Evaluation of the Effectiveness of Traditional and Nano Materials Used in Consolidation of Sandstone Used in Ramesses III Temple, Karnak, Egypt ()
1. Introduction
Cultural heritage conservation is vital, as historical buildings provide irreplaceable insights into architectural innovation and societal development. This research explores the prominence of sandstone in ancient Egyptian construction and artistry, examining its role in iconic temples and sculptures, and highlighting its cultural significance [1]. Ancient Egyptian temples were constructed from sandstone, a sedimentary rock prone to weathering, face degradation due to high porosity and moisture exposure [2]. Salt crystallization beneath the surface of porous stone causes structural pressure, leading to cracking due to hydration-dehydration cycles [3]. This study explores how geological background affects sandstone characteristics, focusing on predictive relationships between mineralogical properties and uniaxial compressive strength [4]. Iron compound oxidation in stone leads to color alteration and structural degradation.
The clay-rich cementing phase in sandstones predisposes them to degradation through moisture-driven expansion/contraction and salt-mediated stress [5] [6]. Deterioration symptoms through granular disintegration, exfoliation, detachment, cracking, efflorescence, discoloration, and microbiological colonization [7]. Paraloid B72’s suitability for stone conservation is substantiated by numerous studies demonstrating its adhesive and consolidate properties [8]. Studies confirm Paraloid B72’s efficacy, providing comprehensive pore filling (90%) and particle coverage, enhancing sandstone durability [9]. Ethyl silicate consolidants, producing colloidal silica, offer excellent compatibility with silicate-based stones like sandstone [10]. Nano Estel restores stone cohesion via nano silica’s siloxane bond (Si-O-Si) formation through hydrolysis, condensation, and polymerization. Hydrolysis-induced silanol formation and subsequent condensation polymerization facilitate nano silica-mediated stone consolidation [11]. Recent research confirms improved consolidation efficiency and strength of ancient building materials using nano silica and nano titanium [12]. This study explores Nano composite applications in consolidation of sandstone, demonstrating improved physical, chemical, and mechanical properties, and enhanced durability for stone monuments [13], comparative evaluation of treated sandstone samples reveals enhanced consolidation and protection via nanoparticle-acrylic polymer composites, nanoparticle-infused polymers demonstrate improved efficiency in sandstone consolidation and preservation.
2. Ramsses III Temple
The Temple of Ramses III, situated within the Karnak temple complex in Luxor, showcases ancient Egyptian architecture’s grandeur (Figure 1, Figure 2) [12]. Sandstone degradation accelerates in harsh environments, characterized by temperature fluctuations, moisture and pollution, environmental factors, including temperature swings and moisture, exacerbate sandstone deterioration, thermal expansion-induced cracking threatens sandstone integrity in fluctuating environmental conditions.
Chemical characteristics, including solubility, corrosion resistance, and weathering resistance, are intimately linked with physical properties such as density, porosity, and hardness. A strong correlation exists between chemical qualities (solubility, corrosion resistance, weathering resistance) and physical attributes (density, porosity, hardness) of materials [13]. Sandstones predominantly comprise quartz, a resilient detrital mineral characterized by its strong silicon-oxygen bonds, resistance to chemical weathering, and absence of cleavage [14]. Sandstone weathering durability is closely tied to pore space characteristics, including porosity, permeability, and pore geometry, especially in clay-dominated matrices/pseudo matrices [15].
Figure 1. The first hypostyle hall of Ramesses III Temple.
Figure 2. Location of Karnak in Egypt (https://www.britannica.com/place/Karnak).
