Issue 74

N. Meddour et alii, Fracture and Structural Integrity, 74 (2025) 227-261; DOI: 10.3221/IGF-ESIS.74.16

Explanation:

Alveolization

Efflorescence

Scaling

Disaggregation

Biological colonization

Cracking

Erosion

Spots and deposits Figure 25 : Deterioration mapping of the southeast fort façade.

Mapping and quantitative analysis Quantitative analysis assesses façade deterioration through affected surface area (Fig. 25), spatial distribution, and severity, employing indices (mild, moderate, severe) based on visual and measured criteria [28]. Efflorescence, covering ~15% of the façade (~40% of central-upper blocks, ~70% of total affected area), manifests as moderate whitish deposits, concentrated in sun-exposed central-right and upper zones, due to rapid evaporation. Disintegration affects ~15% of the surface (~50% of central blocks, ~30% of lower blocks, ~50% of total affected façade), ranging from moderate to severe, with friable, cavity-ridden textures prominent in moisture-retaining central lower regions. Biological colonization impacts ~5% of the surface (~10% higher plants in left-central joints and blocks, ~5% lichen/algae stains, right-side dominant), rated moderate, reflecting advanced but limited rooting and superficial staining. Cracking, affecting ~10% of the façade surface, manifests as micro-cracks (~5% of blocks, left-central) and degraded joints (~5–10%), with mild-to-moderate severity indicating superficial damage and early structural cracking near biologically colonized zones due to root pressure. Erosion, spanning ~10% of the surface (~30% of upper blocks, ~10% of central blocks), rated moderate, with smoothed surfaces and material loss concentrated in runoff-exposed upper and disintegration-prone central areas. Staining/soiling covers ~10% of the façade, including non-biological dark and brownish stains of mild-to-moderate severity, predominantly in right-upper regions, likely from windborne pollutants, distinct from lichen-related marks. Alveolization, covering ~20% of the façade, manifests as severe damage, concentrated in upper-right and left zones, primarily attributed to saline crystallization (NaCl, CaCl ₂ ) induced by the marine environment, exacerbated by variable porosity and chemical dissolution of calcite by chloride ions. Solar radiation accelerates wet-dry cycles, intensifying thermal and mechanical stresses. High-porosity zones (fossils, microfissures) and permeable joints are particularly susceptible. Tab. 16 summarizes the weathering types of Tamentfoust fort facade.

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