Concrete screws - smaller stainless screws tested

IanWalker

Active member
Hi all

I've done some testing on small stainless concrete screws, i.e. ones that use a 6 mm diameter hole.

I thought this might be of interest to others, so I've written up the findings in a 4 page report (see attached).

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  • Concrete screw testing 02-04-2024.pdf
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Bob Mehew

Well-known member
Neat piece of work. I should add that the standards are quite unclear about the number of tests one needs to do and thus the value for strength that one deduces from such work. So frankly, a single result means little. (Especially as we found some anchors had metallurgical defects which seriously undermined their strength.) Another point which was revealed by Simon's work is that the behaviour of limestone varies quite dramatically between naturally eroded exposures and exposures created by quarrying. (Blasting in quarries does create micro factures so that the bed rock has a much lower strength.) So the spread of results was quite large for testing done in quarries, reducing the overall deduced strength.

For what it is worth, BCA has an anchor puller with a 50 kN load cell. It normally is used for axial pulls, but using the approach devised by Simon Wilson it could be adapted for radial testing using a suitably sized concrete step.

PM me if you want more detail. It's a long story.
 

IanWalker

Active member
I have assumed that the manufacturer has appropriate quality control to produce a consistent product. The tests were to see if they suit my application.

I don't intend to place them in a quarry. But yes, rock variability is a potential issue (as it is with an anchor placed in the rock). Cheers
 
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