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 called 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.
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 in 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 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 the United States until 1868; the first Portland
cement was not manufactured in the United States until the 1870s.
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. 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.
From 1867 to 1881 Monier received patents for
reinforced concrete railroad ties, floor slabs, arches, footbridges, buildings,
and other items in both France
and Germany .
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.
William E. Ward built the first reinforced concrete
building in the United States
in Port Chester , New York
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, entitled 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.
E. L. Ransome of 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
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 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.
References
1)
Kirby, R. S., and Laurson, P. G., 1932, The Early
Years of Modern Civil Engineering (New Haven :
Yale University
2)
Kirby, R. S., and Laurson, P. G., 1932, The Early
Years of Modern Civil Engineering (New Haven :
Yale University
3)
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
4)
Kirby, R. S., and Laurson, P. G., 1932, The Early
Years of Modern Civil Engineering (New Haven :
Yale University
5)
Ward, W. E., 1883, "Beton in Combination with Iron
as a Building Material," Transactions ASME, 4, pp. 388-403.
6)
Kirby, R. S., andLaurson, P. G., 1932, The Early
Years of Modern Civil Engineering (New
Haven : Yale University Press), p. 275.
