Browsing by Author "Ozkul, M. Hulusi"

Now showing 1 - 3 of 3

Citation Count: 1
Effect of EVA Addition on the Properties of Portland Cement Mortars
(Istanbul Technical Univ Faculty Civil Engineering Printhouse, 2012) Ekincioglu, Ozgur; Ozkul, M. Hulusi; Patachia, Silvia
Due to the water sensitivity of polyvinyl alcohol (PVA), poly(ethylene-co-vinyl acetate) (EVA) is preferred in Portland cement mortar and concrete as modifier. The influence of EVA addition in Portland cement mortar is investigated by using mechanical strength tests as well as impermeability tests. Furthermore the pore size distribution by mercury intrusion porosimetry (MIP) and the interaction between cement paste and EVA by Fourier Transform Infrared Spectroscopy (FTIR) were searched.
Citation Count: 2
Effect of TiO₂ Addition on the Properties of Macro Defect Free Cement
(Istanbul Technical Univ Faculty Civil Engineering Printhouse, 2012) Ekincioglu, Ozgur; Ozkul, M. Hulusi; Patachia, Silvia; Moise, Georgeta
Macro-defect free (MDF) cement is a cement-polymer composite with superior flexural strength although produced by mixing cement with small amounts of polymer and water. Special production technique and the crosslinking occurred between cement and polymer are important factors for obtaining such high strengths. However, MDFs lose considerable strength when exposed to water. The objective of this study was to explore the effects of TiO2 addition on flexural strength and water sensitivity of MDF. In this study, MDF cements were produced by adding up to 4% TiO2 by weight of cement. Biaxial flexural test as well as Atomic Force Microscopy (AFM) and Fourier Transform Infrared Spectroscopy (FTIR) tests were conducted in order to investigate the effect of TiO2 addition. TiO2 addition improved the water resistance of MDF cements in some batches, especially with 2% addition possibly due to the C-PVA-O-Ti-O-C-PVA bond and this cross-linking mechanism together with C-PVA-O-Al-O-C-PVA bonds cause a more stable polymer network.
Citation Count: 39
Optimization of material characteristics of macro-defect free cement
(Elsevier Sci Ltd, 2012) Ekincioglu, Ozgur; Ozkul, M. Hulusi; Struble, Leslie J.; Patachia, Silvia
Macro-defect free (MDF) cement is a high-strength cement-polymer composite produced by mixing cement (commonly calcium aluminate cement) with small amounts of polymer (commonly polyvinyl alcohol acetate) and water, applying high shear, and finally applying relatively low pressure (about 5 MPa) and modest temperature (about 80-100 degrees C). However, MDF cements lose considerable strength when exposed to water. The objective of this study was to explore the effects of cement and polymer compositions on flexural strength and water sensitivity. Calcium aluminate cements were used with Al2O3 contents between 42% and 79%. Production of MDF cement was successful with all cements, but the highest strength (268 MPa) was obtained with 70% Al2O3 cement. Secondly, PVAs were used that differed in their degree of hydrolysis between 73% and 99%. Of these, the one with a moderate degree of hydrolysis produced the highest strength (228 MPa). All mixtures had strength loss on exposure to water, but PVAs with moderate degrees of hydrolysis exhibited the lowest strength losses (50-60%). (C) 2011 Elsevier Ltd. All rights reserved.