EFFECT OF ALKOXYSILANE-BASED TREATMENT ON THE DURABILITY OF NORTH CYPRUS STONES FOR CONSTRUCTION

2021 ◽  
Vol 16 (1) ◽  
pp. 179-196
Author(s):  
Nejdet Ziyaettin ◽  
Kübra Ekiz Barış ◽  
Leyla Tanaçan

ABSTRACT Limestones are generally vulnerable to various weathering effects, hence, protection and consolidation of them is necessary. Locally available limestones of Northern Cyprus have been used in both historical buildings dated back to the 16th century for conservation applications and new buildings mostly as a cladding material. However, certain decay patterns exist on these stones. In the current study, the service life of Cyprus stones was inspected. Alkoxysilane-based consolidation and protection treatments were applied on new quarried stones to enhance the stone properties and aged stones to conserve and protect the architectural heritage. Service life assessment was performed by applying accelerated aging tests on both new and aged stones before and after treatments. The treatments improved the physical, mechanical and durability properties of the stones in terms of unchanging the water vapor diffusion resistance factor, decreasing the porosity and the water absorption ratio, increasing the ultrasound pulse velocity, the compressive and the flexural strengths, and improving the resistance of the stones against wetting-drying, freeze-thaw, salt crystallization and SO2 vapour effects. The combination of consolidation and protection treatment (K2) was more efficient on the properties of the stones compared to only protection treatment (K1) due to the better penetration capacity, higher decreasing ratio of the porosity, and higher improvement of the physical, mechanical and durability properties. The treatments also improved the properties of the aged stones; thus, it may be inferred that treatment would benefit the conservation of historical buildings.

2014 ◽  
Vol 1 (1) ◽  
pp. 24-34
Author(s):  
Alireza K. ◽  
Hossein Ahmadi ◽  
Mohsen Mohammadi

Lubricants and leather dressings are the most common treatments of dry and water logged historical leathers. Color change has a great importance during the time and treatment process, due to visual and aesthetic values of historic leather relics. Polyethylene glycol (PEG) and silicone oil (SiO) are frequently used leather dressings in the conservation procedures. Therefore, color stability of treated leathers with PEG and SiO were investigated before and after heat accelerated aging. Moreover, application of ascorbic acid was evaluated as an antioxidant additive for PEG (PEG+AA).Color change after treatment and aging were studied by colorimetry technique in the CIE *L*a*b system. Results indicated to severe color alteration in PEG treated and aged leathers with or without ascorbic acid. Whereas, SiO treated samples showed better stability and minimum color shift after aging. Silicone oil was characterized as the best dressing for historical leathers with compared to PEG and PEG+AA, due to its high stability and aesthetical properties.


2011 ◽  
Vol 15 (3) ◽  
pp. 691-704 ◽  
Author(s):  
Gordana Bakic ◽  
Vera Sijacki-Zeravcic ◽  
Milos Djukic ◽  
Stevan Maksimovic ◽  
Dusan Plesinac ◽  
...  

The service life of thick-walled power plant components exposed to creep, as is the case with pipelines of fresh- and re-heated steam, depend on the exhaustion rate of the material. Plant operation at elevated temperatures and at temperatures below designed temperatures all relates to the material exhaustion rate, thus complicating remaining life assessment, whereas the operating temperature variation is a most common cause in the mismatching of real service- and design life. Apart from temperature, the tube wall stress is a significant variable for remaining life assessment, whose calculation depends on the selected procedure, due to the complex pipeline configuration. In this paper, a remaining life assessment is performed according to the Larson-Miller parametric relation for a ?324?36 pipe bend element of a fresh steam-pipeline, made of steel class 1Cr0.3Mo0.25V, after 160 000 hours of operation. The temperature history of the pipeline, altogether with the pipe bend, is determined based on continuous temperature monitoring records. Compared results of remaining life assessment are displayed for monitored temperature records and for designed operating temperature in the same time period. The stress calculation in the pipe bend wall is performed by three methods that are usually applied so to emphasize the differences in the obtained results of remaining life assessment.


2008 ◽  
Vol 78 (1) ◽  
pp. 140-144 ◽  
Author(s):  
Sabri Ilhan Ramoglu ◽  
Serdar Usumez ◽  
Tamer Buyukyilmaz

Abstract Objective: To test the null hypothesis that accelerated aging has no effect on the surface microhardness and roughness of two light-cured lingual retainer adhesives. Materials and Methods: Ten samples of light-cured materials, Transbond Lingual Retainer (3M Unitek) and Light Cure Retainer (Reliance) were cured with a halogen light for 40 seconds. Vickers hardness and surface roughness were measured before and after accelerated aging of 300 hours in a weathering tester. Differences between mean values were analyzed for statistical significance using a t-test. The level of statistical significance was set at P < .05. Results: The mean Vickers hardness of Transbond Lingual Retainer was 62.8 ± 3.5 and 79.6 ± 4.9 before and after aging, respectively. The mean Vickers hardness of Light Cure Retainer was 40.3 ± 2.6 and 58.3 ± 4.3 before and after aging, respectively. Differences in both groups were statistically significant (P < .001). Following aging, mean surface roughness was changed from 0.039 μm to 0.121 μm and from 0.021 μm to 0.031 μm for Transbond Lingual Retainer and Light Cure Retainer, respectively. The roughening of Transbond Lingual Retainer with aging was statistically significant (P < .05), while the change in the surface roughness of Light Cure Retainer was not (P > .05). Conclusions: Accelerated aging significantly increased the surface microhardness of both light-cured retainer adhesives tested. It also significantly increased the surface roughness of the Transbond Lingual Retainer.


2013 ◽  
Vol 739 ◽  
pp. 85-89
Author(s):  
Qing Zhen Wen ◽  
Chao Yu ◽  
Jin Hua Zhu

The heat seawater method was designed and the accelerated aging tests of the neoprene were carried in laboratory. The toughness and strength of the neoprene in aging time was investigated. The rule of toughness and strength and aging time was studied. The service life prediction functions of the neoprene were established and service life at 25°C was estimated based on the index of toughness and strength. It is concluded that toughness and strength of the neoprene decreases in exponential form with aging time, and the service life of the neoprene used in sea water at 25°C is 29.5 years.


Author(s):  
Dimitrios Stefanoudakis ◽  
Eftychia Apostolidi

Historical buildings from the period of Promoterism constructed between 1850 and 1910, called “Gründezeitgebäude,” represent a main part of the building stock in Vienna. A typical building from this period is presented, along with the pathology of such buildings. A step-by-step strengthening and modernization strategy is described, including structural analysis data and design of sections data before and after interventions, along with detailing according to the respective codes.


Sign in / Sign up

Export Citation Format

Share Document