WE BUILD BY SCIENCE

1995. The opening ceremony at Bina international airport. One of the most important strategic facilities of a country which gained its independence just a few years ago, is being put into operation. Azerbaijan's national leader President Heydar Aliyev thanks officials and the whole team who played a part in its construction. The owner of the German company Wirtgen says in reply: "Many thanks to you, Azerbaijanis. This is to the credit of your scientist Ali Aliyev. Thanks to the new technology he developed, we were able to carry out such responsible work to a high level of quality."

Fifteen years have passed since that memorable event, and each of us, when approaching the airport, notes the comfort and convenience of the access roads with a sense of pride and satisfaction and feels at ease when landing on his return home.

What is the secret of the successful technology involved in building roads and airfields, as developed by doctor of technical sciences, Ali Aliyev?

Ali Musa oglu Aliyev, a great scientist and man of action, is a laconic person. He is the author of more than 100 scientific works, 4 monographs and a number of teaching aids. His scientific and technological research is protected by 20 certificates and patents for inventions. In recognition of his great achievements in the study and creation of scientific bases for the regeneration of asphalt concrete cover and new technologies for the construction of roads and airfields, he has been elected to membership of several international academies.

In 2004, A. M. Aliev was elected vice-president of the International Academy of Research in the Turkic World. In 2005, he was awarded a gold medal for his services to the Turkic world, an international diploma, "Academic of the Year", and in 2006 he was declared the first winner of the Ataturk International Prize.

- You are the author of an enormous body of work, worthy of a scientific research institute. You have been building bridges and roads for 20 years and have 55 years of practical experience. Will you share the secret of how to build long-lasting roads?

- Science can answer many questions, but it draws all the answers from life itself and nature, that is, from practical experience. Each of us builds his house and thinks primarily about its reliability and, second, about its beauty and appearance. The reliability of a house is achieved by building a strong foundation. The same can be said about roads. The basis of a road is its foundation and road bed. In recent years, we have used limestone mineral materials as a base in the construction of roads and airfields. Limestone is a mountain carbonate rock. Our homeland is rich in limestone; it is found in almost every district, including the whole area of the Abseron Peninsula. For the first time in world practice, we used our technology to produce material based on natural self-cementation from limestone waste during the construction of the runway at Bina airport.

- But some managers of construction companies, representatives of city and state authorities, the head of Wirtgen and the head of Germany's central laboratory, Dr. Nissa, were against the use of limestone waste in the construction of the Bina runway and roads in general.

- Yes, there were objections and doubts. And this is understandable. There is no right to err in the construction of a significant and important strategic facility; the work was entrusted to the Road Trust Company of Baku and Wirtgen. The German side, understanding the responsibilities devolved to them, did not want to take a risk and did not believe our promises. In order to prove the validity and effectiveness of the use of limestone in the construction of roads and airfields, I had to spend more than 20 days in Germany. Using samples of limestone waste from Azerbaijan and the results we had from a pilot trial, we proved the feasibility of using limestone.

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Later, Wirtgen managers would hand a letter of thanks to Professor Ali Aliyev for his technological assistance and they would add the use of limestone waste in the construction of roads and airfields to the standard practices of their company.

The successful exploitation of the runway at Bina airport for almost 15 years has confirmed the correctness of Professor Aliyev's earlier findings: that limestone waste is effective when used in the construction of airfields and roads. Subsequently, this technology justified itself and was used in the construction of airports in the cities of Ganca, Lankaran (by the way, they belong to the highest class - A) and Zaqatala, in the reconstruction of the Azizbayov metro station-Airport-Bilgah road, as well as in the construction of highways.

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- But you can also use crushed stone and gravel as a base?

- You can use anything, but how practical is it technically and economically? Practice showed the opposite. We first used limestone waste in 1985, during the construction of a 250 metre experimental section in Bayil, where we used a mixture of limestone waste. At the same time, in a parallel 120 metre section, we used gravel and sand mineral materials. More than 20 years have passed and during this period, repeated and thorough examinations have proved that the first road is in good condition without bulges or serious damage. The second one was reconstructed in 1997, although they were used in similar conditions.

- How about the construction of roads on wetlands?

