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Water retention and volumetric characteristics of intact and re-compacted loess
, Article Canadian Geotechnical Journal ; Volume 53, Issue 8 , 2016 , Pages 1258-1269 ; 00083674 (ISSN) ; Sadeghi, H ; Belal Hossen, S. K ; Chiu, C. F ; Alonso, E. E ; Baghbanrezvan, S ; Sharif University of Technology
Canadian Science Publishing
2016
Abstract
Alaboratory testing program was conducted to investigate the effects of microstructure on the water retention curve (WRC) and wetting-drying induced volume change in loess. The axis translation and vapor equilibrium techniques were adopted to control suction in the range of 0-400 kPa and 4-140 MPa, respectively. Hysteresis in the WRC of loess was observed for the entire range of suction studied. Compared to re-compacted loess, intact loess exhibits a more pronounced hysteresis in the suction range below 20 kPa, which can be explained by the ink-bottle pore neck effect or constricted pores. The hypothesis is supported by microstructural evidence of mercury intrusion porosimetry and scanning...
Mechanical properties of fiber-reinforced high-performance concrete incorporating pyrogenic nanosilica with different surface areas
, Article Construction and Building Materials ; Volume 101 , December , 2015 , Pages 130-140 ; 09500618 (ISSN) ; Khaloo, A ; Hosseini, P ; Esrafili, A ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
The aim of the present study was to investigate the effect of pyrogenic nanosilica with different specific surfaces areas (200 and 380 m2/g) on mechanical properties of fiber-reinforced high-performance concrete (FRHPC) produced with two different types of fibers including steel and polypropylene fibers. Accordingly, different mechanical tests (compressive, splitting tensile and flexural strengths) as well as electrical resistivity were performed at 7, 28, and 91 curing days. In addition, the modulus of rupture and flexural toughness of FRHPC prisms were calculated based on the flexural testing results. Also, scanning electron microscopy test (SEM) was conducted to evaluate the...
Effect of Cu2+ ion on biological performance of nanostructured uorapatite doped with copper
, Article Scientia Iranica ; Volume 24, Issue 6 , 2017 , Pages 2845-2855 ; 10263098 (ISSN) ; Sadrnezhaad, S. K ; Vahdati Khaki, J ; Sharif University of Technology
Abstract
Nanostructured copper-doped uorapatite (Cux.Ca(10X).(PO4)6.F2) having crystallite sizes of 19, 29, and 34 nm at x = 0:9, 0.4, and 0.0, respectively, was synthesized by planetary ball milling of CaO, P2O5, CaF2, and CuO powders. Specifications of the products were determined by Fourier-transform infrared spectroscopy, eld emission scanning electron microscopy, transmission electron microscopy, and X-ray di raction analyses. In-vitro studies and Mossman's Tetrazole Test (MTT) assays were also conducted by incubating Cux.Ca(10X).(PO6).F2 powder into Kokubo's Simulated Body Fluid (SBF) and against BT-20 cell, respectively, to determine bioactivity and biocompatibility of the materials....