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http://www.iaeme.com/IJCIET/index.asp 1132 [email protected]
International Journal of Civil Engineering and Technology (IJCIET)
Volume 10, Issue 05, May 2019, pp. 1132-1146, Article ID: IJCIET_10_05_113
Available online at http://www.iaeme.com/ijciet/issues.asp?JType=IJCIET&VType=10&IType=5
ISSN Print: 0976-6308 and ISSN Online: 0976-6316
© IAEME Publication
DIAGNOSIS OF THE ENCLOSURE OF THE
MEDINA OF SALÉ IN MOROCCO - CASE OF
RECTANGULAR TOWERS
Driss ELHACHMI, Lahcen BAHI, Latifa OUADIF, Rachid BENKMIL
L3GIE Laboratory, Mohammadia School of Engineers, Morocco
ABSTRACT
The enclosures of the historic cities are important constituents of the heritage built
in Morocco. These historical monuments enrich the history, architecture and culture
of the country. The development of this patrimony and its preservation requires
serious and tireless efforts on the part of all.
The Salé enclosure is considered among the oldest Islamic defensive works in
Morocco. Unfortunately, it is not highlighted and is in a state of advanced
degradation that threatens its existence. It suffers from structural pathologies whose
main causes are humidity and anthropogenic factors.
The objective of this article is the visual diagnosis of this enclosure, the inventory
of the different pathologies and the possible causes. This diagnosis will later focus, on
the case study of the existing rectangular towers on this enclosure, the main
pathologies that affect them and the evaluation of conservation states implemented for
the preservation of this heritage.
Key words: heritage built, historical monument, degradation, pathologies, diagnosis.
Cite this Article: Driss ELHACHMI, Lahcen BAHI, Latifa OUADIF, Rachid
BENKMIL, Diagnosis of the Enclosure of the Medina of Salé in Morocco - Case of
Rectangular Towers, International Journal of Civil Engineering and Technology
10(5), 2019, pp. 1132-1146.
http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=10&IType=5
1. INTRODUCTION
The city of Salé is a medieval city founded in the eleventh century. It experienced a real urban
development in the Almohad (twelfth century) and Marinid (14th century), because of its
strategic position on the land routes linking Fez to Marrakech and thanks to its port, a trading
center between Europe and Morocco (HASSAR-BENSLIMANE, 1992).
Due to the combined effects of the environment (climatic factors, air pollution, etc.) and
lack of maintenance, the major part of this heritage is now damaged. Today, it has become
essential to intervene so as to preserve and reveal the aesthetic and historical values of this
monument.
The objective of this article is the enhancement of this heritage. A diagnosis was
established on this enclosure to identify its various constituents and the record of the various
Diagnosis of the Enclosure of the Medina of Salé in Morocco - Case of Rectangular Towers
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pathologies found in its entirety. The diagnosis will be focused on one of the components of
this enclosure which are the rectangular towers. The main pathologies that affect them and
proposal of the conditions of conservation for the preservation of this heritage.
2. DESCRIPTION OF THE ENCLOSURE OF SALÉ
The Salé medina extends to the northern embouchure of the Bou Regreg River, its enclosure
includes masonry defensive walls made of stone erected around the city for a distance of
approximately 4.5 km and delineating an area of 90 ha. Its north façade is about 1600 m long,
the east façade is about 700 m long, the south facade is about 1600 m long and the seafront
(west side) is about 600 m long. This enclosure includes, in addition to battlements (walls),
rectangular towers, bastions (Borj) and doors (Bab), mainly built in stone masonry.
2.1. Brief historical overview
The enclosure of Salé dated since Almoravids but has been indicated in no document. The
Eastern and Northern parts were restored by the Almohads during the reign of Ya'qub Al
Mansur. Then the Mérinides built the South and West part (HASSAR-BENSLIMANE, 1992).
It encompases doors (Bab) and Borj classified Historical Monuments in 1914.
2.2. Environmental overview
The medina of Salé, according to the Emberger-Sauvage classification, belongs to the
Mediterranean subhumid bioclimatic domain and exposed to oceanic influences. The climatic
data of Rabat Salé Kenitra region are grouped in the following Table 1.
