Smart Business Idea

Warm Heart has developed a simple, replicable system to convert styrofoam into a useful product, providing an opportunity for both men and women to build a sustainable business while helping clean up our environment.

It does not take much money to start-up, and the product has many possible uses.

Styrofoam Recycling

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

Warm Heart’s current styrofoam supply – collected in one day from local village dumps

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.

styrofoam recycling

Failed brick made from hand-torn pieces of styrofoam

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

Schematic of Warm Heart styrofoam grinder

styrofoam recycling

Warm Heart’s styrofoam grinder is made of scraps from various construction projects. Missing is the collector bag (a large trash bag) that clips on below the grinder.

styrofoam recycling

Looking inside the plywood hopper, you can see the grinder made from a piece of light gauge aluminum pipe from the recycling yard studded with drywall screws.

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

Five buckets of styrofoam fuzz and one bucket of cement powder ready to mix, enough for approximately 22 of our bricks

styrofoam recycling

Adding one bucket of cement powder to five buckets of styrofoam fuzz

styrofoam recycling

Mixing the styrofoam fuzz and cement powder before adding water

styrofoam recycling

Adding one bucket of water (add more if necessary, but sparingly!)

styrofoam recycling

The wet mix

styrofoam recycling

The wet mix up close – clumpy, will form loose ball

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.

styrofoam recycling

Example of Warm Heart test mold – effective for testing but not production grade!

styrofoam recycling
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

Simple, two brick “ladder” mold

styrofoam recycling

Making styrofoam bricks

styrofoam recycling

Pressing a rectangle of wood into the mold to compress the mix and flatten the top

Styrofoam Recycling: Drying

styrofoam recycling

Rows of new bricks drying. Even wet they are so light that they sit on just two bamboos.

Styrofoam cement roofs

styrofoam recycling

Warm Heart’s tin roofed biochar lab that was once unbearably hot in the sun.

styrofoam recycling

5 cm styrofoam cement roof laid on top of biochar lab tin roof for insulation

styrofoam recycling

Detail of styrofoam cement roof laid on biochar lab tin roof for insulation

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.
styrofoam recycling

Smooth surface, 5:1 brick after 90 seconds exposure to open flame

styrofoam recycling

Close up of open surface, 5:1 brick after 120 seconds exposure to open flame