Behind the bitumen

When most people hear the word ‘bitumen’ they think of the roads we drive on. But there’s a whole history to the material – bitumen has been used for a myriad of applications, from jewellery to waterproofing.

What is bitumen?

Bitumen is known for its waterproofing and adhesive properties, and is created through the crude oil distillation process. The process removes lighter crude oil materials such as diesel and gasoline, and leaves the heavier bitumen behind. The process is often repeated several times to get the finished product.

The bitumen material contains a complex composition of hydrocarbons and elements such as calcium, iron, sulphur and oxygen.

Importantly, bitumen is produced differently according to the specifications of its end use.

While it’s usually manufactured industrially, bitumen can also be found in nature. For example, natural bitumen can be found at the bottom of ancient lakes where prehistoric organisms have decayed. The heat and pressure that the organism is subjected to often creates the bitumen.

The history

Bitumen has been used for centuries in many different ways. 

It’s believed that approximately 40,000 years ago, the Neanderthals in Syria used bitumen. Historians found the material adhered to stone tools.

Bitumen was also used in Syria during the Uruk and Chalcolithic periods, mainly to construct buildings and waterproof reed boats.

In antiquity, bitumen was used as an adhesive to repair broken statues or pottery. It was also used to manufacture handles for tools. In fact, the use of bitumen to attach stone edges to handles of various tools was widespread until the Neolithic era, with samples found in Syria dating back to 6800BC, in Israel from 8900–7800BC and Pakistan from 3500BC.

Interestingly, bitumen was also used during the mummification process in Egypt. The bitumen was sourced from the Dead Sea, which was known to the Romans as Palus Asphalites, translated to Asphalt Lake. The connection between the ancient Middle East and the mummification process is also understood through the actual word ‘mummy’, which is derived from the Arabic word for bitumen – mumiyyah.

The most frequent use of the material seemed to be in the construction industry. Bitumen was widely used as mortar and, while sometimes found in ordinary dwellings, the most common use was for prestigious buildings such as temples and palaces. The bitumen was mixed with chopped straw, clay and sand to create the mortar. In fact, an ancient Greek historian has even gone so far as to say the walls of ancient Babylon were reinforced using bitumen.

Bitumen was also used in the jewellery market, with beads of bitumen found on necklaces in graves dating back to the Ubaid period. Glue manufactured from bitumen was used to decorate rings made from seashells, and the material was used in many gold and silver pieces, as well as for brooches attached to clothing.

Modern uses

It’s estimated that bitumen production currently sits at 87 million tonnes per year. The majority of this is used in paving, followed by roofing. The highest global demand for bitumen comes from the Asia Pacific region at 37 per cent, North America comes in second at 25 per cent and the European Union sits at third, with 17 per cent of demand.

According to a report produced by the Asphalt Institute and Eurobitume, 85 per cent of bitumen is used as a binder in asphalt pavements for roads and airfields. Of the remaining amount, 10 per cent is used for roofing, including shingles. This is generally because of bitumen’s waterproofing capabilities. The final amount is used for small-volume demands, for example waterproofing, water pipe coating and sealing materials.

In everyday road paving applications, bitumen is mixed with mineral aggregates to produce a very strong and hard-wearing material called asphalt. Asphalt is the most commonly used road surfaces in the world.

Bitumen and asphalt are also 100 per cent recyclable, with milled surfaces being re-incorporated back into new production. With global asphalt production standing at around 1.5 billion tonnes, this makes asphalt the most recycled material in the world.

A diverse material

Bitumen is a material that has stood the test of time, with its first appearances found in ancient history. While its composition may have changed and its various uses adapted for the modern world, the resourceful material continues to remain as versatile today as it was thousands of years ago.