So Sunday morning secondguessing and wonder your thoughts:
Had a basement room that had a dirt floor (at my house). Got it all prepped and ready (poly, rebar), had three assistants to help with the placement. 4.5 yards is what I estimated and 4.5 yards is what they ended up mixing and pumping.
Pump operator ran 4″ line from road, down driveway (16′ drop over 150′) under a carport (why we needed the pump), and then elbowed and reduced to 3″ hose going through rim joist into basement room.
I ordered concrete (on-site-mix) and pump from reputable local companies. It was right at freezing. Both were nudgy about the temps, about the distance, about downhill, both said they could do this no problem.
Pump operator says he will send me a really stiff mix, which is what I wanted anyway. I see the test mix they shoot into a wheelbarrow and it is perfect. We get all set, I go downstairs, and give (via radio) the go signal. In the next instant, I’ve got 25 gallons of cement water out the hose in 4 seconds, and the area is saturated with a pond. I was supposed to be getting grout/sand mix. I got grey water. I radio my wife to tell the pump guy to stop and get his a$$ down stairs.
He comes down and promises that it’s all stiff now, and will be good to go. I insist we’re not moving until all this water gets cleaned up. So I and the crew use buckets and cups to clean out the low spots and towels for the rest. He promises “the rest is stiff.”
Start pumping again and it’s coming out like complete soup. Probably 2 yards is out in 30 seconds. We stop again. Operator comes down. It’s all stiff from now on. You get the picture.
The last 2.5 yards does come out a lot stiffer. so half the slab is what it should be, and half the slab is the soupiest stuff I’ve ever seen.
The concrete mixer operator comes down and says that basically, the pump operator had lots of water in his system and primed the line with way too much moisture. So to salvage the soup, he gets me 5 half full 5 gallon pails of dry cement powder, and we proceed to carefully mix this with the soup in the buckets and then mix this into the soup. Pretty soon, this actually works well to stiffen the mix up. We soak up some of the excess water on the surface and toss those towels aside.
We get nearly done, everything is a freaking mess, I’m superpissed and wondering why I just didn’t mix 200 bags 2 at a time, but at least I would have had control. Ends I barely had to screed this because it basically self-leveled. I pulled a bull float over it and walked away. Bleed water was on it for hours yesterday, and I left it alone.
This morning I’ve got a flat, level and solid surface.
I expect this is a pretty weak pad (but there’s no structural purpose for it, thankfully). I expect the surface will dust. It’s a bonus storage room, and we’ll probably just lay (w/o adhesive) a piece of linoleum over it.
But holy heck, I thought the pump was going to save me stress and work…
Seems to me the pump guy is to blame on this one?
Replies
what size aggregate?
Did the pump guy have a pump truck or was it a towable hopper? i know those towable hoppers have limited capabilities with aggreates and do sometimes wet it a little more than one would like to get it thru the line.
your slump test: was that out of the pump line or the mixer?
sounds like the pump guy was wetting it to much
thanks
slump test was out of the mixer. Being 200' away and out of sight, down in a basement, left me at a disadvantage. I had to totally rely on the pump guy to manage this.
It was a trailer pump (Schwing)
funniest thing...
the best concrete of the day (perfect slump, etc. was what was left in the lines and dumped on to tarps at the end of the job. Actually, that just makes me sad.
Oh?
This crap is precisely why I quit pumping after 4 major disappointments and lots of promises. The final experience, the head of the large pump company drove an hour to supervise my pour. Just as crappy as my previous experiences.
Wouldn't help you, but I bought a crane to lift concrete buckets. No problem after that. Many here said they had good results with pumps. Not my experience, with every pumper I could find. Pay through the nose, and get poor results.
Pumping concrete can be very stressfull. Particulary if you don't do it for a living regularly. Even though I've mixed and placed tons and tons of concrete over the years as a G.C., I always hire a professional concrete sub for pump jobs. I am also there to see that everything goes as planned. The minute things go awry, it is my responsiblity to bring it to my subs attention and negotiate an acceptable resolution . If that doesn't happen, then the only one to blame is me. In your case, the only one to blame for the fiasco is yourself. I say this because you continued on with the pour despite obvious, unresolved problems. Not saying you didn't try to make the best of a bad situation; just pointing out respective responsibilities here.
The resulting psi may not be what you ordered; only core testing could probably verify it at this point. Like you said, it probably is not a strucutral issue, only cosmetic and longevity of integrity. You not only paid for inferior concrete, but also for a valuable learning experience. Probably not a lesson you'll likely repeat. We all do that at some point in our careers.
This is how it's supposed to work.
The pump operator is at the end of the hose with a remote, not at the pump. He runs the hose and knows what comes out. He may need some help moving the hose when he shifts position. Any water in the hose should have been pushed out by the concrete into a location out side the area where concrete is to be placed, then when concrete reaches the end of the hose he starts to place it. The truck driver knows when to add concrete to the pump when he sees it pumping and stops when it stops. It sounds like your pump operator didn't know what he was doing. That has potential not only for a bad pour but for a disaster. I saw a nozle blow off a pump that absolutely would have killed anyone in the way. If the concrete company sent this pump out be sure to tell them.
Pump is usually how you get concrete here if it is not a driveway or something they can park next to.
The operator poured a bucket of water down that hose before he started the mud. Otherwise it wouldn't make it to the end. Maybe on a long run they tossed in 2 buckets of water
Typically you make a dinosaur poop out of the first few CU to get a clean stream and then keep going until you are done.
Stopping for any significant time will get you another bucket of water.
In an enclosed space, you try to minimize the water but you are getting some. Squirt it out where you plan on ending and start working back there from the far end. Hopefully it will be down in the substrate by the time you get there. At least the water will be where you can get at it.
Who does the clean up is always a crap shoot.