EPOKA UNIVERSITY Tirana, ALBANIA 2011 Faculty of Engineering and Architecture Department of...
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EPOKA UNIVERSITY Tirana, ALBANIA 2011 Faculty of Engineering and Architecture Department of Architecture Arch 322 Historical Environment and Conservation
EPOKA UNIVERSITY Tirana, ALBANIA 2011 Faculty of Engineering
and Architecture Department of Architecture Arch 322 Historical
Environment and Conservation Lida MIRAJ Lesson 6
Slide 2
Historic Building Survey, Inspection and Recording. Design,
relief, environment. Diagnosis of Building Failures.
Slide 3
Architectural Restoration History of Architectural Techniques.
The informative and methodological aspect, the traditional
architectural cultures, their language system and the
technique-constructive aspects. Architectural relief and the
critical reading of specific examples.
Slide 4
Vitruvius, writing around 25 BC in his Ten Books on
Architecture, distinguished types of aggregate appropriate for the
preparation of lime mortars. For structural mortars, he recommended
pozzolana, which were volcanic sands from the sandlike beds of
Puteoli brownish-yellow-gray in color near Naples and reddish-brown
at Rome. Vitruvius specifies a ratio of 1 part lime to 3 parts
pozzolana for cements used in buildings and a 1:2 ratio of lime to
pulvis Puteolanus for underwater work, essentially the same ratio
mixed today for concrete used at sea
Slide 5
By the middle of the 1st century, the principles of underwater
construction in concrete were well known to Roman builders. The
City of Caesarea was the earliest known example to have made use of
underwater Roman concrete technology on such a large scale.
Rebuilding Rome after the fire in 64 AD, which destroyed large
portions of the city, the new building code by Nero consisted of
largely brick-faced concrete. This appears to have encouraged the
development of the brick and concrete industries.
Slide 6
In most usage, the raw concrete surface was considered
unsightly and some sort of facing was applied. Different techniques
were characteristic of different periods and included: Opus
incertum: small irregular stones. Opus reticulatum: small squared
tuff blocks laid in a diamond pattern. Opus quadratum: regularly
laid courses of ashlars. Opus latericium: regularly laid courses of
brick. Opus spicatum: brick laid in a herringbone pattern. Opus
vittatum: square tuff blocks intersected by brick bands at regular
and irregular distances. Opus africanum: vertical chains of upright
blocks with alternating horizontal blocks. Opus testaceum: thick
horizontal brick work.
Slide 7
Roman concrete (also called Opus caementicium) was a material
used in construction during the late Roman Republic through the
whole history of the Roman Empire. Roman concrete was based on a
hydraulic-setting cement with many material qualities similar to
modern Portland cement. By the middle of the 1st century, the
material was used frequently as brick-faced concrete, although
variations in aggregate allowed different arrangements of
materials. Further innovative developments in the material, coined
the Concrete Revolution, contributed to structurally complicated
forms, such as the Pantheon dome.
Slide 8
Concrete, and in particular, the hydraulic mortar responsible
for its cohesion, was a type of structural ceramic whose utility
derived largely from its rheological plasticity in the paste state.
The setting and hardening of hydraulic cements derived from
hydration of materials and the subsequent chemical and physical
interaction of these hydration products. This differed from the
setting of slaked lime mortars, the most common cements of the
pre-Roman world. Once set, Roman concrete exhibited little
plasticity, although it retained some resistance to tensile
stresses. The setting of pozzolanic cements has much in common with
setting of their modern counterpart, Portland cement. The high
silica composition of Roman pozzolana cements is very close to that
of modern cement to which blast furnace slag, fly ash, or silica
fume have been added.
Slide 9
Italy, Rome, via Appia antica, tomb. The remains show the
internal core of the building, made in roman concrete (cementizio:
opus caementicium).
Slide 10
Opus Caementicium was the core of every Roman wall after the
2nd century BC. Mostly walls made in opus caementicium were covered
with other materials to make a more robust and workable surface.
