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CONTENTS
Volume 4, Number 3, September 2015
 

Abstract
The aim of this investigation is to prepare geopolymer resin by alkali activation of ceramic waste (AACW) with different sodium hydroxide (NaOH) and liquid sodium silicate (LSS) concentrations. In order to prepare geopolymer cement, AACW was replaced by 10 and 30 % by weight (wt.,) of concrete waste (CoW) as well as 10 and 30 wt., % ground granulated blast-furnace slag (GGBFS). The results showed that, the compressive strength of AACW increases with the increase of activator content up to 15:15 wt., % NaOH: LSS. All AACW hardened specimens activated by 3:3 (MC6), 6:6 (MC12), 12:12 (MC24) and 15:15 wt., % (MC30) NaOH: LSS destroyed when cured in water for 24h. The MC18 mix showed higher resistivity to water curing. The results also showed that, the replacement of AACW containing 9:9 wt., % NaOH: LSS (MC18) by 10 (MCCo10) and 30 (MCCo30) wt., % CoWdecreased the compressive strength at all ages of curing. In contrast, the MCCo10 mix showed the lower chemically combined water content compared to MC18 mix. The MCCo30 mix showed the higher chemically combined water content compared to MC18 and MCCo10 mixes. The compressive strength and chemically combined water of all AACWmixes containing GGBFS (MCS10 and MCS30) were higher than those of AACWwith no GGBFS (MC18). As the amount of GGBFS content increases the chemically combined water increases. The x-ray diffraction (XRD) proved that as the amount of CoWcontent increases, the degree of crystallinity increases. Conversely, the replacement of AACW by GGBFS leads to increase the amorphiticity character. The infrared spectroscopy (FTIR) confirms the higher reactivity of GGBFS compared to CoW as a result of successive hydration products formation, enhancing the compaction of microstructure as observed in scanning electron microscopy (SEM).

Key Words
alkali activated ceramic waste; calcium sources; geopolymer cement; geopolymer resin

Address
Sayieda R. Zedan: Housing and Building National Research Center, Giza, Egypt
Maha R. Mohamed, Doaa A. Ahmed: Faculty ofWomen of Arts, Science and Education-Ain Shams University, Cairo, Egypt
Aya H. Mohammed: Faculty of Engineering and Technology-Future University, Cairo, Egypt


Abstract
Biodegredable and injectable nanocomposites based on polypropylene fumarate (PPF) as unsaturated polyester were prepared .The investigated polyester was crosslinked with three different monomers namely N-vinyl pyrrolidone (NVP), methyl methacrylate (MMA) and a mixture of NVP and MMA (1:1 weight ratio) and was filled with 45 wt% of hydroxyapatite (HA) incorporated with different concentrations of chemically treated natural bone powder (NBP) (5, 10 and 15 wt%) in order to be used in treatment of orthopedics bone diseases and fractures. The nanocomposites immersed in the simulated body fluid (SBF) for 30 days, after the period of immersion in-vitro bioactivity of the nanocomposites was studied through Fourier transform infrared (FTIR), scanning electron microscope (SEM), energy dispersive X-ray (EDX) in addition to dielectric measurements. The degradation time of immersed samples and the change in the pH of the SBF were studied during the period of immersion.

Key Words
biodegradable polyester; nanocomposites; bone powder; dielectric spectroscopy; biophysical properties

Address
Nagwa A. Kamel, Salwa L. Abd-El-Messieh and Kamal N. Abd-El Nour: Microwave Physics and Dielectrics Department, National Research Centre, Dokki, Cairo, Egypt
Samia H. Mansour: Polymers and Pigments Department, National Research Centre, Dokki, Cairo, Egypt
Wafaa A. Khalil: Biophysics Department, Faculty of Science, Cairo University, Egypt


Abstract
Friction coefficient of epoxy metal matrix composites were investigated. The main objective was to increase the friction coefficient through rubber sole sliding against the epoxy floor coating providing appropriate level of resistance. This was to avoid the excessive movement and slip accidents. Epoxy metal matrix composites were reinforced by different copper wire diameters. The epoxy metal matrix composites were experimentally conducted at different conditions namely dry, water and detergent wetted sliding, were the friction coefficient increased as the number of wires increased. When the wires were closer to the sliding surface, the friction coefficient was found to increase. The friction coefficient was found to increase with the increase of the copper wire diameter in epoxy metal matrix composites. This behavior was attributed to the fact that as the diameter and the number of wires increased, the intensity of the electric field, generated from electric static charge increased causing an adhesion increase between the two sliding surfaces. At water wetted sliding conditions, the effect of changing number of wires on friction coefficient was less than the effect of wire diameter. The presence of water and detergent on the sliding surfaces decreased friction coefficient compared to the dry sliding. When the surfaces were detergent wetted, the friction coefficient values were found to be lower than that observed when sliding in water or dry condition.

Key Words
friction coefficient; epoxy metal matrix composites; copper wires; flooring materials

Address
Rehab I. Ahmed, Moustafa M. Moustafa, Ashraf M. Talaat
and Waheed Y. Ali:Production Engineering and Mechanical Design Department, Faculty of Engineering,
Minia University, P.O. 61111, El-Minia, Egypt

Abstract
The study presents a preliminary investigation on the applicability of Shirasu (a pyroclastic flow deposit characterized by high percentage of volcanic glass) in geopolymer. Comparative study on compressive strength and internal pore structure has been done between geopolymers with alkali activated Shirasu and fly ash as aluminosilicates. Mortar mix proportions are selected based on variations in ratio of alkaline activators to aluminosilicate and also on silica to alkali hydroxide ratio. From the experimental study, Shirasu geopolymer exhibited fairly good compressive strength. Mix proportion based on silica to alkali hydroxide ratio is observed to have profound effect on strength development.

Key Words
aluminosilicate; alkali activation; geopolymer; polymerization; pyroclastic flow; Shirasu

Address
Dhruva Narayana Katpady: Kagoshima University, Department of Ocean Civil Engineering, 1-21-40, Korimoto, Kagoshima, Japan
Koji Takewaka and Toshinobu Yamaguchi: Department of Ocean Civil Engineering, Kagoshima University,1-21-40, Korimoto, Kagoshima 890-0065, Japan


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