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«A1 Bauinstandsetzen Restoration und Baudenkmalpflege of Buildings and Monuments 19. Jahrgang, Heft 2/3, 2013 Vol. 19, No. 2/3, 2013 Contents / Inhalt ...»

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Restoration of Buildings and Monuments Bauinstandsetzen und Baudenkmalpflege Vol. 19, No. 2/3, 179–186 (2013) Natural Polymer-based Hydrogel Incorporating Self Healing Mortar M. Ertuğ1, O. Üzüm2, A. Şendemir Ürkmez2,3 and Ö. Andiç Çakır1,3* Ege University, Engineering Faculty, Department of Civil Engineering, Bornova, Izmir, Turkey 2Ege University, Engineering Faculty, Department of Bioengineering, Bornova, Izmir, Turkey 3Ege University, Graduate School of Natural and Applied Sciences, Materials Science and Engineering, Bornova, Izmir, Turkey *Corresponding author, Ö. Andiç Çakır, E-mail: ozge.andic@ege.edu.tr Abstract In this study, the self healing capacity of mortars incorporating a natural polymer-based hydrogel (chitosan) as a healing agent is compared to control mortars without the healing agent. The hydrogels are placed into mortars after two different methods of encapsulation. The aim of encapsulating the healing agents is to provide water proofness during the fresh state of mortars. The chitosan macrospheres (diameter≈1 mm) were stabilized by lyophilizing and encapsulated by a synthetic polymer and cement based insulation material provided from the market. Pre-trials have shown that the encapsulated hydrogel macrospheres have shown a considerable expansion after the capsules were torn. The method for observing the self healing mechanism is as follows: control and test series were cast and cured for 7 days in water at standard conditions, and then, a controlled pre-load is applied at three-point bending. The pre-loading causes controlled cracking at the lower mid points of the mortar specimens. Just after the pre-loading, the microphotographs of the cracks were taken by stereomicroscope and their ultrasonic pulse velocity (UPV) values were determined. The specimens were then placed into air-tight containers and cured over water for a further 21 days. The UPV measurements were taken after curing and the microphotographs of the cured samples were taken. The difference between the UPV measurements compared to control samples before and after curing and leaking of hydrogels into the cracks are the confirmations of the healing mechanism. The findings obtained from this study reveal promising results for incorporation of the chitosan hydrogel as a self healing agent for cementitious mixtures.

Keywords: Self healing; Mortar, Chitosan; Hydrogel; Encapsulation.

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Restoration of Buildings and Monuments Bauinstandsetzen und Baudenkmalpflege Vol. 19, No. 2/3, 187–194 (2013) Bond Behavior of Polymer Modified AR-Glass Yarns Embedded in Cement Paste M. Y. Yardimci1*, A. Bentur2, M. Puterman2, R. Tirosh2 and P. Larianovsky2 Department of Civil Engineering, Gediz University, Izmir 35665, Turkey National Building Research Institute, Faculty of Civil and Environmental Engineering, Technion – Israel Institute of Technology, Haifa 32000, Israel *Corresponding author: M. Y. Yardimci, E-mails: myyardimci@gmail.com, mert.yardimci@gediz.edu.tr Abstract In this paper, the evaluation of the bond behavior of polymer modified alkali resistant (AR) glass yarns embedded in cement matrix is presented. The multifilament AR-glass yarns were extracted from a warp knitted fabric and modified by two types of slurries containing polystyrene and styrene acrylic polymers which are non-film forming and film forming, respectively. Two types of pull-out sample preparation methods (namely wet and dry processes) have been applied before the incorporation of modified yarns into the cement paste. Unmodified and polymer modified yarns were embedded on one side in a cement paste matrix of 0.40 water to cement ratio and in the other in a polyester matrix grip for pulling out of the yarns from the cement paste matrix. The bond behavior of unmodified and polymer modified AR-glass yarns were evaluated by the pull-out load – displacement relationship and in-situ breakage of filaments during pull-out, and its quantification in terms of the proportion of filaments broken at each stage of pull-out. For that purpose a special set up was used based on the transmission of light through unbroken filaments and quantification by image analysis. All test procedures have also been applied to aged samples to find out the effectiveness of microstructure modification on long-term properties. The test results revealed that polymer modification of the microstructure of AR-glass yarns has a significant effect on the bond properties. As a result the relatively brittle failure characteristic of unmodified AR-glass yarns could be turned into a less brittle controlled telescopic pull-out mode. The effectiveness of polymer modification was found to be highly dependent on the polymer type and the nature of the treatment of the yarns with the polymer slurry.

Keywords: Polymer modification; AR-glass yarn; Textile fibers; Pull-out test; Bond.