Opus caementicium is a construction technique using an aggregate,
water and a binding agent. The aggragate functioned as a filler
like gravel, chunks of bricks or stones and rubble. The binding
agent is usually called mortar like lime, gypsum or pozzolana
(nowadays (Portland) cement is used). Most Roman buildings are made
up of opus caementicium, a sort of concrete which was laid into
timber structures until it hardened. The resulting walls were very
solid, but not nice to see, so very often some sort of facing was
applied.
Slide 11
The Romans developed a very effective kind of mortar by mixing
pozzolana, a volcanic ash of the region around Naples, with lime;
they obtained a cement which was resistant to water. In his work De
Architectura (a treatise on architecture dedicated to Emperor
Augustus) Vitruvius so described pozzolana: There is a species of
sand which, naturally, possesses extraordinary qualities. It is
found about Bai and the territory in the neighbourhood of Mount
Vesuvius; if mixed with lime and rubble, it hardens as well under
water as in ordinary buildings. This seems to arise from the
hotness of the earth under these mountains, and the abundance of
springs under their bases, which are heated either with sulphur,
bitumen, or alum, and indicate very intense fire. The inward fire
and heat of the flame which escapes and burns through the chinks,
makes this earth light; the sand-stone (tophus), therefore, which
is gathered in the neighbourhood, is dry and free from moisture.
Since, then, three circumstances of a similar nature, arising from
the intensity of the fire, combine in one mixture, as soon as
moisture supervenes, they cohere and quickly harden through
dampness; so that neither the waves nor the force of the water can
disunite them.
Slide 12
Slide 13
Opus incertum was an ancient Roman construction technique,
using irregular shaped and random placed uncut stones or fist-sized
tuff blocks inserted in a core of Opus caementicium.
Slide 14
Terracina (provincia di Latina, Lazio, Italia), tempio di Giove
Anxur, fianco della terrazza su cui sorgeva il tempio, in Opus
incertum.
Slide 15
Opus incertum was the most common facing for ordinary concrete
walls of the 2nd and 1st centuries BC. The face of the concrete was
studded with 3- to 4-inch (8- to 10-cm) irregularly. Initially it
consisted of more careful placement of the coementa (rock fragments
and small stones mixed with concrete), making the external surface
as plain as possible. Later the external surface became further
plain by reducing usage of concrete and choosing more regular small
stones. When the use of concrete between stones is particularly
reduced, it is defined opus (quasi) reticulatum. Used from the
beginning of the 2nd century BC until the mid-1st century BC, it
was later largely superseded by Opus reticulatum.
Slide 16
Opus incertum Using irregualar shaped and random placed uncut
stones or fist-sized tufa blocks inserted in a core of opus
caementicium, used from the beginning of the 2nd century BC, later
superceded by opus (quasi) reticulatum
Slide 17
Opus reticulatum used on the exterior wall of Hadrian's Villa
used as a retreat for the Roman Emperor Hadrian in the early 2nd
century.
Slide 18
Opus Reticulatum Opus reticulatum (also called Opus certum and
known as reticulated work) is a form of brickwork used in ancient
Roman architecture. It consists of diamond-shaped bricks of tuff
which are placed around a core of opus caementicium. The
diamond-shaped tufa blocks were placed with the pointed ends into
the cement core at an angle of roughly 45 degrees, so the square
bases formed a diagonal pattern, and the pattern of mortar lines
resembled a net. Reticulatum is the Latin term for net, and opus,
the term for a work of art, thus the term literally translates to
"net work". This construction technique was used from the beginning
of the 1st century BC, and remained very common until opus
latericium, a different form of brickwork, became more common. Opus
reticulatum was used as a technique in the Renaissance Palazzo
Rucellai in Florence, the skill having been lost with the end of
the Roman Empire, and rediscovered by means of archeology by Leon
Battista Alberti. The initial, rough form of opus reticulatum, an
advancement from opus incertum is called opus quasi
reticulatum.
Slide 19
Detail of Opus Reticulatum
Slide 20
Opus (quasi) reticulatum Small square tufa blocks placed
diagonally to form a diamond-shaped mesh pattern, often
supllemented by other materials at frames of windows and doors or
at reinforments at corners of buildings with oblong tufa
blocks
Slide 21
Opus Latericium and Opus Testaceum Opus latericium (also called
opus testaceum) was a construction technique using bricks. It was
first used in the first century BC, and it was the dominant
construction technique throughout the imperial period. Many of the
large imperial structures, such as the imperial baths of Rome, were
built in opus latericium. Structures in opus latericium are often
easily datable, because they are stamped by the producer. These
brick stamps were common from the first century BC until 164 AD. At
this time all the brick producing plants had passed into imperial
hands and the brick stamps disappeared, to reappear only in the
reign of Diocletian in the late 3rd century.
