Mazen Alshaaer

University of Aveiro | UA · GeoBioTec — Geobiosciences, Geotechnologies and Geoengineering Research Center,

Because the impact of the full-scale substitution of Ca2+ in brushite (CaHPO4·2H2O) with Ni2+ ions has never been systematically explored, it is the focus of this investigation, as it holds potential for use in CaxNi1−xHPO4·nH2O production. These biomaterials have many beneficial characteristics that can be modified to suit diverse applications, in...

In this study, coarse magnetite (>63 μm) is introduced as a reactive component in wollastonite-based chemically bonded phosphate ceramics (WPC). It is found that WPC with coarse magnetite results in the formation of new stable microstructural phases such as iron phosphate cementitious matrix. The new ceramics (M-WCP) exhibit much lower shrinkage th...

In this chapter, besides its biomedical applications, the synthesis and properties of brushite were investigated. Brushite consists of two types of crystals, platy and needle-like, and their formation depends on the pH of the medium during precipitation. Platy crystals are formed in a slightly acidic medium, pH = 5, and needle-like crystals at a hi...

This study introduces the usage of date palm fibers (DPFs) as reinforcement of geopolymer matrices. The DPFs were subjected to alkaline treatment by immersion in alkaline solution (5 M) for 24 h at 40 °C. Because of the subsequent strong alkaline geopolymerization, the natural resin (lignin) was removed and the DPFs with a diameter around 600 µm on...

The gradual replacement of Ca2+ with Cu2+ ions in brushite (CaHPO4·2H2O) has been extensively studied and discussed. The approach adopted in this work has not been systematically explored in previous studies. This novel approach may prove beneficial for the production of Ca1−xCuxHPO4·nH2O materials with desired properties suitable for medical appli...

This study describes the properties of geopolymer composites reinforced with bidirectional jute fibers. Their flexural strength is 12 MPa, four times higher than the strength of non-reinforced reference geopolymers. The bidirectional jute-reinforced geopolymer composite (JGC) is characterized by ductility and high elongation as well as strain harde...

The present study investigates the gradual replacement of Ca2+ with Mg2+ ions in brushite (CaHPO4·2H2O). To date, this approach has not been systematically explored and may prove beneficial for the production of Ca1−xMgxHPO4·nH2O materials with tailored properties which are suitable for environmental and medical applications. For their production,...

Brushite (CaHPO 4 .2H 2 O) is an important calcium phosphate encountered in bone tissue engineering and bone cement formulation. There are many studies on the synthesis and characterization of brushite, but full-scale substitution and replacement of Ca by Sr in brushite as a key element in medical and environmental applications has not yet been exp...

The microstructure of a wollastonite chemically‐bonded phosphate ceramic (WCPC) and its long term stability can be characterized in terms of functions over time and at intermediate temperatures (RT, 40 ˚C, 60 ˚C and 80 ˚C). As seen through SEM images and EDX analysis, the ceramic microstructure comprises brushite, wollastonite and an amorphous hete...

The atmospheric pressure He- H 2 O plasma jet has been analyzed and its effects on the Kapton polyimide surface have been investigated in terms of discharge power effect. The polyimide surfaces before and after plasma treatment were characterized using atomic force microscopy (AFM), X-ray photoelectrons spectroscopy (XPS) and contact angle. The res...

Porous biphasic bioceramics that contain hydroxyapatite and tricalcium phosphate were synthesized in this study using luffa cylindrical fibres (LCF) as the template. In addition to improving the pore structure, using this template led to a chemical coating of the pores´internal surfaces by important minerals such as magnesium and phosphorous from t...

This paper introduces a novel, green, self-healing composite based on vascular luffa fibres (Luffa Cylindrical Fibres, LCF) and a geopolymer matrix. The self-healing effect of LC fibre in reinforced geopolymer was investigated. For comparison purposes, other two geopolymer composites, GC4 and GJ4, were prepared using synthetic carbon fibre and natu...

This work aims to investigate the production of heavy fuel oil fly ash (HFO)-based geopolymers for passive cooling systems. The processing technique entails adding HFO as the porous filler material to a geopolymer matrix derived from metakaolin. A weight ratio of 10% —compared with the powder precursor (metakaolin)— was added to the metakaolin-base...

