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Abstract
The objective of the present paper is to valorize granite powder wastes generated from granite mining and processing industry which cause vast environmental pollutions, in production of valuable building materials using of geopolymer technology by alkaline activating. The current work focuses on the effect of incorporation of granite waste from 0 up to 15% on the characterization of the formed geopolymer and track the formed hardened materials using Fourier transform infra-red (FTIR) and X-ray diffraction technique (XRD), whereas the compressive strength and water absorption were used to estimate the optimum ratio of granite waste that can be used without a negative effect on the hardened mortar. Also, the effect of various compaction loads at 12.5 and 25 MPa on the physico-mechanical properties of the hardened mortar using low liquid to solid ratio. The results showed clear enhancement in the structure and performance of the produced geopolymer mortar up to 7.5% granite waste addition giving compressive strength values more than 46 MPa, while the compaction positively enhanced the compressive strength of the formed mortar with increasing of pressure loads with about 20-25% and decreasing the water absorption values by about 70% which can be related to better compaction of the matrix.
Key Words
granite waste; geopolymer; compact; composite
Address
H.M. Khater, A.M. El Nagar, M. Ezzat and M. Lottfy: Housing and Building National Research Centre (HBNRC), 87 El-Tahreer St., Dokki, Giza, P.O. Box 12411, Cairo, Egypt
Abstract
The stability functions are calculated to obtain critical elastic buckling loads of asymmetric and axisymmetric one-span non-sway bending frames made up of laminated thin beams and columns with through-thickness mechanical properties variation subjected to axial compression. The shear and axial deformations are neglected. It is assumed that the members are perfect and axial compression is applied to neutral axis without eccentricity. The relative rotations of beams with respect to columns are occurred due to semi-rigid connections at joints of the bending frame. The perfect connection of two different rectangular thin plates with the same width and dissimilar elasticity modulus and thickness produces intact laminated members with similar curvature at junction of the plates in the buckled member. The mechanical and geometrical properties of laminated members in axial direction are invariant, as result the stiffness coefficient, modified stiffness coefficient, reduced stiffness coefficient and carry over factor are independent from thickness, length and layers
Key Words
buckling; non-sway bending frame; axisymmetric and asymmetric shape modes; semi-rigid connection; composite member; stability function
Address
Mostafa G. Ghadimi: Department of Civil Engineering, Sarab Branch, Islamic Azad University, Sarab, Iran
Abstract
In the present study, geometrically nonlinear behavior of relatively thick composite laminates containing square and rectangular cutouts with or without initial geometric imperfection has been investigated. The effects of cutout size, shape and presence of initial geometric imperfection for plates under uniaxial in-plane compressive load are studied. The structural model is based on the first-order shear deformation theory and Von-Karman
Key Words
geometrically nonlinear behavior; square/rectangular cutouts; composite laminates; plate assembly technique; penalty method
Address
S.A.M. Ghannadpour and M. Mehrparvar: New Technologies and Engineering Department, Shahid Beheshti University, G.C, Tehran, Iran
Abstract
Mixed matrix membrane (MMM) composed of organic and inorganic materials has been widely studied for its potential use in water and wastewater treatment, owing to its improved properties compared to the pristine membrane. In this work, the filtration performance of MMM composed of polyethersulfone (PES) and hydrous manganese oxide (HMO) nanoparticles was further improved by adding pore forming agent - poly(ethylene glycol) (PEG) into dope solution to improve membrane hydrophilicity and structural morphology so as the developed membranes are suitable for handling highly concentrated oily solution (30,000 ppm oil concentration). Compared to the structure of control PES membrane that was composed of irregular microvoids, the presence of PEG and hydrophilic nanomaterial in the MMM was able to form extended finger-like structure from top to the bottom section of membrane and enhance its surface hydrophilicity, significantly improving water permeability. The improved water flux of MMM did not compromise the rejection rates of oil and chemical oxygen demand (COD) as the MMMs achieved comparable separation efficiency like the control membrane. The findings of this work revealed the potential use of MMM for the treatment of highly concentrated oily wastewater.
Key Words
mixed matrix membranes; PEG; HMO; oil rejection; flux
Address
Ning Jie Lee, Gwo Sung Lai, Woei Jye Lau and Ahmad Fauzi Ismail: Advanced Membrane Technology Research Centre (AMTEC), Universiti Teknologi Malaysia,
81310 Skudai, Johor, Malaysia; School of Chemical and Energy Engineering, Universiti Teknologi Malaysia, 81310 Skudai, Johor, Malaysia
Abstract
In the present paper, changes in the residual stress of carbon/epoxy laminated composites as a result of
adding graphene nanoparticles (GNPs) content were studied theoretically and experimentally. Three dissimilar weight
fractions of GNPs, i.e., 0.1%, 0.25% and 0.5%, were added into an epoxy matrix. Unidirectional carbon fibers (CFs)
were used as reinforcement to fabricate cross-ply laminated composites. Mechanical and thermal properties of the
GNP/epoxy nanocomposites were then characterized via tensile tests as well as thermomechanical analysis (TMA).
Based on experimental observations, adding even small fractions of GNP to epoxy matrix caused to decrease in the
coefficient of thermal expansion (CTE) significantly while the epoxy resin Young
Key Words
laminated composites; residual stresses; polymer; graphene nanoparticles; Coefficient of thermal expansion; Young
Address
M.M. Shokrieh and M. Shams Kondori: Composites Research Laboratory, School of Mechanical Engineering, Iran University of Science and Technology, Narmak, 16846-13114, Tehran, Iran
