Tuesday, January 1, 2013

Burlap Cement & Asphalt Emulsion Experiments

This so-called gazebo structure is an amalgam of papercrete recipes. In that way it taught me a good bit about papercrete -- the recipes improved over the weeks of layering. But some of the areas first covered are soft, and rain was actually eroding them. I wanted to extend the umbrella roof, creating an eave for aesthetics but also to help keep the rain off those soft sections until I can invest the time to save or re-do them.

The roof is made from a picnic table umbrella coated with a latex paint/cement/sand mixture. It seems to be holding up, but I didn’t see how to attach lathe or hardware cloth as an armature for an eave.

I wound up using raw burlap soaked in bonding agent, then saturated with crack resistant grout. I was inspired to try this approach by this great website (http://annesley.wordpress.com/burlap-crete-explained/). I could not find the rapid set grout this author writes about, and settled for Quickrete Professional Crack Resistant Grout purchased at Lowes.

Doing a section the width of the burlap  at a time, I just lay a double layer of the grout-saturated cloth in place at roof's edge and used a board to prop the overhang up until it cured. I wrapped the board in cellophane sandwich wrap to help keep the grout from adhering to it. After I saturated the burlap with grout and positioned it, I added more layers of grout, then let it cure several days before removing the board. I wouldn't try to do pull-ups from it, but it seems very sturdy.

I've begun layering the entire roof with a papercrete mixture including asphalt emulsion (2 parts sand, 2 parts cellulose, 1 part portland cement, a nice gob of asphalt emulsion. I let the dry mix tumble in the mixer for awhile, put a little in a bucket, added water, drill mixing until crumbly, then mixed in the asphalt emulsion by hand).

I'd used this mix layering a section of the gazebo (the issue at that time was getting papercrete to stick to the armature, and I really like the finished product. I'm interested to see how this mix holds up to the South Carolina humidity, sun, and heat. I'm trying to create a sort of layered, thatched look on the roof.


  1. Thanks for sharing with us this kind of information really great for us.

  2. I found this post of yours to be really helpful and guiding. Thanks for sharing your ideas with us.

  3. So far this roof has held up well. I just completed a similar roof on my outdoor shower project, covering an old umbrella with paint-crete, mortar, and finally with a papercrete/asphalt emulsion mix. I've also been using a touch of asphalt emulsion in my papercrete mix on some sculpture projects.