DIAGNOSIS OF THE ENCLOSURE OF THE MEDINA OF SALÉ IN ... · Diagnosis of the Enclosure of the...

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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


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.



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



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;



Figure 4 Remparts Pathologies

Figure 5 Pathologies of the towers

Figure 6 Door and Borj Pathologies



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;



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



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:



- 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.



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



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%



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%



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).



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.

REFERENCES

[1] J. HASSAR-BENSLIMANE, Le passé de la ville de salé dans tous ses états Histoires,

archéologies, archives, 1992.

[2] A. BENALIOULHAJ, "Contribution à l'élaboration d'une méthodologie d'étude de

restauration des monuments historiques.Application au bati traditionnel de la médina de

fes," Mohammadia School of Engineers, Rabat, 2015.



[3] D.-A. CLIM, L. GROLL and L.-I. DIACONU, "Moisture- the main cause of the

degradation of historic buildings," BULETINUL INSTITUTULUI POLITEHNIC DIN

IAŞI, 2017.

[4] H. Z. Shoureshe Kanani, "A Study of the Damages to Historical Monuments due to

Climatic Factors and Air Pollution and Offering Solutions," International Journal of

Humanities and Social Sciences, 2011.

[5] S. Belhaj, L. B. Ahmed and Akhssas, "Study of Moroccan Monumental Heritage

Traditional for Valorization and Conservation of Collective Memory and for Socio-Eco-

Tourism Sustainable Development-case Kasbah Chellah,Rabat," Energy Procedia, pp.

531-538, 2016.

[6] J. Reyes1 and al., "Influence of Air Pollution on Degradation of Historic Buildings at the

Urban Tropical Atmosphere of San Francisco de Campeche City, México," Monitoring,

Control and Effects of Air Pollution, 2011.

[7] I.-E. E. A. E. HASSANI and H. E. AZHARI2, "Evaluation des propriétés physico-

mécaniques des pierres de construction du Maroc à partir des vitesses des ondes P et de la

résistance au choc," Bulletin de l’Institut Scientifique, Rabat, section Sciences de la Terre,

pp. 41-54, 2009.

[8] B. Rachid, B. Lahcen, A. Ahmed and O. Latifa, "contribution to the characterization of

construction materials of historical monuments -case study," International Journal of Civil

Engineering and Technology (IJCIET), pp. 1680-1688, 2018.

[9] ICOMOS, International charter on conservation and restoration of monuments and sites

(charter of venice 1964), 1964.

[10] I. Vidovszky, "Impact-based diagnostic approach for maintenance monitoring of historic

buildings," Procedia Engineering, pp. 575-582, 2016.

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