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BONUS DIY VIDEO - DIY Tiller Powered Sieving Machine

[Donnie_M.]

Glad you posted this. It seems there might be consolidation issues or risks with this as you see it cavitates (creates voids) and cracks under the surface. This may be fixed with substrate reinforcement (rebar) and vibration of form (to minimize void development) prior to the watering step. Time will tell when you test it for for strength and durability.

[amwood]

Your wife will wondering what happened to her big Pyrex bowl.

[ArtificialBanana]

I never realized how popular the topic of concrete was on YouTube!

[terrylutke]

Concrete doesn't actually 'dry' in the sense that some people think. Powdered Portland Cement creates bonds between sand/stone aggregate when hydration is introduced. This bonding reaction continues for years in many cases, although most of the mix design strength occurs within 21days. The idea of using a mixer would be to insure that all sand and stone particles are evenly and sufficiently coated with Portland/water paste prior to placement.
There's another process called 'soil cementing', where dry Portland Cement or lime is knifed directly into wet soil to improve it's load bearing capacity.

[doncrist]

As a mason and concrete person, the reason the sides showed it hardening so fast is when concrete starts to harden it shrinks just enough to allow the water being sprayed to flow just a bit to reach the outer edges. It will take alot longer to reach the inner sections but eventually the slab will be solid

[johnlee]

Worth noting relative to your friends 14, 000 lb truck. That “huge” load undoubtedly has a contact area of at least one square foot, or more than 140 square inches. That’s only a load of about 100 psi, or far less than the 3, 000 psi design strength of the concrete, so really not much of a test.

The other thing is that concrete doesn’t generally fail catastrophically at first, and especially not if it’s green. What is more likely to happen is that microscopic stress cracks begin which propagate over time resulting in noticeable and premature failure later in life.

[michaelkennedy]

Would be interesting to see a side by side, one with the dry pour method and then mixing a small batch in the traditional method in a glass bowl. The results would be seen by testing hardness in a few days.

[TexasChickDiana]

😂😂 cracked up when you tipped the bowl to show the top's texture! Love your videos! Keep em coming!

[esparka]

All of the patience sure is paying off. Our well-spoken friend Paul has the gift…. We are entertained

[no_handle_required]

Biggest question for me is how do you know when you've added enough (or too much) water to a dry pour that you can't see through

[MadSceintist]

This like every other one of my comments will be at the bottom of the algorithm.
Mixed cement has a strength advantage because the activation of components being bound by the heat that concrete inherently causes in a molecular level. The water isn't just the activator, its a lubricant to mix it easily.
Ask yourself why they don't pour dry concrete on a professional job of any kind

[fhuber]

Change the amount of agitation (mixing) and you do change concrete strength.

You find this by taking matched samples of concrete mix, adding equal water, agitating each sample a different amount, then doing a hydraulic press to failure PSI test. A small amount of agitation goes a long way. common 3000 PSI concrete in 7 yard batch generally has 100 turns of the big drum on a cement mixer truck.

You can change the pressure to cause failure by changing the agitation.

A good substrate under a slab can help it survive the truck test.

Your truck is at 30 PSI to 90 PSI air in the tires. (depending on which truck) Compare that to the generally desired 3000 PSI concrete strength rating...

The truck test is stupidly easy to pass. It's more a test of the compressability ot the dirt under than it is a test of the concrete.

[captainlurk]

Now, you need to make a video about a respirator and how important it is .

[bitmaxim]

After a few days, I'd probably end up breaking it apart with a sledgehammer to check the middle.

[basiltrim]

You could save all this time drizzling water going through intervals, just by simply mixing the cement with water for just a minute, and then leaving it to solidify, that could save us time also, don't you think? This process has to be done in a transparent pot while the whole procedure is messy for your laptop as well..

[ytwatcher]

Thanks for posting, but this actually demonstrates why this should not be done. You can see the weak spots and the areas where it wasn't saturated leaving spaces. This will not last in countries like Canada.

[freedom_aint_free]

Paper bags of cement in storage for long time even without contact with the floor just by absorbing moisture from the air get hard as rock in due time, so thin set does that fairly quickly by the way, this is due to the fact that the amount of water necessary for the concrete to set is way less than what is normally used, we pour more water for the sake of workability.

[jasonreisenberger]

Pro tip; wash your hands and any other skin that comes in contact with the concrete with vinegar. The acid in the vinegar will neutralize the alkali in the portland and prevent chemical burns.

[michaeljlangford]

Spent a lot of time in MN. The freeze/thaw cycles were severe, so we mixed concrete with 6% air entrainment. We have to test our dry pour samples with freeze/dry cycles, after curing, to check of surface spalling resistance. We need to know if sealing against that is advisable.

[NeverGone]

I was wondering how this worked. Thanks for the interesting video