National Research Center of Egypt

Cairo, Egypt

National Research Center of Egypt

Cairo, Egypt

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Nanotechnology is one of the most active research areas with both novel science and useful applications that has gradually established itself in the last two decades. Nanoparticles belong to be prospective materials in the field of civil engineering. Some researchers have employed nanoparticles into cementitious materials-based on Portland cement (PC) aiming to modify some properties of this system. This paper presents an overview of the previous works carried out on the effect of using nano-Al2O3, nano-Fe2O3, nano-Fe3O4 and nano-clay into the cementitious materials. Some properties of the modified composites as heat of hydration, workability, setting time, mechanical strength, water absorption and durability were reviewed. This overview can be used as a short guide for Civil Engineer. © 2013 Elsevier Ltd.


Rashad A.M.,National Research Center of Egypt
Construction and Building Materials | Year: 2013

The development of new binders, as an alternative to Portland cement (PC), by alkaline activation, is a current researchers interest. Alkali-activated metakaolin (AAMK), belongs to prospective materials in the field of Civil Engineering. This paper presents a comprehensive overview of the previous works carried out on the use of MK in alkali activation. © 2013 Elsevier Ltd. All rights reserved.


Rashad A.M.,National Research Center of Egypt
Construction and Building Materials | Year: 2013

Kaolin can satisfy the world demand for filler, paper and ceramic industries. Kaolin converts to a pozzolan material named metakaolin (MK) after suitable thermal treatment. MK can be used in mortar and concrete to improve their properties. In addition, MK can be used as a source of cementing materials in alkali activation or geopolymer. This part presents a comprehensive overview of the previous works carried out on kaolin history, MK sources, production and composition. © 2012 Elsevier Ltd. All rights reserved.


Youssef A.M.,National Research Center of Egypt
Polymer - Plastics Technology and Engineering | Year: 2013

Polymer nanocomposites markedly improved packaging properties due to their nanometer size dispersion. These enhancements include increased modulus and strength, decreased gas permeability, and increased water resistance. Additionally, biologically active ingredients can be added to impart the desired functional properties to the resulting packaging materials. Accordingly, polymer-based nanocomposites packaging materials with bio-functional properties have a huge potential for application in the active food packaging industry. In this review, recent advances in the preparation and characterization of polymer nanocomposites, and their potential use in packaging applications are addressed. © 2013 Copyright Taylor and Francis Group, LLC.


Polyaniline (PAni) nanocomposites were prepared via in situ emulsion polymerization using dodecylbenzene sulfonic acid (DBSA) as an emulsifier and doping agent in the presence of titanium dioxide nanowires (TiO 2-NWs). Firstly, TiO2 nanoparticles (P25) were converted to TiO2 nanowires through a hydrothermal process using 10% NaOH, subsequently the TiO2-NWs were dispersed in a DBSA solution. After, the aniline monomer was added and the polymerization occurred on the addition of ammonium persulfate as an initiator in the absence of any added acid. The ratio of TiO2-NWs in the nanocomposites varied from 5 to 15 wt%. The tubular morphology and crystalline structure of the prepared PAni/TiO2 nanocomposites were analysed using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). Furthermore, the prepared nanocomposites have been characterized using different spectroscopic methods such as UV-visible spectroscopy and gel permeation chromatography (GPC). The thermal stability of the nanocomposites was characterized using thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). In addition, the AC-conductivity of the prepared PAni/TiO2 nanocomposites was evaluated. The prepared nanocomposites can be used as conductive packaging materials. © 2014 The Royal Society of Chemistry.


The development of new binders, as an alternative to Portland cement (PC), by alkaline activation, is a current researchers interest. Alkali-activated fly ash (AAFA) binder is obtained by a manufacturing process less energy-intensive than PC and involves lower greenhouse gasses emission. Utilizing AAFA system as binder material can limit the consumption of virgin materials (limestone and sand) required in PC manufacture. AAFA belongs to be prospective material in the field of Civil Engineering where it can resist aggressive acids, resist sulfate attacks, resist aggregate alkali reaction, and resist elevated temperatures. Researchers have employed different fibers, chemical admixtures, mineral admixtures, additives and other materials in AAFA system aiming to modify special properties of this system. This paper presents a comprehensive overview of the previous works carried out on using different admixtures and additives in AAFA system. © 2013 Elsevier Ltd.


