Historic Masonry

Abstract

Masonry is a composite material characterised by its good behaviour under dead loads and in a nonaggressive environment. However, this noble material does not satisfactorily resist seismic loads. The different types of historical masonry that have remained over time are characterised by an adequate mixture of materials with low chemical reactions that are degrading due to environmental conditions. There are numerous historical masonry construction techniques in the world, reflecting local conditions of materials and workmanship. The key to its permanence and maintenance over time despite the effects of earthquakes is the construction technology and quality of materials used. As a result of earthquake damage observation and experimental research, various technical solutions for rehabilitation and retrofit of masonry are now available. Finite element modelling has become a very useful tool to identify the damage problem in historical masonry but requires a significant contribution of parameters obtained from destructive and nondestructive tests.

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
Chapter
Historic Masonry
Noemi GracielaMaldonado, PabloMartín,
Gerardo Gonzálezdel Solar and MaríaDomizio
Abstract
Masonry is a composite material characterised by its good behaviour under
dead loads and in a nonaggressive environment. However, this noble mate-
rial does not satisfactorily resist seismic loads. The different types of historical
masonry that have remained over time are characterised by an adequate mixture
of materials with low chemical reactions that are degrading due to environmental
conditions. There are numerous historical masonry construction techniques in the
world, reflecting local conditions of materials and workmanship. The key to its
permanence and maintenance over time despite the effects of earthquakes is the
construction technology and quality of materials used. As a result of earthquake
damage observation and experimental research, various technical solutions for
rehabilitation and retrofit of masonry are now available. Finite element modelling
has become a very useful tool to identify the damage problem in historical masonry
but requires a significant contribution of parameters obtained from destructive
and nondestructive tests.
Keywords: heritage, ceramic units, mortars, compatibility, modelling, strengthening
. Introduction
Masonry is a material composed of natural or manually manufactured units
joined with fresh mortar, which constitute an important inventory of existing
buildings in the world from the Egyptian civilization to the present day. The most
widely studied and investigated construction techniques correspond to the masonry
of the Greek and Roman constructions that have remained to this day. In Africa
and Asia, the oldest masonry was made of stone or earth. In America, ceramics
were used as masonry in the late nineteenth century that are now part of the local
cultural heritage.
The preservation of heritage buildings requires knowledge to guide technical
and economic maintenance strategies []. Building materials degrade over time
when in contact with the environment, and this is a natural and inevitable process.
From the perspective of use, the main unknown behaviour is the rate of deteriora-
tion, necessary data to raise the estimated construction service life in relation to
safety and/or functionality [].
The use of masonry has significant advantages in cost, installation speed,
aesthetics, durability, sound insulation, thermal insulation, fire resistance and
accidental damage, energy consumption, maintenance and repair, availability

Masonry Structures

of materials and local workmanship and potential recyclability. Regarding the
disadvantages, we have detected the need for greater resistant area compared to
reinforced concrete, the need of better foundations, problems in the insulation, the
size of the openings, in the arrangement of the joints, considerations of safety and
health, durability problems by presence of water and salts and currently lack of
skilled labour.
The architectural function of the masonry is the envelope of the building
to protect its inhabitants and their belongings from environmental agents,
for example, the effect of rain. They can be constituted as walls of barriers or
drainage.
Structural masonry can be classified as bearing or nonbearing. The bearing
masonry resists the own weight and wind loads or earthquake and gravitational
loads generated by the floors or ceilings supported on it [].
The presence of moisture, whose origin may be the wet soil, rainfall or faulty
drainage services, causes damage to old masonry. Although moisture can be mea-
sured by different techniques, the results are not repeatable. In other cases, new
interventions with new materials have increased moisture problems [].
The application of the finite element method using nonlinear constitutive
models is a tool to verify the observed damages and stress states of historic masonry.
But nevertheless, laboratory and field tests are necessary in order to characterise
masonry materials and provide reliable data on the design parameters needed for
building modelling although the number of samples to be extracted should be
minimal.
. Methodological evaluation of historical construction
The methodology used in the study of cases evaluates at the beginning whether
the historical works have heritage values or not (Figure ), defining the responsi-
bilities before specifying the procedure []. All the activities involved in this task
involve the interaction of different disciplines and an important responsibility of
the maintenance management of the heritage.
Figure  presents the different steps of the procedures followed for the reha-
bilitation of historic buildings, applying safety criteria stated in the regulations
and conservation criteria of the International Council on Monuments and Sites
(ICOMOS) charts []. In this evaluation, the impact of the durability of the mate-
rials and the environmental sustainability with the built environment must be
incorporated in addition to the safety in the structure.
Figure 1.
Basic criteria for recovery of historical works.