Field Observations and Deterioration Causes
Ramesses III temple walls exhibit pronounced deterioration, particularly in lower sections, due to fluctuating temperature and relative humidity. Repeated expansion and contraction of mineral granules induce internal stresses, leading to cracking [16]. The Temple of Ramses III’s proximity to the Nile River, coupled with its elevated position (2 m above surrounding land), exposes sandstone structures to heightened moisture levels from subsurface water, exacerbating deterioration. Groundwater infiltration into the Temple of Ramses III’s foundations, facilitated by capillary action, introduces salts detrimental to stone blocks. Temperature and humidity fluctuations exacerbate sandstone degradation through mineral grain disintegration [17]. The Temple of Ramses III’s sandstone surfaces undergo physical, chemical, and mechanical deterioration due to plant root growth, bird droppings, and bacterial activity. Soluble salts in avian excrement exacerbate degradation (Figure 3) [18].
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Figure 3. Different deterioration symptoms of Ramesses III temple (A) macro-cracks spread on the surfaces. (B) Black weathering due to Loss of scales. (C) alveolar weathering due to lose of stone material. (D) Relief. (E) Break out due to natural cause. (F) Efflorescences to light-colored crust changing the surface. (G) Microbiological colonization to dark-colored crust tracing the surface. (H) Granular disintegration into powder. (i) weathering out dependent on stone structure.
3. Materials and Methods
3.1. Materials
3.1.1. Preparation of Sandstone Samples
Sandstone samples from Jabal Al-Silsilah quarries (Figure 4) were precision-cut into 3 × 3 × 3 cm cubes, oven-dried (65˚C, 24 h) and cooled (RH 50%) according to ASTM standards, ensuring constant weight for treatment testing.
Figure 4. The prepared representative samples.
3.1.2. Consolidation Materials
Paraloid B-72, a 70/30 ethyl methacrylate (EMA) and methyl acrylate (MA) copolymer, was prepared as a 3% (w/v) solution in toluene.
SILRES BS OH 100, an ethyl silicate-based consolidate, penetrates construction materials via capillary action, forming a durable SiO2 gel binder upon reaction with atmospheric humidity or moisture. The treated area should be protected against rain during the following two to three days. It is also important that the area be protected against direct sunlight prior to treatment. If the building material is allowed to absorb too much heat, the product will evaporate too quickly and therefore will not penetrate sufficiently. The optimum temperatures for application are between 10˚C and 20˚C. The relative humidity should be >40%.
Nano Estel, a colloidal nano-silica dispersion (10 - 20 nm), exhibits enhanced penetrability and stability due to sodium hydroxide (NaOH < 0.5%) stabilization, demonstrating an alkaline pH (9.8 - 10.4).
Because of the water evaporation, the particles bind among themselves forming a silica gel, similarly to what happens for ethyl silicate, and thus determining the consolidating effect. Nano Estel’s Nano-silica particles undergo evaporative-induced aggregation, forming a three-dimensional silica gel network, thereby enhancing material cohesion.
A nanocomposite consolidant was synthesized by dispersing 3% silica nanoparticles within Paraloid B-72/trichloroethylene solutions, as shown Table 1.
Table 1. The consolidation materials and Sample’s number.
Samples code |
Consolidation Materials |
|
1 - 6 |
Nano Estel |
5% |
7 - 12 |
Paraloid B-72 |
3% |
13 - 18 |
Nano Estel + B-72 |
5% - 3% |
19 - 24 |
Ethyl Silicate |
5% |
3.2. Methods
3.2.1. Examinations
The mineralogical composition of sandstone samples was investigated using transmitted polarized light microscopy (Olympus BX50) and X-ray diffraction (Pert Pro Phillips MPD PW 3050/60) at HBRC laboratories, Dokki, Giza, Egypt. Scanning Electron Microscopy (SEM) investigation was performed on deteriorated sandstone samples using a JEOL JSM-5500 LV (JEOL, Japan) at laboratories of South valley university. Scanning Electron Microscopy (SEM) investigation aimed to assess consolidation material penetration and distribution within sandstone grains and components, evaluating consolidation efficacy.
3.2.2. Physical and Mechanical Properties of the Samples
The impact of consolidation materials on physical and mechanical properties of sandstone samples were assessed through quantitative measurements.
1) Visual examination
Post-consolidation, sandstone samples exhibited varying degrees of visual change, dependent on treatment material.
