Assessment of the Current State of Qanibay al-Rammah Complex (908 AH/1502 AD), as a Procedure Precedes the Restoration Process

An assessment should be made of the current state of the historic buildings before starting in any intervention procedures. Where, any procedures of conservation of the building must be outrun by a perfect diagnosis according to the international conventions. Chemical, physical, mechanical properties and structural status are extremely important to give information about the current condition of Qanibay al-Rammah madrasa, which situated within Saladin square in Historic Cairo. This building has been affected by several deterioration factors since the construction and still suffering damage factors at the moment, which led to the occurrence of several damage aspects to the building, such as fissures in architectural elements, granular disintegration, loss of stone material, peeling of limestone surface, splitting in building material, the efflorescence of salts, pitting in limestone surface, black spots in stone surface, hard black crust, etc. The aim of this study is evaluation of the condition of Qanibay al-Rammah madrasa by two methods, firstly by different scientific techniques such as X-Ray Diffraction (XRD), EDX analytical methods, Scanning Electron Microscopy (SEM), Polarizing Light Microscopy (PLM), and Stereo Microscopy, and secondly by Numerical analysis based on 3D finite elements analysis to determine the critical places of the building. The followed methodology in this study allowed us to the assessment of the current status of the building by various scientific techniques to determine the real causes of damage, which must be taken into account during the intervention procedures.


Introduction
Limestone is considered the most important stone which has been widely used in historic Cairo's buildings on throughout history; Mokattam, Tora and Maasara quarries are considered the most important quarries that played a major role in construction of archaeological buildings in ancient Egypt [1]. Several researches conducted on limestone used in most of the Islamic archaeological buildings in historic Cairo confirmed that they date back to the middle Eocene.
This kind of limestone was used as a major building material in madrasa of Qanibay al-Rammah which situated in Saladin square, Historic Cairo. The major building material (limestone) used in case study has been suffering from several deterioration factors such as effect of saturated soil with contaminated water, groundwater raised, air pollution, microbiological deterioration, urban trespasses and man-made destruction, variation between temperature and relative humidity; it is also suffering damage factors and causes at the moment. Wet and dry cycles cause complex mechanical damage in particular when salts are found in the pores of limestone; because the limestone is characterized by high porosity, so it has ability to absorb moisture from air or ground, thus facilitating penetration of salts spray into its components causing physiochemical damage, especially when the dissolved salts turn to different crystalline sizes, causing cracks in internal structure of the stone due to internal pressures [2] [3]. Water saturated with salts seeping into the pores of building materials causes the loss of mechanical strength [4] [5]. When water evaporation occurs the salts recrystallize within the pores of the stone resulting in significant pressure on the pore walls from the inside which leads to cracks in the internal structure of the stone resulting in fall of some parts of the stone [6]. The rate of damage is more serious in urban areas because amount of SO 2 which is generated by humanitarian activities far exceeds the quantities from natural sources, which leads to the speed of damage of archaeological buildings located in urban areas. As such found in the case study [7] [8], the interaction between air pollution gases and building materials leads to the formation of black hard crust on the surface of the stone; this causes loss of stone material due to the physiochemical interactions between the stone components and acid gases [9] [10]. The wind has a very big role in limestone damage as it works to increase the rate of evaporation of salt solutions inside the stone pores, which helps the efflorescence of salts on the surface [11]; in addition to the destructive impact of groundwater on building materials, it helps the growth of microorganisms that produce different types of organic acids such as carbonic, oxalic, sulfuric and nitric acids [12]. These acids interact with the mineral components of limestone leading to its degradation, microorganisms cause of physical changes in the size of stone pores, as well as changes occur in water distribution in the chemical composition of stone surfaces, leading to a weak internal structure of mineral crystals [13] [14]. Structural damage causes of monuments are showing in three of the problems that effect on the buildings, namely: seismic action, soil differential settlement owing to the variability of the  [15].
Madrasa of Qanibay al-Rammah has been suffering damage factors and causes since ancient times because of the old earthquakes and raised groundwater level, it is also suffering damage factors and causes at the moment.
The present research study has been oriented by the following hypothesis: -According to international conventions, the building must be evaluated by the different scientific techniques before intervention procedures.
-Assessment of current state of the building gives an indication of different properties of building materials and structural behavior as well as the physical condition of the building.
-The current status report resulting from the evaluation process refers to the identification and classification of deterioration symptoms of building materials.
-Optimal assessment of building materials enables us to use appropriate restoration methods for the condition of the building.
-Strategies, policies, and objectives that achieve conservation of the buildings as a historical and archaeological value should be preceded by the study and identification of problems and risks that threaten these buildings; this is achieved through the evaluation of building materials.
-Intervention procedures of restoration methods are based on the current status report of the building.