Table 1 Climate data of the region of rabat salé kenitra-Meteorology Department of Morocco
Climate data Unit Value
Annual Precipitation mm 600
Monthly Sunstroke Duration Hour 211
The Average of Monthly Relative Humidity maximum % 92,4
minimum % 50,96
Average Monthly Temperature maximum °C 23
minimum °C 13
2.3. Brief structural description
The walls
The battlements of the medina of Salé are built of rough rubble arranged in almost perfect
beds between which are aligned small stones to ensure the solidity of the whole.
These battlements consist of : Figure 1
On the outer part, the walls have an average height of 6 m, a linear profile with crenels from
one side to another and a thickness of about 1.50 m.
On the inside, the section is reduced to 0.60 m and forms a parapet for walkway measuring an
average of 0.90 m. stairs cut into the wall provide access to this path.
Driss ELHACHMI, Lahcen BAHI, Latifa OUADIF, Rachid BENKMIL
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Figure 1 Cup on the wall
Historical doors:
Made of stone, in the form of horseshoe arch broken or not, or semicircular.
Rectangular Towers:
They are 53 rectangular towers distributed on the north, east and south facades of the
enclosure of Salé, Figure 2. Construct in the same materials as the walls, in rubble masonry.
Figure 2 Plan of the enclosure of the Medina of Salé
Diagnosis of the Enclosure of the Medina of Salé in Morocco - Case of Rectangular Towers
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3. PATHOLOGICAL ANALYSIS
3.1. Diagnostic methodologies
For the diagnosis of the enclosure of the Medina of Salé, we adopted the following
methodology:
Figure 3 Diagnostic methodologies
3.1. Observed pathologies
The various pathologies found on the enclosure of the Salé medina are grouped in the
following Table 1 and shown in Figure 4, Figure 5 and Figure 6 .
Table 2 Pathologies observed on the Salé enclosure
Non-structural pathologies Structural pathologies
Vegetations; Vertical or oblique cracks
Large trees and Palms; Detachment and breakage of elements
Lichens and Mushroom Collapse of walls;
Black or Saline Stains Wall puff ;
Public Waste
Humidity and Infiltration
Water Drainage Defects;
Micro Cracks;
Degradation and Detachment of Plaster
Degradation of Joint Mortar
Alveolization
Scratches and Graffiti;
Fire;
Mosses;
Driss ELHACHMI, Lahcen BAHI, Latifa OUADIF, Rachid BENKMIL
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Figure 4 Remparts Pathologies
Figure 5 Pathologies of the towers
Figure 6 Door and Borj Pathologies
Diagnosis of the Enclosure of the Medina of Salé in Morocco - Case of Rectangular Towers
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3.2. Degradation factors
The degradations observed on the enclosure of Salé are the result of a conjunction of several
factors of which one can quote the following:
Effect of Humidity
Moisture or the presence of water is the main cause of several degradations that affect
traditional buildings (BENALIOULHAJ, 2015) (CLIM, GROLL, & DIACONU, 2017). It can
be of several types:
Capillary Humidity
This type of humidity is manifested by the penetration of water inside the walls and its
upward rise by capillarity. This phenomenon is due to several factors, including:
Raising of the ground which is in contact with the masonry (road, embankment);
Impermeability of soil around walls that increases humidity, and favors stagnation of runoff;
Presence of green spaces and planting of trees near the monument;
Presence of the sanitation network adjoining the walls;
Use of waterproof materials such as cement, which make it very difficult to evacuate moisture.
Rainfall
The average rainfall is 600 mm / year. The rainiest periods are in winter (up to 112 mm in
November). A high concentration of rainfall is found between the months of November and
April with 90% of annual rainfall. Thus, the average air temperature varies from 7 ° C in
winter to 28 ° C in summer, Figure 7.
Figure 7 Average monthly internal precipitation and average temperature (Meteorology
Department of Morocco)
Whipping rain, runoff, splashing, infiltration by joints can cause significant damage to the
historic monument. And because of the rainfall, the environment is conducive to the growth
of fungi and moss resulting in the detachment and crumbling of the mortar (Shoureshe
Kanani, 2011).
The degradation due to precipitation can be promoted by:
Absence of water evacuation devices;
Existence of public waste;
Existence of microcracks;
Lack of maintenance of drainage systems;
Driss ELHACHMI, Lahcen BAHI, Latifa OUADIF, Rachid BENKMIL
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No periodic maintenance.
Rain also promotes biological activity and growth of vegetation around monuments, it
deteriorates materials and their aesthetics (Belhaj, Ahmed, & Akhssas, 2016).
The danger of rainwater also comes from the fact that it is chemically aggressive by
carbon dioxide and the salts it contains (BENALIOULHAJ, 2015).
Relative Humidity of the Air
Relative humidity and air temperature have certain effects on the stability and resistance of
monuments (Shoureshe Kanani, 2011). The relative humidity of a certain quantity of air is
defined as the ratio between the quantity of humidity of a certain quantity of air and the
humidity necessary for the saturation of the same quantity at the same temperature (Shoureshe
Kanani, 2011).
The average monthly relative humidity in the Rabat Salé Kenitra region varies from 46%
to 94% , Figure 8 .
Figure 8 Relative Humidity Monthly Average (Meteorology Department of Morocco)
Atmospheric Pollution
Air pollution is a consequence of population growth and the proliferation of mechanical
vehicles. Indeed, the degradation of historical monuments is strongly influenced by the
presence of atmospheric pollutants such as sulfur dioxide SO2 and nitrogen oxides NO
(Reyes1 & al., 2011).
With a minimum amount of water, sulfur dioxide (SO2) oxidizes to sulfuric acid (H2SO4),
which is known for its destructive and wear-out effects (Shoureshe Kanani, 2011). Then
(H2SO4) reacts easily with limestone to form gypsum (Reyes1 & al., 2011). Gypsum
incorporates atmospheric particles, dust and biomass into its mineral structure to form what is
known as black crust (Reyes1 & al., 2011). When gypsum loses moisture, it can re-crystallize
and become porous, causing microcracks and fatigue of materials (Reyes1 & al., 2011).
In urban areas, oxygen O3 and nitric oxide NO also react with water to form nitric acid
(HNO3), which dissolves limestone to produce calcium nitrate (CaNO3)2 (Reyes1 & al.,
2011). The latter (CaNO3)2 is transported through porous capillaries to finally crystallize on
the surface of the monuments to be washed during rainy events (Reyes1 & al., 2011).
The wind
Diagnosis of the Enclosure of the Medina of Salé in Morocco - Case of Rectangular Towers
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Wind is an important factor in the degradation of historic monuments in the coastal zone
when it blows very violently. Thus, the wind comes through the transport of atmospheric
particles and aerosols to the structures of the enclosure.
Properties of Salé stone
The stone used in the construction of the Salé enclosure is a sedimentary rock composed of
detrital elements (fragments of rocks and minerals) and bioclasts (fragments of shells) bound
by an essentially calcareous matrix (HASSANI & AZHARI2, 2009). This stone is
characterized by its high porosity 23.90% and a strong water absorption 12.37% (HASSANI
& AZHARI2, 2009).
The water absorbed by this stone can induce chemical reactions and the crystallization of
salts, causing the loss of materials and the decrease of their mechanical capacities (Reyes1 &
al., 2011).
Figure 9 Pathologies on Borj Arrokni and Sqala
Inadequate Restoration
The restoration must be based on a better knowledge of the historical heritage, its
characteristics, the mode of behaviour of the materials and an accurate analysis of the
structure (Rachid, Lahcen, Ahmed, & Latifa, 2018). This restoration concept is based on three
fundamental principles: authenticity, minimal intervention and reversibility (ICOMOS, 1964).
Thus, any inappropriate intervention can damage the heritage structure. This improper
restoration can be manifested by:
Driss ELHACHMI, Lahcen BAHI, Latifa OUADIF, Rachid BENKMIL
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- The use of incompatible materials (cement, concrete, etc ...), which can create negative
interactions with the components of the heritage structure (Figure 4-M1, Figure 6-B6, Figure
9-P1, P2, P3 ) (BENALIOULHAJ, 2015);
- Unskilled and inexperienced labor or trained in traditional enforcement rules;
- Failure to comply with the method of execution of the work;
- Failure to respect the deadlines necessary for the use of materials, indeed, the duration of
ripening of the lime before its use has a significant impact on the mechanical and physical
characteristics of a lime mortar (BENALIOULHAJ, 2015).
