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Showing papers on "Geopolymer published in 2004"


Journal ArticleDOI
TL;DR: In this paper, the microstructure and the bonding strength of the interface between natural siliceous aggregates and fly ash-based geopolymers was studied and it was found that when the activating solution that contained no or little soluble silicates, the compressive strengths of the geopolymeric binders, mortars and concretes were significantly weaker than those activated with high dosages of soluble silicate.

180 citations


01 Jan 2004
TL;DR: In this article, the authors introduced two types of sustainable cementitious composites, geopolymer and magnesium phosphate cement, which possess some common and individual characteristics compared with Portland cement concrete.
Abstract: Portland cement (PC) concrete is the most popular and widely used building material because its raw materials are available over the world. This paper introduces two types of sustainable cementitious composites, geopolymer and magnesium phosphate cement. Compared with PC, these two cements possess some common and individual characteristics. The paper presents recent developments of these two materials. Investigation has shown that they have superior properties compared to PC such as high early strength, excellent volume stability, better durability, good fire resistance, and easy manufacture process.

160 citations


Journal ArticleDOI
TL;DR: In this article, the effects of five kinds of water-soluble organic polymers on the mechanical and physical properties of uncalined-kaolinite geopolymer were examined.

100 citations


Journal ArticleDOI
TL;DR: Results indicate that a geopolymer is effective at reducing the leach rates of many metals from the fly ash, such as calcium, arsenic, selenium, strontium and barium.

97 citations


01 Jan 2004
TL;DR: In this paper, a heat treatment at 75°C for 4 hours yields satisfactory results for reinforced particle boards with desirable properties like water resistivity, limited shrinkage and sufficient strength values.
Abstract: Geopolymer binders based on a commercial metakaoline, water glass and sodium hydroxide have been investigated with respect to their application for building materials. Mixture compositions with favourable properties couldbe identified. For the production of building materials, a process technology at ambient temperature may be less feasible due to delayed setting and strength evolution. Therefore curing at elevated temperatures was tested. A heat treatment at 75°C for 4 hours yields satisfactory results. With this production technology geopolymer binders seem to be suitable for selected building materials like reinforced particle boards. This is on the one hand due to a long processing time together with a rapid strength development during temperature treatment. On the other hand they develop desirable properties like water resistivity, limited shrinkage and sufficient strength values.

78 citations


Patent
30 Jan 2004
TL;DR: Cementitious materials including stainless steel slag and geopolymer can be added to conventional cement compositions, such as Portland cement, as a partial or total replacement for conventional cement materials as discussed by the authors.
Abstract: Cementitious materials including stainless steel slag and geopolymer can be added to conventional cement compositions, such as Portland cement, as a partial or total replacement for conventional cement materials The stainless steel slag may comprise silicates and/or oxides of calcium, silicon, magnesium, iron, aluminum, manganese, titanium, sulfur, chromium and/or nickel The geopolymer may comprise aluminum silicate and/or magnesium silicate In a preferred embodiment, curing of concrete materials by the action of water on the cementitious materials is enhanced with the addition of an activator component selected from calcium bromide, calcium nitrate, calcium nitrite, calcium chloride, calcium oxide, and sodium bromide

64 citations


Journal ArticleDOI
TL;DR: In this article, a combination of scanning and transmission electron microscopy along with energy-dispersive X-ray analysis of argon-milled sections were used to study fly ash matrices containing arsenic and found that little arsenic was incorporated in the matrix of hydration product but it was associated with iron derived from the hydration of the fly ash.
Abstract: A variety of natural and industrial waste product materials rich in SiO2 and Al2O3 may be activated with alkalis to produce cementitious systems which when cured under mild temperature conditions, set and harden to give a very compact paste. When fly ash is the activated material, fast setting and rapid strength development have been reported. In addition to their application in construction, they may have a role in the immobilisation of toxic waste. Alkali-activated fly ash matrices containing arsenic were studied by a combination of scanning and transmission electron microscopy along with energy-dispersive X-ray analysis of argon-milled sections. Little arsenic was incorporated in the matrix of hydration product but it was apparently associated with iron derived from the hydration of the fly ash. There was no association of As with added Fe2O3.

52 citations


Journal ArticleDOI
01 Apr 2004-Wear
TL;DR: In this paper, solid-particle erosion studies were conducted on a geopolymer derived from fly ash and granulated blast-furnace slag, and the material-loss mechanisms were studied by scanning electron microscopy (SEM).

51 citations


Journal ArticleDOI
TL;DR: In this article, it has been shown that the nature of the source materials used during synthesis has a significant effect on the final chemical and physical properties of the geopolymeric matrix, and that partial dissolution of specific wastes serves to either weaken or strengthen the newly formed structure.
Abstract: Geopolymer technology has emerged as an effective solution for the stabilization of industrial by-products and the immobilization of heavy metals. It has been established that the nature of the source materials used during synthesis has a significant effect on the final chemical and physical properties of the geopolymeric matrix. In particular, it has been established that the partial dissolution of specific wastes serves to either weaken or strengthen the newly formed structure. Moreover, leaching tests have shown that the use of either kaolinite or calcined kaolinite (metakaolinite) in fly ash based geopolymers affects the propensity of the matrix to immobilize heavy metals. This observation has practical implications for the application of geopolymer technology to the capping of mine tailings ponds or the backfilling of mines. The differences in dissolution behavior and the effect on final properties of geopolymeric materials have been studied for the kaolinite and metakaolinite system, with a view of ...