- We have such experience in our practice. During the reconstruction of the Baku-Alat road from Sixov to the village of Sanqacal, instead of an underlying layer of sand, we used limestone waste. The road was laid on a pulverised and wet base, 2-3 km of which adjoins wetlands. At some sites, we laid structural layers using crushed stone and sand from the Bahramtapa and Mingacevir quarries. Five years of operation under vehicle loads and the impact of climatic conditions (high temperatures and rainfall) had different effects on the asphalt cover of this section. Thus, transverse cracks and deformations appeared on the surface above gravel and sand structures, whereas in places where limestone waste was used, no such fractures occurred.

Although these sections were used in equally difficult ground-hydrological conditions and under heavy traffic, no deformation occurred where constructive layers were of limestone waste.

- So why is limestone preferable?

- A road is a single engineering facility, and all its layers are interrelated and complement each other during operation. One of its important segments is the road bed, which should be stable during its period of service, regardless of groundwater, hydro-geological and climatic conditions. But as practice shows, the road bed often fails to stand up to the loads permitted. Soil that is too dry or too wet cannot be consolidated. To avoid these problems, it is necessary to improve the quality of the road bed or to replace it before construction. In the old days, limestone was used in order to make the road bed stronger. Even the Romans and the Chinese knew that limestone absorbs water from the ground and thus becomes strong, cold-resistant and durable.

An important factor in limestone is the concentration of calcium oxide. That is, it provides natural cementation. To do this, the rock should be consolidated by rolling and split into small pieces. When limestone waste is mixed with water in optimal quantities, a physical-chemical process takes place on the verge of two phases. Thanks to this technological process, particles of crushed limestone become saturated with moisture, forming solid, naturally cemented, long-lasting limestone concrete. Thus, limestone waste, with its feature of self-cementation, helps to increase the overall carrying capacity of road and airfield cover and redistribute the load arising under pressure from transport across a larger area. And it contributes to the stable operation of the cover, even in adverse climatic conditions.

On the other hand, the very process of natural cementation contributes to the blocking of capillaries, which increases water resistance and prevents further waterlogging. That is why this technology is used successfully in road construction in wetlands or in zones of high groundwater. By the way, we faced this problem during the construction of the runway at Bina. The runway was in a zone of groundwater which was above the permitted level for the base. Thus, to prevent water from penetrating the bottom of the road bed, we had to remove the old foundation, dry the layers with the help of a machine and then add limestone waste, at the same time solidifying it with rollers. We retained an optimal amount of water. If the water reappeared, we continued to dry the layers until we achieved the required result. With the passage of time, we created natural cementation, closing the capillaries against any further penetration of water.

- How does the use of limestone waste affect the cost of work? After all, road construction is a laborious business, requiring enormous expenditure on materials...

- The use of local limestone material instead of the traditional mixture of imported gravel, crushed stone and sand at the base of the road brings tremendous savings. Compare: during the construction of the runway at Bina airport, we used waste limestone, and our expenditure amounted to 4 million dollars. Within the same parameters, the construction of the runway at Tbilisi airport, where they used sand-gravel materials, was several times more expensive. In addition, the Baku airport runway is still in good condition and is noted for its strength. In Baku, we used activated mineral powder in the asphalt concrete mixture, instead of the imported powder offered by our German colleagues.

In the mid-80s, we established the procedure of using waste limestone in the construction of roads and airfields, thereby solving another important problem - the prevention of environmental pollution. According to the Dadasov Scientific Research Institute for Construction Materials, the volume of waste from rock mining limestone quarries in Abseron alone is 8.9 million tonnes annually, including 1.3 million tonnes from the Qaradag quarry. To date, the volume of waste accumulated from stone sawing at limestone quarries in the republic is more than 30 million tonnes.

In general, limestone waste gives extra strength to road and airfield construction, allowing you to avoid using gravel and sand, it does not pollute the environment, is harmless to humans, non-corrosive and completely safe and economical.

P.S. This technology, developed by Professor Ali Aliyev, was patented in 1993. Currently we are working on the manual "The Use of Lime in Road and Airfield Construction". It should be noted that Professor Aliyev is the author of a number of manuals, including the recently published two-volume textbook "Building Roads and Airfields", which is in great demand and is popular in institutions of higher education in Russia and Central Asia. Hence, here is a man who is a prophet recognised in his own country.