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Historic Masonry
DOI: http://dx.doi.org/10.5772/intechopen.87127
. Masonry materials
. Historic masonry units
.. Natural stone
Stone has been used from earliest times. Stone as a material is geographically
widespread. Its use in structures is often confined to local materials from a nearby
quarry. Load bearing stonework was used up to about the late nineteenth century,
but many earlier structures were built of rubble or brick faced with stone ashlar.
Since about the year , stone has been mostly used as facade to cheaper masonry
or as cladding for other materials.
Stone masonry construction may be of ashlar, squared/coursed rubble, random
rubble, etc. Composite rubble/ashlar walls have often been used. It cannot be
assumed that a pier or wall with ashlar facing is of solid construction through its
entire section; often the core will be of very weak material [].
.. Bricks and blocks
Bricks are the oldest man-made building material. Examples of sun-
dried clay bricks (adobe) date back to BC, and fire bricks were used by
BC.Clay bricks were traditionally made locally. Urban buildings of the
late nineteenth century and early twentieth century were made of masonry of
fired ceramic bricks []. In the transition to the use of steel, concrete construc-
tions appear, which employ hybrid metal profiles for supporting floor slabs or
as bridges and columns within the masonry to withstand earthquakes known
as sidero-brick []. Since  the use of reinforced concrete in the world is
Figure 2.
Procedures of study of heritage construction.

Masonry Structures

widespread, leaving the brick masonry walls for minors or cladding in rein-
forced concrete structures or termination of facades.
Although features may be more reliable as a dating aid, brickwork may some-
times be approximately dated by the brick size. However, there are regional varia-
tions which may be greater than those relating to age []. Bricks can be fired clay,
calcium-silicate or concrete.
Figure  shows different placement patterns of solid bricks: stretcher bond,
header bond, English bond and Flemish bond, which have different applications in
construction (walls, landscaping, pavements).
These patterns allow to identify the time of construction but not the elements
of metallic union that were placed from the middle of the nineteenth century in the
form of flat strips every four or six courses. Its presence is detected by the slight but
regular cracking in these joints due to the increase in volume due to iron corrosion.
The walls with inner cavities are later than  for thicknesses close to .m
and preponderance from  to thicknesses of .m. These walls generally have a
common brick course, an air layer of .m and a course of decorative purposes or
tightness control.
The first uses of concrete blocks are at the beginning of the twentieth century
with an important growth due to the demand of houses before World War II.Since
World War II, the use of concrete blockwork increased dramatically because of the
promotion of cavity walls and the need for improved thermal insulation, which was
achieved by the use of lightweight concrete blocks for the inner skin.
Block sizes vary from  ×  × mm to  ×  × mm. The blocks
may be solid, cellular or hollow. Densities vary in the range kg/m (autoclaved
aerated) to kg/m (normal aggregate).
. Historical binders
The mortars present in the historic masonry of buildings are typically composed
by simple or hydraulic limes. There are two kinds of binders, aerial or hydraulic,
depending on the mechanism of hardening [].
They can be subdivided into simple mortars, hydraulic mortars and composite
mortars. The binder can be cement, lime or mix of both. In the past, same mortars
contained ash to give a dark colour.
Figure 3.
Common solid brickwork bonds: stretcher (up, left), header (up, right), English (down, left) and Flemish
(down, right) bonds [5].

