One of the main infrastructures of every civilized country is its public access road network. Not only do they interconnect towns and cities, the country’s citizens circulate through it in their daily work, as well as all the materials, food and other consumer goods necessary for the maintenance of society.

However, have you ever wondered about the reason why all-important constructions mainly use concrete; instead, asphalt is used for road construction? Perhaps this material is not the most suitable.

Why is asphalt used for road construction?

The main advantage of using asphalt for road construction is fundamentally its cost. We have to remember that bitumen or asphalt is the main solid residue at room temperature from the distillation of crude oil. So as a waste and even when it is a product derived from petroleum, its cost is low enough and its availability high enough to be used for this purpose after being reheated and mixed with different granulometries of aggregates. This mixture that we commonly call asphalt, in turn allows transport over long enough distances without altering its properties too much. Another advantage of asphalt for this purpose is its ease of handling and installation.

Fig.1 Diagram of the oil distillation process obtaining asphalt as a residue.

However, are these advantages enough to justify the use of waste to pave our environment?

Of course, not, most of the disadvantages of use do not attend to merely technical aspects; we must also highlight purely ecological and even economic issues.

The useful life of a road built with asphalt is estimated to be between 15 and 20 years on average, as long as the weather conditions allow it, since this material is very sensitive to deterioration caused by both high and low temperatures, rain and infiltration of water etc. In addition, it is a relatively fragile material and easy to damage by mechanical means, such as the simple rolling of heavy vehicles on its surface, a task for which it is supposed to have been chosen due to its properties.

The maintenance of the roads made with this material is necessarily continuous and it is enough to look a little at any of the streets, highways or roads in our environment with a minimum of years of use, to observe all kinds of maintenance work on its surface with the naked eye repairs, pothole filling, partial resurfacing, etc. All this supposes a continuous and endless economic expense, of an unpredictable nature, which forces to maintain a high budget destined for this purpose or otherwise renounce the good general condition of the same.

Fig. 2. Damage and repairs on an asphalt road.

Finally, we must also consider the ecological and even health consequences that the use of these asphalts entails, since they are one of the main sources of micro plastic emissions in our atmosphere, responsible for the decrease in air quality in the area. , contribute to greater pollution and CO2 emission due to their low durability and their continuous maintenance and even partial reconstruction. In short, a very unsustainable element.

Advantages of roads built with concrete

One of the main arguments for opting for concrete when building a road is its greater durability (significantly greater with the use of waterproofing additives). Thus, using this element, a useful life of 30-50 years can be achieved, since the material is much more resistant and rigid than asphalt and therefore suffers less surface deterioration such as potholes, fractures, cracks, subsidence…

At the same time, concrete has a higher light reflection index, which makes it much safer for use at night by providing greater visibility and reflecting a greater amount of sunlight during the day and with it temperature, which helps to mitigate the “heat island” effect.

Taking into account another aspect related to road safety, the braking distance is considerably shorter and the phenomenon of aquaplaning is largely avoided by largely eliminating the possibility of stagnation and puddles on its surface.

Fig.3. Road section built in concrete.

From an environmental point of view, cement is not a petroleum residue and its greater durability makes it more sustainable since it reduces the energy and emissions required for its installation, maintenance and upkeep. It is completely recyclable and is produced locally or near the construction, which implies greater local development.

Above all one of the most striking aspects is the reduction in fuel consumption in the vehicles that circulate on it, as it has better rolling properties than asphalt roads; this is significantly lower in heavy vehicles, even reaching consumption close to a 15% minor.

All these aspects only make us wonder if the use of asphalt for the construction of roads is still justified, especially considering the current costs of oil, or if it is time to seriously consider the alternative of concrete. The following link summarizes all these arguments quite well.