Slide 22
Opus testaceum / latericium Brickfaced masonry - kiln-backed
bricks; the dominant technique throughout the imperial period
Slide 23
Ostia
Slide 24
Herculaneum Gate, Pompei
Slide 25
Baths of Caracalla
Slide 26
Baths of Durres
Slide 27
Roman Bath Durres Prefurnium Sewage
Slide 28
Opus Quadratum Opus quadratum is an ancient Roman construction
technique, in which squared blocks of stone of the same height were
set in parallel courses, often without the use of mortar. This
technique was used by the Romans from about the 6th century BC and
over time, the precision and accuracy of the block cutting
improved. The technique continued to be used throughout the age of
the Roman Empire, even after the introduction of mortar, and was
often used in addition to other techniques. The type of stone, the
size of the blocks, and the way the blocks were put together can
all be used to help archeologists date structures that display the
technique.
Slide 29
Opus quadratum Walls of cutstone, recangular in form
Slide 30
"Opus quadratum" at Mura Serviane (left) and at Foro di Augusto
(right).
Slide 31
Opus Quadratum Etruscan way In early usage (often called the
"Etruscan way"), the joints between the blocks introduce
discontinuities, making the blocks uneven. Examples of such
construction can be found in reservoirs, basements, terrace walls,
and temple podiums in Etruscan cities and Rome. Greek way
Subsequently (the "Greek way"), the blocks would be placed in one
of two rotations. "Stretchers" would be placed so the longer side
was on the face of the wall, and "headers" would be placed so the
shorter side was on the face of the wall, and would thus extend
further back into the wall thickness. Various patterns could be
produced by changing how the blocks were placed, and it was common
to strengthen the wall by ensuring that the joints between blocks
were centered over the blocks in the row below.
Slide 32
The earliest walls built in Europe were constructed placing
stones one upon the other without any mortar to bind them together
(dry-stone walls). Near Rome examples of such walls can be seen at
Alatri, Segni and at other locations south of the city: they are
called cyclopean, because archaeologists felt that only the
mythical Cyclopes could have moved the enormous boulders which made
up these walls. Improvements in the tecnique used for cutting
stones led to the construction of walls with stones having the same
size (Isodomum - Vitruvius - De Architectura). In order to
strengthen the wall, blocks were placed alternately with the longer
side (stretchers) or the shorter side (headers) on the face of the
wall (opus quadratum). Romans were so fond of the texture effect of
opus quadratum that they continued to use this technique even after
having developed more effective kinds of masonry. The wall built at
Foro di Augusto with the blocks projecting from the surface
inspired Renaissance
Slide 33
Influence of Roman arches on Renaissance (left: Palazzo
Lancellotti) and Neoclassic (right: Palazzo Braschi)
architecture.
Slide 34
Opus Vittatum Opus vittatum was a ancient Roman construction
technique, sometimes square with tuff blocks intersected by one or
more brick-bands at regular or irregular distances, and Opus
caementicium. This technique was mostly used to erect high walls,
as in the Baths of Caracalla and the Aurelian Walls in Rome.
Slide 35
Opus vittatum Oblong (or occasionally square) tufa blocks
intersected by one or more brickbands at (ir-)regular
distances
Slide 36
Roman concrete With the introduction of Roman concrete,
continuous outer walls were often constructed, with some blocks
laid as headers in order to attach to the inner wall. Tile or
marble can be found cemented to such walls, but this was less
common for those structures that were particularly load-bearing,
such as arches and pillars used for bridges and aqueducts.
Slide 37
Opus vittatum mixtum (wall facing) Oblong or occasionally
square tufa blocks intersected by one or more brick bands, at
regular or irregular distances. Square blocks (re-used reticulate
blocks) appear mainly in third century masonry. After that they
disappear as building material. Opus vittatum mixtum has two
subgroups: A and B. The distinction is made purely for
chronological reasons. From the Severan period throughout late
antiquity.
