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].

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.

3.1.1. 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

Paraloid B-72, a 70/30 ethyl methacrylate (EMA) and methyl acrylate (MA) copolymer, was prepared as a 3% (w/v) solution in toluene.

Ethyl Silicate

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

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.

Nano Estel+ Paraloid B-72

A nanocomposite consolidant was synthesized by dispersing 3% silica nanoparticles within Paraloid B-72/trichloroethylene solutions, as shownTable 1.

Table 1. The consolidation materials and Sample’s number.

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].

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.

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).

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.

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.

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).

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.

Figure 11. The mean values compressive strength of the treated samples.