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

PRESENTED BY: GPRS Construction professionals know that utilities and concrete reinforcements can cause big problems when you’re on the job. GPRS helps you avoid them. We use ground penetrating radar to detect rebar, conduit, and post tension cables before you cut, core, or drill. And our concrete scans are 99.8% accurate - we guarantee it - helping you reduce hits, downtime, expenses, and keep your people safe. To keep your jobsite safer, visit: https://www.concretelogicpodcast.com/GPRS 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 INFODr. Jon Belkowitz Intelligent Concrete Website: https://www.concretelogicpodcast.com/intelligent-concrete CONCRETE LOGIC ACADEMY Got a concrete problem no one can explain? Bring it to the Concrete Logic Academy. Ask questions. Share what you’re seeing. Get real answers you can use on the next pour. Simple as that. Free trial for pros here: https://www.concretelogicpodcast.com/pro SUPPORT THE PODCAST If this episode helped you... If you learned something... If it made you think differently... Support the show here: https://www.concretelogicpodcast.com This podcast runs on Value for Value. Give whatever you think the episode was worth. PARTNERS KUIU (performance gear Seth actually uses): https://www.concretelogicpodcast.com/kuiu Interested in advertising or working with us? Email: seth@concretelogicpod