2) Physical Properties
Physical properties (density, water absorption, and porosity) of untreated and treated sandstone samples were evaluated using standard test methods [19] [20].
3) Mechanical Properties
Compressive strength values of untreated and consolidated sandstone samples were determined following [standard/test method, e.g., ASTM C109] [21]-[23].
4. Consolidation Process
Consolidation treatments were applied to 24 sandstone samples, divided into four groups: Nano Estel (A), Paraloid B72 (B), Paraloid B72/Nano Estel (C), and ethyl silicate (D).
Treatment materials’ suitability for consolidation of sandstone were assessed through immersion testing to ensure safe and effective application, Sandstone samples underwent 21-day consolidation treatment via immersion in respective materials, allowing complete polymerization, as shown Figure 5.
Figure 5. The sandstone samples after consolidation.
5. Results and Discussion
5.1. Mineralogical and Textural Composition
Petrographic examination indicated the quartz arenite sandstone sample is characterized by quartz grains (95%) cemented by micritic carbonate and featuring localized iron oxide coatings, and also, thin orange and brown coating at edges of some quartz grains which due to presence of iron content as shown in (Figure 6). On the other hand, XRD showed a complete agreement with polarizing microscope as quartz represents the primary mineral in studied sandstone forming minerals associated with traces of feldspar (albite) as detected in XRD pattern (Figure 7).
Figure 6. Photograph of the deteriorated sandstone.
Figure 7. XRD pattern of the deteriorated sandstone.
5.2. SEM Results
Scanning Electron Microscopy (SEM) facilitated characterization of consolidation material properties and sandstone interaction, illustrating treatment efficacy, the samples were shown in (Figure 8). Consolidation treatments yielded varying degrees of success, visible through SEM micrographs that show different consolidation effects:
1) Nano Estel: Deep penetration and dense packing.
2) Paraloid B-72: Good penetration and pour filling.
3) Nano Estel + B-72: Enhanced coating and filling.
4) Ethyl Silicate: Uniform diffusion.
Figure 8. SEM micrographs of the treated sandstone samples. (A) The SEM examination of the treated samples with Nano Estel (1.500X). (B) The examination of the treated samples with Paraloid B-72 (1.500X). (C) The SEM examination of the treated samples with Nano Estel+B-72 (1.500X). (D) The examination of the treated samples with Ethyl Silicate (1.500X).
5.3. Physical Properties of the Treated Samples
Consolidation material success hinges on minimal visual impact, specifically no discernible color or appearance alteration of the building materials, Visual inspection of treated samples provides preliminary assessment of treatment efficacy, subsequent testing follows visual evaluation, with materials exhibiting noticeable appearance changes being disqualified, it is excluded even if this material proves to be successful in the other tests. Treated sandstone samples underwent visual inspection and comparison to untreated controls to determine consolidation effectiveness, Visual evaluation ranked consolidation materials by transparency: Nano Estel (1st), Paraloid B72/Nano Estel (2nd), Paraloid B72 (3rd), and Ethyl Silicate (4th) (Table 2).
Table 2. Visual examination of the consolidated samples.
Samples cod |
Consolidation Material |
Effect of appearance |
A |
Nano Estel |
No Surface changes |
B |
Paraloid B-72 |
slight color change |
C |
Nano Estel + B-72 |
slight color change |
D |
Ethyl Silicate |
Noticeable color change |
Water repellency testing ranked consolidation materials: Paraloid B72 (1st), Paraloid B72/Nano Estel (2nd), Ethyl Silicate (3rd), and Nano Estel (4th) (Figure 9).
Figure 9. Water Repellents of the treated samples after consolidation.
