ASTM C138-Unit weight of concrete and C231-Air content via pressure air meter

[@EnglebertHumperdinck]

Matt yourss are the best concrete cert vids on youtube IMO though this one has a couple small flaws in your procedure (didnt wet the measure and all of your concrete scoops went in on the same spot on the perimeter instead of moving around it). Thanks for going to the trouble of uploading these I know there are a lot of us out there who appreciate it but probably dont comment.

[@MurphysColesLaw]

Good points! This was take 2, so the container was wet, but I forgot to do it for the camera. :)

[@rickyharrison6697]

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[@tatumzaiden7498]

@Ricky Harrison instablaster ;)

[@rickyharrison6697]

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[@rickyharrison6697]

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[@EnglebertHumperdinck]

Forgot all this stuff since I first certified, back watching again before my recert. Matt I get the impression you are too smart to be a career concrete tester. I'd be interested to hear how your career has progressed. Thanks again for the videos.

[@drcornelius8275]

You sound too arrogant to be one. I wouldn't trust you to do the job properly onsite.

[@edrendon2042]

⁠​⁠​⁠@@drcornelius8275lmao i’m pretty sure that was a compliment😂😂why are u hurt??!

[@drcornelius8275]

@@edrendon2042Why? Well, because I believe the competent concrete field testers are invaluable. They make my life easier and save everyone time/money while ensuring the placed concrete's quality performs. I'm curious why you think a compliment for one that disrespects so many is ok? You might be too "smart" to understand....

[@386fishing5]

Love the videos man! Thank you for posting!

[@signaltouch7413]

Thank you Matt!

[@jamesglines4698]

thanks for doing this. this is a good run through, I am studying for the ACI test and if you did this again, verbally state all the steps and make sure to say "uniformly spreading concrete into measure" etc as this could be used against testees

[@laxmiprasadrai1385]

What is limitation of air void content percentage

[@jamesglines4698]

Depends on specs of mix design

[@laxmiprasadrai1385]

If it was c40 50

[@OfficialLILV]

Should you dampen the bowl first?

[@MurphysColesLaw]

The ASTMs are annoyingly inconsistent in that regard. C138 does not mention dampening the bowl, but C231 does. Seeing as the two tests are typically done together, it's a bit of a contradiction. Honestly, unless you leave standing water in the bowl, it won't affect the result significantly.

[@EnglebertHumperdinck]

2017 ASTM C138 6.2 states "Dampen the interior of the measure and remove any standing water from the bottom." immediately prior to weighing the measure (or tare it out on your scale if you want to save yourself a step later).

Excuse me, i don't understand what I have to subtract (minute 11:00).. Thanks!

[@MurphysColesLaw]

Hello! What you subtract is something called the "Aggregate Correction Factor". When you do the pressure air meter test, the pressure from the meter can force water into the aggregate. This will cause the air content reading to be higher than the actual air content of the concrete. To correct for this, an aggregate correction factor is applied. The exact value depends on the type of aggregate being used-for most aggregates, it's less than 0.5. If you're going for certification, the correction factor will be given to you-you don't need to calculate it or memorize it beforehand.

[@drcornelius8275]

only needed with high absorptive aggregates

[@GundamTech]

dude, this was very informative, thank you!

[@RaglandNaturalMedicne]

Excellent! Thank you.

[@adariganesh7285]

I have dought sir, the unit weight of pain cement concrete is 24kn/m3, but I have dought while doing this test which grade of concrete is taken

[@lacoste5547]

What will be happened if we adjust meter initial point at 5 instead of 3 is will give us more air or less air?

[@amandastrand800]

Thanks for the share, well appreciated.

[@amandastrand800]

149.6

[@lacoste5547]

Plz clausing of airmeter valves after make pressure it's important step should be clause or we can keep it not clause and what is the effect of that.. Thanx

[@leerx7015]

full weight minus empty weight, equals weight of concrete. divided by volume of container. equals unit weight pounds per foot...

[@HectorLopez_]

He sounds like a dude who actually does the test out in the field

[@drcornelius8275]

no, he's way too slow

[@chrisbergey9470]

Took this guy forever to do the test. Christ the truck would be empty already...

[@greggmitchell4173]

That's the problem, you have to do these steps very quickly.