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Historic Masonry
DOI: http://dx.doi.org/10.5772/intechopen.87127
The function of the mortar is to hold together the masonry units and compen-
sate its dimensional tolerances. Also the purpose of mortar is to transfer the gravi-
tational force uniformly through the brickwork, the tying effect being achieved by
friction and the staggered pattern of the bricks.
Pure lime mortars, containing no clay or silt, are hardened by carbonation of
calcium hydroxide. This can take many years, depending on the porosity of the
stone or brick and on the thickness of the wall.
In the case of mortars made from hydraulic lime, where the limestone is ground
and fired with some clay or silt, the lime reacts with water for initial strength gain,
supplemented subsequently by carbonation of any free lime.
Pure lime mortars (lime-sand) are relatively weak and flexible. Pure cement
mortars (cement-sand) may be stronger and stiffer than the stone or brick. If the
mortar is too strong, any cracks in the masonry from whatever cause may therefore
go through the stones or bricks rather than follow the joints.
Cement-lime mortars (cement-lime-sand) have intermediate strengths; the
greater the proportion of cement, the stronger the mortar. Small additions of
cement to lime mortars increase the strength marginally but reduce the permeabil-
ity significantly. This can result in frost damage in porous stone or brick.
Mortar joints are eroded by rain running down faces of walls. This effect is
aggravated by chemical breakdown of the binder, because of the acidity of the
rainwater. The resistance to this weathering increases with the total proportion
of binder to sand. Sulphates, from whatever source, can cause the expansion and
disintegration of mortar. Some bricks contain sulphates which may be leached out
into the mortar.
The strength of the mortar influences the strength of the masonry in compres-
sion, tension and flexure but not to a great degree.
Lime-sand mortars were traditionally used. They were able to accommodate
movement, both from the bricks themselves and from the structure as a whole. It
was considered a good practice that the mortar should never be stronger than the
brick. This must be taken into account when specifying the repair mortar.
Strong cement-rich mortars tend to shrink, which can lead to poor bonding and
water ingress into the wall.
The compressive strength of mortar in existing joints cannot be measured
directly. The ratios of cement/lime/sand can be established by chemical analysis of
mortar samples taken from the joints.
. Historical masonry construction techniques
The basic method of construction has barely changed in several thousand years:
the units are placed one above the other in such a way that they form an intertwined
assembly in at least two horizontal directions. Sometimes order is achieved in the
third dimension. Most of the time, an intermediate layer of mortar is used to save
small to large inaccuracies between units and make the walls waterproof, airtight
and soundproof.
There are four main techniques for achieving stable masonry []:
. Irregularly shaped and sized but generally laminar pieces are selected and
placed by hand in an interlocking mass (e.g. dry stone walls, see Figure ).
. Medium to large blocks are made or cut very precisely to one or a small range
of interlocking sizes and assembled to a basic grid pattern either without
mortar or with very thin joints (e.g. ashlars or thin-joint).

Masonry Structures

. Small-to-medium units are made to normal precision in few sizes and assem-
bled to a basic grid pattern, and the inaccuracies are taken up by use of a
packing material such as mortar (e.g. normal brickwork, see Figure ).
. Irregularly shaped and sized pieces are both packed apart and bonded together
with adherent mortar (e.g. random rubble walls).
. Seismic behaviour of historic masonry
The behaviour of historical masonry to permanent vertical loads has been
satisfactory. A different approach to heritage building occurs when there is a
seismic-risk region. The way in which a structure is damaged during an earthquake
is strongly influenced by its proximity to the area of fault rupture.
Under the great demands on acceleration and displacement of the seismic events
studied, only the conjunction updated with new design procedure regulations, a
regular good structural design, static redundancy and proper implementation will
allow structures to survive strong earthquakes [].
By definition, “repair” refers to the post-earthquake repair of damage, caused by
seismic ground motion that does not increase the seismic resistance of a structure
beyond its pre-earthquake state.
“Strengthening”, “seismic strengthening”, or “seismic upgrading”, however,
comprises technical interventions in the structural system of a building that
improve its seismic resistance by increasing strength and ductility. According to
the proposed terminology, strengthening a building before an earthquake is called
“rehabilitation”, whereas strengthening after the earthquake is called “retrofit” [].
The law procedure and how to decide the appropriate methods are different
in each country. However, the practice between safety and historical preserva-
tion is almost the same in all countries that have some preservation regulations,
Figure 4.
Photographs of Mendoza, Argentina: (a) prehispanic stone walls (Uspallata), (b) stone bridge (Luján de
Cuyo), (c) Jesús Nazareno church (Guaymallén).
Figure 5.
Photographs of historical masonry heritage of Mendoza, Argentina: (a) provincial Museum of Fine Arts
(Luján de Cuyo), (b) Caro wine vault (Godoy Cruz), (c) Arizu winery (Godoy Cruz).