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Restoration of Buildings and Monuments Bauinstandsetzen und Baudenkmalpflege Vol. 19, No. 2/3, 195–202 (2013) Fire Reaction and Mechanical Performance Analyses of Polymer Concrete Materials Modified with Micro and Nano Alumina Particles M. C. S. Ribeiro1*, C. M. C. Pereira1, S. P. B. Sousa1, P. R. O. Nóvoa2 and A. J. M. Ferreira2 INEGI - Institute of Mechanical Engineering and Industrial Management, Porto, Portugal FEUP - Faculty of Engineering of University of Porto, Porto, Portugal *Corresponding author: M. C. S. Ribeiro, E-mail: cribeiro@inegi.up.pt Abstract In the present study, fire reaction and mechanical behaviour improvements of an epoxy polymer mortar (PM) formulation, induced by binder modification with alumina particles at micro and nano-size levels, were analysed and quantified. For this purpose, several series of PM specimens, modified with different types of microparticles, nanoparticles and nanodispersion of aluminium oxide were manufactured and tested for fire reaction, flexural and compressive load carrying capacities. Obtained results were compared with those obtained for plain epoxy polymer mortars.

Fire reaction properties, such as time to ignition, heat release rate, smoke extinction area, carbon monoxide and carbon dioxide yield rates were assessed by means of cone calorimeter test.

Test results revealed that the addition of alumina particles to binder matrix of polymer mortars, even in small amounts (3.9 % in weight of total mass), are effective in improving flexural and compressive behaviours of resultant polymer mortars, especially in the case of alumina nanoparticles. However larger amounts of aluminium oxide nanoparticles will be required to attain effective levels of fire retardancy.

Keywords: Polymer mortars; Aluminium oxide; Micro and nanoparticles; Fire reaction; Mechanical behaviour.

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Restoration of Buildings and Monuments Bauinstandsetzen und Baudenkmalpflege Vol. 19, No. 2/3, 203–210 (2013) Behavior of Glass Fabric Reinforced Polymer Concrete Composites under Flexural Loads H. N. Atahan*, B. Y. Pekmezci, E. Y. Tuncel and A. Paksoy Istanbul Technical University, Faculty of Civil Engineering, Maslak, Istanbul, Turkey *Corresponding author: H. N. Atahan, E-mail: atahanh@itu.edu.tr Abstract One of the reinforcement types for the cementitious composites is fabrics. Fabric reinforcement has found an area of utilization recently in civil engineering industry as an alternative to the short fibers. In this experimental study, the glass fabrics, which are beneficially used in cement based composites, were adapted to a polyester polymer concrete mixture. Polymer concrete (PC) beam samples with the dimensions of 10x50x350mm were reinforced with three layers of glass fabrics. Each layer of glass fabric was inserted into the beam samples during production with equal spacing. For the comparison of the effect of different fabric types on the flexural behavior of the PC composites, three different types of glass fabrics with different densities were selected. In accordance with the flexural tests, the behavior of glass fabric reinforced PC composites was evaluated. Results have shown that, with the use of glass fabric in PC as reinforcement, the flexural strength of the composites can be easily reached up to 40 MPa. Specific fracture energy of the plane PC mixture, on the other hand, was improved up to 10 times depending on the glass fabric type used.

Keywords: Polymer concrete; Glass fabric; Flexural behavior; Compressive strength; Reinforcement.

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Restoration of Buildings and Monuments Bauinstandsetzen und Baudenkmalpflege Vol. 19, No. 2/3, 211–218 (2013) Performance of Silane Water Repellent and Flexible PCM Coating Applied on ASR Deteriorated Structures after over 20 Years M. Wakasugi1*, M. Yamamoto1, H. Sakakibara1 and T. Miyagawa2 Sumitomo Osaka Cement Co., Ltd Kyoto University Graduate School of Engineering *Corresponding author: M. Wakasugi, E-mail: mwakasugi@soc.co.jp Abstract Concrete structures deteriorated due to Alkali-Silica Reaction (ASR) were repaired with silane water repellent and flexible polymer modified cementitious (PCM) coating over 20 years ago. Concrete core specimens are drilled from the structures to investigate the performance of the repair materials. Remaining depth of the silane water repellent is examined by differential thermal analysis (DTA) and water and vapor permeability are measured at the appropriate depth of silane impregnated concrete. Furthermore water and vapor permeability, adhesive strength and elongation of the flexible PCM coating are measured. Energy dispersive x-ray spectroscopy, scanning electron microscope and DTA are conducted to observe the condition of cement particles hydration and polymer film formation. As a result of the investigations, silane water repellent still maintains waterproof and vapor permeable performance after over 20 years at the impregnated depth of 2-10 mm. The flexible PCM coating which is exposed to the outdoor during over 20 years is also more waterproof and vapor permeable than initial. Adhesive strength increased to twice the initial after 5 years, and maintains the performance after over 20 years. Crack elongation performance increased after over 20 years although it decreased after 2 years. Hydration of cement particle was remarkably inhibited and the polymer film had almost no damages after over 20 years.

Keywords: Silane water repellent; Flexible polymer-modified cementitious coating; Repair of concrete; Water permeability; Vapor permeability.

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