Ssampling Freshly Mixed Concrete

[Sandman]

I have this discussion on most every project and would like to know how others deal with this.

Ready-mix concrete is delivered from the batch plant per approved mix design and there will be some placements where a pump truck is necessary to convey the concrete; 1) Is it correct to sample from the truck chute or at the point of discharge (the end of the pump hose), 2) Why? and 3) How can a correct sample be taken per ASTM C172 from the end of a pump hose?

 

[peach]

dont have the ASTM handy, but I've never seen sampling taken from the pump - always the chute.

 

[Msradell]

dont have the ASTM handy, but I've never seen sampling taken from the pump - always the chute.

That's where I've always seen it sampled too!

 

[conarb]

Same here.

 

[Mark K]

I believe you will find the answer in ASTM C94. Either location is acceptable for making of strength test cylinders.

Some project specifications will require that air content tests, or slump measurements be taken at the point of placement because the process of pumping can result in different results at the two locations. But unless there the project requirements specify otherwise the chute is a good location.

 

[Alias]

dont have the ASTM handy, but I've never seen sampling taken from the pump - always the chute.

Same here, never have taken a sample from from the pump hose. I have taken samples from the chute before it was pumped.

 

[globe trekker]

Sandman,

Agree with the others! What do the project specs. call for? IMO, at the end of the chute

is the most typical. Also, if you are collecting samples, be sure to watch the driver

carefully. They have been known to arbitrarily add water to "speed up the mix delivery".

If they DO actually increase additonal water amounts, they may have just ruined the

whole mix and any warranties.

 

[GBrackins]

back when I was in the field we always performed a slump test off the chute, if the product was bad no sense messing up the pump. we'd also grab sample off chute for testing.