Thursday, November 17, 2011

First Round of Shotcrete Panels

This week I got around to shooting a couple test panels with the new shotcrete setup. Like anything it is going to take a couple versions to get things just right. Glass fiber reinforced concrete (GFRC) countertops consist of a sprayed face layer followed by a fiber reinforced backer layer. The spraying gives a very uniform texture and the fiber reinforced layer allows a much thinner and lighter section.
For the trial, first a polymer modified Type S mortar mix was sprayed on thin.

Turns out it was a little too thin. I was aiming for 1/4" but ended up with something more like 1/8" or just enough to coat the mold. Especially on the sides you can still see some white. 

Then a fiber reinforced backer mix was placed by hand. I did make enough material and this layer was pretty thin too. The panels turned out about a 1/4" thick. The goal in the future will be to get this up to about 3/4". 

I stripped one of the molds after 8 hours just to see. The garage was cool and it wasn't strong enough. Notice the hole in the lower left panel. The rest stripped just fine at 24 hours. They don't weigh anything and are pretty strong, comparatively. For a first try things went well. The corners need more attention to reduce sand build up and everything could be thicker. 

I am using these panels as an opportunity to do a head to head trial of a few different sealants. I have 12 sealants or combinations of sealants in the test. Then I am going to test for water absorption, red wine staining, mustard staining, vinegar erosion, and heat resistance using a hot bolt. The panels are pretty green yet so that test won't be until this weekend. 
A couple more trials are going to be required to get the mix and spray technique just right. 

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