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karimwassef
09/05/2017, 10:14 PM
So.. glass is heavier than concrete (or at least the same). Lightweight concrete is actually much lighter.

They're ~comparable in tensile and compression strength.

But concrete can be formed with an internal matrix (steel rods) to give it more tensile strength.

I'm working on a large tank that uses internal braces that tie the far ends of the tank with glass members. The brace is basically a second glass floor a foot or so off the bottom.

However, I would like to convert those members to concrete (maybe plastic rod reinforced?)

But I'm not certain of the adhesion of concrete to silicone so that it can act as a glass end to glass end brace?

Would this work?

karimwassef
09/07/2017, 10:05 PM
No one can speak to using concrete inside a glass tank for cross-bracing?

Is it that wild and crazy of an idea?

How about this simple question- will silicone form a structural bond with concrete the way it does with glass?

Based on this reference, it should work!

https://d-lab.mit.edu/sites/default/files/D-Lab_Learn-It_Adhesives.pdf

karimwassef
09/07/2017, 11:05 PM
Here's the construction I'm considering (overall tank is 12' x 8'):

<a href="http://s1062.photobucket.com/user/karimwassef/media/Designs/0_zpsoq0hdqhx.jpg.html" target="_blank"><img src="http://i1062.photobucket.com/albums/t496/karimwassef/Designs/0_zpsoq0hdqhx.jpg" border="0" alt=" photo 0_zpsoq0hdqhx.jpg"/></a>

<a href="http://s1062.photobucket.com/user/karimwassef/media/Designs/1_zpsdljszdex.jpg.html" target="_blank"><img src="http://i1062.photobucket.com/albums/t496/karimwassef/Designs/1_zpsdljszdex.jpg" border="0" alt=" photo 1_zpsdljszdex.jpg"/></a>

<a href="http://s1062.photobucket.com/user/karimwassef/media/Designs/2_zpsxkvctint.jpg.html" target="_blank"><img src="http://i1062.photobucket.com/albums/t496/karimwassef/Designs/2_zpsxkvctint.jpg" border="0" alt=" photo 2_zpsxkvctint.jpg"></a>

<a href="http://s1062.photobucket.com/user/karimwassef/media/Designs/3_zpshv8n8xi7.jpg.html" target="_blank"><img src="http://i1062.photobucket.com/albums/t496/karimwassef/Designs/3_zpshv8n8xi7.jpg" border="0" alt=" photo 3_zpshv8n8xi7.jpg"></a>

<a href="http://s1062.photobucket.com/user/karimwassef/media/Designs/4_zpsczzcyccw.jpg.html" target="_blank"><img src="http://i1062.photobucket.com/albums/t496/karimwassef/Designs/4_zpsczzcyccw.jpg" border="0" alt=" photo 4_zpsczzcyccw.jpg"></a>

<a href="http://s1062.photobucket.com/user/karimwassef/media/Designs/5_zpsba8i7iff.jpg.html" target="_blank"><img src="http://i1062.photobucket.com/albums/t496/karimwassef/Designs/5_zpsba8i7iff.jpg" border="0" alt=" photo 5_zpsba8i7iff.jpg"></a>

karimwassef
09/11/2017, 10:39 AM
No one has experience with silicone adhesion to concrete?

Am I all on my own here? :)

Hate to be the guinea pig.

Sharpimage
09/11/2017, 05:02 PM
Concrete is 150 pcf. Lightweight is 120 pcf at best. Also, concrete is not an exact science. It is batched based on weight per cubic yard, so there are variables.

I have no idea about adhesion from concrete with silicone

karimwassef
09/11/2017, 05:30 PM
I'm looking at GFRC to give it strength and reduce weight

Desert Sea
09/12/2017, 06:00 AM
No one has experience with silicone adhesion to concrete?

Am I all on my own here? :)

Hate to be the guinea pig.

I don't have experience using silicone in the application you are intending on using it for but know from experience that silicone does not adhere well to masonry materials including concrete. It may have something to do with "dusting" of the masonry materials. Concrete and masonry surfaces can be dusty no matter how well you try to clean them. Guessing the dust interferes with good adhesion.

I've used polybutyl caulk for masonry in the past with good results but not sure how it would hold up to the forces your dealing with and if it is safe for tank inhabitants.

If it was me, I would look to do some type of mechanical attachment between the glass and concrete. If possible a glass shoe embedded in the concrete.

karimwassef
09/12/2017, 07:38 AM
That's a good idea but it adds a lot of complexity to the structure.

I can also expand the ends of the concrete to create a bigger attachment food but that is also more complex.

GFRC is made with glass fibers and polymer plasticizer. The surface can be polished to be like stone. So I don't expect dust to be an issue. But that does emphasize the importance in surface treating the adhesion edges to make a more secure bond. Thanks!

I'll make some small test coupons and run them through a strain test to see how they compare... glass-glass vs. GFRC-glass

karimwassef
09/14/2017, 06:58 AM
I added a couple of glass braces to help. Just made a walk through video of the plan to my build thread.

http://www.reefcentral.com/forums/showthread.php?t=2589632&page=25