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What cement admixtures would help bullet resistance?
- Thread starter c1steve
- Start date
Roman’s used volcanic ash/lime which made for incredibly strong concrete.
There are several studies on it.
Sirhr
Adding to that.
MIT or Berkeley (I forget which but big time school), figured out that the secrete was larger chunks of limestone in the mix
We had the recipe for hundreds of years but it wasn’t until this one group put it through some lab testing etc
It’s “self healing” because the limestone bleeds out and fills in the cracks, and works especially well with salt water
Apparently finely ground limestone which was already known doesn’t have the mass to “bleed enough”.
Under some microscopes and such they saw larger crystals and off they went
I think the article is from 2 years ago?
The other sorta strange thing in that article was their interest in the case, before and after firing. I didn't read it carefully, just skimmed it.
This all kinda reminds me of the “almost Heaven” thing Bo Gritz did in this area back in the day.
I remember people building concrete bunkers, fenced property topped with razor wire, I even poured concrete for a few buried facilities. People were putting in air pipes for fresh air. Was fun and exciting.
I remember people building concrete bunkers, fenced property topped with razor wire, I even poured concrete for a few buried facilities. People were putting in air pipes for fresh air. Was fun and exciting.
I had always heard it was the volcanic ash, but that never made sense to me, and it's not like we don't have access to it, and how much different than fly ash could it be...? This is the first I'm hearing of the large limestone inclusions making it self healing, but that makes perfect sense. It's not that it never cracks or degrades, it's that it naturally fills these in. Also interesting about the sea water, because those Roman concrete piers on the coasts are by far more incredible than even the aqueducts still standing.
They had a huge supply of ash because of the Campi Flagre (Sp) eruption about 100,000-50,000 years ago that probably took out the Neandrathals and most of the human population. IIRC, the human race was down to a few hundred thousand folks mostly in some coastal areas. The DNA analysis is interesting as to how close we came to 'not' making it!
But the layers of limestone that came from Italy's many eruptions gave the Romans not only incredible soil, but great basis for concrete and limestone for building.
The 'problem' is that they had all that nice ash on top of volcano's and earthquake zones... And Campi Flagre is very active... has a track record of erupting every 100K years or so. And is overdue, in theory. It makes Vesuvius look like a champagne cork.
In addition, they are looking at the pressures and activity in Vesuvius and one of the concerns is that it has a 'plug/cap' in it... made of super strong... Roman-cement that naturally formed. So Campi Flagre and Vesuvius are both going to be prone to building up massive pressure before they blow. When either goes, it's going to be very, very bad for Southern Europe (Vesuvius). Or all of humanity (Campi Flagre is technically a supervolcano... )
So build your bunker... but in the end it won't help!
Sirhr
It is a nice area, but 15 miles away there are areas with an abundance of criminals. I am worried about being targeted. Those people are often looking for a score, and hoping for little resistance. All it takes is for someone to open the front door to the wrong person, and then anything is possible.
Remember the Byrd and Melanie Billings home invasion in Florida, from 2009? They had a fortified house of some sort, but the intruders came in from an unlocked back door, plus one of the kids opened the front door.
https://en.wikipedia.org/wiki/Murders_of_Byrd_and_Melanie_Billings
Lots of great recommendations here, I really appreciate it. That study on MDPI.com was very helpful. They only experimented with 1/4" and 1/2" long fibers, but found that steel fibers will make UPHC concrete bullet resistant in as thin as 2".
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I can't logically speak to your concrete question, other than asking for fiber and UHPC concrete. It'll probably cost you 30 times more per yard. You'd be money ahead building with two 2x4 walls with AR steel between them. 8" of insulation would be nice too!
Semi-related, but if ever in a gun fight, just hide behind hay bales. I can't even get my 338 to make it through one in the long direction.
Semi-related, but if ever in a gun fight, just hide behind hay bales. I can't even get my 338 to make it through one in the long direction.
If you're building an elevated concrete floor, you have to consider your load strength.... The floor above will have load on top of the strength required to self support the concrete. I would look at pre-stressed concrete if it were my own install. It becomes part of the floor and would also allow for other materials if you wanted additional properties.
ETA: I wouldn't want a heavy floor overhead that was under-engineered or left any doubt about its strength. 4" concrete is NOT going to be strong enough before even considering any ballistic properties.
ETA: I wouldn't want a heavy floor overhead that was under-engineered or left any doubt about its strength. 4" concrete is NOT going to be strong enough before even considering any ballistic properties.
Since flamethrowers were already mentioned...
Do you have sprinklers installed in your lawn?
Mike
Do you have sprinklers installed in your lawn?
Mike
Volcanic ash probably performs about like fly ash. It actually doesn’t make the concrete any stronger, just makes it flow better without making it too much hotter to work with. It works great if kept to a very small percentage, but too much ash actually just weakens the concrete. Funny thing about that is the wizards at the DOT all insist on using fly ash in concrete and the idiots in the next office are saying to quit burning coal which produces fly ash.
People used a lime / sand mixture in the old days. Lime is self healing and becomes limestone again with time.
I had to dismantle and move a cabin built in the 1850's in central Texas and I couldn't dicern the limestone rock from the mortar, it had all become one solid mass. There were no cracks in the structure and had to be chipped apart.
There is a plague in west Travis Co. in Austin where new Gunite swimming pools are falling apart within a year of being built. They are referring to it as 'pool cancer.'
To be able to keep up with demand, the Gunite suppliers were not adding fly ash, which is in short supply, which is causing pools to crumble and disolve.
I've used superplasticizers on a few thin table tops and shooting benches , I'm amazed how well it works and how hard the finished product is.