Qanibay al-Rammah Complex
Qanibay al-Rammah complex at Saladin square was inscribed as a World Heritage Site (UNESCO) in 1979 as a part of Historic Cairo. This madrasa was established by Prince Qanibay Amir Akhur in 908 AH/1502 AD in the Sultanate of Qansuh al-Ghuri (1501-1516 AD) at Saladin square which considered of the suspended schools, their layout follows iwan style, it has two facades, the first is at the eastern side where there is a door leading to a building that was annexed to the school. The second façade at the southern side is the main one and overlooks a yard between this mosque and al-Mahmudiyya Mosque and includes the dome, the minaret, the sabil, the kuttab and the main entrance which is high and ascended to by stairs leading to the door of the mosque, this mosque consists of a courtyard on which, four iwans are perpendicular. The southeastern iwan is the biggest and is covered with three vaults. It is clear from the madrasa design integration of elements and balance as well as the good distribution of elements according to their function and relationship to each other ( Figure 1).

Building Materials Characterization
Limestone is considered the main building material which was used in construction of Qanibay al-Rammah madrasa, addition to different types of marble, which were used as casing on walls of building and lime-gypsum mortar used as bind materials.

Present Condition of the Studied Building
The building materials have been suffering from several deterioration factors such as raise ground water level, effect of saturated soil with contaminated water, air pollution, variation between temperature and relative humidity, microbiological deterioration, urban trespasses, effect of earthquakes and man-made destruction, it is also suffering damage factors and causes at the moment such as ground water raised, urban trespasses, pollution and infection of ground water beneath the building soil. The ground water are contained various types of mineral salts, in which they are the most important physiochemical weathering and damage processes that affected on the building materials. When the water bearing salts evaporate, the salts crystallize inside the pores of building materials, resulting in pressure occur inside the pores leading to cracks occur in the material's structure. Also continuous changes in temperature and relative humidity leads to occur a complex damage mechanism that effects on the different properties of building materials [17] [18] [19]. Volume of these materials is changing with expansion and contraction resulting in decays the building materials on long term [20]. The occurrence of acid rain on building materials surfaces cause of chemical reactions drive to degradation of building materials [21].

Properties of the Building Materials Used in the Case Study
Besides current conditions of the building materials of Qanibay al-Rammah madrasa that determined by visual observation, physical, chemical and mechanical properties were investigated by laboratory studies, stones (limestone, marble) and mortars were collected from the deteriorated parts of the building. In order to assessment of building materials properties used in case study, physical properties tests, such as bulk density, water absorption, porosity, and mechanical       Continued   L3  60  -9  -5  ---6  10  10   M1  60  5  5  30  -------M2  66  -14  -19  ------M3  60  -9  -7  3  10   Limestone and marble samples were cut into cubes 5 × 5 × 5 cm, that were then subjected to physical and mechanical properties tests. Then, the average of the cubes test readings were taken separately, as shown in Table 3, Table 4.
The results of physical properties of the deteriorated samples explain that there is increase in porosity, water absorption and decrease in the density, in particular the limestone samples which contained on high concentrations of mineral salts, clay minerals and iron oxides, also all the deteriorated samples have been decreased in its mechanical properties.

Mortars
There are two mortars (lime-gypsum) used as binding materials in the joints of stones' courses. Mortars samples were investigated by SEM, the lime mortar samples showed calcium carbonate with an abundance of sand which used as a filler material, the examination shows the presence of fine particles of calcite and quartz, in addition to hematite, feldspar, and gypsum as minor minerals. The second kind of mortars used in case study is gypsum mortar, where it was investigated by SEM, which showed aggregates of gypsum with particles of calcite and quartize. From examination showed disintegration of mortar crystals due to loss of bonding materials, which led to appearance of voids and disassembled particles, this is due to the effect of groundwater on building materials (Figure 9). X-ray diffraction patterns of mortars samples revealed that the lime mortar mainly consist of calcite, quartize, hematite and feldspar, where presence of hematite and feldspar indicate on use of red brick powder between the components of the lime mortar. Investigated gypsum mortar by XRD showed it consist of quaritze and gypsum as major minerals, in addition to minor minerals of calcite ( Figure 10 and Table 5).   Earthquakes loads were calculated in two orthogonal directions (X-X) and (Y-Y), structural elements were represented with consideration that the walls and roofs as shell elements, arches as frame element and the pillars as a hinged support.

