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Showing papers on "Geopolymer published in 2003"


Journal ArticleDOI
TL;DR: In this paper, the use of granulated blast furnace slag as an active filler in the making of geopolymers was described, and a 10 mm thick geopolymer panel was exposed to a 1100 °C flame, with the measured reverse-side temperatures reaching less than 350 °C after 35 min.

719 citations


Journal ArticleDOI
TL;DR: In this paper, a series of geopolymer composites were prepared containing 10−20% of various granular inorganic fillers ranging from waste demolition materials through mineral tailings to engineering ceramics.

454 citations


Journal ArticleDOI
TL;DR: In this paper, the compressive strength of amorphous aluminosilicate polymers produced by sodium silicate activation of metakaolinite were studied, with particular reference to chemical optimisation of the Compressive strength according to the relative concentrations of Si, Al and Na in the polymer.
Abstract: High strength cements can be synthesised by alkali activation of materials rich in Al2O3 and SiO2. In this study, amorphous aluminosilicate polymers produced by sodium silicate activation of metakaolinite were studied, with particular reference to chemical optimisation of the compressive strength according to the relative concentrations of Si, Al and Na in the polymer. The sodium silicate was manufactured from silica fume and sodium hydroxide. The compressive strengths of polymers with Si∶Al molar ratios of 1.0–3.0 and Na∶Al molar ratios of 0.5–2.0 were considered. The polymers were cured at 75 °C for 24 h and their compressive strengths measured after aging for 7 days. The strength was found to depend systematically on the relative amounts of Si, Al and Na, with the maximum being 64 ± 3 MPa for an Si∶Al∶Na molar ratio of 2.5∶1∶1.3. X-Ray diffraction/scattering data indicate qualitatively that the bonding network in the amorphous aluminosilicate alters systematically with composition.

407 citations


Journal ArticleDOI
TL;DR: In this article, the effect of phase composition on the dissolution behavior, reactivity, and final physical and mechanical properties of fly ash-based geopolymeric materials is investigated using XRD and FTIR techniques.

398 citations


Journal ArticleDOI
TL;DR: In this paper, the thermal stability of the K-polysialate and K-PSDS has been investigated and it has been shown that the charge-balancing alkali ions in these two networks behave similarly to those of Na geopolymers, dehydrating on heating and moving into the feldspar lattice.

308 citations


Journal ArticleDOI
TL;DR: In this paper, a kaolinitic residue has been used for the synthesis of geopolymer-based building materials, which takes place through a calcination step followed by a polycondensation step.
Abstract: In this work a kaolinitic residue has been used for the synthesis of geopolymer-based building materials. The synthesis takes place through a calcination step followed by a polycondensation step. The calcination step was carried out at temperatures ranging from 500 to 750 °C and times ranging between 2 and 6 h. Optimum calcination conditions were found by evaluating the reactivity of the calcined products by differential scanning calorimetry (DSC). The polycondensation step was carried out at temperatures ranging from 25 to 85 °C by reaction with sodium or potassium silicate. The compositions of polycondensation systems stoichiometric for the synthesis of polysialate (PS), polysialatesiloxo (PSS) and polysialatedisiloxo (PSDS) geopolymers were tested, but only the first two were successful. An original quantitative analytical method was employed to determine the amounts of reacted silicate and water after polycondensation. The products obtained were tested for unconfined compressive strength, apparent density, porosity, surface area and pore size distribution. The results show that it is possible to produce good quality building materials starting from a kaolinitic residue.

175 citations


Journal ArticleDOI
TL;DR: In this paper, the fracture-toughness of the inorganic polymeric cement called geopolymer or PSS has been studied in recent years as a binder for mortar and concrete.
Abstract: The inorganic polymeric cement called geopolymer or PSS, has been studied in recent years as a binder for mortar and concrete. The present work reports the fracture toughness studies in mortars made of PSS cement matrix reinforced by wollastonite microfibers (Ca(SiO 3 )). K 1 -curves for PSS cement composites were determined according to the superposition asymptotic assumption and compared with reference Portland cement (PC) composites. The maximum toughness gain occurs in both composite systems with V f = 2%. For higher fibre volumes (3 and 5%), K I values decrease, due to an increase in porosity. Microstructural analyses showed that toughening mechanisms, as debonding and pullout of the fibers, are more common in PSS cement composites than in the reference PC composites. The difference of toughness between PSS and PC cement (0% of fibers) is about 80%. This demonstrates the high performance of these geopolymeric materials.

