pozzolana before the birth of Christ. They found large deposits of a sandy volcanic ash near Mt. Vesuvius and in other places in Italy . When they mixed this material with quicklime and water as well as sand and gravel, it hardened into a rocklike substance and was used as a building material. One might expect that a relatively poor grade of concrete would result, as compared with today's standards, but some Roman concrete structures are still in existence today. One example is the Pantheon (a building dedicated to all gods) which is located in Rome and was completed in A.D. 126. Most people believe that concrete has been in common use for many centuries, but this is not the case. The Romans did make use of cement calledbefore the birth of Christ. They found large deposits of a sandy volcanic ash nearand in other places in. When they mixed this material with quicklime and water as well as sand and gravel, it hardened into a rocklike substance and was used as a building material. One might expect that a relatively poor grade of concrete would result, as compared with today's standards, but some Roman concrete structures are still in existence today. One example is the Pantheon (a building dedicated to all gods) which is located inand was completed in A.D. 126.

England in 1796 and was sold as "Roman cement." Various other deposits of natural cement were discovered in both Europe and America and were used for several decades. The art of making pozzolanic concrete was lost during the Dark Ages and was not revived until the eighteenth and nineteenth centuries. A deposit of natural cement rock was discovered inin 1796 and was sold as "Roman cement." Various other deposits of natural cement were discovered in both Europe andand were used for several decades.

United States until 1868; the first Portland cement was not manufactured in the United States until the 1870s. The real breakthrough for concrete occurred in 1824 when an English bricklayer named Joseph Aspdin, after long and laborious experiments, obtained a patent for cement which he called Portland cement because its color was quite similar to that of the stone quarried on the Isle of Portland off the English coast. He made his cement by taking certain quantities of clay and limestone, pulverizing them, burning them in his kitchen stove, and grinding the resulting clinker into a fine powder. During the early years after its development, his cement was used primarily in stuccos. This wonderful product was adopted very slowly by the building industry and was not even introduced into theuntil 1868; the first Portland cement was not manufactured in theuntil the 1870s.

Credit is usually given to Monier, however, for the invention of reinforced concrete. In 1867 he received a patent for the construction of concrete basins or tubs and reservoirs reinforced with a mesh of iron wire. His stated goal in working with this material was to obtain lightness without sacrificing strength. The first uses of concrete are not very well known. Much of the early work was done by the Frenchmen Francois Le Brun, Joseph Lambot, and Joseph Monier. In 1832 Le Brun built a concrete house and followed it with the construction of a school and a church with the same material. In about 1850, Lambot built a concrete boat reinforced with a network of parallel wires or bars.. In 1867 he received a patent for the construction of concrete basins or tubs and reservoirs reinforced with a mesh of iron wire. His stated goal in working with this material was to obtain lightness without sacrificing strength.

France and Germany . From 1867 to 1881 Monier received patents for reinforced concrete railroad ties, floor slabs, arches, footbridges, buildings, and other items in bothand

Another Frenchman, Francois Coignet, built simple reinforced concrete structures and developed basic methods of design. In 1861 he published a book in which he presented quite a few applications. He was the first person to realize that the addition of too much water in the mix greatly reduced concrete strength. Other Europeans who were early experimenters with reinforced concrete included the Englishmen William Fairbairn and William B. Wilkinson, the German G. A. Wayss, and another Frenchman, François Hennebique.

United States in Port Chester , New York , in 1875. In 1883 he presented a paper before the American Society of Mechanical Engineers in which he claimed that he got the idea of reinforced concrete by watching English laborers in 1867 trying to remove hardened cement from their iron tools. William E. Ward built the first reinforced concrete building in thein, in 1875. In 1883 he presented a paper before the American Society of Mechanical Engineers in which he claimed that he got the idea of reinforced concrete by watching English laborers in 1867 trying to remove hardened cement from their iron tools.

An Account of Some Experiments with Portland cement Concrete, Combined with Iron as a Building Material. In this book he praised the use of reinforced concrete and said that "rolled beams (steel) have to be taken largely on faith." Hyatt put a great deal of emphasis on the high fire resistance of concrete. Thaddeus Hyatt, an American, was probably the first person to correctly analyze the stresses in a reinforced concrete beam and in 1877 he published a 28-page book on the subject, entitledIn this book he praised the use of reinforced concrete and said that "rolled beams (steel) have to be taken largely on faith." Hyatt put a great deal of emphasis on the high fire resistance of concrete.

San Francisco reportedly used reinforced concrete in the early 1870s and was the originator of deformed (or twisted) bars, for which he received a patent in E. L. Ransome ofreportedly used reinforced concrete in the early 1870s and was the originator of deformed (or twisted) bars, for which he received a patent in

San Francisco , Ransome built the Leland Stanford Jr. Museum. It is a reinforced concrete building 312 feet long and two stories high in which discarded wire rope from a cable-car system was used as tensile reinforcing. This building experienced little damage in the 1906 earthquake and the fire that ensued. The limited damage to this building and other concrete structures that withstood the great 1906 fire led to the widespread acceptance of this form of construction on the West Coast. Since 1900-1910, the development and use of reinforced concrete in the United States has been very rapid. 1884. These bars, which were square in cross section, were cold-twisted with one complete turn in a length of not more than 12 times the bar diameter.7 (The purpose of the twisting was to provide better bonding or adhesion of the concrete and the steel.) In 1890 in, Ransome built the Leland Stanford Jr. Museum. It is a reinforced concrete building 312 feet long and two stories high in which discarded wire rope from a cable-car system was used as tensile reinforcing. This building experienced little damage in the 1906 earthquake and the fire that ensued. The limited damage to this building and other concrete structures that withstood the great 1906 fire led to the widespread acceptance of this form of construction on the West Coast. Since 1900-1910, the development and use of reinforced concrete in thehas been very rapid.

References

Kirby, R. S., and Laurson, P. G., 1932, The Early Years of Modern Civil Engineering ( New Haven : Yale University Press), p. 266. 1)Kirby, R. S., and Laurson, P. G., 1932,Press), p. 266.

Kirby, R. S., and Laurson, P. G., 1932, The Early Years of Modern Civil Engineering ( New Haven : Yale University Press), pp. 273-275. 2)Kirby, R. S., and Laurson, P. G., 1932,Press), pp. 273-275.

Straub, H., 1964, A History of Civil Engineering ( Cambridge : MIT Press), pp. 205-215. Translated from the German Die Geschichte der Bauingenieurkunst ( Basel : Verlag Birkhauser), 1949 3)Straub, H., 1964,: MIT Press), pp. 205-215. Translated from the German: Verlag Birkhauser), 1949

Kirby, R. S., and Laurson, P. G., 1932, The Early Years of Modern Civil Engineering ( New Haven : Yale University Press), pp. 273-275, 4)Kirby, R. S., and Laurson, P. G., 1932,Press), pp. 273-275,

Ward, W. E., 1883, "Beton in Combination with Iron as a Building Material," Transactions ASME, 4, pp. 388-403. 5)Ward, W. E., 1883, "Beton in Combination with Iron as a Building Material,"4, pp. 388-403.