General, Research, Technology

Why does modern asphalt deteriorate so quickly?

Today, most highways andthe sidewalks are covered with asphalt and this is clearly one of the most common building materials in the world. Thanks to the smooth asphalt surface, cars drive as smoothly as possible, and people do not stumble on the sidewalks. But this is only on condition that the coating is fresh and there is no damage on it. Asphalt began to be widely used in the 1800s and in those days it was very durable - it was not afraid of either the vagaries of nature or the weight of many cars. And now the asphalt begins to deteriorate in the very first months after laying. If you don't believe me, pay attention to the roads and sidewalks near your house - you will surely find a huge number of irregularities. Recently, Japanese scientists decided to find out what exactly is the cause of the fragility of asphalt and conducted an experiment, the results of which at least partially clarified the situation. Perhaps thanks to this discovery, the asphalt will become stronger.

Modern asphalt decays faster than old, but why?

What is asphalt?

Scientifically, asphalt is a mountainresin, which is a black substance that melts at 100 degrees Celsius. This material is actively used in the construction of various roads, up to the runways for aircraft. Also, for many people it may come as a surprise that asphalt is part of some glues and varnishes, and a high-class substance is used even in painting. But it should be borne in mind that asphalt is of natural and artificial origin. Natural asphalt is used as a component for varnishes and other substances, and only artificial asphalt for road construction.

In Russia, laying asphalt looks something like this

Road asphalt in Russia is the most correctcalled asphalt concrete. This building material usually includes crushed stone, sand, mineral powder and bitumen. You probably already know the first two components, but what do the last two terms mean? Mineral powder, also known as filler, is a mixture of crushed limestone and industrial waste. It gives the coating mechanical strength and at the same time makes it slightly elastic. Bitumen, formerly called "earthen tar", is a mixture of hydrocarbons and their derivatives. If you do not delve into chemistry, then this is a black and viscous substance that sticks together all the other components of the asphalt.

Spilled bitumen

Interesting fact: in Great Britain, the asphalt concrete we are used to is called tarmac... And in Europe, asphalt has an ordinary composition,but it is laid in a more complex method, due to which it has increased strength, but it is more expensive. The main feature of the "European" styling is that the mixture heats up to 250 degrees Celsius, after which it becomes very soft and lies flat on the ground.

Why does asphalt deteriorate quickly?

A group of Japanese scientists led by AkihiroMoriyoshi has long noticed that modern asphalt degrades much faster than material produced in the 1960s. To find out the reason for the decline in quality, scientists studied asphalt samples from around the world, as well as fragments of asphalt from 60 to 120 years old. In the course of scientific work, they recreated the conditions for their use and followed the changes in the asphalt structure through a computer tomograph. Let me remind you that this technology allows you to look inside objects without destroying their outer shell.

Distribution of cracks in new asphalt (a) and 120-year-old sample (b)

Between old and new asphaltthe work revealed one important difference - modern material contains too many unnecessary components. We are talking about phthalates, phosphates and other chemical compounds that quite accidentally penetrate into the material during its creation. The concentration of excess substances is very low and is only from 0.0012% to 0.25%. But this amount is more than enough for the road surface to become brittle and covered with holes after a few months from the date of laying. Scientists also found that the strength of asphalt decreases due to a component that makes the coating water-repellent.

The main problem of modern asphalt is that it contains a lot of unnecessary impurities.

There is little hope that manufacturersasphalt concrete will pay attention to the results of the study and change the composition of the material. They should also change the way they pave the asphalt. But even if the composition changes, the roads can still collapse. The fact is that the environmental conditions also affect the durability of the asphalt pavement. So, during heavy rains, the roads are covered with water. Water penetrates into the pores and stays inside for a long time, up to cold snaps. With the onset of frost, it freezes and turns into ice, which breaks the coating, forming cracks.

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It is worth noting that on hot days, asphalt concrete can harm your health. You can read what the danger is at this link.