Asphalt: The ubiquitous road surface material


Asphalt is a sticky, black and highly viscous liquid or semi-solid form of petroleum that is present in most of the road surfaces across the world.

What is Asphalt?

Asphalt is a by-product of the petroleum refining process. When crude oil is distilled to produce gasoline, jet fuel, diesel and other petroleum products, a heavy black residue called bitumen or asphalt cement is left behind. Asphalt is essentially composed of highly complex organic compounds containing carbon, hydrogen, oxygen, nitrogen and sulfur. It generally has other modifiers added to improve its properties for specific applications.

Asphalt Production

The Asphalt production process starts with identification of suitable grade of bitumen at the oil refinery. This selected bitumen is then transported to special asphalt mixing plants where it is heated to temperatures between 150–200 °C for fluidization. The heated bitumen is then mixed with pre-heated aggregates like sand, gravel or crushed stone along with other additives as per the required specifications.

The hot asphalt mixture is then transported using insulated trucks to the construction site. At the site, the still hot asphalt mixture is laid down using mechanical pavers and compacted using heavy rollers to achieve the required density and smoothness. The compacted asphalt solidifies on cooling to form a strong, durable and water-resistant pavement surface.

Uses of Asphalt

Asphalt is the most commonly used material for road construction across the world due to its excellent performance and economical advantages over other materials. Some key uses of asphalt are:

– Paving of roads, highways and streets: Asphalt concrete is used to pave over 95% of the roads globally due to its high strength, durability and cost-effectiveness.

– Airfields runways and taxiways: Asphalt is the preferred pavement material for aircraft runways and taxiways due to its ability to withstand heavy loads and impacts from aircrafts.

– Asphalt shingles: Manufactured asphalt roofing tiles called shingles are used extensively for waterproofing rooftops of homes, buildings and other structures.

– Bike/walking paths and recreational surfaces: Porous asphalt mixtures are used to construct paths, trails and playgrounds to allow for drainage.

– Waterproofing purpose: Liquid asphalt is used for waterproofing applications such as pond lining and roof coatings.

Advantages of Asphalt Over Other Materials

Here are some major advantages of asphalt over other commonly used road construction materials:

1. Cost-Effectiveness: Asphalt pavement has lower initial capital cost compared to concrete and offers cost savings over the lifetime of the pavement structure.

2. Easy to Install and Maintain: Asphalt is easy to lay down and compact with paving equipment at the construction site. Small repairs are also inexpensive to carry out.

3. Durability: Well-designed and constructed asphalt roads can last over 20-30 years with only minor surface repairs if maintained well.

4. Smoothness and Safety: Asphalt gives a smooth driving surface that contributes to driving comfort, tire efficiency and enhanced road safety.

5. Protection Against Weathering: Asphalt pavement protects the underlying base and sub-base layers from aging due to exposure to air, water, frost and other environmental conditions.

6. Recyclability: Used asphalt pavements can be recycled by heating and mixing the reclaimed material with new asphalt for reuse in new road construction projects. This offers environmental benefits over other non-recyclable materials.

In a nutshell, asphalt is the most preferred paving material globally majorly owing to its technical performance, cost-effectiveness over the life of the pavement and ease of construction, maintenance and recycling. Asphalt paved roads help towards smooth transportation and enhanced safety.

1. Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile it