Shielding properties of the ordinary concrete loaded with micro- and nano-particles against neutron and gamma radiations

2018 ◽  
Vol 136 ◽  
pp. 27-31 ◽  
Author(s):  
Asghar Mesbahi ◽  
Hosein Ghiasi
Keyword(s):  
Nano Particles ◽  
Ordinary Concrete ◽  
Shielding Properties ◽  
Gamma Radiations

Strength and Drying Shrinkage of Pavement Concrete with Nano-Particles

2013 ◽  
Vol 662 ◽  
pp. 182-185
Author(s):  
Mao Hua Zhang ◽  
Hong Guang Wang
Keyword(s):  
Chemical Properties ◽  
Drying Shrinkage ◽  
Nano Particles ◽  
Shrinkage Rate ◽  
Nano Materials ◽  
Nano Tio2 ◽  
Science Field ◽  
Ordinary Concrete ◽  
Nano Sio2 ◽  
Pavement Concrete

With the development of national economy in Mainland China, the heavier vehicles and traffic flow have arisen in highway transportation. Concrete pavement has high strength and good durability, and thus is widely used in high-grade highway. Due to the small dimension, nano- materials have many unique physical and chemical properties, and become the focus of material science field. In this thesis, based on the unique characteristics of nano-materials, the ordinary concrete with nano-SiO2 or nano-TiO2 is prepared to research the drying shrinkage of pavement concrete. The test results indicate that the concrete with nano-SiO2 and nano-TiO2 in the amount of 2.0% and 1.0% by weight of binder have the respectively biggest drying shrinkage rate of the same concrete type, which are significantly increased than the ordinary concrete. After 28 days, the dying shrinkage rate of the concrete with nano-TiO2 is 1.6 times to the ordinary concrete.

scholarly journals Monte Carlo Calculation of linear attenuation coefficients and photon scattering properties of novel concretes loaded with Osmium, Iridium and Barite nanoparticles

2021 ◽  
Vol 27 (4) ◽  
pp. 291-298
Author(s):  
Samira Keramat Jou ◽  
Asghar Mesbahi ◽  
Reza Eghdam Zamiri ◽  
Farshad Seyednejad
Keyword(s):  
Monte Carlo ◽  
Atomic Number ◽  
High Density ◽  
Photon Flux ◽  
Scattered Photon ◽  
Monte Carlo Code ◽  
Photon Scattering ◽  
Attenuation Coefficients ◽  
Ordinary Concrete ◽  
Shielding Properties

Abstract Introduction: Recent studies have shown that the use of high-density nanoparticles (NPs) in concrete composition improves its radiation shielding properties. In the present study, the linear attenuation coefficients and photon scattering properties of newly developed high-density Nano-concretes have been calculated using the MCNPX Monte Carlo code. Material and methods: The shielding properties of Nano-concretes containing 10%, 20%, and 30% weight percentage of Osmium, Iridium and Barite NPs (100 nm) as well as ordinary concrete were investigated. The 6 and 18 MV photon beams of Varian Linac and 60 Co photons were used for simulation. Photon scattering flux was calculated for all Nano-concretes with 30 wt% of NPs and ordinary concrete at different angles. Results: In general, by adding Iridium, Osmium and Barite NPs to ordinary concrete, the linear attenuation coefficients increased. Despite a lower density relative to Iridium and Osmium, Nano-concretes containing Barite exhibited a higher linear attenuation coefficient due to their higher electron density. Conclusions: The results revealed a dependence between the scattered photon flux and the effective atomic number of Nano-concretes. With increasing the atomic number of fillers, the intensity of the scattered photon flux enlarged. Also, the scattered flux was higher for all types of concretes at 180 degrees relative to other angles.

Physical-radiation shielding properties of concrete contains colemanite and ulexite

2020 ◽  
pp. 1420326X2096797
Author(s):  
Nazım Uçar ◽  
Adnan Çalık ◽  
Muhammet Emre ◽  
Iskender Akkurt
Keyword(s):  
Elastic Modulus ◽  
Flexural Strength ◽  
Gamma Rays ◽  
Construction Material ◽  
Radiation Shielding ◽  
Ordinary Concrete ◽  
Important Phenomenon ◽  
Shielding Properties

Radiation is an important phenomenon as it is used in a variety of different fields. However, its possible hazardous effect should be taken into account and it should be shielded. As the concrete is a widely used construction material, the mechanical and radiation shielding properties of concretes containing boron-bearing aggregate additives have been studied. The results show that the addition of colemanite or ulexite into concrete has significant effects on density, workability, compressive and flexural strength, elastic modulus and radiation shielding. The results also show that concrete containing colemanite or ulexite is no more effective in the attenuation of gamma rays than ordinary concrete.

Electron holography of catalysts

1995 ◽  
Vol 53 ◽  
pp. 416-417
Author(s):  
A. K. Datye ◽  
D. S. Kalakkad ◽  
L. F. Allard ◽  
E. Völkl
Keyword(s):  
Heterogeneous Catalysts ◽  
High Surface ◽  
High Surface Area ◽  
Atomic Scale ◽  
Nano Particles ◽  
Phase Image ◽  
Electron Holography ◽  
Specimen Thickness ◽  
Phase Information ◽  
Particle Structure

The active phase in heterogeneous catalysts consists of nanometer-sized metal or oxide particles dispersed within the tortuous pore structure of a high surface area matrix. Such catalysts are extensively used for controlling emissions from automobile exhausts or in industrial processes such as the refining of crude oil to produce gasoline. The morphology of these nano-particles is of great interest to catalytic chemists since it affects the activity and selectivity for a class of reactions known as structure-sensitive reactions. In this paper, we describe some of the challenges in the study of heterogeneous catalysts, and provide examples of how electron holography can help in extracting details of particle structure and morphology on an atomic scale.Conventional high-resolution TEM imaging methods permit the image intensity to be recorded, but the phase information in the complex image wave is lost. However, it is the phase information which is sensitive at the atomic scale to changes in specimen thickness and composition, and thus analysis of the phase image can yield important information on morphological details at the nanometer level.

Coherent electron nanodiffraction from clean silver nano particles in a UHV STEM

1993 ◽  
Vol 51 ◽  
pp. 1058-1059
Author(s):  
J. Liu ◽  
M. Pan ◽  
G. E. Spinnler
Keyword(s):  
Supported Catalysts ◽  
Imaging Techniques ◽  
Nano Particles ◽  
Metal Particles ◽  
Shape Structure ◽  
Dynamical Simulations ◽  
Small Metal Particles ◽  
Extract Information

Small metal particles have peculiar chemical and physical properties as compared to bulk materials. They are especially important in catalysis since metal particles are common constituents of supported catalysts. The structural characterization of small particles is of primary importance for the understanding of structure-catalytic activity relationships. The shape and size of metal particles larger than approximately 5 nm in diameter can be determined by several imaging techniques. It is difficult, however, to deduce the shape of smaller metal particles. Coherent electron nanodiffraction (CEND) patterns from nano particles contain information about the particle size, shape, structure and defects etc. As part of an on-going program of STEM characterization of supported catalysts we report some preliminary results of CEND study of Ag nano particles, deposited in situ in a UHV STEM instrument, and compare the experimental results with full dynamical simulations in order to extract information about the shape of Ag nano particles.

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