That concrete block test

bushblade

bushblade

Joined
Apr 1, 2002
Messages
143
I have seen and heard a bit about knives being able to chop through a concrete block with little or no damage to the blade, but can't belive it.

I use concrete blocks nearly every day at work, and have come accross many different sorts ranging from soft cinder "breeze" blocks to heavy duty concrete. The soft cinder blocks would be very easy to chop through. But actual concrete blocks? no way:eek:

I have hit concrete blocks with various tools (shovel, spade, pick etc.) but find when they do break, they split appart, not get chunks cut out like in the demmo picks.

So is it really a CONCRETE block? or just a breeze block? (which quite frankly any large knife could cut chunks out of)

Will
 
thats a damn good question, i mean everyone has seen those amazing things they do with the "as seen on tv" stuff and we all do know that theres always a trick behind it right?
 
Howz this.....
If Lynn Thompson & the CS crew posted that....
It would've been labeled 'hype'

Personally, I'd rather see tests that reflect real usage.
Gaucho's reviews come to mind.
Free hanging rope, hanging leg o' lamb, coconut chop, et al.
:D
 
I did a job at a factory in Georgia that made synthetic concrete blocks. Sorry I don't remember what they were made of, but they were really lightweight. You don't think they'd try to fool us by using those for the tests, do you? :)
 
Yeah, synthetic blocks, thats what it looks like in the swamp rat pic.

Some of those even float in water:eek: indeed, if you have to shape them, soaking them in water makes them even easier to cut.

Will
 
I chopped through one, it was pretty easy to do. I am not sure what kind of block it was, but I believe a cinder block. To cinder blocks have small gravel in them? Mine did. It wasnt what I consider a valid test of a knife, but I did it just to see what would happen.
 
Yeah cinder/synthetic looks quite fine grained, almost like a grey sponge, concrete is quite course and a lot heavier.

It would be interesting to hear a swamp rat/busse reply to this?
 
Busse chopped up a 8" building block live at Blade with one of his wifes SwampRat knifes.
Someone brought it up so they just grabbed one of the production knifes off of the table, grabbed a block and chopped it up.
The knife cut though the first 2/3rds then the block broke the last 3rd.

Very little to no damage to the knife.

By the way, retail on the knife they used was only $148.95
A lot of people saw it...YOU can call it hipe if you want, but it chopped the crap out of that block with little damage to the edge.
 
When you say chopped... do you mean driven through like a chisel... or chopped as in overhead tomahawk slam?

Driven through, I can easily believe. Its not that hard to cut blocks with the right kind of chisel. The only trick to a knife would be hitting it evenly to keep from torqueing or twisting the blade, thats what they can't hold up to. A knife blade is very hard and won't deform much under compression.

If they can tomahawk chop through, I would be very impressed with the knifes ability to withstand impact and chipping.
 
God I just read the similar thread in Swamp Rat and that looks too good to be true (I know it was demonstrated live at blade but it's still unbelievable)
:eek:
 
The test at BLADE Show was impressive. It was a brand new Concrete block. . . not synthetic. . . not cinder. . . . It was rung up as a Heavy duty concrete block when it was purchased. These were not short, low-impact chops, which would ultimately yield the same result with little damage, but were rather, full over the head, full force swings. The test was done "live" so that the "force" of the impacts could be witnessed.

This test is very valid in determining the shock and impact resistance of a blade. Heavy-use knives are subject to all sorts of "real-life", unexpected, heavy impacts. I can't think of a single large field knife that I have owned that hasn't been accidentaly smashed into some rocks or other "unintentional" hard, potentially destructive, target.


Jerry Busse
 
This test is very valid in determining the shock and impact resistance of a blade. Heavy-use knives are subject to all sorts of "real-life", unexpected, heavy impacts. I can't think of a single large field knife that I have owned that hasn't been accidentaly smashed into some rocks or other "unintentional" hard, potentially destructive, target.
Click to expand...

I can think of a couple of other threads recently in which this might have been said to great effect! I wonder if this will end the debate on whether or not this test is "meaningful"?
 
Thanks for all the replys.

I do not doubt the validity of the test or that it did chop through the block, what I do have difficulty in believing is that it was concrete. Like I say, there are so many different grades of block labled as concrete.

The ones we are using at the moment are the most heavy duty I have come across, and there is no way any knife is gonna chop through one. However the blocks we had at another site were still heavy duty concrete, but they were very brittle, you could split them with a shovel no probs.

I think in the swamp rat test it was advised to get new blocks, as the old ones were too easy, which would indicate the softer block as these soften up a bit after time and weathering.

Will
 
Originally posted by matthew rapaport
I wonder if this will end the debate on whether or not this test is "meaningful"?
Click to expand...
At least in a hatchet, it is a meaningful test. I went to camp last May and we have to split some firewood. The ground was soft so it wouldn't help chopping those thing with a hatchet, and we end up trying it on concrete. We end up hitting concrete on the final blow a couple of times and blunted the hatchet quite fast. Too bad I didn't carry a sharpener.
 
Time for me to put my name on the line. It was there. It's my ugly mug you see in the pics. The block was definately concrete. Having handled thousands of cement blocks I am confident in telling all who read this that the block was a cement block. It was not cinder, synthetic or some other facsimile of the real thing. I sliced cardboard with the knife immediately after the chopping. The blade was not re-sharpened, dressed up or otherwise altered before being put right back out on the display table, resting on the pieces of block it had chopped.

I don't say that I would buy a knife (this or any other) for breaking cement blocks as their are much better tools designed for this function. However, in a tough use knife, unexpected contact with stones, aggregate and other items/substances that could be harmful to an edge comes with the territory. Likewise their are shocks that a blade must endure sometime when chopping though a medium with some inexpected material within; a spike or large nail within wood comes to mind. Accordingly, deliberately chopping into (and through) a cement block maybe more of a real work test than one may think at first blush.
 
I saw the test at Blade with the Swamp Rat knife and the concrete block. Having put myself thru college by working as a mason's laborer, I know what a real concrete block is. They weigh about 30 lbs apiece and are tough as sh##. This Swamp Rat chopped thru it with no significant damage to the knife. It was very impressive to say the least!
 
Contender,

that was exactly the answer I was looking for, thanks:) you know your blocks, seen the test, and I am assuming have no conection to busse/swamp rat (no offence to Jerry or Nimrod):)

Will
 
bushblade :

The ones we are using at the moment are the most heavy duty I have come across, and there is no way any knife is gonna chop through one.
Click to expand...

To clear up some possible misconceptions, you don't actually slice slabs out of the block like you would on a piece of 2x4. The knife slams into the block, which then breaks in a spatter of sand, cement, rock and sparks. You do this often enough and you "cut" through it.

The front notch in the following picture took fifty heavy shoulder driven chops to make :

http://www.physics.mun.ca/~sstamp/images/concrete_block_chop_heavy_side.jpg

This "test" as well as many others, are not done strictly to indicate possible actual use. However, based on how a knife performs you can make predictions how it will fare in other actual usage which is dependent on similar materials properties.

Saying it isn't valid because you would never actually try to cut a block with a knife, is the same as saying a Rockwell test isn't valid as when is a diamond ever going to be slammed into the side of the knife.

Concerning "fake" blocks or whatever, it would be pretty stupid indeed of Busse to overhype his knives considering he encourages test duplication by the owners. There is no "yes my knives can do that, as long as you don't actually try it."

-Cliff
 
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