109 citations


Journal ArticleDOI
TL;DR: In this article, the influence of the aluminosilicate source, its activation temperature, and the order of mixing raw materials were studied on the workability of the blending paste, the microstructure and the Vickers hardness of the geopolymer samples.
Abstract: Alkali activation of dehydroxylated kaolin or clay yielded high-strength polymeric materials, so-called geopolymers. They were synthesized by mixing the aluminosilicate with solutions of sodium metasilicate and KOH followed by adding 45 wt.% of ground-granulated blast furnace slag. The influence of the aluminosilicate source, its activation temperature, and the order of mixing raw materials were studied on the workability of the blending paste, the microstructure, and the Vickers hardness of the geopolymer samples. The polymeric material is completely amorphous according to x-ray diffraction. Solid-state 27Al and 29Si magic-angle-spinning nuclear magnetic resonance showed that the geopolymer consists of AlO4 and SiO4 tetrahedra linked together through a polymeric network constituted by branched entities SiQ4(4Al) and SiQ4(3Al), but also by less-polymerized silicates SiQ1 and SiQ2. Scanning electron microscopy showed a homogeneous polymeric gel matrix containing unreacted slag (and quartz) grains; thermogravimetric analysis and differential scanning calorimetry exhibited a high content of water and an elevated melting point (1260°C). Vickers hardness values are in the range of 200 MPa.

89 citations


Journal ArticleDOI
TL;DR: In this article, the microstructure properties of aluminosilicate hydrogels were investigated by differential scanning calorimetry (DSC), X-ray diffraction (XRD), solid-state magic angle spinning nuclear magnetic resonance (MAS-NMR) spectroscopy and small amplitude oscillatory rheometry.

62 citations


Patent
18 Mar 2003
TL;DR: In this article, a geopolymer binder based on fly ash is proposed, which is intended for the production of pastes, mortars and concretes or waste fixation and which contains 70 to 94 percent by weight of power station fly ash with a measurement surface of 150-600 m2/kg.
Abstract: The invention relates to a geopolymer binder based on fly ash, which is intended for the production of pastes, mortars and concretes or waste fixation and which contains 70 to 94 percent by weight of power station fly ash with a measurement surface of 150-600 m2/kg and 5 to 15 percent by weight of an alkaline activator, wherein said activator consists of a mixture of alkaline hydroxide and alkaline silicate, for example, water glass. Said activator contains 5 to 15 percent by weight Me2O and a proportion of SiO2/Me2O ranging from 0.6 to 1.5, wherein Me is Na K. The invention is characterized in that said binder contains 1 to 15 of a lime-containing compound, for example, CaCO3, CaMg(CO3)2, CaSO4, CaSO4.2H2O, Ca(OH)2, ground limestone or dolomite limestone, waste gypsum rock from chemical productions, waste gypsum rock from sulfur separation processes and reprocessed cement from concrete. The particle size of the lime-containing compound is advantageously from 1 to 200 µm. The fly ashes should advantageously contain over 3 percent by weight of CaO.

21 citations


01 Jan 2003
TL;DR: In this paper, the effects of aggregate particle size on the formation and the mechanical properties of geopolymeric materials are investigated in the current work and the results indicate that the surface area of aggregate influences the strength development of a geopolymer.
Abstract: Due to enhanced mechanical and chemical properties, geopolymeric materials are a potential alternative to ordinary Portland cement and high -strength cement for the construction industry The effects of aggregate particle size on the formation and the mechanical properties of geopolymeric materials are investigated in the current work The addition of soluble silicates to the alka line activator was found to increase the dissolution of silicate ions from the aggregate into the geopolymer binder phase The results indicate that the surface area of aggregate influences the strength development of a geopolymer

01 Jan 2003
TL;DR: Wang et al. as mentioned in this paper developed a process to manufacture fire-resistant geopolymer based on serpentine waste, and the experiment results show that the waste serpentine-based geopolymers have very good physical/mechanical characteristics.
Abstract: There are more than half million tons of serpentine waste produced per year during mining operation in Taiwan. This study is to develop a process to manufacture fire-resistant geopolymer based on serpentine waste. The experiment results show that the waste serpentine-based geopolymer have very good physical/mechanical characteristics. For fire resistance tests, a 10 mm thick geopolymer panel was exposed to a 1100 flame, with the ℃ measured back-side temperatures reaching less than 450 after 30 minutes. Th ℃ e products can be fabricated for construction purposes and have great application potential. Keyword: Serpentine, Geopolymer, Recycling, Fire-resistance

