Polystyrene beads act as aggregates in lightweight concrete called Styrofoam concrete or expanded polystyrene (EPS) concrete. The beads introduce air into the concrete and replace heavier aggregates such as gravel. Air is between 4 and 7 percent of the mixture’s volume. This concrete has good thermal insulating properties, and is used for decoration and counter tops. Homemade EPS concrete is not used for structural purposes.
- Skill level:
Things you need
- Portland cement
- Polystyrene beads
- Latex paint
- Fine sand
- Wheelbarrow or other container for mixing concrete
- One each of 20-litre (5.2 gallon), 10-litre (2.6 gallon), and 5-litre (1.3 gallon) buckets or plastic containers.
- Soapy water for soaking polystyrene beads
- Water for mixing the cement
- Large plastic bag enough to hold the polystyrene beads
- Face mask
- Gloves and protective clothing
Put on the face mask, gloves, and protective clothing. Decide how much concrete you will make. Use the buckets or containers to measure out the concrete mixture in the amounts you need. Ensure that the proportions of the mixture by volume are 2 parts cement, 2 parts sand, 1 part water, 1 part latex paint, and 16 parts polystyrene beads.
Place the beads in a waterproof bag. Pour in soapy water and allow the beads to soak. Agitate the bag from time to time so that the beads wash well and leave overnight. Cut a small hole in the bottom of the plastic bag and allow the water to drain. The remaining polystyrene beads should look like slurry. Without the soaking, the light beads will fly around in the air and attach to anything through static electricity.
Pour the polystyrene bead slurry into the wheelbarrow. Add the sand on top of the beads, and the cement above the sand. Ensure that the cement does not create too much dust
Mix the latex paint with water in the 20-litre (5.2 gallon) bucket. The latex will act as a suspension agent to stop the polystyrene beads from separating away from the concrete after mixing. Polystyrene does not bond as well with cement paste as other aggregates like sand and gravel. Pour the water and latex mixture slowly over the cement, sand, and beads in the wheelbarrow. Use the shovel to mix everything together. When all the ingredients have combined, pass the mixture to a helper who will pack it in place.
Spray the cement with water twice daily when it has set. Leave for at least seven to 10 days to cure and reach final strength.
Tips and warnings
- Ensure that the concrete mixture is well mixed. Scrape the sides of the wheelbarrow or container to stop the polystyrene beads from attaching.
- Do not to use too much water as the concrete will lose strength. If moisture seeps out of the concrete, it is too wet.
- Remember always to use the protective clothing. Concrete is very corrosive to the skin.
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