Historic Masonry
DOI: http://dx.doi.org/10.5772/intechopen.87127
but the problems are exacerbated when the effect of seismic actions is added.
The California Historical Construction Code [] has joined the vision regarding
heritage aspects and safety. It includes the subject of use and occupation; protection
against fire; escape routes and accessibility; structural requirements, materials and
old methods of construction; requirements of mechanical and electrical installa-
tions; and drains, whenever the building merits the identification of heritage value.
In the United States, the bearing walls of unreinforced masonry (URM) cor-
respond to before  with two courses of bricks joined at their upper end. When
the interior was filled with rubble, it was stiffened elastically and modified the
behaviour of the frames where the masonry is inserted.
The behaviour of horizontal diaphragms in historic masonry is often deficient
because they are not sufficiently connected to transfer the horizontal seismic forces
to the resistant side walls. They are usually made of wood, supported by beams
anchored in wall inserts, which are affected by deformations outside the plane of
the loaded wall, which can lead to the overturning of the wall and the collapse of
the building [].
The Long Beach earthquake (California, ) showed the bad behaviour of
this masonry, causing the prohibition to use it in school buildings. The UBC of 
established that the masonry had to meet the same criteria of design of the rein-
forced concrete of that time, appearing the armed masonry.
The Santiago (Chile) and City of México (); Izmit, Turkey, and Quindío,
Colombia (); Pisco, Perú (); L’Aquila, Italy (); Lorca, Spain ();
Kathmandú, Nepal (); and Manabí, Ecuador () earthquakes have shown
that nonengineering masonry buildings have suffered significant damage, espe-
cially the masonry constructions in adobe and in stone [, , ].
. Masonry laboratory tests
The tests of historic masonry specimens obtained from existing structures are
scarce. However, there are several investigations carried out in small-scale replicas
of URM or in different scales carried out in the United States, Italy and Yugoslavia
in the last years [, ].
There are in situ testing techniques to measure the compressive strength of the
masonry, which produce some damage and require special equipment. The experi-
mental static tests can be applied: flat-jack test and pull out. Ultrasonic, geo-radar,
acoustic emission, static monitoring, thermography, X-ray diffraction can be used
as non-destructive tests; which sometimes are not justified for masonry routine
evaluations that have less thickness than the historic masonry.
The dynamic tests can be ambient vibration testing, even to register a long-term
dynamic monitoring.
. Historic masonry durability
From the point of view of durability, the walls as an open system are in contact
with other contiguous structures that take part in the dynamics of the overall
behaviour. Even when any infiltration can be successfully eliminated, contact with
the ground or with adjacent walls provides moisture sources by capillarity. Virtually
all walls contain soluble salts, either dispersed within porous materials or locally
concentrated. They can be present as efflorescence that form different aggregates
of crystals with various shapes and located on the surface, such as sub-springs that
form crystalline aggregates below the surface, and as solutes in aqueous solutions on
and inside the walls.

Masonry Structures

The main known salts produced in the walls are carbonates, sulphates, chlorides,
nitrates, oxalates and sodium, potassium, calcium, magnesium and ammonia. The
different salt species, precipitated from multicomponent systems, vary consider-
ably depending on the materials present, but the type of salt found can, therefore,
very often give indications of their origin.
Both the plasters and the paint layer of the walls are typically open structures
with high porosity (their pores can easily be intercommunicated). This means that
there is a large surface exposed to the degradation agents and there is easy perme-
ability to fluids in contact with it both liquids (solutions of salts diluted in the wall)
and gases (atmospheric pollutants and water vapour) [].
. Material’s compatibility
In masonry it is required that the chemical compatibility between the mortar of
replacement and the old mortar, the physical compatibility in relation to the process
of solubility of salts and water of transport and the structural compatibility where
the resistance of the new mortar must be similar to that of the masonry historical in
order to avoid damages by the use of mortars with Portland cement.
As far as mortars are complex systems, different approaches can be used for their
characterisation. Nowadays, the reconstruction of the original composition is quite
complex and requires the application of various and complementary techniques. In
addition, the technological culture of making lime mortars has been lost, although
from the economic point of view they would be of lower cost []. The need for
mortar compatibility has led to the design of specific products to avoid damage by
chemical reactions as shown in Figure  [].
. Masonry modelling
The directed behaviour of the geomaterials (shear as a function of compressive
strength) requires computational models that allow capturing the different failure
modes and, without losing precision, represent them in a simple way. In accordance
with this, there are several modelling techniques; the micro-models consist of the
modelling of the masonry units and the mortar as continuous elements, while the
Figure 6.
Evolution of the mortar compatibility process during rehabilitation of school building [2].

