Bio-Asphalt: Paving the Way for Greener Roads

Asphalt is vital to the construction industry in the US. It’s commonly used in the construction of roads, driveways, and on the roofs of houses. Asphalt is on 94 percent of the 2.7 million miles of paved roads in America.

In its most basic form, asphalt is the waste left over from refining crude oil. Also known as bitumen or liquid petroleum, this material contains toxic, heavy metals, like nickel, lead, mercury, and arsenic. When oxidized, these metals may cause cracks in the pavement, making it unsafe for passage. Potholes may develop over time due to old age and frequent usage. And local asphalt repair shops need to work on these cracks to prevent further damage and hazard on the road.

A new kind of asphalt, though, may change how this material performs and create an impact on the environment.

What is Bio-asphalt?

The adverse effects of commercial asphalting have led to the search for suitable alternatives to paving roads. The material’s production is highly dependent on the oil industry, making it energy and resource intensive. Since petroleum is a nonrenewable energy source, production of commercial asphalt is not ideal or sustainable.

Researchers discovered bio-asphalt in an attempt to produce nonpetroleum-based material independent from nonrenewable sources.

Bio-asphalt is a greener alternative to commercialized asphalt derived from crude oil waste deposits. Bio-asphalt, made of microalgae, proves to be a sustainable alternative to asphalt. Though the chemical composition of bio-asphalt varies immensely from that of asphalt derived from crude oil waste, both share some similarities; including its rheological properties (e.g., viscosity and penetration) and its black tint.

Researchers were able to produce bio-asphalt from microalgae waste. They used a hydrothermal liquefaction process, where pressurized water in a specific state turns microalgae into a black, sticky substance akin to liquid petroleum (asphalt). The current conversion efficiency of this material is at 55 percent.

Aside from its use on road pavements, bio-asphalt, in its liquid form with a temperature exceeding 212 degrees Fahrenheit, can also coat mineral aggregates.

But researches are still developing ways to produce bio-asphalt that can withstand any kind of weather and temperature. Where it currently stands, cold areas make bio-asphalt mixtures brittle and prone to damage. A solution to this would be creating a variety of asphalt fit for every climate.

Using Bio-asphalt and its Effect on the Environment

thinking green

Switching to bio-asphalt as the main source for binding oil in construction supply can be good for the environment. It can also cost significantly less than standard asphalt and can reduce the heat island effect on dark colored pavements through dyeing of the material.

According to a study, using bio-asphalt reduces paving costs by 20 percent, decreases overall carbon footprint, reduces greenhouse emissions, and increases the average lifespan of pavements.

Replacing commercial asphalt with bio-asphalt reduces carbon footprint without sacrificing on quality. There are no known toxic metals in the chemical composition of bio-asphalt, making it suitable for use. Because it uses renewable resources, the production of bio-asphalt won’t endanger the environment as much as current oil refineries do for commercial asphalt.

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