Making and Breaking Concrete

Lab Note #5
Apr 02, 2014

Good Afternoon Backers,

Long time no speak. We hope that all of you are having an awesome week and living the dream.

Thanks again for your support. We are getting closer to our final mixture. Today was our 14 day breaks for the first round of Geopolymer Mixtures. A cylindrical sample measuring 2 inches (50.8 mm) in diameter and 4 inch (101.6 mm) tall was placed in a closed loop hydraulic pressed. A metered load of 110 pounds per sec was used until the sample failed. We attached a video showing the process (technical difficulties-repost will be available shortly).

The following mixtures were tested:

A. GEO46 - Mid/High Grade Slag, High Grade Class F Fly Ash, Hydrated Lime, Binder/Water ratio - 0.45

B. GEO47 - Mid/High Grade Slag, Extremely Low Grade Class C Ash, Binder/Water (b/w) ratio - 0.45


The GEO46 successfully achieved a compressive strength of 2150 psi and 2090 psi at 14 days. You'll see that the sample is a forrest green. This is due to the hydration of the slag used in the mixture. The green color will oxidize in the sun after a few weeks to months.

The GEO47 did not set up after 14 days. Although this did not make us happy, this is an obstacle we MUST and WILL get past.Stay tuned for the new iteration.

As a reminder we will be refining the water, binders and chemicals to reach a 28 day compressive strength of 5000 psi (+/-500 psi) while maintaining a semi-fluid slump. 2100 psi at 14 days is a great start and we are happy with our results. We will update you when the 28 day results are available and with our next round of mixtures.

We are having an awesome time with this project.

If you have any questions don't hesitate to ask.



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