Consumer grade ballistic concrete testing

The sharpest sand like material I can think of would be crushed iron slag for sand blasting.
It used to cost $4 per bag now it's more than double that. That price doesn't put it completely out side the realm of possibility.

 

I haven't looked into it much, but where does one get chopped fiberglass? I know it would be a horrific mess and the end of days if you did it wrong (and weren't covered head to toe with a mask on), but could you pull apart fiberglass insulation and mix it in? Just curious.

 

Crushed iron slag doesn't havery a lot of iron in it and it doesn't rust, it appears to be inert. It's mostly silicon oxide from dirt that goes in the furnace with the ore and, calcium oxides from the lime stone and other oxidized impurities from the blast furnace.
It looks and feels like black sand, but is not magnetic.

 

I think I got a pretty good test that wont blow the samples to bits with the first shot.
The .22mag 40gr FMJ fired from a rifle from about 2 feet from the muzzle.
One shot severely damaged a 12 inch paver. Muzzle side made a 3.25 inch wide crater 5/8 of an inch deep at the deepest then blew a 4 inch wide chunk .25 inch deep chip off the back and cracked the block. Spalling could be considered failure. These pavers are not very strong or tough.
2nd shot placed about 1 inch away from the first penetrated and busted the block.
The pavers were painted orange to better highlight the damage.



Another test I took a piece of stucco from my house, figured a 22mag would easily punch straight through, so I hit it with my 25 cal pellet rifle. Before you laugh it fires a 43 grain chunk of lead at 550fps, pretty close to a 22CB round. The stucco only offers about as much protection as dry wall. The pellet gun had almost the same effect on the stucco as the 22mag had on the paver.

Also doing some reading removal of air can be quite beneficial, for every 1% air entrapment reduces strength by as much as 5%. Remember there is typically 9% to 20% air in concrete. That could be substantial.

 

Found out shortly after I posted Friday there is vacuum concrete. I figured there was. They take a fairly standard concrete truck, apply steam to the air inside the drum, seal it off air tight as possible and let the steam cool.
Now a perfect steam vacuum is about 27 inches of Hg out of 30. A concrete truck is filled about half way up. My guess is it will draw about 20 inches of Hg max if it doesn't leak at all, because you can't heat the concrete up as hot as the steam.
My plan is to pull a much higher vacuum, with a 2 stage HVAC pump.

Also I was thinking about what could be added to say existing concrete to make it stronger so I took so left over nearly 12x12 tile scraps with left over moarter and slapped a tile on top of a paver. Since the paver is my base line.
My wife saw the paver tile hybrid and asked what it was. As a joke I told her it was an accent paver, she liked it a lot so I guess I will be making alot more of those now.
Then I took some left over 2x4 and mortar and made a form around a paver then slapped about 5/8 of an inch of l polymer enhanced mortar on top of a paver now I just got to let it sit for a month.

Then this week I need to cast mini a slab for my new 2 ton split heat pump that should be here any day now. I will make some more test pavers when I do that.

In another test I have samples of stucco off my house, I'm going to see what adding another layer will do if anything.

 

Dad did the math I moved the materials .
I worked concrete when I was a kid but i wouldn't do concrete now for the life of me.
What I remember for hardness is concrete poured under water was harder because it went off slow.
That's about the extent of my knowledge of concrete.
I know, ain't much.

 

Yeah have too at least keep it damp.
My paver plus mortar has a plastic bag over it to lock in the water.

 

Alright my air conditioner is coming in today, earlier than I expected.

I'm going to get more paver and tile to make those accent pavers my wife liked so much and more cheap concrete to cast up some paver sized test pieces and my air conditioner pad.

 

Made some test forms. The first test samples are of the cheapest quickcrete at Lowes.
They are the same size and thickness as pavers.
Mixed the concrete so I had almost no slump, not very workable.
One block I just added water, the other block I used a 25% mix of polymer enhancer. That stuff is expensive so I don't think I will be using it straight. Since it's $30 for 2 gallons.
I'll do another one made with 50% polymer enhancer. I just can't see really even using that much.

Then from there I think I will start adding steel.
Fisrt one use a piece of stucco backing in the center of the casting as if it were cast as part of a wall. Same paver size, same paver thickness.

Then maybe do something like cast a slightly thinner block with steel on the front and back as if i cast walls with stucco backing lining the forums then trawl some mortar mix or concrete on the outside or strike face later bringing it to final standard test thickness, then coat the inside with asphalt, epoxy, concrete paint, just something that could be used on a basement wall. Making it the same thickness as the other tests. I figure more steel will help to reduce spalling and eliminate a lot of cracking.

 

I think the steel reinforcement acts to distribute more evenly, the impact energy through the whole structure, rather than it being all localised at the point of impact.

Varying the angle of the bocks from vertical would be another interesting variable. The same thickness and composition of concrete would be expected to be more effective at deflecting heavier duty projectiles: Much the same way that sloped armour on AFV's offer more efficient armour protection than armour that is closer to vertical.

 

Agree with Chell. It's worked pretty well in the past..

World War II museum D-Day Normandy 1944 Atlantic Wall

 

I'm going to keep the test shots as close to perpendicular as possible since that is worse case scenario.
The further away from perpendicular the armor acts like it's thicker and the tests favor the armors hardness more than strength.
If I tested my paver ceramic tile hybrid off perpendicular it would likely to very well because the tIle has a very hard, tough and smooth surface but it's very brittle.

I also picked up an air powered turbine vibrator that can be bolted to something holding concrete to settle the concrete into corners and remove some of the air bubbles.
Just a little cheap little chicom unit.

 

This is going to be fun.
I'm thinking about ways to go full scale.
Since I don't want to shoot at a 4 inch thick wall all day with a 22mag.
I think a good standard test would be a 308 or equivalent.
As an intermediate between 308 and 22mag I think 30carbine would be good.
Then the ultimate test would be something big like 50bmg but I don't have a 50bmg so will have to make a baby 50 with something that fires 400 or 500gr .458'' FMJ bullets.
My full scale or as full scale as I want to go will use my air conditioner concrete form which uses 2x6 boards to cast 2'x42'' air conditioner bases. So in theory I could cast a 2 foot by 42 inch block that is about 5.75 inches thick. I believe most places it's code to use 4 inches.

So I'm kind of splitting the test, "new builds" were I cast up paver sized samples and "improve old work":
1 where take a paver which we will say is an existing concrete wall and slap something on top of it to try to make it stronger.
2 add another layer of somthing on to my old stucco. (I put in bigger windows and saved the stucco scraps so I have actual samples of what my house is made of to blast)