This work aims to investigate the production of heavy fuel oil fly ash (HFO)-based geopolymers for passive cooling systems. The processing technique entails adding HFO as the porous filler material to a geopolymer matrix derived from metakaolin. A weight ratio of 10% —compared with the powder precursor (metakaolin)— was added to the metakaolin-base...

This work aims to investigate the stabilization of heavy oil fly ash (HFO) using a geopolymerization technique. The stabilization technique entails adding HFO as the filler material to a geopolymer matrix derived from metakaolin. Weight ratio of 20% — compared with the powder precursor (metakaolin) — were added to the metakaolin-based geopolymer. X...

This study reports on the preparation, microstructure, density and mechanical properties of new geopolymer composites (LG-composite) that are unidirectionally and randomly reinforced with 10 vol% natural Luffa Cylindical fibres (LCF). The geopolymer matrix was synthesized from metakaolin activated with sodium silicate and sodium hydroxide solutions...

Three-dimensionally ordered macroporous biomaterials containing hydroxyapatite were synthesized using natural luffa cylindrical fibres (with diameter of 100–400 µm) as templates. The preliminary evaluation of this novel method for production of porous bioceramics showed promising potential applications in bone tissue engineering. The produced bioce...

This work aims to investigate the stabilization of heavy oil fly ash (HFO) using a geopolymerization technique. The stabilization technique entails adding HFO as the filler material to a geopolymer matrix derived from metakaolin. Weight ratio of 20% - compared with the powder precursor (metakaolin) - were added to the metakaolin-based geopolymer. X...

The dielectric relaxation behavior of pure (3-hydroxybutyrate), PHB and its copolymer (3-hydroxybutyrate-co-3-hydroxyvalerate), PHB-HV, is investigated in wide range of frequency from 0.001 Hz to 1x10 7 Hz at different fixed temperatures. It is observed that, pure PHB and its copolymers with different ratios of hydroxyvale rate are characterized by...

AC conductivity of pure (3-hydroxybutyrate), PHB and its copolymers (3-hydroxybutyrate-co-3-hydroxyvalerate), PHB-HV, is investigated in wide range of frequency. The Arrhenius plots of AC conductivity showed a remarkable change in the conduction mechanism in glass transition temperature region of pure PHB. Broadband dielectric spectroscopy for all...

The aim of this work is to investigate the microstructural characteristics and the adsorption potential of zeolitic tuff–metakaolin (ZM) geopolymers. For the identification of microstructure, X-ray diffraction (XRD) and scanning electron microscope (SEM) analyses were used. XRD showed that mordenite, a major zeolite mineral, disappeared upon geopol...

In this study, a new approach, which involves the application of a steam curing cycle for the production of kaolinite-based geopolymers, is investigated. This approach aimed to accelerate geopolymeric reactions and eliminate the content of residual alkalis within the geopolymer mass and the formation of efflorescence at the surface of the specimens...

New geopolymer formulations were designed by sodium silicate/NaOH activation of metakaolin, iron oxide and red mud mixtures. The effects of source materials on the microstructure and mechanical properties were studied. Each formulation induces different degree of geopolymerization reaction as reflected by the phase composition where the amorphous p...

The effect of immersion in alkali solution as a second-phase geopolymerization of kaolinite-based geopolymers on their properties was investigated in this study. The aim of this work was to improve the geopolymer properties by increasing both its resistance to water absorption and mechanical performance. It was found that immersion in alkali soluti...

Injectable load-bearing calcium phosphate scaffolds are synthesized using rod-like mannitol grains as porogen.These degradable injectable strong porous scaffolds, prepared by calcium phosphate cement, could represent a valid solution to achieve adequate porosity requirements while providing adequate support in load-bearing applications.The proposed...

Large deposits of impure kaolins exist in Jordan and many parts of the world; geoplymers can re-duce environmental impacts and have multi-application in many fields, such as water purification, waste treatment, fire proof construction, etc. The aim of this research is to investigate the use of alkali activated zeolitic tuff and low purity metakaoli...