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Historic Masonry
DOI: http://dx.doi.org/10.5772/intechopen.87127
masonry-mortar interface is represented by means of discontinuous elements. As
the macro-models, these are phenomenological models in which masonry units,
mortar and interface are represented as a composite by means of a continuous
element. The technique to be used is based on the level of accuracy and simplicity
desired [].
Phenomenological models allow focusing on the overall response of the struc-
ture at a lower computational cost. For this to happen, it is necessary to establish a
constitutive model whose response is representative of the behaviour of the com-
posites. The constitutive model of Drucker-Prager [, ] allows to represent the
behaviour of the masonry as an elasto-plastic material with a strong dependence on
the acting pressure. The low number of variables to define makes this model attrac-
tive. In turn, the characterisation of these variables can be carried out in a simple
way through a diagonal compression test in laboratory or application of flat-jack in
situ.
To obtain the modelling parameters of the masonry, laboratory tests are carried
out in a : scale on specimens of different thickness []. With the experimental
results achieved, a finite element model is formulated using the Abaqus software
[] whose parameters allow to obtain a behaviour similar to that observed during
the tests.
Figure 7.
Comparison of stress state modelling and building damage status [17].
Figure 8.
Comparison between stress state modelling and building damage status [17].

Masonry Structures

Figure 10.
Damage due settlements of different sectors [18].
Based on the model generated and calibrated, the building geometry and the
state of applicants loads are simulated, the results of which are compared with the
real damage evidenced in the structures analysed. The analysis of the results from
Figure 9.
Simulation of facade damage due to inefficient foundation [17].


Historic Masonry
DOI: http://dx.doi.org/10.5772/intechopen.87127
the structural simulation allows a better understanding of the causes of the dete-
rioration as well as the cracking patterns. These results have allowed us to make a
proposal for its repair and subsequent rehabilitation.
Figure  shows the general structural model and the state of stresses of the
masonry of an educational building []. It shows the concentration of stress associ-
ated with the wall encounters and points of application of loads, points that must
be reinforced locally, while the rest of the masonry is subjected to a normal tension
level below the stress maximum. In Figure  we can see the result of the modelling
for the damage in archs, and Figure  shows the detachment of the main facade.
In the case of the museum in Figure , the stress concentration in the walls of
the central nave is observed as a result of the differential settlement between this
sector and the lateral ones [].
. Study cases
Table  shows the cadastral characteristics of historic masonry buildings studied
in Mendoza, Argentina, from  to  [].
Table  shows the data obtained in the evaluation of the condition of the historic
masonry buildings prior to the value enhancement [].
Table  shows the soil criteria and masonry modelling for different buildings
studied. It is taken as a criterion modelling by finite elements for walls using the
type plate element of four or eight nodes. Drucker-Prager model has been used
for the simulation of material failure []. The foundation is modelled by elastic
springs, or the soil is modelled directly, considering its rigidity (elastic), since in
this type of structure soil stiffness plays a fundamental role. For the roof structure,
which is generally flexible, main resistance elements such as trusses or girders
(ridges, etc.) are modelled, distributing loads to these elements. The seismic action
is determined by applying the methods established by the regulations as propor-
tional forces to the mass of each node of the finite element mesh [].
Evaluated Saint Francis
Ruins, Capital
Mitre School,
Capital
Giol Chalet,
Maipú
Fader House,
Luján de Cuyo
Date of building XVIII century Late nineteenth
century−
  house
– paints
Date of study   and   
Charge heritage National
Direction
Architecture
Municipality of
Capital
Direction of
Heritage
Government of
Mendoza
Municipality of
Maipú
National
Direction
Architecture
Direction of
Heritage
National
Direction
Architecture
Intended use Outdoor
museum
Educational
museum
Vintage museum Fine arts museum
Archaeological
and historical
background
Historical and
archaeological
studies
Few
historical and
archaeological
studies
Few historical
studies. No
archaeological
studies
Few historical
studies. No
archaeological
studies
Table 1.
Data on the buildings studied.

