NON-DESTRUCTIVE ASSESSMENT METHODS FOR STATE OF DETERIORATION AND CONSOLIDATION TREATMENTS OF HISTORICAL TIMBER BRIDGES

Date

2023-9-11

Author

YILMAZ, SÜHEYLA

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Testing the efficiency of timber strengthening applications requires monitoring the changes in the performance properties of deteriorated timber before and after the consolidation process in the laboratory and on-site. To achieve this, using non-destructive analysis methods, being able to make quantitative analyses by the use of these methods, and determining measurable parameters for performance analysis are the essential research topics that need to be enhanced in this field. However, there is a scarcity of reference data in the literature that can be guiding in this context, particularly for enabling the use of non-destructive methods as precise and quantitative analytical tools. Within the scope of the study, the original black pine and the new yellow pine samples were taken from the structural timber elements of the Historical Güvem Timber Bridge, which is located in Çankırı Province and has survived since 19th century by keeping its original details. The state of deterioration of these samples was assessed, and following the consolidation by Paraloid B72 and Paraloid B72+ Nano-sized ZnO solution, the performance of the treated samples were examined. The main goal of the study is to outline the non-destructive examination that will allow on-site quantitative analysis of the structural timber elements of historical timber bridges, to examine the complementary aspects of ultrasonic testing and thermal imaging techniques when used together, and to establish reference data for in-situ assessment of historic timber bridges. In this regard, basic physical, physicomechanical, mechanical properties including compatibility characteristics of timber samples were examined before and after consolidation treatment with laboratory analyses. The study involves visual inspection supported by optical microscopy analyses and laboratory tests involving bulk density, color measurements, equilibrium moisture content in various relative humidity conditions, water vapour diffusion resistant coefficient, rate of warming up/cooling down (thermal inertia characteristics), ultrasonic pulse velocity, compression test, dynamic modulus of elasticity analyses. PB72 and PB72.ZnO consolidation products provided a noticeable improvement in the physical, physico-mechanical, mechanical and thermal performance properties of deteriorated black pine samples while did not change their breathing properties. After consolidation treatments, improvements observed in the performance properties of deteriorated black pine timber samples accompanied by a decrease in heating and cooling rates and an increase in ultrasonic velocities. Reference data has been established for in-situ measurements of timber on site using infrared thermography and ultrasonic testing.

Subject Keywords

Historical Timber Güvem Bridge, timber conservation, non-destructive methods, Paraloid B-72, nano sized ZnO solution.

URI

https://hdl.handle.net/11511/105559

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Graduate School of Natural and Applied Sciences, Thesis