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RE: Concrete slump

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>1. Yes.
>2. The slump decreases because there is a lost of water content due to the
heat from the pump and also from the cohesion of the concrete mix with the
pipe as it flow through it. 
>3. Slump test is the measure of water cement ratio.
>4. No additional water will take place. Water loses during pumping 
due to buildup of temperature inside the pipe.
>5. Better to conduct a slump test after pumping of the concrete.

>> From our experience, contractors prefer to pump concrete that is not too
viscous-too viscous concrete mix causes the pump to explode or even the


-----Original Message-----
From: James Allen [mailto:allen(--nospam--at)]
Sent: Friday, October 06, 2000 12:14 AM
To: 'Sturctural Eng List Server'
Subject: Concrete slump

Does anyone have experience or know of technical resources that address the
change of concrete slump during placement by pumping.

I have been told that the pumping process changes the concrete slump.
1. Is this correct?
2. If pumping does change the slump does the slump increase or decrease?
3. Without additives, i.e. plastizers, water reducers, etc. isn't  the slump
test basically a measure of the relative water content in the mix?
4. If the slump changes where does the additional water come from if the
slump increases or where does the water go to if the slump decreases?
5. If the pumping process changes the slump, what is the slump? Is it the
slump of the design mix prior to pumping or after?

Thanks for your assistance.

James Allen, P.E
Homer, AK