Sharif Digital Repository

Cement kiln dust (CKD) is one of the most important waste materials in the cement industry. The large amount of this material, has encouraged researchers to propose new ways to recycle and reuse it. In this paper, effects of adding cement kiln dust to the ordinary Portland cement, on the physical and mechanical properties of ordinary and lightweight concrete were investigated. Results showed that concrete containing CKD, presents lower workability and modulus of elasticity; however, improvements in strength was observed by adding particular amounts of CKD. Eventually, it was found that adding 10% of cement weight CKD is the appropriate percentage for utilizing in manufacturing ordinary and... 

The effects of SiC addition on the foaming behavior and compressive properties of AlSi7 metal foams were studied. Elemental powders of Al, Si, SiC and TiH2 were mixed, hot compacted and foamed at temperatures between 750 and 810 °C. The role of SiC volume fraction up to 10 vol.% and its particle size (3, 8 and 16 μm) was investigated. It was found that the foaming behavior of AlSi7 alloy, i.e. the maximum foam expansion and its stability, depends on the size and volume fraction of SiC particles. Increasing the amount of the ceramic particles and/or decreasing the particle size leads to less melt drainage whilst the cell structure becomes non-uniform. This is attributed to the effect of the... 

Aluminum metal-matrix nanocomposites (AMMNCs) fabricated by conventional stir-casting process usually show high porosity and poor distribution of nanoparticles within the matrix. In the current study, for the improvement of nanoparticles distribution in the aluminum matrix and enhancement of the mechanical properties, a mixture of Al/nano-Al2O3 powders were injected by pure argon gas into the molten 7075 aluminum alloy and this mixture was extruded at high temperature. Mechanical behavior of the final product was investigated by tensile and compression tests, hardness measurements, Scanning Electron Microscopy (SEM), High Resolution Transmission Electron Microscopy (HRTEM) and Optical... 

Aluminum metal-matrix nanocomposites (AMMNCs) fabricated by conventional stir-casting process usually show high porosity and poor distribution of nanoparticles within the matrix. In the current study, for the improvement of nanoparticles distribution in the aluminum matrix and enhancement of the mechanical properties, a mixture of Al/nano-Al2O3 powders were injected by pure argon gas into the molten 7075 aluminum alloy and this mixture was extruded at high temperature. Mechanical behavior of the final product was investigated by tensile and compression tests, hardness measurements, Scanning Electron Microscopy (SEM), High Resolution Transmission Electron Microscopy (HRTEM) and Optical... 

Nanocrystalline Al-5vol%Al2O3 nanocomposite was synthesised by mechanical milling of a mixture containing nanometric alumina with an average particle size of 35 nm. Morphology of as-synthesised powder was investigated by SEM while crystallite size of Al matrix was determined by XRD analysis. The results confirmed formation of nanocrystalline Al matrix induced by severe plastic deformation during mechanical milling. Nanocomposite bars were produced by hot powder extrusion route. TEM investigation of as-extruded nanocomposite revealed formation of elongated grains along the extrusion direction decorated by alumina nanoparticles. Tensile and compressive properties of as-extruded nanocomposite... 

Toughness improvement of an epoxy resin and respective hoop wound composite were investigated systematically using amine-terminated butadiene acrylonitrile (ATBN) liquid rubber. Rubber modification improves fracture toughness of epoxy resin with slight reduction in the glass transition temperature (Tg), flexural and compressive properties of resin. Impact resistance of composite is improved by rubber modification similar to modified resin. Interlaminar shear strength (ILSS), compressive modulus and strength, and flexural strength of composite decreased slightly with rubber modification. To interpret the data, the void content of composite samples was determined and the damaged surfaces of... 

Biocompatible and biodegradable three-dimensional scaffolds are commonly porous which serve to provide suitable microenvironments for mechanical supporting and optimal cell growth. Silk fibroin (SF) is a natural and biomedical polymer with appropriate and improvable mechanical properties. Making a composite with a bioceramicas reinforcement is a general strategy to prepare a scaffold for hard tissue engineering applications. In the present study, SF was separately combined with titanium dioxide (TiO2) and fluoridated titanium dioxide nanoparticles (TiO2-F) as bioceramic reinforcements for bone tissue engineering purposes. At the first step, SF was extracted from Bombyx mori cocoons. Then,... 

Liquefaction phenomenon is usually accompanied by large amounts of settlement owing to disruption of soil structure. In addition to that, large settlement also occurs by a significant increase in soil permeability during seismic excitation. To properly simulate the post-liquefaction settlement, it is important to take the compressibility properties of the liquefied sand as well as the permeability increase into account. Using initial permeability coefficient in the course of simulation of liquefaction leads to underestimation of settlement. In addition to that, using unrealistic values for permeability may cause erroneous predictions of other aspects of soil behavior. Therefore, an accurate...