Characterization the Laser Cleaning Effects on Sandstone From the Canadian Parliament Building
Notice bibliographique
Résumé
Laser cleaning has been used in the rehabilitation and conservation program of the Canadian Parliament Buildings in order to remove the black crust on sandstone surfaces. This study was carried out to characterize the effect of laser cleaning on sandstone from the Canadian Parliament Buildings. First, characteristics of the sandstone and the black crust itself were studied using microscopy, x-ray fluorescence (XRF) spectroscopy, and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS). Two kinds of sandstone samples, Berea/Ohio sandstone and Nepean sandstone, were taken from the West Block of the Parliament Buildings for testing. The results showed that the black crust was a very thin layer covering the surface of the quartz grains and also filling the gaps between the quartz grains on the surface of the sandstone. The characteristic elements of the black crust were sulfur (S), calcium (Ca), iron (Fe), and lead (Pb). Copper (Cu) and chlorine Cl were detected in some samples. Gypsum in the black crust was confirmed by the back-scattered electron (BSE) images. The Fourier transform infrared (FTIR) spectroscopy results indicated that the organic materials of the black crust contained hydrocarbon oil. Second, surface morphology and elemental composition before and after laser cleaning were studied by microscopy, XRF, and SEM-EDS. The cleaning effect of three laser cleaning systems was discussed in terms of cleaning effectiveness and damage to the sandstone. The results showed that the black crust on the Berea/Ohio sandstone and the Nepean sandstone can be removed by using the LaserArt-100 Cleaning System, the main focus of the study, but that residues of the black crust were still found on the cleaned surface and caused the color of cleaned surface was darker than the fresh sandstone surface. Gypsum crystals were also identified on the cleaned surfaces. XRF and SEM-EDS results indicated that the characteristic elements of the black crust still existed in the residues. No direct damage was found on the cleaned surface. The results of the RILEM tests showed the water absorption rate of the cleaned Berea/Ohio sandstone was increased significantly after laser cleaning. The water absorption rate of the cleaned Nepean sandstone was a little higher than that of the black crust surface, which was near zero. The sandstone would be vulnerable to weathering caused by water when water absorption rate increased. Therefore, keeping some residues during the laser cleaning would benefit the long-term preservation of the sandstone surface because the residues can prevent water infiltration
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Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,001 | 0,000 |
| Communication savante | 0,000 | 0,001 |
| Science ouverte | 0,001 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».