Slide 38
Opus vittatum mixtum A (wall facing) Alternating oblong tufa
courses and brick bands, 1:1. Tufa blocks usually rather well cut.
From the early third century throughout late antiquity. Main
appearance in the third and fourth century.
Slide 39
Opus vittatum mixtum B (wall facing) Alternating oblong tufa
courses and brick bands, in all other combinations than 1:1.
Oblong, often rather egg- shaped tufa blocks appearing in an
irregular number of courses, and alternated at irregular distances
with one or more courses of brick. Main appearance in later fourth
century. Continuing until the Mediaeval period.
Slide 40
Opus vittatum simplex (wall facing) Oblong tufa blocks without
any other interference. Blocks very well cut during the Republic
and early Principate. From the last decades of the Republic mostly
found in combination with opus reticulatum. In late antiquity an
increasing tendency to egg-shaped blocks, which appear in the
fourth century. From the Republic until Nero. Re-appears in the
third century.
Slide 41
Opus reticulatum mixtum or Opus mixtum (wall facing) Masonry of
reticulate (small tufa blocks placed diagonally) reinforced and/or
intersected by brick bands (normally five to six courses). The
reticulate and the bricks are sometimes interlocking. The
reticulate fields are rather large.
Slide 42
Opus (reticulatum) mixtum Masonry of reticulated material
reinforced and/or intersected by brickbands or interlocked with
bricks
Slide 43
Opus Mixtum, Incertum e Testaceum Amphitheater of Durres
Slide 44
Roman Wall in Ostia: Opus Mixtum of Reticulatum and
Testaceum
Slide 45
Opus spicatum (floors) A floor (or wall) made of quite small,
elongated tiles, laid in a herringbone pattern or in a fishbone
pattern.
Slide 46
Opus sectile (floors and walls) Decoration of walls or floors
with marble slabs laid in a regular pattern.
Slide 47
Opus sectile Decoration patterns and figures at walls (and
floors) with precisely cut pieces of polychrome stone, usually
marble
Slide 48
Opus craticium Term both used for wattlework and walls of
half-timer construction, filled in with stones and/or staw and
plastered with mortar
Slide 49
Opus signinum (floors and walls) Waterproof floor- and
wall-revetment consisting of mortar mixed with terracotta sherds
and crushed tiles or bricks.
Slide 50
Opus signinum Waterproof floor- and wall-revetment of mortar
mixed with terracotta sherds and crushed tiles or bricks
Slide 51
Structure of an arch (Porta Asinaria).
Slide 52
The Romans learned from the Etruscans the use of arches to make
large openings in a wall; the gates of the Etruscan towns (see for
example Arco Etrusco at Perugia) show the first examples of arch.
The laws of Physics explaining the conditions required for an arch
not to collapse were not fully understood until the XIXth century;
yet the Etruscans, and after them the Romans, developed empirical
methods for designing arches which still stand more than 2,000
years later.
Slide 53
Etruscan Arch, IIIrd cen AD
Slide 54
Arch included in an "opus quadratum" structure at Arco dei
Pantani
Slide 55
Travertine arches forming the supporting structure of Colosseo.
An important aspect the Romans paid attention to was the choice of
materials: travertine proved to resist stress with limited strain
and was widely employed to build arches. Roman architects found
also a way to link the arch to the wall which was both effective
from a structural viewpoint and decorative from an aesthetic
one.
Slide 56
Bibliography: Jean-Pierre Adam, Anthony Mathews, Roman
Building, 1994. Lynne C. Lancaster, Concrete Vaulted Construction
in Imperial Rome, Cambridge University Press, 2005. Heather N.
Lechtman & Linn W. Hobbs, Roman Concrete and the Roman
Architectural Revolution, Ceramics and Civilization Volume 3: High
Technology Ceramics: Past, Present, Future, edited by W.D. Kingery
and published by the American Ceramics Society, 1986. W. L.
MacDonald, The Architecture of the Roman Empire, rev. ed. Yale
University Press, New Haven, 1982.