Monday, May 02, 2011

Essay: Influence of Concrete on the Development of Roman Architecture

Much of my time from 2008 to 2010 was spent taking courses at Athabasca University. One course was titled ‘A Survey of Western Art’. I thought that it might be of interest if I converted some of my assignment essays into blog posts. This early example was  ‘A Discussion of the Influence of Concrete in Roman Architecture as contrasted to previous builders’:
 Introduction
The use of concrete by Roman builders defined much of what made Roman architecture distinctive and familiar to us today.
In a sense, the history of Roman architecture is a dialogue between the traditional rectilinear forms of the Greek and early Italic post-and-lintel traditions on the one hand, and the freedoms afforded by this malleable material on the other.
(Davies et al: Janson’s History of Art  p. 182)
Concrete allowed the Romans to create great spanning arches, vaults and domes that often remain standing 2000 years afterwards.
The Romans borrowed many architectural concepts from their earlier neighbours such as the Greeks, the Etruscans and the Egyptians.  Those previous builders never attempted to roof over spaces as high or as wide as the Romans did.  While the best attempts of the earlier builders looked wonderful on the outside, their interiors often depended upon a thick forest of supporting columns.  Much of roofs and ceilings were built of wood.  Therefore, most of their best interior spaces have long since collapsed into the soil of history.

Earlier Builders and Building Methods
Earlier builders did create public buildings that projected a powerful image.  By looking at three representative ancient buildings – the Great Ziggurat at Ur (2100 BCE), the Temple of Amun-Ra (ca 1290 – 1224 BCE) and the Mausoleum at Halikarnassos (ca 359 – 351 BCE) – we can see how pre-Roman builders tried to create durable exteriors and great interior spaces.  Their efforts would have dazzled with their exterior splendour; but few visitors would have been allowed to enter the small interior rooms which were more like reception rooms than large gathering spaces.  These building used massive amounts of material in a manner that was quite inefficient when compared to the use of concrete and the arch.
The Ziggurat of Ur was 190 feet long by 130 feet wide and 50 feet high.  This is only one third as long, one third as high and one quarter as wide as the Colosseum in Rome.  Its construction required massive quantities of mud and baked brick which created an impressive exterior yet the only interior space was some long lost temple set upon its summit. (Janson’s  p. 31–32)
A visitor to the Temple of Amun-Ra at Karnak walked up great sculpture-guarded avenues and through impressive open courtyards.  The most impressive interior space was the Hypostyle Hall.  Massive amounts of stone spanned relatively small aisle ways.  Its roof is long gone.  According to Janson’s:
Here, a visitor would be awed by a forest of columns, their sheer mass rendering the human form almost insignificant.  Unlike wooden lintels, these had to be kept short to prevent them from breaking under their own weight. (Janson’s  p. 65)
The Mausoleum at Halikarnassos in some ways was a combination of the ziggurat and the Egyptian temple.  Its base was nearly as big as the Great Ziggurat of Ur while its roof rose three times higher to about 140 feet.  Its outside decoration was so spectacular that the word Mausoleum was been applied to any great monumental tomb.  It was basically a solid artificial hill with a relatively small interior space enclosed in the upper temple structure.  Eventually an earthquake knocked most it to the ground.

What is concrete?
Concrete is made by mixing mortar and pieces of aggregate stone.  When pozzolana sand was added Roman builders found the key to a durable building material.  It could be poured into temporary wooden forms assembled into a wide variety of shapes.
The advantages of concrete were quickly evident: It was strong and cheap, and could be worked by relatively unskilled labourers.  It was also extraordinarily adaptable… builders could mould it to shapes that would have been prohibitively time-consuming, if not outright impossible to make using cut stone, wood, or mud brick. (Janson’s  p. 181)

How did the Romans use concrete?

The Romans used concrete in ways that were both mundane and sublime.  They used it to create great public warehouses such as the Porticus Aemelia (Janson’s  p. 182), aqueducts such as in Segovia (Janson’s  p. 209) and public theatres such as the Theatre Complex of Pompey (Janson’s  p. 184).  Concrete was even used in domestic architecture and enabled the builders to create insulae having “many features of a present-day apartment block…. Some were as many as five stories, with balconies above the first floor.” (Janson’s  p. 214)
Writing about the vast Theatre Complex of Pompey the textbook notes that:
It was not, for instance, nestled into a pre-existing hillside.  Instead the architect created an artificial slope out of the concrete, rising on radially disposed barrel vaults, which buttressed one another for a strong structure.  Concrete, in other words, gave the designer freedom to build independent of the landscape.  (Janson’s  p. 184)
Two of the greatest examples of Roman architecture – The Colosseum and the Parthenon – are both available for us to view today.  Neither would have been imaginable without the use of concrete.  The Colosseum was constructed as a colossal permanent amphitheatre.  It was ordered by Vespasian for gladiatorial games and completed by his son Titus in 80 CE.  It was far larger and more massive than more ancient theatres, mausoleums or temples.  Yet its archways were honey-combed with open spaces for crowd movements and storage of animals.  “Concrete faced with travertine, was the secret of its success…. Each barrel vault buttressed the next, making the ring remarkably stable.” (Janson’s  p. 205)
“Of all the masterpieces Roman architects accomplished with concrete, the Pantheon is perhaps the most remarkable.” (Janson’s  p. 205)  The Pantheon has a vast domed roof set on an upright drum.  Inside it is 143 feet tall and just as wide.  (That might have been enough to completely house the fabled tomb at Halikarnassos).  Its building materials are used in for durability and efficiency:
The Pantheon is the extraordinary result of a developed confidence in the potential and strength of concrete.  The architect carefully calibrated the aggregate as the building rose, from travertine to tufa, then brick, and finally pumice, to reduce its weight.  (Janson’s  p. 208-209)
 Late Roman builders
Caracalla’s baths, built in 211 to 216 CE, must have been quite astounding in both size and opulence:
By the time of the late Empire, architects in Rome had more or less abandoned the straightforward use of post-and-lintel construction….  Column, architrave, and pediment took on decorative roles, superimposed on vaulted brick-and-concrete cores.  Imperial bath buildings demonstrate this well.  (Janson’s  p. 223)
The builders of the Great Hagia Sophia church that was ordered by Emperor Constantine in the year 532 demonstrated that there was more than one way to cover an immense interior space.  The great dome was built on pendentives and rose 40 feet higher than the Pantheon.  New technique including “thin bricks embedded in mortar, permits the construction of taller, lighter, and more economical domes”.  Once we are inside Hagia Sophia all sense of weight disappears.  (Janson’s  p. 258)

For more than 500 years there would be few attempts to span such a vast space and none would be as successful as the Hagia Sophia or the Pantheon.  “Byzantine architecture never produced another structure to match the Hagia Sophia.”  (Janson’s  p. 268)

Conclusion
It is probably fair to say that Roman architecture has had a more lasting impact on western building through the ages than any other ancient tradition. (Janson’s  p. 179)
Much of what that impact endurance was due to the use of concrete.  The Romans architects created on a massive scale using an efficient use of materials that would not be rivalled for many centuries afterwards.   One can only speculate what heights the builders of Greek temples, Persian palaces or medieval cathedrals might have attempted if they had known the secrets of concrete construction.

References used in this Essay
Davies, Penelope J.E. et al. Janson’s History of Art: The Western Tradition, 7th edition.
Upper Saddle River, NJ: Pearson Education Inc., 2007.

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