You can collect styrofoam before it is thrown away or after. The easiest way to collect a lot of styrofoam is to arrange with appliance stores to keep it for you. Appliances from radios to refrigerators are packaged with blocks of styrofoam that go straight to the dump. Stores are happy to let you save them the hassle of disposing of the stuff. You can also find lots of styrofoam litter on the side of the road and in village dumps. If the styrofoam you collect is greasy – for example, old food containers – make a large drum full of soapy water and stir them around in it. Rinse well.
Styrofoam Recycling: Grinding
To use styrofoam to make cement products, you must break it down into its smallest “cells.” We call this “fuzz.” It flies everywhere and sticks all over. But if you do not reduce the styrofoam to these small cells – for example, if you tear it into small pieces with your fingers – your bricks will not hold together.
To keep it simple, grind styrofoam to fuzz by scrubbing it with a wire brush. You should do this by holding the styrofoam in a large plastic trash bag and scrubbing the wire brush across its surface. The “fuzz” will collect in the bag.
If you want to look more professional, you can make a simple mechanical grinder. The specific design will depend on what materials and tools you have on hand, but there are four basic parts: (1) a hopper for the styrofoam, (2) the grinder itself, (3) a power source, and (4) a “fuzz” collector.
The Warm Heart grinder now has a plywood hopper and an electric motor, but it started with a big tin can and old bicycle. The grinder itself was a piece of PVC pipe that we studded with nails by heating them with a cigarette lighter and then melted into the PVC. We carved wooden plugs for the ends of the PVC so we could put an axle through and pinch-clipped a trash bag onto the contraption to collect the fuzz.
Styrofoam Recycling: Mixing
We experimented with many ratios of styrofoam fuzz and cement powder before settling on 5:1. 5:1 bricks use a lot of styrofoam, neither break nor crumble easily, bear a big load, provide good thermal and sound insulation, and are light and inexpensive. Our standards may not be yours, and our standards are not scientific. We cannot test, for example, load-bearing capacity. Where we work, however, contractors use brick as infill between load-bearing columns and do not build load-bearing brick walls. Our brick, therefore, needs only to support its own weight to a height of three meters.
If you plan to use styrofoam cement to bear loads – in foundations or walls – you will need to test the structural properties of whatever ratio you select and, indeed, of styrofoam as a cement additive.
If you chose to go ahead and use styrofoam cement, it is easy to make and use. You will require (1) lots of styrofoam fuzz, (2) cement powder, (3) water, (4) a large mixing container, (5) a bucket to use as a standard measure, (6) a hoe for mixing and, if you are making bricks, (7) molds, mold-sized rectangles of wood for packing and flattening cement in the molds, and a drying area. If you are planning to make roof tiles, you will need the tile forms. If you are planning to lay a styrofoam cement roof, you need to have prepared the frame to contain the cement at the edges of the roof.
Styrofoam Recycling: Molds
Bricks are the easiest product to make with styrofoam cement mix. To make bricks, you will need brick molds. Remember, you will need to have available at least as many molds as are required to use up a single batch of mix!
The easiest molds to make are “ladder” molds for two or three bricks. (Do not go for more. They get unwieldy very fast. Better to have many molds than a few big, awkward molds.) The key thing to remember is that you want all of your bricks to be exactly the same size – and a standard construction size so that anything you might buy – window or doorframes, for example, or columns – match up with them properly.
Unless you are truly experimenting, make good quality molds that will last. Your molds will take a beating; make them out of good, solid wood that is well fastened together.
To make insulating roof tiles for a building with an existing roof, make molds by taking a sheet of the same roofing material as the roof and built a frame around it. The height of the frame will depend on how thick you want the tile to be. Shovel styrofoam cement mix onto the tile form and spread evenly with your hands. Allow to cure for several days. Paint with water-based urethane if possible or otherwise any exterior latex.
To use, lay on top of the existing roof after making a low ledge with drain holes along the bottom edge of the roof.
Styrofoam Recycling: Drying
Styrofoam cement roofs
Styrofoam cement external wall plaster and secondary brick walls
To insulate a house or building against heat or sound, either build a secondary wall of styrofoam cement bricks doubling an external wall that faces the sun or, for example, a busy road. Alternatively, apply styrofoam cement as a thick (5-10 cm) plaster to existing walls to provide heat and sound insulation.
Warnings about styrofoam cement products
There is concern about the flammability of styrofoam and so of styrofoam cement products. These concerns have not been borne out by Warm Heart’s tests. Exposed to open flame, 5:1 styrofoam bricks do not burn readily and do not off-gas rapidly. (See test video and photos below.)
This said, for potential fire safety and toxic gas safety, Warm Heart still recommends the following:
- Use styrofoam cement products for external applications: insulating roof treatments, wall plasters and outer brick walls.
- Where styrofoam brick is used for a single wall with an internal exposure, cover the exposed internal face with a fire retardant – cement skim coat, plaster, gypsum board or other.