PORTABLE 3D OPTICAL MICROSCOPE AS A TOOL FOR IDENTIFICATION OF CLIMA CHANGE INFLUENCE ON HERITAGE ASSETS

Size: px

Start display at page:

Download "PORTABLE 3D OPTICAL MICROSCOPE AS A TOOL FOR IDENTIFICATION OF CLIMA CHANGE INFLUENCE ON HERITAGE ASSETS"

Shawn Booker
7 years ago
Views:

1 PORTABLE 3D OPTICAL MICROSCOPE AS A TOOL FOR IDENTIFICATION OF CLIMA CHANGE INFLUENCE ON HERITAGE ASSETS Petra Štukovnik Roko Žarnić Violeta Bokan Bosiljkov

2 Introduction Heritage assets that embrace also historical buildings and their collections are the most visible and important foundation of the European cultural heritage and contribute significantly to the attractiveness and identity of Europe.

3 Introduction Historical buildings are often in bad shape, due to decay of materials and damaged structural and nonstructural elements. Causes of damages are in many cases due to changes of climatic influences of indoor and outdoor environment.

Adequate combination of nondestructive techniques (NDT) is the most appropriate approach for such buildings, combined

4 3D Digital Microscope HIROX Accurate diagnosis of the historical building condition before planning of intervention actions is of prime importance. Adequate combination of nondestructive techniques (NDT) is the most appropriate approach for such buildings, combined with minor destructive tests (MDT), when allowed. Among NDT techniques in-situ application of portable 3D optical microscope system seems to be a powerful tool to gain important information about damaged heritage assets.

On-site measurements with 3D Microscope For on-site measurements with 3D microscope special supporting system was constructed in framework of the EU CfC project, in order to enable the application of

5 On-site measurements with 3D Microscope For on-site measurements with 3D microscope special supporting system was constructed in framework of the EU CfC project, in order to enable the application of the 50x-400x zoom lens and available adapters for microscopic observations, measurements and taking of images or movies. Humidity fluctuations and moisture transport through the walls often activate other decay factors such as freezing/thawing, soluble salts transport and crystallisation, corrosive gases from polluted air, biodegradation, etc. Decay caused by these factors usually develops severely at the wall surface or beneath it. In the case of wall paintings, the painted layers suffer most of the damage.

Brežice Castle measurements of cracks Castle was built in 16th century and is located in temperate continental climate cone of eastern Slovenia.

6 Brežice Castle measurements of cracks Castle was built in 16th century and is located in temperate continental climate cone of eastern Slovenia. There are beautiful baroque frescos in the castle, in the Knight s Hall, castle chapel and staircase. We can observe different damages of surfaces covered by frescos, such us cracks, holes, bulging, spalling, etc.

Brežice Castle measurements of cracks The Knight s Hall will be tempered by low temperature wall heating system close to the hall s floor, and the chapel will remain unheated.

7 Brežice Castle measurements of cracks The Knight s Hall will be tempered by low temperature wall heating system close to the hall s floor, and the chapel will remain unheated. Therefore we can expect different behaviour ( breathing ) of already formed cracks in the Knight s Hall and in the chapel. Measuring of width of cracks (magnification of 50X) on surfaces covered by frescos on selected measuring points and in several time intervals throughout the year (non-contact monitoring) can provide data about cracks breathing in non-heated and tempered conditions and thus also information about possible positive or negative influence of tempering. 372 μm Position μm

The same is actually true for the whole crack segment presented by the 3D image.

8 Brežice Castle measurements of cracks Maximum width of crack at the measurement point 1 is at the surface and is gradually narrowing trough the plaster towards the base wall. The same is actually true for the whole crack segment presented by the 3D image. This indicates that the crack is most probably surface crack in coloured layer and plaster and does not propagate in the structural wall.

9 Biodegradation in church of Holy Three Kings Church of Holy Three Kings stands on an altitude of 1188 m of Slovenian Pohorje Mountains. The church is from 16 th century and was built in gothicrenaissance style.

10 Biodegradation in church of Holy Three Kings Visually detected biodegradation in form of green areas covers about 7 m 2 of the tested location surface. The microscopic observation revealed that biodegradation is in progress and has influence on the outer layer of the plaster. The other damages are salt crystallization, cracks, spalling, alveolisation, bulging and scaling of plaster.

biodegradation (based on visual observation). Difference is about 500 µm.

11 Biodegradation in church of Holy Three Kings On the multi-focus image we can see that green surface (extent biodegradation) is closer to the microscope lens as surface that should be without biodegradation (based on visual observation). Difference is about 500 µm. From the image we can also see that the root system is progressing towards non-damaged part of the plaster (magnification 100 x).

12 Biodegradation in church of Holy Three Kings Polarizing microscope examination revealed that plasters and renders are made with lime binder and localy available aggregates. Aggregate particles are composed of different local igneous and metamorphic rocks.

13 Salt weathering of Agios Petros Domikanon Agios Petros Domikanon (early 13th century) is one of the most important Dominican churches on the island of Crete. The church is positioned on the coast line. The salt efflorescence can be observed on all the church walls.

14 Salt weathering of Agios Petros Domikanon In the area of recovered fresco (1st measuring point) severe efflorescence and several cracks were detected. Monday, (magnification 50x) Monday, (magnification 100x) Multifocus picture, salt efflorescence in the crack. Multifocus picture, salt efflorescence in the crack.

15 Salt weathering of Agios Petros Domikanon Different types of salt on the fresco surface were detected at 3rd measuring point. Two different salts are seen very well on the multifocus picture.

16 Salt weathering of Agios Petros Domikanon Salt efflorescence and biodegradation (algae+mite) were detected with a 3D microscope system at 2nd measuring position, close to the church floor. Movie captured by dynamic rotary head at magnification of 400 x.

17 Conclusion Short presentation of images obtained on-site by the 3D microscope and analyses of these images reveals that the equipment can provide important information about extent and type of damages on heritage assets. Various types of damages of mineral surfaces such as alveolisation, bulging, scaling, spalling and/or cracking can be identified, measured and monitoring, if needed. Beside, efflorescence can be analysed and different types and shapes of salt crystals can be identified. In case of biodegradation different biological colonisations can be distinguished and progress of the colonisation can be observed. Results of the measurements presented in the paper show that 3D microscope can be a powerful non-destructive method for the on-site research of surfaces of heritage assets.

PERFORMANCE GUIDELINES

1. Foundation/Basement 17 PERFORMANCE GUIDELINES 1. FOUNDATION/BASEMENT 1.1 Efflorescence on concrete or masonry surfaces Efflorescence is the formation of a white crystalline or powdery deposit on the