The Shear Force Affecting the Building
The shear force is represented the force that affects in a perpendicular direction  The shear force resulting from earthquakes force affects the building in two directions (X-X) and (Y-Y). From the resultant deformations in Figure 11 showing that the areas most exposed to high shear strength more than the allowable value were in the upper parts of the east wall of the kiblah Iwan, when the shear force was parallel to the section in direction (Y-Y), and when it was perpendicular on the section in direction (X-X) the lower parts of the wall are the most affected by shear force stresses (Figure 12(A), Figure 12(B)).

The Bending Moment Affecting the Building
Tensile stresses affecting the building were calculated in two axes Y and X. These Open Journal of Geology -The east northern arch of the great Iwan ( Figure 12(C), Figure 12(D)).
-The upper parts of corners and the middle-upper part from the east northern wall of the shrine (Figure 12(E)).
-The upper parts of corners of the west southern facade of the shrine ( Figure   12(E)).
-The upper parts of corners of the east northern facade of great Iwan ( Figure   12(H)).

Results and Discussion
Weathering forms on building materials which used in the case study were identified and classified according to four groups of weathering forms ( Figure 2 and Table 1). The study concluded that the weathering forms represent an important parameter for the characterization, quantification, and evaluation of building materials deterioration where it was found that weathering forms of building materials used in the case study rang from very slight damage to very severe damage depending on its various properties and the damage intensity.
We observed the building materials used in the southern partition of the building such as the southern east façade, the southern east iwan and the shrine contain advanced stages of various deterioration symptoms, due to that this part of the building has been subjected to greater damage factors since the time of construction until at the moment, while rest of the madrasa was reconstructed after that it was ruined ( Figure 13) [29] [30].
The investigations of building materials were performed by polarized light Figure 13. Qanibay al-Rammah complex, the western north iwan, part of the western south iwan and minaret are ruined. The investigations showed that all marble samples contain of massive texture, micro cracks, and rare crystals of quartz. Anorthite, ankerite, chlorite, and biotite were observed in texture of all samples; in addition to the presence mosaic texture was in most of marble samples.
From examination showed occurrence disintegration of mortar crystals due to loss of bonding materials, which led to appearance of voids and disassembled particles, because of groundwater effects on building materials.
The results of physical properties of the deteriorated samples revealed that there are increase in porosity, water absorption and decrease in the density, in particular the samples which contained on high concentrations of mineral salts, clay minerals and iron oxides, also all the deteriorated samples have been decreased in its mechanical properties.
The investigations results indicated that the physical, chemical and mechanical properties of building materials played the main role with the surrounding environment factors in deterioration of building materials used in the case study.
The permissible shear force was calculated according to Egyptian building code, which was 140 N, this means that if the force exceeds this value, the building will be exposed to cracks. From designed model by (F.E.M) was determined the critical places of Qanibay al-Rammah madrasa which is next the east northern arch of the great Iwan, the upper parts of corners, the middle-upper part from the east northern wall of the shrine, the upper parts of corners of the west southern facade of the shrine, and the upper parts of corners of the east northern facade of great Iwan. These places show different cracks with different size, due to effect the shear force of earthquakes ( Figure 11 and Figure 12).
The bending moment in directions (X and Y) was calculated by PROKON software, the allowable value of bending moment was 4.78 Kn•m in direction (X-X), and 29 Kn•m in direction (Y-Y), this means that if the bending moment exceeds this value, the building will be exposed to cracks and collapse, where determined the critical places of Qanibay al-Rammah madrasa (Figure 12).

Conclusions
The building materials used in Qanibay al-Rammah madrasa have been affected The study concluded the stability of the building materials against the weathering strongly depends on their chemical, physical, mineralogical and petrographic properties, where the study results showed that the samples which contain on minerals salts, clay minerals, and iron oxides have more damage and decrease in its physical, mechanical properties.
From determining the critical places of Qanibay al-Rammah madrasa we can appropriate supporting methods to these places whether in the direction (X-X) or the direction (Y-Y).
The study results give way to us to identify the current state of Qanibay al-Rammah madrasa (as a procedure precedes the restoration) to find the appropriate method to the intervention with improving the building materials properties and reinforcement of structural elements subjected to cracks and supporting the places exposed to a high bending moment and shear force.