Tuesday, June 23, 2009

[papercreters] Heat curing papercrete appears to improve tensile strength.

I discovered something interesting over the weekend.

I was playing around with a small bucket of slurry. I was making a few small samples. They are intended to be given away to a group of people I'm going to be talking to next weekend.

Anyway... that's not realy important.

What's important is what I may have discovered. Since I don't have time to wait for the typical air drying time of a few weeks, I wanted to speed the process along. What to do? I decided to pop them in the oven.

Yeah... I know... Haste makes waste, and I was in a hurry. That rush made me waste some precious energy resources. If I had been on top of my game, I would have made these samples a month ago when I had the chance, but I procrastinated. Hey... nobody's perfect... especially ME!!

I baked my small sample blocks... (approx 6" x 6" x 2") in the oven at 275F for 4 hours. (convection cycle)

It worked as expected. Dried them right out. No problems. There was some shrinkage as expected, and a very slight bit of curling of the corners. No big deal. I'm going to trim up the blocks on my saw to make them look nice and pretty.

However... I happened to have a few small scraps from a previous small batch that used the same recipe.

While both samples are very similar... the baked ones are MUCH more durable. They seem to be pretty similar in compression strength... (I haven't actually tested them yet.) However... my very SUBJECTIVE "Charles Atlas" test tells me that these new samples are a lot more difficult to pull apart. A LOT MORE DIFFICULT.

I have no idea why they seem so much stronger... but the samples don't lie.

I need to rig up a big fish scales and test the samples to get some actual numbers to see how big of a difference there is.

I also would like to compare the two samples under a microscope, but that will have to wait a while.

Anyway... that's what I learned over the weekend. How about everyone else? What did you learn?

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