Injectable load-bearing calcium phosphate scaffolds are synthesized using rod-like mannitol grains as porogen. These degradable injectable strong porous scaffolds, prepared by calcium phosphate cement, could represent a valid solution to achieve adequate porosity requirements while providing adequate support in load-bearing applications. The propos...

This paper deals with the development of functional geopolymers based on local resources such as kaolinitic soil and zeolitic tuff for the construction of water storage containers and water transfer channels. The effect of water content on the mechanical performance and phys-ical properties of synthesized geopolymers was evaluated. The results conf...

Four geopolymers were synthesized by NaOH-activation of a mixture of kaolinite (Jordanian kaolinite or Ukrainian kaolinite) and a filler (zeolitic tuff or silica sand). X-ray powder diffraction (XRD), Fourier-transform infrared spectrometry (FTIR), and solid-state magic angle spinning nuclear magnetic resonance (MAS-NMR) were employed to monitor th...

This work deals with geopolymers based on local Jordanian resources, namely, kaolin and zeoltitic (phillipsite) tuff. The geopoly- mers were prepared from these two materials by a reaction with an alkali solution at 80ºC. The research group of the present work has demonstrated in previous work that addition of zeolitic tuff to kaolin based-geopoly...

Geopolymerization is the process of polymerizing minerals with high silica and alumina at low temperature by the use of alkali solutions. Geopolymers could be a substitute for Portland cement and for advanced composite and ceramic applications. The geopolymer technology would eliminate the need for energy requirement as they may be cured at ambient...

A new hydrothermal post curing (HTPC) technique is developed in this study to overcome the long term evolutions such as shrinkage and cracking of Inorganic Phosphate Cement (IPC). HTPC is based on thermally induced transformation of the unstable calcium phosphates phases, e.g. brushite and amorphous calcium phosphate (ACP), into more stable phases,...

Phase and mechanical changes of Inorganic Phosphate Cement (IPC) are identified along with changes in macro properties as functions of temperature and time. In addition to amorphous phases, the presence of significant amounts of brushite and wollastonite in the reference IPC is confirmed using X-ray diffraction. The thermal behavior of IPC up to 10...

A geopolymer produced from Jordanian kaolinite is described in this work. The aim is to produce low environmental impact materials from local raw materials. In this paper the emphasis is on the general characteristics of the material and on its durability. With the used kaolinite, specimens with compressive strength of 41 MPa under dry conditions a...

The formation REBa2Cu3O7−δ (RE= Gd, Sm and Ho) superconducting ceramics from metal oxalate precursors with average grain size less than 50 nm using the coprecipitation method is reported. The metal oxalate powders were heated at 900oC for 12 hours, pelletized and then sintered at 920°C for 15 hr. The high-TC phase was observed for all samples as an...

Some important research on the development, and applications of Low-cost functional geopolymeric materials was conducted.. This paper focuses on geopolymerization technique intended for the stabilization of natural geomaterial samples collected from various deposits in Jordan. The obtained materials are environmentally friendly and need only a low...

Some important research on the development, and applications of Low-cost functional geopolymeric materials was conducted.. This paper focuses on geopolymerization technique intended for the stabilization of natural geomaterial samples collected from various deposits in Jordan. The obtained materials are environmentally friendly and need only a low...

IntroductionExperimentalResults and DiscussionConclusions Acknowledgment

The adsorption of lead [Pb(II)] ions onto adsorbents prepared by alkali solid-state conversion of kaolin and natural zeolite mixture was investigated. The adsorption isotherms were obtained and the Langmuir parameters were calculated in order to make a comparison between the adsorption capacities of synthesized adsorbents and those of their constit...

Geopolymers consist of an amorphous, three-dimensional structure resulting from the polymerization of aluminosilicate monomers that result from dissolution of kaolin in an alkaline solution at temperatures around 80 degrees C. One potential use of geopolymers is as Portland cement replacement. It will be of great importance to provide a geopolymer...

Through chemical polymerisation reactions, minerals, such as clay, can be hardened and transformed into useful construction materials. These mineral polymers are produced at temperatures under 80 °C by using minimal energy input. They can be used as structural materials, due to their attractive properties in construction and other applications such...