Masonry Structures

Evaluated Saint Francis Ruins, Capital Mitre School,
Capital
Giol Chalet, Maipú Fader House, Luján de Cuyo
Valid
contributions
from different
epochs
: Put in value
Maintenance Ruins Park and
archaeological exploration
Maintenance (paint, flooring)
: Replacement of floating floors
: Reinforcing bases
Different uses over time (bank deposit,
file, housing)
Summer house
: Put in value as a museum
Subsequent updates of aesthetic value
Masonry type Masonry handmade ceramic solid
mortars with different types of
bonding Variable thicknesses
Handmade ceramic solid .m (head
and rope)
Good constructive technique
Handmade ceramic solid .m (head)
with metal profiles on walls
Handmade ceramic solid .m (head
and rope)
Slab of masonry and metal beams
Good constructive technique
Main problems
detected,
damages and
durability
: Destruction by earthquake
Deterioration by weathering
(capillarity)
Cracking in critical areas
Imposition of vegetation
Cracking cut eardrums 
earthquake
Separation facade  earthquake
Lack of perimeter chains
Settlement arches for lack of
foundation bearing capacity
Water drainage and sewers problems
Efflorescence and soluble salts
Expansion mortar corrosion of wires and
profiles on walls
Reinforcement corrosion losses in storm
drains
Contributions of soil moisture plumbing
losses
Presence of soluble salts
Cracking of supporting structures,
mixtures of materials, lack of soil bearing
capacity
Contributions of soil moisture
Problems in storm drains
Masonry deterioration by weathering,
efflorescence and presence of salts
Problems with gardens
Regional
seismic risk
High (alluvial soil) High (alluvial soil) High (alluvial soil) High (alluvial soil)
Causes of
structural
damage
Mendoza earthquake of  and
later
Mendoza earthquake of  and later Lack of maintenance Several earthquakes
Interventions
Lack of maintenance
Table 2.
Characteristics of previous interventions, masonry and existing pathologies.

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Historic Masonry
DOI: http://dx.doi.org/10.5772/intechopen.87127
. Repair, rehabilitation and retrofit of historic masonry
A large number of historical structures do not meet safety requirements because
today’s requirements are more demanding than those at the time of construction
and because many years have passed by since their construction and structural
safety has deteriorated due to use and time. To bring these historic buildings to a
level of safety standards today, it is necessary to adapt its structure. However, his-
torical value may be lost due to intervention; therefore, new approaches are needed
to achieve sufficient safety.
The San Fernando, California, earthquake of  demonstrated that the
adaptation of the parapets to avoid their fall was effective. The  Northridge,
California, earthquake showed little damage to historic reinforced masonry with
respect to URM that suffered damage and collapse [].
The structural rehabilitation of historical buildings could be done by hiding those
new structural elements or exposing them. Sometimes, the exhibition of new struc-
tural elements is preferred because alterations of this type may be reversible; in the
future they can be changed without losing the historical character of the building [].
The decision to hide or expose structural elements is complex, and there is to be
a consensus with the preservation professionals who are participants of the project.
In high seismic-risk area, it is difficult to strictly follow the principles of the differ-
ent restoration charts (Venice, Athens, etc.), and the task is a challenge of structural
engineering [, ].
The strengthening techniques depend on the building response to the earth-
quake. Different response leads to different strengthening methods. Three main
groups could be:
• Interventions to obtain better global response of the building (in case of build-
ing box type behaviour and a prevailing in-plane response, Figure )
Evaluated Saint Francis
Ruins, Capital
Mitre School,
Capital
Giol Chalet,
Maipú
Fader House,
Luján de Cuyo
Modelling soil Triangle  nodes
Mohr-Coulomb
elastic theory
Plaxis Bv
Triangle  nodes
Mohr-Coulomb
elastic theory
Plaxis Bv
Elastic theory Elastic theory
Interaction with
Abaqus
Modelling
structure
Elastic
Midlin theory
Plaxis Bv
Eight nodes
isoparametric
nonlinear Abaqus
SAP linear
retrofit
Linear masonry
plates
SAP linear
retrofit
Nonlinear model
Drucker-Prager
masonry Abaqus
SAP linear
retrofit
Estimate safety It supports
earthquake IV
MM
> of the
original
> of the
original
> of the
original
Type of
proposed
intervention
Reversible
(temporary
propping)
until the final
consolidation
project
Reversible
(outer metal
reinforcement
chained)
Irreversible in
foundation
Irreversible
(removal
of corroded
profiles)
Without
intervention
foundation
Reversible
(outer metal
reinforcement
chained)
Irreversible in
foundation
Present status Executed Executed Proposed Executed
Table 3.
Modelling and type of intervention.