The Paraloid B72/Nano Estel mixture yielded a porosity rate of 6.71%, representing a 55.53% reduction compared to the untreated sample (15.09%); Paraloid B-72 treatment yielded a porosity rate of 8.67%, representing a 42.54% reduction from the untreated sample (15.09%); Nano Estel-treated samples exhibited a porosity rate of 9.72%, showing a 35.58% reduction. Ethyl Silicate-treated samples ranked lowest, Ethyl Silicate-treated samples exhibited the highest porosity rate (10.72%), representing a 29.68% reduction from the untreated sample (15.09%) (Table 3, Figure 10).
Table 3. The means values of the physical properties of the treated samples.
Samples code |
Consolidation Material |
Porosity % |
Density g/cm3 |
Water absorption % |
X |
Untreated Sample |
15.09 |
2.17 |
27.2 |
A |
Nano Estel |
9.72 |
2.25 |
17.16 |
B |
Paraloid B-72 |
8.67 |
2.30 |
15.63 |
C |
Nano Estel + B-72 |
6.71 |
2.35 |
12.11 |
D |
Ethyl Silicate |
10.61 |
2.20 |
19.14 |
Figure 10. The mean values of physical properties after treatments.
The Nano Estel + Paraloid B-72 mixture exhibited the lowest water absorption rate (12.11%), representing a 55.47% reduction compared to the untreated sample (27.2%), Paraloid B-72-treated samples exhibited an average water absorption rate of 15.63%, representing a 43.53% reduction compared to the standard sample, Nano Estel-treated samples showed 17.16% water absorption, a 36.91% reduction. Ethyl silicate-treated samples exhibited 19.14% absorption, a 29.63% decrease (Table 3, Figure 10).
Density measurements were conducted to assess the efficacy of various consolidating materials. The results indicated a significant increase in density values for treated samples, with Paraloid B72/Nano Estel-treated samples achieving an average density of 2.35 g/cm3, representing an 82.94% increase compared to untreated samples, which recorded 2.17 g/cm3. Subsequently, Paraloid B-72-treated samples exhibited a mean density of 2.30 g/cm3, representing an 59.90% increase compared to untreated samples. Nano Estel-treated samples exhibited a mean density of 2.25 g/cm3, representing a 36.86% increase. The average density of ethyl silicate-treated samples was 2.20 g/cm3, with an 18.43% enhancement (Table 3, Figure 10).
5.4. Mechanical Properties
The Paraloid B-72/Nano Estel-treated samples achieved the highest compressive strength value of 232 kg/cm2, compared to 170 kg/cm2 for the untreated sample. The compressive strength of Paraloid B-72-treated samples reached 218 kg/cm2, exceeding the untreated sample. The compressive strength of Nano Estel-treated samples reached 192 kg/cm2. Finally, samples treated with ethyl silicate showed a compressive strength of 188 kg/cm2 (Table 4) (see Figure 11).
Table 4. The means values of mechanical properties of the treated samples.
Samples code |
Consolidation Materials |
Compressive strength (Kg/cm2) |
X |
Untreated Sample |
170 |
A |
Nano Estel |
192 |
B |
Paraloid B72 |
218 |
C |
Nano ESTEL + B72 |
232 |
D |
Ethyl Silicate |
188 |
Figure 11. The mean values compressive strength of the treated samples.
6. Conclusions and Recommendations
Dependence on the obtained results among the recent study, it can be concluded that:
1) The selection of consolidation materials for the studied sandstone required materials closely resembled to its physical, mineralogical, and chemical characteristics.
2) Four consolidation materials were chosen carefully to achieve the aim of the recent study. Two of them were classified as traditional involving Paraloid B72 and Ethyl Silicate while others were classified as nano consolidated materials involving Nano Estel and Nano Estel added Paraloid B72.
3) The positive effect of consolidation materials can be appeared from the regression in the water absorption and porosity for treated samples compared to untreated sample associated with increase in values of bulk density and compressive strength for treated samples in compare with untreated samples.
4) The most promising obtained results achieved by treated sandstone samples with 5% nano estel particles with 3% Paraloid B_72 compared to individually treated with nanomaterials.
Finally, it can be recommended that Nano Estel + B72 the most suitable consolidation materials for the studied sandstone.