OK So we have had a small problem.And I was wondering if any one else is going through the same thing,.... So whats happening Is when we are using the 47m or 52m and we take a test We are losing 5%.They test it before the pump it is 5-7%.When they take it out of the hose it is 1-3%.These trucks do have cuffs on them.From what I understand they are saying that the pressure of the concrete,From the concrete in the boom The AE is getting squeezed out?  So I guess what I am asking is...Is any one else having this issue,And if so what are you doing to get around it?

Thanks guys!!!

Can't the Ready Mix company take the air entrainment higher to compensate for loss when it is being pumped?

How are they taking the test? At the point of the pour  when you have a full stream or are they making you swing it over to them? What i do if i have to swing to them is kink the hose as quickly as you can so you will build up a bunch in the hose. When you dump it in the wheelbarrow have the hose bent so the mud slides out real easy with out plopping that should cure the problem.

I believe the theory on loss of entrained air during pumping is that it is lost during the free-fall and impact in the elbows.  Also from the transition from a pressurised state to a vacuum, causes the bubbles to 'implode'.  I think this is the case for the largest amount of entrained air lost.

The Roughneck hose was made to reduse the air loss, by keeping the pipes full to the end of the tip hose, in otherwords, the mud doesn't see a 'vacuum' condition.  A steady pumping rate and a nice even stream of concrete coig out the hose goes a long way to controling lossof entrained air.

started having a similar problem on this job i started in sep. what i've found is that you can't let the concrete fall through the boom, in other words stretch out the boom,i run a 5 stage z boom so its easy to give a sample close to the pump once the boom fills up i lay the hose in the wheelbarrow so it doesn't fall very far through the discharge hose either. i usally lose only .5% air. are you doing a d.o.t. job?

I have not been on the jobs since the problem arose,I was just discussing it with my boss...They are definitely having to swing over to give the sample to the tester...I will pass on these suggestions to the boss. I would also love to hear any other suggestion as to how to deal with this,It is becoming a nuisance

I would consider running a 5-4 reducer and let the inspectors know they need to maybe help with the way they get their sample the kinking of the hose is a good idea

penn dot regs state 1 test at point of placement then 1 test from truck this is called corrolation test and if we pass we can keep testing out of trucks no more swinging the boom around! but we have to be within 1% on air and 1 inch on the slump, 95% of the time we pass. they always test the first three trucks and then every 50 yds.

I have never had the air tested at the tip hose. Any job I have pumped, all the concrete is tested before it hits my boom. I was told the reason for this is because it is the job of the ready mix plant to get the mix right and just my job to pump it. If it is tested at the tip hose then that puts the ownus on the pump which has no way of controling the mix design. I asked a similar question about slump once when the finisher wanted water added to the drum because it was too hard for him to screed off. He asked to take the slump test at the tip hose to prove his point and the tester just told him that it is not up to the pump to get the mix right, he only pumps it that is why it is tested at the truck and the truck only.

OK we are running air cuffs on these truck so that in it's self should do away with the kinking of the hose shouldn't it? also I am curious to know if any one else has seen drops in the AE this high from 5-7% down to 1-3%,The reason I ask is... this seem to be just a recent developement and I am curious if it possiblely could have some thing to do with the chemical it's self 

seen 4% drops  like i said no falling concrete thru boom lay hose in wheelbarrow 1/2% loss, no problems

what type boom z or r/f

R/F  I will pass on the "lay the hose down" tid bit

Just curious are they using two different pressure meters? Possibly one not calibrated right. Done jobs where the mixer company was testing at the back of the pump and testing agency at the end of the boom and there was a big difference until they started using the same meter at both ends.Anyways just a thought.

I have seen these drops in ae when concrete is falling you have to keep a steady flow when it falls is when you have issues falling splatting on 90s wheelbarrows whatever the ae dissipates the best I have seen to help is reduction to 4 in or less lot easier to get that stream goin, the best way I have found to give a sample is while your pumping get wheelbarrow on the edge of pour hoseman pushes hose puts it in wheelbarrow not the best answer but it helped

Concrete that spatters will lose a ton of air every time.The full hose approach is the ticket.It all depends on how coopritive the tester/contractor is.

My guess is a meeting with super/tester to work something out.Anytime one has to swing over and give a sample you lose.

extend or fold boom as to no free falling mudd at point where testing is to take place,also use a 5 to 4 reducer with 4in tip hose.been through it about a thousand times,and this works everytime.usually lose .25 to .5 persent on air,and have actually gained .5 to 2in on slump,dont ask me how but mudd has been sent back/turned down for that. well trained testers i guess.ya right....... 

The ACPA has a report on air entrainment. The ACPA hired a well known concrete expert, Ken Hover, PHD to do a study on concrete pumps and air entrainment. It is the definitive paper on the subject.

Well it is only a problem when they have me swing it over to test. WHen taken while I am pumping the test works out fine everytime. So what I do is carry two 5 gallon buckets and, get the mud from the stream. Also I find using a metal reducer that the tests fail more than with the roughneck hose. Another thing is try to have the boom extended more, there are some sites where I have moved further back, when I could have easily A-Framed the job. It helps eliminate the plopping in the 90s when having to pump slow.

To reduce the air loss when pumping you have to control the free fall either by reducing the hose to create back pressure or position the boom to reduce the free fall. Most state jobs that I have been on test concrete at point of placement not at the hopper. Have the tester take samples on the first truck at the hopper and point of placement thats what there for. Don't add water thats going to increase the air.When pumped correctly the air loss should be minimal and within spec.

I seen a pump a few years ago that put more elbows on the tip to keep the boom full. Anyone ever tried that? put it over head instead of that stupid ass s-tube looking thing. I would think that would keep from loosing any more air than ness.