What is sulphur concrete?

Sulphur concrete is a type of concrete in which modified sulphur is the binder, instead of cement and water. Like ordinary concrete it contains mineral aggregates and fillers, such as sand, gravel, ground limestone or fly ash. A well-known brand name was Thiocrete from Shell.

How is it made?

1. Sulphur is melted and mixed with a modifier and the aggregates.
2. The hot mix is poured into a mould or formwork.
3. The material hardens by cooling, not by a chemical reaction as with cement. As a result it can take load after a short time.

The principle resembles asphalt, where bitumen is the binder that stiffens as it cools.

Advantages

• Resistant to acids and salts: suitable for chemically aggressive environments where cement concrete is attacked.
• Dense and water-repellent: few pores, so water hardly penetrates.
• Quick strength gain: once cooled the product can be used almost immediately.
• Remeltable: sulphur concrete can be remelted and reused.

Disadvantages

• Thermoplastic: at elevated temperatures it loses strength and softens. It is therefore not suitable for load-bearing structures in buildings, nor for places exposed to heat, such as near a fireplace or barbecue.
• Fire: sulphur is combustible, which limits its use inside buildings.
• Separate waste stream: sulphur concrete must not end up in the recycling stream for ordinary cement concrete.

Applications

• Sewers, manholes and wastewater treatment plants.
• Floors and containment basins in the chemical industry.
• Paving, kerbs and other precast products for outdoor use.

For DIYers, sulphur concrete is not something to make yourself: handling molten sulphur requires an industrial plant and safety measures.

Related terms

• Stoneware pipe
• Asphalt
• Sewer
• Concrete compaction

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