Anthropogenic factors
The role of man in the degradation of historical monuments is very important. The
anthropogenic factors that contribute to the degradation of the Salé compound are:
- Deposit of public waste;
- Neglect, lack of maintenance and poor heritage management Figure 4, Figure 5, Figure 6 and
Figure 9;
- Proliferation of graffiti or tags with paint (Figure 6- B5);
- Fire inside or near the monument (Figure 4- M7, Figure 9- P4);
- Lack of awareness and vandalism (Figure 9- P4);
- Street vendors (bab sebta), etc ...
Urban factor
Urbanization is a factor that acts on the degradation of the Salé enclosure and its conservation.
It manifests itself by:
Overpopulation of the city with the houses back to the patrimony (Figure 6- B2 inside);
Creation of new traffic lanes with demolition of historic walls and gates (Bab Sidi Bouhaja
road in the south to Borj mtemmen in the Northeast);
Upgrading of common ways to the walls;
Shock of traffic vehicles on the underside of doors (Figure 6- B3);
Creation of concrete openings in the wall for vehicles and pedestrians (bab sebta, and sidi
benaacher road in the south to sidi moussa in the north).
4. DIAGNOSIS OF RECTANGULAR TOWERS:
4.1. Characterization
All the towers inspected are built entirely of rubble and clay mortar with an ashlar stone. They
do not have the same dimensions, they are from 4.50 to 6 meters wide and from 3.60 to 4.10
meters of saille and heights varying between 5 to 8 meters.
Diagnosis of the Enclosure of the Medina of Salé in Morocco - Case of Rectangular Towers
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Figure 10 Rectangular towers of Salé enclosure
The 53 rectangular towers of this enclosure are distributed on the external facade of the
walls at irregular intervals. They exist in two types: Type 1 has an uncovered platform, and
type 2 is raised from a defence chamber with a terrace, Figure 10.
After analysis of the results, the predominance of Type 1 Towers was found to be 77% of
the total number of towers studied, Figure 11.
This is due on the one hand to the simplicity and the speed of execution of this structure,
on the other hand, considering the military character of this city the multiplicity of this type of
towers allows a better control of the city and better attack with the surrounding dangers.
Figure 11 Distribution of rectangular towers on the enclosure by type and facades
Figure 11 shows that the predominance of type 1 towers on the wall of the north facade of
the medina. Note that following historical research, the north and east facades are the first
sections built in the Almohad dynasty to cope with land attacks. After, the other south and
west facades overlooking the wadi and the ocean were built by mérinides.
4.2. Pathology
Driss ELHACHMI, Lahcen BAHI, Latifa OUADIF, Rachid BENKMIL
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To determine the needs for maintenance, upkeep, restoration and shoring, a study of the states
of conservation was started following the pathologies found.
After analysing the results of the investigations on the towers, and in order to facilitate the
analysis of the degradations observed, the anomalies and pathologies were grouped into two
groups of structural and non-structural pathologies, Table 3.
Table 3 Classification of found Pathologies
Non-structural pathologies Structural pathologies
V -Vegetation; VOC Vertical or Oblique Cracks ; LM - Lichens and Mushroom; DRE Detachment and Rupture of Elements; LTP -Large Trees and Palms; WP - Wall Puff PW -Public Waste ; HI -Humidity and Infiltration; WDD -Water Drainage Defects; DDP -Degradation and Detachment of Plaster; DJM -Degradation of Joint Mortar ; BSS - Black or Saline Stains; MC -Micro Crack;
Figure 12 Percentage of found pathologies
Figure 12 shows the percentages of pathologies found on the rectangular towers. It
follows from this diagram that the non-structural anomalies are the most answered in relation
to the structural pathologies which are minimal compared to the total of the towers. They
represent the following percentages Table 4.
