Nano Particles and Nano Composites for Preservation of Historic Marble Minbars with Application on the Minber of Soliman Pasha Al-Khadim Mosque in Salah El-Din Citadel in Cairo, Egypt

Minbar, in Islam, the pulpit from which the sermon (khutbah) is delivered. In its simplest form, the minbar is a platform with three steps. Often it is constructed as a domed box at the top of a staircase and is reached through a doorway that can be closed. Soliman pasha Al-Khadim mosque in Salah El-Din citadel in Cairo is considered the first mosque with ottoman architectural style. This Minbar exposed to aggressive human intervention by mosque workers and archaeological crafts unity-ministry of antiquities in Egypt, to lose more of its historical and architectural values. Now this Minbar undergoes restoration process, they are removing all modern pigments and remains of last reconstruction in 2014 so we proposed some Nano particles and Nano composites for Preservation of it. The study started with the characteristics of the historic architectural elements of Mibars and their joining structural mortars in order to risk assessment and to define the necessary characteristics of the intervention retrofitting new materials, which will be used in the ongoing preservation work of these stucco architectural elements. To achieve such, several analyses and laboratory tests like ultra-sonic pulse method testing and uniaxial compression test were carried out to determine their basic, physical and mechanical properties, along with the microstructural properties determination using Mercury porosimeter. On the other hand, the morphological description, petrography, mineralogical and microstructural properties were determined using scanning electron microscope equipped by EDS, transmission electron microscopy TEM, polarizing light microscopy, XRD and XRF. The results proved the superiority of the samples that have been How to cite this paper: El Hady, M.A., Hemada, S. and Algohary, M. (2019) Nano Particles and Nano Composites for Preservation of Historic Marble Minbars with Application on the Minber of Soliman Pasha Al-Khadim Mosque in Salah El-Din Citadel in Cairo, Egypt. Open Journal of Geology, 9, 957-973. https://doi.org/10.4236/ojg.2019.913099 Received: November 24, 2019 Accepted: December 16, 2019 Published: December 19, 2019 Copyright © 2019 by author(s) and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY 4.0). http://creativecommons.org/licenses/by/4.0/ Open Access M. A. El Hady et al. DOI: 10.4236/ojg.2019.913099 958 Open Journal of Geology strengthened by nano lime concentration of 2% with Wacker OH 100 concentration in 5%.


Introduction
Historical stone and marble minbars in Islamic mosque architecture all over the This minbar was exposed to reconstruction processes more than one time. In 2014, by the department of Archaeological Crafts of the Ministry of Antiquities. This pulpit suffered from many human damages caused by the acts of vandalism and explosion that occurred on citadel, the mosque in the early twentieth century and all the facilities located in the citadel of Salah El-Din Al-Ayyubi, as well as the effect of the irrigation water from the gardens surrounding the mosque. Geologists see that the existence of the mosque on a part of Mokattam   Formations with the containment of child metals in the geological formation is strongly influenced by the presence of water in various forms and sources. Unfortunately, the pulpit was exposed during the last decade to dismantle and re-install by the department of Archaeological Crafts of the Ministry of Antiquities.
The most damage caused by human factors as wrong conservation intervention that happened by unity of archaeological crafts-ministry of archaeology (without any scientific plan introduced with conservators and engineers' team), this minbar exposed to destructive reconstruction and need to be detached and reconstructed again and aggressive problem (see Figure 3). Exactly the environmental condition has affected on this minbar that appears in high relative humidity and variation of temperature degrees. The gardens around the mosque and damaged irrigation systems caused rising of groundwater table which have impact on the structure of the mosque and the minbar inside.
Recently, nanomaterials and various synthetic nanocomposites have been widely used in consolidation and protection of archaeological stone artworks.
Paraloid B 72 is an acrylic co-polymer formed by ethyl methacrylate (70%) and methyl acrylate) (30%) provides a good combination of rigidity, resistance and adhesion, but it has also some drawbacks, as the treated surfaces become yellow because of its oxidation by UV radiation and its water repellence decreases over time [2] [3].
Organosilans have been commonly used since the 1960s [4] and have been a popular consolidation choice, particularly in Europe [5]. The British Museum  started to use them in the 1980s, but to a lesser extent than the continent's institutions, and for several years it has not used them. Only consolidants based on silicone are used to enhance internal cohesion [6] [7].
Nano TiO 2 mixed with polymer commonly used to improve and enhance historical materials, improve also their mechanical properties and be super water repellent and self-cleaning [8]. TiO 2 has the ability to show high transparency and photocatalytic activity by cleaning up organohalides found in groundwater and environmentally friendly [9] [10].
Nano silica and nano titanium improved its efficiency in the consolidation and strengthening of the historic bricks in aggressive marine environment also these nanomaterials were very effective in the preparation of the restoration mortars [11] [12].

Concept and Construction Techniques of Minbars
Well understanding of the design and construction technique of the minbar is initial phase before its intervention retrofitting. Its size must be compatible with the area of Iwan AlQebla and has a ratio between over components which divided into two sections: • RUNWAY (ALMADRAG) [staircase-two sides-door handrail].
Golden ratio is very important to have stable and compatible minbar [13]. The golden mean proportion is a proportional system whereby two elements are related to each other by a set proportion. Two segments of a line not equal to each other are related in a proportion: a/b = (a + b)/a ( Figure 4). It is this unique point that divides the single line into segments with qualitative proportions [14].
Especially for stone minbar, it must be stood on stable isolated footing and the behind wall must be prepared to force the load of this sample structure as mentioned and displayed in Figure 5.
In the Islamic world, most minbars are made of wood because it is a light material, making the minbar easy to move around and are highly decorated. There   are other minbars (plural. manabir) that have been built with various materials such as marble, stone, even iron during Umayyad era.
In Ottoman era, although most minbars were made of wood some of the most important were built of marble. Thus, in the Selimiye Cami in Edirne there is a tall minbar of Marmara marble which is widely regarded as the finest in Turkey.
The form of this minbar with its solid portal, its steep stairs and tall hood are all characteristic Ottoman features [15].

Digital Light Microscope
Optical (or light) microscopes are used to magnify small objects and can provide information about the structure and characteristics of a sample [16].

Stereomicroscope
Stereo microscopes provide lower magnification than compound microscopes.
Stereo microscope magnification typically ranges from 5× -80× and the images seen are three-dimensional images rather than a flat image. A stereo microscope may also be referred to as a dissecting microscope. Sputter Coater, England.

Transmission Electron Microscope (TEM)
The JEM-2100 is a multipurpose, 200 kV analytical electron microscope. Multipurpose 200 kV TEM with simple and ease-of-use operability and excellent expandability Excellent LaB6 electron gun promises excellent performance with a reasonable cost. Ultrahigh TEM resolution as high as 0.19 nm (in UHR configuration) enables us to perform an observation at atomic resolution. EDS (Energy Dispersive X-ray Spectrometer) with a 0.28 sr of solid angle (in HR configuration with a 50 mm 2 detector) performs highly sensitive analysis at nanometer resolution. Highly stable specimen stage enables us to perform a long-term observation and analysis.

X-Ray Florescence
A Philips X-ray Fluorescence equipment, model Philips PW/1404, with RH target and six analyzing crystal for determining major and trace elements, The concentration of the analyzed elements were determined by using software Kernl X-44, The maximum power for the equipment 3 Kwt. The samples were prepared by fusion bead machine perlx 2 presser for pressed pellets.

Petrography Study of Marble Minbars
Twelve Marble samples collected from minbar of Soliman pasha AL Khadim have been analyzed and examined with mentioned analytical methods and devices to identify the mineral composition and microstructure of the marble under investigation in addition to the characterization of the degradation and disintegration patterns. The broad analytical study revealed that the construction material of the minbar is white Carrara marble (see Figure 6). The marble thin section examinations under stereo microscope explain the substrate formation and its thickness (  The quantitative micro analysis via the X-ray Florescence XRF confirmed the previous analytical results and the marble type is Carrara marble, the main elements and its percentage are presented in Figure 6(d).

Marble Samples Preparation and Nano Composites (Consolidants)
We have collected 36 cubic weathered and disintegrated marble specimens coming from an old masonry and naturally aged and have the same mineral composition and statue of preservation of our historical marble samples of minbar. All specimens prepared approximately in (3 cm × 3 cm × 3 cm) and divided into 12 groups each group have code name and composed of three specimens as shown in Figure 7(a). Then dried in electric oven for 24 hours at 100+/−5˚C. The consolidation and protective materials have been used is Paraloid B 72 is an acrylic co-polymer formed by ethyl methacrylate (70%) and methyl acrylate) (30%). It provides a good combination of rigidity, resistance and adhesion. The other stone strengthener and protective is the SILRES®BS OH is a solventless ethyl-silicate manufactured by Wacker Chemie AG, it is commonly used as water-repellent/consolidants material [21] [22]. Consolidation materials and nanocomposite materials and their percentage used in our experimental study are summarized in Table 1.   The nanomaterials (nano lime-nano titanium) prepared in laboratory of nanotechnology science institute in Beni-Sauf university, according to international standards and approved by the analytical and examination techniques (XRD, TEM and SEM).
All consolidants prepared in laboratory of national research center for distribution of nano materials by using ultrasonic base and applied in lab of conservation department, faculty of archaeology in Cairo university. I have bought all nanomaterials from institute of nanotechnology in Benisauif university. All nanomaterials particles (nano lime-nano titanium) from 75 -50 nm according to data sheet of any selected materials shown in Figure 8 & Figure 9.
Consolidants applied with immersion technique for 3 hours and then left to dry off for 3 weeks at room pressure and temperature, to affirm polymerization process of consolidants (Figure 7(b)).

Physical Properties before and after Consolidation
The physical properties (Bulk density (ρ), water absorption (Wa) and apparent porosity (n)) of these samples were determined by calculating the volume of each sample, measuring the dry weight and the wet weight of each sample. The physical properties were calculated as follows.

Density (ρ, ASTM C97/C97M-15)
Density is the weight of the oven-dried rock divided by its total volume. It obtained by dividing the dry Mass (after drying for 24 h at 110˚C) of the specimens by the total volume (solids and voids) (Christaras, 1996). ρ in g/cm 3 was determine as follow in Equation (1)

Apparent Porosity (n, ASTM C97-83)
Porosity is the ratio of the volume of pore space to the total volume of the sam- ( ) ( ) where M1 is the Mass of the dried specimen, M2 the Mass of the soaked specimen, and V the total volume of the sample.

Water Absorption (W.a, ASTM C97/C97M-15)
The weight of water absorbed by the rock after 24 hours of immersion in water divided by its oven-dried weight expressed as a percentage of its oven-dried weight. It was calculated by dividing the absorbed water weight (after a bath of 24 h, in vacuum) by the dry weight of specimens, as shown in Equation (3). The porosity of samples treated with only Wacker OH 100 with concentration %5 had decreased to low level of porosity after consolidation, in another side, the additives of nano materials like titanium and calcium hydroxide have acceptable changes and successfully. Paraloid B72 has a good level change and decreasing of porosity but very low changes with nano lime additive. Water absorption of marble samples (W, WL.3, WL.5, WT.3, P) have decreased obviously from (0.6% -0.7%) on another side nano titanium with concentration (2% -5%) and nano lime 5% + Paraloid B72 5% dispersed in acetone showed low decreasing in water absorption degree ranged from (0.3% , 0.4%) as shown in Figures 10-12.

Mechanical Properties, Compressive Strength (σc)
The compressive strength is the maximum load per unit area that the stone can bear without crushing. A higher compressive strength indicates that the stone can withstand a higher crushing load. The required values range from 1800 psi        Figure 13 and summarized in Table 2.

Examination and Analytical Characterization
Scanning The results of the physical and mechanical tests gave a clear indication of the most effective consolidation materials to be submitted and investigated to show the changes that took place using the above methods. Figure 14 represents the submitted specimens which examined by using SEM with magnification 500× for control sample and treated marble specimens.
In Figure 14  In Figure 15, the specimen treated with nano lime 3% dispersed in (Wacker

The Conservation Processes of the Minabr
In accordance with the decision of the Standing Committee of Islamic Antiquities dated 17/12/2018 to approve the removal of colors and modern gilding with prominent decoration, all gilding decoration removed by mechanical methods.
To remove remains of varnish and modern golden paints, chemical solvents mixture prepared from (1/4 Di Methyl Formamide: 1 Acetone: 1 Alcohol) had been used and then all area washed for 3 times with water and alcohol due to removing all remains of previous chemical solvents as shown in Figure 16.  Conservation team still working till now in conservation of this minbar to finish the conservation procesees. The selected area (Panel) before and after conservation is presented in Figure 17 and Figure 18.

Conclusions
In Egypt, there are stone and marble minbars unique from different eras. Unfortunately, they all exposed to different environmental damage factors, but the human factor has a greater role and affective in the damage of these minbars. In this study, we shed light on one of the most important marble minbars from ottoman era, minbar of Suleyman Pasha El-Khadem Mosque (Sariet-Al Gabal) in Salah El-din citadel in Cairo, which was found by examination and analysis of marble Carrara. To enhance and improve the physical and mechanical properties of the marble samples, eleven consolidants had been used. Some traditional stone strengthener polymers like Wacker OH 100 and Paraloid B 72 had been used for consolidation of marble samples. Some Nano particles and Nano composites of nanomaterials powder like nano titanium dioxide and nano lime also had been used in the experimental study. In addition to its ability to make protective coating surface. After consolidation process physical and mechanical properties showed that Wacker OH 100 alone or with nanomaterials had a remarkable result. The consolidant mixture of nano lime 3% dispersed in Wacker OH 100 5% in ethanol (WL.3) showed great enhancement of physical and mechanical properties.
By using SEM coupled with EDX and PLM showed that (WL.3) sample has an excellent distribution of nanomaterials in polymer network between grains, inside micro cracks and formed a protective surface layer. All these results applied