Papercrete?? What’s that??
That’s the response I always get when I’m describing my favorite building material. Not surprising since it occupies a spot in that backwater known as ‘alternative building materials’. Papercrete is just what it sounds like actually. It’s concrete made with paper. I tell people to think of it as industrial paper mache. It’s inexpensive to make, amazingly sturdy, lightweight and insulating. Papercrete is made by grinding up paper in water and adding cement. The resulting slurry can be cast into a variety of forms from blocks to panels to poured in place walls. I found out about it in the late nineties. I used to own a magazine distribution company that specialized in small press and unusual magazines. One of the titles we carried had an article about people who were recycling newspapers and building with papercrete down in southern New Mexico. It was a total off the grid hippie dome sort of scene. The domes weren’t my thing but I was captivated by the material and the process of making it. I saved a copy of that magazine and told everyone I knew about it. It was especially appealing to me because I would have to pay to have extra unsold magazines hauled away for recycling. At the time I didn’t have a place to experiment with building projects so eventually the papercrete article went into storage and the idea went on the back burner. My biggest obstacle was the mixer. To make papercrete you have to be able to grind up paper… lots of paper. In order to do so you need a mixer capable of shredding paper. A regular cement mixer won’t shred the paper it will just stir it around. Luckily for me, a guy by the name of Mike McCain had already invented a papercrete mixer that you tow behind a truck. You just throw everything in and drive slowly for about a mile. When you’re done you have papercrete slurry ready to be cast into something.
Four years ago I decided that it was time to build something out of papercrete so I went about collecting the materials to build the mixer. Over the course of a few months I had collected everything I needed from neighbors, the junkyard, and a few other sources. My collection of potential mixer parts languished in the yard for a few more months and finally on Father’s Day I decided “it’s my day, and I’m building this freaking mixer already!!” Well, I built it ( More on that later) and more than a decade after I found out about it I was finally ready to make my first batch of papercrete. We had been collecting all of our junkmail and recyclable trash the past six months just for this occasion. All in all the first run went well, I didn’t spill too much stuff on the road, the mixer didn’t fall apart and papercrete was made. I made about 10 more batches that Summer figuring that a project would emerge to use these blocks I was making. I ended up using them to build the walls for a guesthouse and for making raised gardening beds.
Why I love papercrete:
It’s a really easy material to make- As long as you stick to the rough proportions of water, paper and cement you’ll end up with a usable product. I can make 45 blocks by myself in two hours.
It’s cheap- It costs about a quarter to make a 8″ x 12″ x 5″ high block.
It’s green- Totally overused term these days, I know, but I use all of our paper trash for the year and then quite a bit more. It’s fun to go to the recycling center and see their faces when I ask for paper rather than dropping it off. Now we even grind up all of our plastic trash and mix it right in! Making papercrete turns nearly all of our household trash into building materials.
It’s sturdy but lightweight- A block only weighs a few pounds but can hold up a car!
It’s insulating- It has an r-value of 2 or 3 per inch so a 12″ wall has an r value of 24-36. The requirement for a regular wall in a house is r-19… not too shabby.
It’s easy to work with- Once you have blocks you can use the same papercrete mix as a mortar and plaster to stick them together.
It’s weatherproof- I’ve had blocks out in the elements for 4 years and they haven’t changed at all. It does absorb water like a sponge so if they are going to be used for walls they need to be protected from moisture.
What’s not to love?
Next up I’ll go over how to make a papercrete mixer.
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