Patent
16 Apr 2003
TL;DR: In this article, a liquid geopolymer mixture is first cooled then maintained at a temperature of less than -10 °C, preferably less than −18°C, for at least 24 hours, said cooled resin remaining stable and liquid at -18 °C for a period of between 3 weeks and at least 8 weeks.
Abstract: The invention relates to a liquid geopolymer resin of the sialate type (xSiO2, AlO2), where 'x' has a value of equal to or between 1.75 and 50. The geopolymer mixture is first cooled then maintained at a temperature of less than -10 °C, preferably less than -18 °C, for at least 24 hours, said cooled resin remaining stable and liquid at -18 °C for a period of between 3 weeks and at least 8 weeks. Said resin warmed to ambient temperature is turned into a ready-to-use geopolymer resin just before the use thereof. The geopolymer resins undergo polycondensation at temperatures below 100 °C, preferably at ambient temperature by the addition of selected cross-linking agents, selected from amongst metallic phosphates such as aluminium phosphate, iron phosphate, copper phosphate, zinc phosphate or a mixture of said metallic phosphates.

Journal Article
TL;DR: In this paper, fly ash was used as a basic Si-Al ingredient of geopolymer and three types of curing methods were investigated to obtain the optimum strength of flexural and compressive.
Abstract: Fly ash was used as a basic SiAl ingredient of geopolymer. The amount of fly ash and 3 types of curing methods were investigated to obtain the optimum strength of flexural and compressive. The results show that geopolymer containing 30% fly ash which was prepared at 80 °C for 8 h exhibites high strength. The compressive and flexural strength of the fly ash based geopolymer were 32.2 MPa and 7.15 MPa, respectively. Study of Cl- permeability, freezing and thrawing behavior show that the fly ash based geopolymer concrete has very excellent durability. Infrared spectrum and Xray diffraction measurements show that IR peak at 1 086 cm-1 caused by the stretching vibration of SiO4 tetrahedra shiftes to lower wavenumber around 1 033 cm-1, and the 6fold Al is transformed into 4fold coordination during the synthesis of geopolymer. As a result, the amorphous geopolymer is formed.

Proceedings ArticleDOI
01 Jan 2003
TL;DR: In this article, a commercial geopolymer was studied to get a better understanding of geopolymers in order to enhance its leach resistance for immobilisation of intermediate-level radioactive waste, which is similar to that of Portland cement and has been considered as a possible improvement on cement for several applications including as media for the encapsulation of hazardous or low/intermediate level radioactive waste.
Abstract: Geopolymers are made by adding aluminosilicates to concentrated alkali solutions for dissolution and subsequent polymerisation to take place. Their physical behaviour is similar to that of Portland cement and they have been considered as a possible improvement on cement for several applications including as media for the encapsulation of hazardous or low/intermediate level radioactive waste. We studied in detail a commercial geopolymer to try to get a better understanding of geopolymers in order to enhance its leach resistance for immobilisation of intermediate level radioactive waste. We also briefly investigated two types of experimental geopolymers, one made with a metakaolinite and another from fly ash as the aluminosilicate source. The commercial geopolymer paste had an apparent porosity of 26% and it was possible to reduce it to 17% by adding ∼ 30 weight % foundry sand. The apparent porosities of the geopolymer made from metakaolinite and from fly ash were 13% and 26% respectively. X-ray powder diffraction showed in the three geopolymers, an amorphous phase (deduced by the presence of a very broad diffuse peak centred at a d-spacing of ∼ 0.32 nm), quartz and other minor phases. The energy dispersive spectroscopic analysis under the scanning electron microscope confirmed these. Magic angle spinning nuclear magnetic resonance data from the samples showed Al to be mainly in 4-fold coordination and Si sites varying from Q0 to Q4 coordination as also found by other researchers. 23 Na spectra indicated that the Na was mainly in the pore water. The 133 Cs spectra showed a strong possibility of Cs being mainly bound in the structure while a small amount could still be in the pore water. The initial leach tests showed alkalis were leached out at rates of several orders of magnitude more than the Al and Si network ions. The most likely reason is that a significant alkali inventory is in the pore water. To remove pore water and incorporate simulated radionuclides such as Cs in the network the commercial geopolymer was heated up to 1200°C. Differential thermal/thermogravimetric analysis showed the loss of water occurs in three stages and most had been lost by 700°C. These results are in broad agreement with the Infra red spectra obtained for samples heated over the temperature range 30–900°C. The broad water band intensity in the range 2600-30-900°C. The broad water band intensity in the range 2600–3800 cm −1 decreased steadily with temperature although a small fraction remained even after heating to 500°C. The silanol band had disappeared at 800°C, and the 3619 cm−1 band (due to OH) virtually disappeared by 900°C.Copyright © 2003 by ASME

