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Mihai Bravu Technical College, Bucharest, Romania
Values must circulate! This is the only way mankind evolves. And, of all, what matters maybe the most is the circulation of science values. We can say that the language of Science is the same for everybody, no matter the nationality. For example we think at reinforced concrete, a relatively new construction material. This subject is of interest to us because it’s a part of the profession we are studying for. Reinforced concrete became a very important material a century ago, being used today in different types of constructions: modern buildings, bridges, industrial constructions.
This material was first made known in 1867 at Expo Paris. The inventor of the material is a French gardener named Joseph Monier. Starting from the idea of making a bigger and more solid flower pot, he twined a wire, shaping it as a frame and poured concrete over it. The flower pot became very solid after drying, which showed that the objects made from reinforced concrete are very solid. Immediately after this, in Europe, the engineers and architects of the time thought to use this idea in contrustions, but the method was doomed to failure for three, four decades. Among the disastrous results we recall the collapse of a few buildings built trough this method: in 1889 a building from Paris; in 1890 during the construction of a building in Prague; in 1900 the Celestial Globe bridge from the Universal Exhibition in Paris; in 1903 during the construction of an important hotel, the Black Bear in Basel; a 23 m bridge opening. Until the romanian engineer George Constantinescu found the solution. In 1904, the young engineer published in Bulletin of the Polytechnic Society (Buletinul Societăţii Politehnice) magazine, the article Study on reinforced concrete, which showed, trough theoretical calculations, the utility of the new construction material at the time. Starting next year, the calculation theory was applied for the construction of the first arch bridges.
George Constantinescu (1881-1965) was born in Craiova, on the 4th of October 1881 in a mixed family. His father, Romanian, was a renowned mathematics teacher and his mother was an Alsacian origin, refugee in Timisoara. The student has demonstrated a highly inventive spirit, having prestigious professors of European level. The Construction School was relatively young. In 1852 the French engineer Leon Lalanne founded in Romania The School of Bridges and Roads, Mines and Architecture. It becomes in 1881 The National School of Bridges and Roads. In 1904 George Constantinescu graduated The National School of Bridges and Roads and was hired by the engineer Elie Radu. The young employee elaborates a theory about reinforced concrete, but more important, he uses reinforced concrete for constructions, despite all the opposition of the technical authorities from that time, caused by the collapse of some buildings made of reinforced concrete. At only 25 years old, he was asked to solve the serious problems which had arisen in the construction of the Deputies Chamber within the old Parliament House, on the Metropolitan Hill. A wall shifted 10 inches from vertical and the dome suffered displacements and cracks. Constantinescu succesfully solved the problem, using a concrete belt, breaking through all the criticism and disbelief of the experts in the use if reinforced concrete. The disbelief was so great that, initially, after seeing the two arches, the deputies refused to enter, being afraid that the construction might collapse. Exactly 103 years have passed and the dome is still in place. Thus, Constantinescu, achieved for the first time in the world to build an arch from thin sheets of reinforced concrete, applied to consolidate the dome.
Also, in 1906, he designed the dome of the minaret from the Great Mosque in Constanta, also known as the Carol I Mosque. He designed the dome with an 8 m opening, the biggest opening in the world made from reinforced concrete, by constructing the arches using thin sheets.
George Constantinescu built the first bridge with straight beams made of reinforced concrete in Romania. He was acknowledged abroad as one of the pioneers in the introduction of reinforced concrete in constructions.
The construction solutions based on reinforced concrete reduced the costs with aproximately 30% and ended much faster. Although the equipment had to be imported, George Constantinescu preffered to build by himself a few, such as compressed air machines operated under water.
His technical activity includes the construction, after his conception, of many reinforced concrete bridges in Bucharest and in the Country, among which: the first bridge with a 16 m opening, also named the Bridge Over the Void (vacuum), which we can see today in the Liberty Park (Bucharest); a number of big bridges over Siret; the 14 m opening bridge on the road from Doftana. He massively used concrete in some monumental constructions of the time, in the Capital: The Stock Palace or the Chamber of Commerce (the current National Library of Romania); The Ministry of Public Development (the current City Hall of Bucharest) (1906-1910); The Sports Stadium; Athénée Palace Hotel (1914).
In the following years, he designed a great number of reinforced concret buildings, including The Casino in Constanta (admired by European tourists in their holiday) and castles for water.
Thus, George Constantinescu promoted new uses of the reinforced concrete in the world. He was the first structure engineer who first used with success and viability this material for buildings and bridges, at the beginning in Romania. It was a difficult task because the method failed before and the people did not trust this material anymore. At the beginning even his former professor, the famous engineer Anghel Saligny was against his daring projects. The prove of his success is the fact that these works still resist nowadays.
In November 1910 the Romanian George Constantinescu settles in London for a time. He will maintain yet permanent contact with his country. In London he faces the same skepticism of the industrial businessmen, but the young Romanian never gives up and brings permanently news in the domain. At the London International Exhibition of 1924 a stand written in capitals Constantinesco presented the sonic converter. Over 220 publications debated on this converter and the future of the car. An experimental car provided with this new invention climbs without any effort a steep slope carrying ten persons on board. After new experiments he produced a car without gearbox, extremely economic and which could be driven even by a child. Such a car sport type, modern fashioned was presented in Paris in 1926.
George Constantinescu had inventions in various fields of engineering, which revolutionary changed the world: the reinforced concrete, the asphalt, the sonic, motors for building machines or in other various fields of industry. Can one imagine how the world cities would look without the reinforced concrete? Or the traffic without asphalt? And if the sonicity wouldn’t be discovered during the World War I how this would end?