Table 4 Percentages of found pathologies
Pathologies Percentage
Non
str
uct
ura
l
Degradation and Detachment of Plaster DDP 94%
Humidity and Infiltration HI 89%
Water Drainage Defects WDD 57%
Black or Saline Stains BSS 57%
Lichens and Mushroom LM 42%
Public Waste PW 42%
Vegetations V 40 %
Degradation of Joint Mortar DJM 36%
Diagnosis of the Enclosure of the Medina of Salé in Morocco - Case of Rectangular Towers
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Str
uct
u
ral
Detachment and Rupture of Elements DRE 28%
Vertical or Oblique Cracks VOC 21 %
Wall Puff WP 2%
Figure 13 Pathologies found by type of towers
Figure 13 confirms that towers’ structures of type 1 are the most affected by all
pathologies (structural and non-structural). The towers’ structure of type 2 is affected only by
six non-structural anomalies Table 5.
Table 5 Percentages of pathologies found on type 2 tower
Pathologies Percentage
Non s
truct
ura
l
Degradation and Detachment of Plaster DDP 23%
Humidity and Infiltration HI 15%
Water Drainage Defects WDD 6%
Black or Saline Stains BSS 6%
Vegetations V 4 %
Degradation of Joint Mortar DJM 2%
Driss ELHACHMI, Lahcen BAHI, Latifa OUADIF, Rachid BENKMIL
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Figure 14 Distribution of pathologies by facades
Figure 14 shows the distribution of pathologies by facades. It has been found that the
north facade is the most degraded and subject to all anomalies.
4.3. States of conservation
The conservation statuses of the inspected rectangular towers have been inventoried and
classified according to their degree of obsolescence and the severity of the observed
deteriorations.
The ranking was also established into order of priority of necessary intervention from
degree 0 (good state of conservation) to degree 4 (critical state), Table 6.
Table 6 Description of the states of conservation
Degree Conservation
state Description of conservation state
0 Good condition Intact Structure. Obsolete and lack of maintenance of the Monument.
1 Average state No anomalies on the structure affecting the durability and stability of the
structure. Normal deterioration due to the lack of maintenance.
2 Bad state Restoration is necessary to avoid damage of the structure.
3 Very bad state A restoration intervention is essential so that the state does not become
critical. 4 Critical state Urgent intervention in two stages:
- Emergency shoring of the structure to stop the danger on the passengers;
-Urgent rational restoration of the structure.
Figure 15 shows that the most common states of conservation of the towers are type 0 and
1. It is recommended in Table 3, the need for maintenance operations to avoid any damage
affecting the structure of the towers. These maintenance operations make it possible to
preserve the original structure of the historic enclosure to a higher degree of conservation
(Vidovszky, 2016).
Diagnosis of the Enclosure of the Medina of Salé in Morocco - Case of Rectangular Towers
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Figure 15 States of conservation of rectangular towers
Conservation states 2, 3 and 4 are for type 1 towers (11 on the north side and 1 on the
south side). The intervention on these towers is essential to avoid their ruins, especially 50%
of the towers of the north facade are affected by these states. Thus, a problem noted on nine
towers, and that can lead to the ruin of the latter is the growth of trees on their platform and
the appearance of large cracks that threaten their stability. Indeed, states of conservation 3 and
4 only concern this anomaly.
5. CONCLUSION
The diagnostic study of the Salé enclosure has shown the negligence and mismanagement of
this heritage. In this study we discussed the case of the rectangular towers of this enclosure,
the inventory of the different pathologies that affect them and the conservation conditions that
can be adopted. These towers are built entirely of rubble and clay mortar with chainage angles
stone. They are spread over the three north, east and south facades of the enclosure and most
of them are edged platform.
The result of the inspection indicates the predominance of non-structural anomalies,
including humidity and infiltration, coating degradation and delamination, drainage problems
of water and vegetation. Structural anomalies are less frequent (vertical or oblique fissures,
detachment and breakage of elements and wall blowing) but the towers concerned by these
pathologies are in a critical state.
In addition to moisture, urbanization at the expense of inheritance, inadequate restoration
and human factors can be stated to be factors contributing to the degradation of historic
monuments. These factors combined with the lack of periodic maintenance accelerates these
degradations.
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http://www.iaeme.com/IJCIET/index.asp 1146 [email protected]
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