Hi Dan,
I started pouring blocks like you are but found the three week +/- wait to let them dry unacceptably long. I was doing this in Montana where we have very dry air and 80 degree days. It does get down to 40 at nights but I had most of the flat surface around our site covered with drying bricks and that was turning them regularly after a week after pouring to even out the drying. One thing that will cause the time to dry increase is putting a layer of plastic under them. You were probably thinking to keep the block clean, but that one item (in your picture I see a blue tarp under the mold) will add weeks to the drying process in a humid environment.
You haven't said what the application is but if you could, using slip forms would be much better. You would not be "trimming to size" (which adds another step and takes a lot of time, and you wouldn't need to mix another batch to lay the bricks. Also what Tasha said about the trapezoidal shape you end up with with bricks is really a bummer of a smooth finish on either interior or exterior. This is eliminated with slip forms. If you use the methods shown by Bob the builder, or mine you lock each succeeding layer to the layer below and the wall comes out smooth and strong. There is no wait to dry the resulting wall except that if your mixing capacity exceeds about 2' in height a day. You would want to wait a day or two between 2' of vertical pour so there is no swelling (bulging) in the underlying "green" wall.
I do agree that pressing the blocks helps cure them faster and helps keep the shape and will dry them faster. With your current mold you would have problems with the sides bulging out beyond your 12" width. You would need to put gusssets on the outside of your mold along the long dimension. This would necessitate a flat part to your mold around the outside of the pour area. If you made it strong enough you could drive a Honda ATV, or riding mower over it for the pressure necessary to press the water out with a pressure plate laid on it.
Ron
From: trendawareness <trendlinesystems@gmail.com>
To: papercreters@yahoogroups.com
Sent: Wednesday, June 27, 2012 9:00 AM
Subject: [papercreters] Best way to pour 6" x 12" x 52" block?
I'm working on a project that requires a consistent 6" h x 12" w x 52" long PC block. I've built the molds and have filled one to the top on the first pour and will backfill the shrinkage in a day or two. (photos attached)
My question is whether or not filling a 6" mold on the first pour is the best way or whether I should only fill it half way on the first pour.
For background, my mix is 1# paper, 1# portland, 1# sand, .05 # Borax. I live near Cincinnati and our summers are generally hot and humid.
Thanks
Dan
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