EP #153: Your Concrete Mix Design Still Isn’t Ready… Until You Do This

PRESENTED BY: GPRS
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SUMMARY
Last episode, Dr. Jon Belkowitz walked through how to build a concrete mix design on paper.
This episode picks up where that left off.
Because a design mix is not the same thing as a batch mix.
Dr. Jon breaks down the final adjustments that have to happen before that mix can actually be used in production, including moisture corrections, free water, and admixture dosages.
If you have ever wondered how a mix goes from a neat set of numbers on paper to something a plant can actually batch, this episode clears it up.

WHAT YOU’LL LEARN 

•  Why a design mix is not the same as a batch mix 
•  How aggregate moisture changes your sand and rock weights 
•  What “free water” really means and why it matters 
•  How moisture in the aggregates affects water-cement ratio 
•  How to calculate the water coming from sand and stone 
•  How admixture dosage is calculated from cement content 
•  Why admixtures also add water to the mix 
•  How to calculate final batch water 
•  What the final adjusted batch mix looks like 
•  Why contractors and engineers should understand this math even if the plant computer does it for them 

CHAPTERS

•  00:00 - Intro and how to support the show 
•  02:15 - Why people are actually using the podcast on the job 
•  02:36 - Concrete Logic Academy and PDHs 
•  03:36 - Picking up where the last mix design episode ended 
•  04:22 - What has to change to move from design mix to batch mix 
•  05:44 - The project assumptions for this slab mix 
•  06:28 - Where moisture content and absorption values come from 
•  08:13 - Adjusting sand weight for moisture 
•  10:54 - Adjusting rock weight for moisture 
•  12:05 - What free water is and why it affects your mix 
•  13:24 - Calculating free water from the sand 
•  14:33 - Calculating free water from the rock 
•  15:24 - Admixture dosage explained 
•  16:16 - Calculating admixture ounces per cubic yard 
•  17:28 - Calculating how much water the admixture brings 
•  18:47 - Final batch water calculation 
•  19:34 - Final adjusted batch mix 
•  20:38 - What happens next at the plant 
•  21:03 - Why admixtures are mostly water 
•  24:51 - Withholding water and adjusting slump at the plant 
•  26:53 - How admixture dispensing systems work 
•  29:25 - Wrap-up and what to cover next time 

GUEST INFO
Dr. Jon Belkowitz
Intelligent Concrete
Website: https://www.concretelogicpodcast.com/intelligent-concrete

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CREDITS

Producers: Joseph Swann, Jodi Tandett & Concrete Logic Media

Music by Mike Dunton:
https://www.mdunton.com/

WHERE TO FIND CONCRETE LOGIC

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