Rashad A.M.,National Research Center of Egypt
Construction and Building Materials | Year: 2014

Application of nano-SiO2 (NS) in cementitious materials has drawn much attention, due to the increased demand for new materials with attractive properties. Traditional cementitious materials based on Portland cement (PC) and alkali-activated fly ash (AAFA) systems were improved by applying NS aiming to develop a novel, smart and environment. This paper presents an overview of the previous works carried out on using NS into the traditional cementitious materials based on PC and AAFA. Heat of hydration, workability, setting time, strength, abrasion resistance, freeze-thaw resistance, fire resistance, drying shrinkage, resistance to aggressive environmental, leaching, water absorption, chloride penetration and permeability of PC-based materials modified with NS as well as comparison between NS and other nano types have been reviewed. In addition, previous works curried out on setting time, compressive strength and permeability of AAFA-based materials modified with NS have been reviewed. © 2013 Elsevier Ltd. All rights reserved.


Rashad A.M.,National Research Center of Egypt
Construction and Building Materials | Year: 2013

The development of new binders, as an alternative to Portland cement (PC), by alkaline activation, is a current researchers interest. Alkali-activated slag (AAS) binder is obtained by a manufacturing process less energy-intensive than PC and involves lower greenhouse gasses emission. AAS belongs to prospective materials in the field of Civil Engineering. Researchers have employed fibres, chemical admixtures, mineral admixtures and other materials as additives in AAS system aiming to modify some properties of this system. This paper presents a comprehensive overview of the previous works carried out on using different additives in AAS system. © 2013 Elsevier Ltd. All rights reserved.


Sadek D.M.,National Research Center of Egypt
Journal of Cleaner Production | Year: 2014

Sustainable construction has become a challenge in the engineering community. Some of the important elements in this respect are the reduction of the consumption of energy and natural resources. Big attention is being focused on the recycling of wastes/by-products to produce more sustainable building materials. Blast furnace slag (BFS) is a by-product generated from the production of pig iron in the blast furnace. In Egypt, there are two main types of BFS depending on the used cooling technique; air-cooled slag (ACS) produced by slow cooling of BFS under atmospheric conditions and water-cooled slag (WCS) produced by water quenching. This paper examines the effect of using ACS and WCS without any processing to substitute natural sand (NS) in solid cement bricks. The behavior of the bricks was evaluated at ambient temperature and after exposure to elevated temperatures up to 800 °C. Five mixes were prepared: M1 is the control mix without sand substitution, M2 and M3 are mixes including 50 and 100% replacement of sand with ACS, respectively. Mixes M4 and M5 contain 50 and 100% replacement of sand with WCS, respectively. Results indicate the possibility of recycling ACS and WCS, without processing to conserve energy, as fine aggregate in bricks manufacturing. The use of ACS resulted in a higher deterioration after exposure to elevated temperatures, although it increased the compressive strength of the unheated specimens. On the other hand, the bricks containing WCS are thermally more stable than NS and ACS bricks. © 2014 Elsevier Ltd. All rights reserved.


Contamination of drinking groundwater sources by naturally occurring radioactive materials (NORM) is a rather common problem in several regions in the Middle East and the Arabian Gulf. This contamination which represents public health risks and threat to environment complicates the processes of water treatment and increases their cost. The present work summarizes results of treatment of contaminated groundwater for rejection of radioisotopes.The removal of radium,Ra2+ 226, 228, uranium, as uranyl cation, UO2 2+, or carbonate complexes, UO2(CO3)2 2- and UO2(CO3)3 4-, and radon, Rn222, was investigated by reverse osmosis (RO) and nanofiltration (NF) in comparison with the most common conventional methods of ion exchange resins (IERs), chemical precipitation/softening, coagulation, and adsorption on surface active media.IERs and chemical softening realized radionuclide rejection from 32 to 95%, but with loss of process efficiency which attained 24% due to undesired parallel removal of similar ions. Removal by IERs was too dependent on resin form and water pH and required periodical shutdown for regeneration of resin which was slow and seldom complete. Softening required chemical dosing stoichiometric to isotope removal, disposal of contaminated sludge and subsequent water filtration. Coagulation failed to remove Ra. Its removal of U ranged from zero to 93% depending on pH due to formation of different U complexes.Only RO, parallel to water desalination, showed steady, high rejection of all isotopes which attained 99% without interference of similar ions, regeneration, or subsequent filtration. NF showed similar behavior, but with lower water desalination. © 2013 Elsevier B.V.

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