Trying to pump lite wt. concrete to 6 & 7th floor,using hot

water, super P,1% acellerator. Mud goes into pump at 8 1/2 to 9 inch slump on deck comes out at 3-3 1/2 inch slump. Help!! Thanks

This might be a stupid question but, did they pre-soak the rock? I've been told it should soak for at least 24 hours. The pressure of pumping it drives moisture into the pores of the rock while pumping it. Causing it to tightening the slump.

that's tru.must be pre-soaked for 24 hr befor it's batched.check with the ready mix c.o. and ask if they do. super-p will wont help

yes had the same thing happen to me the other day     52m  and 150 ft of system it was coming out like test cylinders brought the slump up to 11inch slump goining in the pump it was coming out the hose at a 5 and pump it slow even on prime

WHAT YOU NEED TO DO IS, BEFORE YOU PRIME THE PUMP. GET A 5 GALLON BUCKET AND FILL IT UP WITH WATER. WHEN CONCRETE SHOWS UP, GET A HANDFUL OR SO AND THROW IT IN THE BUCKET OF WATER AND IF THE AGGREGATE FLOATS THAN YOU HAVE A GOOD IDEA OF WHAT YOU ARE GOING TO BE DEALING WITH. IF IT SINKS YOUR GOLDEN. PUMP IT OUT

get a water supply in to the hopper when you are pumping as well. with lytag you can never have to much water

NCPumper has the right answer, some of the big batch plants have tanks so they can remove the air and that pulls the water into the lite weight.

All really good suggestions...especially NCpumper.

The problem I see is they are using a water reducer(Super P) AND an accelerator...and if the lite weight is dry, having less water will make everything worse.

If you test the mud with the bucket of water and it is floating, you need more water/less Super P to compensate. 

"Samples of concrete shall be obtained in accordance with ASTM C 172 and shal be transported to a place on hte site where tests can be made and cylinders stored without being disturbed for the first 24 hours.  If the concrete is placed by pumping, samples shall be obtained from the end of the pump discharge line."

"Pumping may result in the reduction of slump and/or air content.  Therefore, the concrete mixture should be proportioned to provide the desired fresh concrete properties at the point of placement"

Taken from page 4; http://www.bigriverind.com/pdf/Structuralguidespec.pdf 

http://www.escsi.org/Default.aspx

It'll be a tuff sell to the inspector because he doesn't want to go to the 8th floor with all his equipment...but the job Super will probably listen.  Most of us have had a scuffle with inspectors and lightweight mud but they really do need to test at point of placement...according to the ASTM.

First time I pumped light weight I did the bucket test. I had never seen rocks float before. I had 200 feet of 2.5 out the hopper was a 8 and the end was a 3. They were pouring steps. I wanted to pump faster but I said it is going good dont fool with it. That job went well, blind luck I guess. Our plant soaks the pile and loads it into a mixer over night. Not the best way but when thats all you have.....

They have to soak it and you cant pump it to hard or fast it will suck the water out of the rock.

#1...You can't cure a low slump problem with Super P. It has to be water! With a pre soaked material your pump pressure should be running at about 200 to 240 bar with about 300' 5" system or 260 to 290 with 4"system. ACI says slump tests MUST BE DONE at point of placement. INSIST!! Most tests say 6" to 7" slumps! I just did (last 4 days) around 1200 yards at a Fed-Ex building through both 4 & 5". Once QC and I had a meeting of the minds,we had few problems. Hats off to the hose crew, as there were 2 to 3 guys pulling the 5" hose for 300' and 300 yards. They were whooped at the end of the day, but they came back for more!

PS NCPumper...Ace Avant!!

fly ash

As long as it's moving through the pipes, what's the problem? Are you having issues pumping? If the inspector is ok with the slump at each end, It's up to the finishers, super, engineer to sort it out.

mudslinger whos solite went thru 4 reducer in nc i just finished uncg project about 1500 yds central concrete rmc it was alot of fun thers wouldnt make it thru reducer 300 ft 5 in only 60 ft of rubber going in at a 8 or 9 coming out 3 or 4 if lucky ps ncrmc solite is always fun thomas rmc is the only one ive had any luck with reducer

Pump jockey has got the right idea, If it is pumping don’t mess with it, Pre soaking for natural material is a must. But I have seen manufactured light weight pump up high-rises at a 4 inch slump. Just be carefull if You the operator alter the load by adding water you could wind up buying it, it is up to the supplier and the contractor to work this out. From the pump side slow down the harder you push it the more pressure and the more water gets squeezes into the agg. So as the pressure builds back off a little. If you are running a Putz, try to avoid using Disturbance/ stroke change switch to much, It will wind up packing mud onto the material piston then you have a bigger issue. Ky chubb, if you would like to talk more about it you can e-mail me your number.

Hay guys many of the posts are true like soaking the mud ect. but what i have done well with is, besides water is (viscosity modifier) or V-MAR . V-MAR incapsulates the rock thus suspending it in the mud so the water wont penetrate the lightweight as much resulting in less water and more pump. The labs can soak and saturate fold and test the lightweight till complete saturation, then put pump pressure to it you will see more water CAN be pressed into the rock. Besides coating the rock sealing it up like paint would try Viscosity modifier if available in your area all QC's say it is completely inert meaning it wont hurt the mud. Good Luck

down here its presoaked 72 hrs unless its done in a vacuum chamber, losing that much slump the rock isnt soaked properly, take a 5 gallon bucket fill it up with water and throw a handull of the concrete in there see how many of those little lava rocks float.

liteweight and super p ? man thats make for tough days cause they always scrooge on the water, no water makes for a long day, and accelerator your asking for trouble hoping its cold as hell wherever your at.

anypump 2 , if I understood you correctly you said a water supply in the hopper, dont do that your asking for a lawsuit. 

yes I've had trouble moving the mud, 2nd day pour was finished with bucket. use air to clean pipes go home shaking head.

Thanks  for all the advice. Not a cherry to lite wt. just having problems. Customer had techs check agg.for moisture content at plant,is in specs,(5.8). The rock is being soaked in mixers. Thanks again.

seemed to me a unit weight of around 122 or above was good.

Only the pump can determine if a mix (lighweight or regular) is pumpable. Specs are like the 'Pirate's Code', they're more of a [u]guideline[/u] (spoken in Captain Barbosa's raspy voice) ;~) I suspect what is needed to ensure that the lightweight stone is more saturated is a vaccuum tank to force more water into it. There's nothing cheap about using lighweight agg, they need to stop cheaping out, if they want the adavantage of a pump. If not, don't sign up for the blood-letting.

Here they heat it and saturate it before delivering to batch plant,benifits of the mine close by.Unit weight gives one the amount of water/moisture in the mix.The heavier the weight the more saturation the agg has.It has nothing to do with the mix and pumpability of that mix.However,there are spec's for how much weight is allowed on tin decks.

The tester could be your best friend.