to handle. 25' lengths are easily carried by one man. (empty of course) You can pull it around much easier and, in fact, hold it on your shoulder without undo strain.

As for whether a 3/4" mix is harder on a pump than 3/8"...I'd tend to think that if they were both crushed stone, that the 3/8" would tend to wear more, owing to the fact that there would be more individual sharp edges of stones to scrape on all the wear surfaces....Just my own personal theory....

I agree that expansion joints are rarely needed, and never for slabs
inside buildings. Cured concrete would have to be heated quite a bit
before it expanded beyond the original (wet) dimensions. Shrinkage
management is the key to a good slab. Note that the larger the
aggregate, the less the shrinkage. Hence the added value of 3/4 or
larger aggregates for slabs.

As for the 3/8 vs 3/4 in pumps, your point is interesting. The pump
manuf would also prob say that 3/4 is no harder on a pump than 3/8
if the hoses are 2.5 or larger. My guess.

 

[RonRock]

Cool info guys. I'll follow the links and learn more. I'm mostly interested in making one that I can use off my Skidloader or possibly build into a trailer type with either a gas engine or a PTO, maybe a hydraulic motor run off the skidloader?
I have the skills and equipment needed to build it. I think, I haven't even seen one yet! I don't need a truck mounted boom pump, just something I can use occasionally on a slab or footing.
I'm a little surprised at the "Don't do it" attitude, I'd of guessed that kind of project would be just what this forum is here for. I understand the economics of just hiring everything out but I am old school and prefer to do it myself.
Still looking for more info.

 

[speedy67]

The 'don't do it' comes from my hard-earned experience with a 'real' concrete pump....it ain't easy. When you plug (& you will ;~) ) you can't say screw it, I'll fix this later....concrete waits for no man.

The other part of 'don't do it' is in regards to using the right parts....namely the hoses and clamps. Although a squeeze pump can't create the pressures that mine was capable of, it is sure to crank out more than 100 psi, I'm sure. That's a LOT of stored energy, waiting for the fastest way out.

Also keep in mind that the proper parts are EXPENSIVE....

Do yourself a favor, hire the pump, buy the concrete, save your money by doing the placing and finishing yourself....you can't do it all (mix, pump, place, finish) yourself anyways. Read up on proper concrete procedure and go for it.

There are a couple concrete pumping forums out there, I'm a member of both: Concrete Pumping Advice Forum and: My ConcretePumping

See you there.

 

[dfkrug]

Cool info guys. I'll follow the links and learn more. I'm mostly interested in making one that I can use off my Skidloader or possibly build into a trailer type with either a gas engine or a PTO, maybe a hydraulic motor run off the skidloader?
I have the skills and equipment needed to build it. I think, I haven't even seen one yet! I don't need a truck mounted boom pump, just something I can use occasionally on a slab or footing.
I'm a little surprised at the "Don't do it" attitude, I'd of guessed that kind of project would be just what this forum is here for. I understand the economics of just hiring everything out but I am old school and prefer to do it myself.
Still looking for more info.

Hey, Ron:

I, for one, do not want to discourage anyone from a DIY project. I have
tried building many things myself when others said "don't do it". Most were
successful. Even failure can be a valuable learning experience.

That said, the only qualifiers I would add are:
> do your research so you don't reinvent too many wheels. Sounds like
you are doing that.
> take apart some real pumps and see first hand how they work. Consider
buying, fixing, and modifying a worn out pump.
> know your limitations, esp when it comes to special tools and special
processes needed to make certain things. As SPEEDY indicates, you may
want to BUY hoses and clamps, rather than try to make those.
> consider re-directing some of your DIY interest toward the most
feasible projects. For example, a concrete conveyor instead of a pump.
Or a hydraulic drum mixer for the FEL. Or?

 

[RonRock]

Thanks guys, I didn't mean to be rude. I'm just trying to figure these pumps out. I did see a trailer mounted concrete pump on E-Bay go for 4K last week. Looks like I could easily spend that much on a pump alone then still have to build the rest of the setup. E-Bay may be the way to go. I do appreciate all of your suggestions. Ron

Speedy, I checked out the forums. Cool stuff there too.

 

[speedy67]

No problems. A concrete pump is a simple concept, but the execution of it is very dificult. Trust me, It takes a lot of concrete to pump for it to pay for itself.

You can justify having a skid-steer around because it can multi-task. I know of only 1 thing a concrete pump can do.

 

[dfkrug]

You can justify having a skid-steer around because it can multi-task. I know of only 1 thing a concrete pump can do.

True enough. But I thought of a 2nd job for a concrete pump.....

A few years ago when the boom truck operator and I were waiting for
the mud to arrive, I had him reach up with his 100+ foot boom and
knock the hanging dead branches off the 110-ft redwood trees that
loom over my homesite. Worked great, and he had a good time, too.

Of course, it would be hard to do that with a trailer pump.

 

[Defective]

If you can get hold of a honey wagon & there's someone around that needs a behavioral adjustment reminder...