Masonry Structures

Figure 12.
Bidirectional tensors for bracing of historic masonry walls, Fader House, 2013.
• Interventions for the local mechanisms (in case of a prevailing out-of-plane
response, Figure )
• Interventions on blocky structures (where the kinematic mechanisms must be
prevented: obelisks, towers and also arches and vaults, Figure ) []
In the PERPETUATE project [], both traditional and innovative intervention
techniques have been evaluated. Some of the methods that are widely used in URM
structures are insertion of horizontal tie rods; insertion of anchors between struc-
tural elements; adding new walls, buttresses and foundations; changing of weak
mortar in joints of existing masonry (repointing); repair of cracks; jacketing of
walls with reinforced concrete; grout injections of stone masonry walls; injections
of cement or epoxy-based grout into cracks; and insertion of reinforced concrete
“ring” beams or moment frames and reinforced concrete slabs. Each of these
mentioned methods has its own advantages and disadvantages.
Figure 11.
Reinforcement of foundations and reversible metallic structures in columns and lattice, Mitre school, 2012.


Historic Masonry
DOI: http://dx.doi.org/10.5772/intechopen.87127
Some innovative methods are strengthening brick masonry with attaching FRP
fabric to the surface, restoration of stone masonry with compatible cement grout-
ing, insertion of transversal connection in stone masonry walls, installing seismic
isolation for single assets scale and installation of energy dissipation devices [].
The choice of rehabilitation technique depends on the condition of the masonry,
the availability of local workmanship and the safety requirements [, , ].
Figure 13.
Support structure of masonry blocks, Saint Francis Ruins, 2011.
Figure 14.
Evaluation of the change of the dynamic properties of the masonry building in the different stages of the
rehabilitation [20].

Masonry Structures

The effectiveness of a rehabilitation can be evaluated by system identification
techniques. They measure the dynamic properties of the structure through environ-
mental vibration before, during and after the structural reinforcement. The vibra-
tions of low amplitude come from different sources, among them, the vehicular
traffic, the micro-tremors, the wind, etc.
In the case of masonry, the parameter used to measure the efficiency of the
structural reinforcement is the period of the walls measured at the top of them.
Before starting the reinforcement work, the environmental vibration in the struc-
ture is measured in order to know the periods of the same with the existing level
of damage. Once the foundations are consolidated and the walls reinforced, new
measurements are taken, and in this way we can know the degree of recovery that
the structure has had up to that stage as indicated in Figure  [].
. Conclusions
The study of rehabilitation of masonry involves a team of specialists from
historians, architects, structural engineers, geotechnical and chemical technicians,
etc. That is, it cannot be considered only as a structural problem.
The seismicity of the site and the abandonment of the old buildings have caused
the collapse of most of the old buildings, leading to the loss of cultural values that
have been part of the local history. Therefore, the rehabilitation of old buildings
should be considered a state policy, in order to preserve the few buildings that
remain for the future.
It is emphasised that in the region with near-source earthquake, historic build-
ings that have been standing are made up of ceramic solid bricks; only very few of
adobe and stone have managed to survive due to the high demand for ductility of
earthquakes near-fault.
Modelling by MEF applying nonlinear constitutive models provides an effective
tool for the simulation and verification of historic masonry heritage buildings, so
it is necessary to research the formulation of efficient constituent models for thick
masonry.
The monitoring through environmental vibration measurement has been a
useful tool to evaluate the level of recovery of construction, allowing in the future
to evaluate the state of conservation of the same. Model calibration is possible from
frequency identification.
Acknowledgements
This work has been part of programme PICT - supported by the
Technological National University of Argentina and National Agency for Promotion
of Science and Technology of Argentina. The authors want to thank the university
staff and the professionals of preservation of Heritage Bureau of Province of
Mendoza and CONICET because they had made the development of the research
programme possible.


Historic Masonry
DOI: http://dx.doi.org/10.5772/intechopen.87127
Author details
Noemi GracielaMaldonado*, PabloMartín, Gerardo Gonzálezdel Solar
and MaríaDomizio
National Technological University, Mendoza, Argentina
*Address all correspondence to: ngm@frm.utn.edu.ar
©  The Author(s). Licensee IntechOpen. This chapter is distributed under the terms
of the Creative Commons Attribution License (http://creativecommons.org/licenses/
by/.), which permits unrestricted use, distribution, and reproduction in any medium,
provided the original work is properly cited.

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