Ballistic concrete

[oil pan 4]

I took a lowly hardware store paver, which are severely damaged by one hit from a 22mag rifle and applied a layer of epoxy to the back side. Only about 1 ounce for a square 1 foot paver.
Normally on a fresh hardware store paver a 22mag hit causes spalling on the back side, where material is blasted away from the back side.
After the epoxy applied and cured the test shot just caused a bulge. That was a pretty cool result.

[oil pan 4]

Didn't some one tell me that adding stucco mesh wouldn't help?

This is what happens when one piece of mesh is suspended in the middle of a sample.
Well this is what happens. Normally 2 shots this close together would break a standard 4,000psi concrete 12x12x1.75 inch sample into 3 or 4 large chunks.


This is 4 shots pretty close together. No regular concrete sample has ever survived more than 3 hits.


This is the back side after 4 shots. The cracks were not really visible to the camera so I drew blue lines over them.


The 5th shot chipped the back. Not much to see on the front side it is just a cluster of craters.


The 6th shot punched through.



I have sample that uses 2 layers of stucco mesh cast on the out side of the form a liner. It took 8 shots to break through and I concentrated the hits closer together to conserve ammo.

[oil pan 4]

After lots of testing it looks like the 2 best things you can add to concrete to make it more damage resistant are pretty much any kind of mesh. Doesn't really matter if its plastic, metal, stucco mesh, chicken wire. As long as you put a fine mesh like the stucco meah on the outside to keep the aggregate from being blasted or chipped away.
Also fibers, I tested polyester fiber, a little polyester fiber made a dramatic improvement. I still need to test fiberglass and higher mixes of fiber like doube, 3x and 4x the recommendation.

Due to the results of the polyester fiber test I also want to test chopped steel cable.

The things that don't appear to do any good are vacuum, vibration, fumed silica (only effective in insane amounts), poly strength booster. All did the same or worse than the controls.
So removing the air is a bad idea for this and most concrete applications.
Now I think this warrants an extra air entrapped concrete mix test.

Some things ruled out, new tests to be continued.

[oil pan 4]

I got a concrete rebound surface hardness testing hammer. Or Schmidt hammer.
I found that the store bought 5,000psi mix and my 1:1:2 mix are equally as hard.
So we know it's possible to make concrete that's as hard as the store bought mix for a lot cheaper.
If you mix up a yard of store bought 5,000psi mix you are looking at around $360 per yard, if you mix your own, you come out probably under $200 per yard, but it all depends on how cheaply you can source local sand and gravel.
By comparison some more common 1:3:4 to 1:4:4 3,000psi mix didn't even register a reading on the Schmidt hammer.
BTW the scale starts at 1,450psi soooo...

[ecomodded]

I have a idea try layers of silk (2nd hand store) mixed with epoxy coated polyester glass surrounding a fine mesh and concrete core for a bullet proof shield


I add Weldbond glue to concrete when i need extra strength and bonding

[oil pan 4]

Any mesh or cloth put in the concrete needs to have holes at least big enough for the sand to infiltrate into. Ideally the mesh holes would be the size of most if not all the large aggregate.
Cloth could be applied to the out side and epoxyed in place. I have tested applying epoxy by its self and it did work. Cloth like fiber glass would be ideal due to cost.

[philb]

OilPan4,
I went down this same road in 2011. Here is a book that will help you make the decisions easier. This guy makes and breaks concrete with rebar, stucco wire, mesh and expanded metal. The book is technical with many graphs and tables. Its available on several websites. It's my go-to-book for anything concrete and mortar.

Ferrocement & Laminated Cementitious Composites BY Dr. Antoine Naaman

I use EVA (ethylene vinyl acetate) in concrete and mortars every time I pour. EVA is usually called 'poly'. It can be found in most paints, tile and stucco mortars, Elmers wood glue and concrete. Solar panels are coated with the stuff as well as the glass face on cell phones. It will make the mix set faster and retain moisture so the chemical hardening process will continue for longer. I also spray a 10% solution of EVA and water on the concrete surface after removing the forms to help it hold water. The Stamp Store.com carries the poly but it's rather pricey. IMHO, Elmers wood glue is just as good when mixed at 1/2 cup per 30 lbs of Portland.

Flyash at 10% to Portland weight will also help lots with hardness. That's another of the concrete companies secret ingredients. They will mix in into the concrete truck batches up to 30% to Portland by weight. Lowes in Colorado has it in a few places. I don't know about NM.


Acrylic additives can and will cause delamination between layers. So if you do use it, pour the whole thing at once. Acryl 60 is one brand that's available at Ace Hardware for about $60/gal. It's mixed at 10 to one ratio with water before adding to concrete.

Here's another site you might check out:
ferrocement.net

[oil pan 4]

I have 15lb of fly ash to mix up. What I can find on structural concrete the authorities on the subject recommend replacing 15% to 80% of the Portland cement with fly ash by weight, depending on the application.

I found that the acrylic additive helps but not much compared to its cost at least for high velocity impact resistance. It is very expensive. You are looking at an additional $150 to $300 per yard to wet concrete with acrylic.
A 25% acrylic to 75% water mix seemed to be almost identical to control sample, that amount would add $75 per yard to the cost.
My 50/50 mix sample showed some improvement, but not $150 per yard worth of improvement.
By comparison a sample with $7 per yard worth of cheap plastic mesh reinforcement preformed much better than the 22x the cost acrylic sample.
I had pretty much abandoned the idea of using acrylic, but I could work on it again. Would be ideal for real small batches for precast special stuff l, where cost per yard isn't a big deal because you are only mixing up a tiny fraction of a yard.

I have some additive containing EVA but have not tested it yet.

I have never seen fly ash in a hardware store. It would be nice if it were easy for me to get. Have to mail order it. Maybe I can special order it as long as I canorder less than a pallet.

Soon I would like to do a test where I make some Portland cement with 15% and then 30% by weight fly ash and mix that special cement up into concrete using the 1:1:2 by volume mix ratio. I just need to find some good angular large agg.

[ecomodded]

Originally Posted by oil pan 4

Any mesh or cloth put in the concrete needs to have holes at least big enough for the sand to infiltrate into. Ideally the mesh holes would be the size of most if not all the large aggregate.
Cloth could be applied to the out side and epoxyed in place. I have tested applying epoxy by its self and it did work. Cloth like fiber glass would be ideal due to cost.

I suggested silk as it ws the original bullet proof Vest (sort of) used back in the day by Asians.

When pierced by a arrow or spear the silk would not pierce instead the arrow or spear would enter the flesh and could be pulled out still wrapped in Silk cloth protecting the veins and artery's to a degree.

Might be a way to use the old tech with a modern additive to actually slow or stop the bullet maybe catch it just inside the meat

You could do a meat test when your feeling good about a material put a cheap cut of roast behind it