01 Jan 2003
TL;DR: In this article, the compressive strength of the gold-tailings is largely enhanced by raising temperature and elongating hardening time as well as staying time in the air, while the serious poisonous CN- in the gold tailings can be trapped physically and fixed chemically in the geopolymers when CN- meets with Fe 2+ or Fe 3+.
Abstract: The geopolymers were synthesized using gold-tailings, metakaolin, water glass, sodium and potassium hydrate With the method of orthogonal experiments, the optimized result is gold-tailings of 80%-825%, powder to alkaline silicate solution mass ratios of 43-47 and water to alkaline mass ratios of 4-5 Based on these results, it is found that the compressive strength is largely enhanced by raising temperature and elongating hardening time as well as staying time in the air The serious poisonous CN- in the gold-tailings can be trapped physically in the geopolymers and fixed chemically in the geopolymers when CN- meets with Fe 2+ or Fe 3+ The mass loss of the geopolymers soaked in 1 mol/L HCl for 30 days averages 56%, showing a good acid-resistance, concerning its 9% hematite and 6% calcite in gold-tailings At 60℃, with hardening time of 24 hours and 72 hours, the compressive strength of the geopolymers reaches 22 MPa after another 6 days in ambient condition and 366 MPa, respectively This result provides the possibilities for geopolymers utilized as construction blocks in industry

Patent
09 May 2003
TL;DR: In this paper, a claim for production of the geopolymer stone by hardening a mixture of the rock residues and a geopolymers comprising sodium, potassium and calcium aluminosilicates is also included.
Abstract: Geopolymer stone for construction and decoration comprises 65-95 wt.% rock residues derived from naturally weathered rock and/or eroded detrital rock and 5-35 wt.% of a poly(sialate), poly(sialate-siloxo) and/or poly(sialate-disiloxo) geopolymer binder. An Independent claim is also included for production of the geopolymer stone by hardening a mixture of the rock residues and a geopolymer comprising sodium, potassium and calcium aluminosilicates.

Journal Article
TL;DR: In this article, the relationship between the compressive strength and the influential factors during geopolymerization of the gold tailing geopolymers was systematically discussed, and it was proved that fillings participated in the process, although they were much lower in solubility than metakaolin.
Abstract: This paper systematically discussed the relationship between the compressive strength and the influential factors during geopolymerization of the gold tailing geopolymers. The samples were synthesized from 80% gold tailing, 20% metakaolin and 10 mol/L NaOH or KOH solution (with mass ratio of solid/liquid=4.7 and mass ratio of water/alkaline=5). It was found that the compressive strength of the geopolymers was enhanced by raising temperatures from 60 to 80℃,molding pressures from 8, 16 to 24 MPa and hardening time from 24 to 72 h. The compressive strength of the samples increased continuously with increase of staying time in air, which is related to obtaining water from air. Under the same mass ratio of solid/liquid and the same mole ratio of (Na 2 O or Na 2O+K 2 O)/SiO 2 , the effect of KOH on compressive strength of the geopolymers was more effective than NaOH. And with increase of K 2 O and Na 2 O in alkaline solutions, the compressive strength arose and reached to the climax when the mole ratio of Na 2 O/SiO 2 or Na 2O+ K 2 O/SiO 2 equals one. It was proved that fillings participated in geopolymerization although they were much lower in solubility than metakaolin in alkaline solutions. And it was found that the geopolymers containing more potassium feldspars had higher compressive strength than those with quartzes or containing fewer potassium feldspars.

Journal Article
TL;DR: In this article, three sorts of steel fiber are mixed into selected batch and then a series of steel fibre reinforced geopolymer-based reactive powder concrte(RPC) are obtained of different strength.
Abstract: Having portion of kaolin clay replaced with fly ash,search most optimum ratio of geopolymer to prepare geopolymer-based reactive powder concrete.In order to select a curing technology which may be helpful to develop the activity of gelling substances,three cur ing systems are compared with each other of the standard one,steam one and pressure-steam one.After that three sorts of steel fiber are mixed into selected batch and then a series of steel fiber reinforced geopoly mer-based reactive powder concrte(RPC)are obtained of different strength.The compressive and bending strength are respectively as high as55.2MPa and22.44MPa.A fur ther test indicates geopolymer-based reactive powder concrete has excellent durability.