46 citations


Journal ArticleDOI
TL;DR: In this article, a geopolymer matrix was investigated as a potential stabilisation method for fly ash obtained from electrostatic precipitators and ash disposal ponds, and the ratio of fly ash and geopolymers was varied to determine the effects of different compositions on leaching rates.

46 citations


Patent
19 Nov 2004
TL;DR: In this article, a method of forming a geopolymer moulded product comprising of an alkali or alkaline earth metal silicate component, an alkaline or alkali earth metal hydroxide, aggregate and water was proposed.
Abstract: A method of forming a geopolymer moulded product comprising: forming a geopolymer concrete composition comprising an alkali or alkaline earth metal silicate component, an alkali or alkaline earth metal hydroxide, aggregate and water wherein the water content is insufficient to provide a slumped concrete and the ratio of SiO2 to M2O is at least 0.8; and casting the concrete into a mould and subjecting the moulded concrete to consolidation in the mould.

Patent
20 Aug 2004
TL;DR: In this paper, the authors proposed a novel geopolymer composition with structurally incorporated boron which has the advantage of a retarded set time and has the following oxide molar ratios: (a) SiO2/Al2O3 = 3.0 - 6.5; (b) M2O/SiO2 = 0.07 - 0.20; (c) H2O /M2O
Abstract: The present invention relates to novel geopolymer compositions with structurally incorporated boron which have the advantage of a retarded set time. The preferred geopolymer composition has the following oxide molar ratios: (a) SiO2 / Al2O3 = 3.0 - 6.5; (b) M2O / SiO2 = 0.07 - 0.20; (c) H2O / M2O = 8.0 - 19.0; (d) B2O3 / H2O = 0.01 - 0.2; and (e) M2O / B2O3 = 0.5 - 6.0 wherein M is a Group I metal. The present invention also relates to methods of forming these novel geopolymer compositions.

Journal ArticleDOI
TL;DR: In this article, Cs and Sr were added to geopolymer samples prepared using fly ash precursors and a commercial metakaolinite geopolymers were studied for comparison.
Abstract: Geopolymers are made by adding aluminosilicates to concentrated alkali solutions for dissolution and subsequent polymerization to form a solid They are amorphous to semi-crystalline three dimensional aluminosilicate networks Although they have been used in several applications their widespread use is restricted due to lack of long term durability studies and detailed scientific understanding Three important tools for the study of geopolymers are transmission electron microscopy (TEM), solid state magic angle spinning nuclear magnetic resonance (MAS NMR) and infra red (IR) spectroscopy Cs and Sr are two of the most difficult radionuclides to immobilize and are therefore suitable elements to study in assessing geopolymers as matrices for immobilization of radioactive wastes In this study Cs or Sr was added to geopolymer samples prepared using fly ash precursors A commercial metakaolinite geopolymer was studied for comparison The geopolymers were mainly amorphous as shown by TEM, whether they were made from fly ash or metakaolinite In the fly ash geopolymer, Cs preferentially inhabited the amorphous phase over the minor crystalline phases, whereas Sr was shared in both The MAS NMR showed that Cs is held mostly in the geopolymer structure for both fly ash and metakaolinite geopolymers The IR spectra showed a slight shift in antisymmetric Si-O-Al stretch band to a lower wavenumber for the fly ash geopolymer, which implies that more Al is incorporated in this geopolymer structure than in the metakaolinite geopolymer


Journal Article
TL;DR: In this article, the main results of a research project on the stabilization of foamed clay with a cold-setting binder named geopolymer were presented, where the components of the material system were defined (model system) to determine the influence of the binder on the stability of the liquid and the strength of the dried and fired specimens.
Abstract: The paper presents the main results of a research project on the stabilization of foamed clay with a cold-setting binder named geopolymer. In a first step, the components of the material system were defined (model system)to determine the influence of the binder on the stability of the clay suspensions and foamed clay and on the strength of the dried and fired specimens. The hardening of the known foam clay composition was then proven. Additionally, the influence of a single addition of bloating glass granulate on the strength of the specimens was investigated. An alternative aim of this project was the determination of the property profile of insulating material prepared only with the cold-setting binder and bloating glass granulate.



Journal ArticleDOI
TL;DR: In this article, the authors used colloidal SiO 2 as an additional component to reduce the metakaolin content while keeping an optimum amount of Na 2 O, thereby increasing the compositional SiO2 /Al 2 O 3 molar ratio.


01 Jan 2004
TL;DR: In this paper, the suitability and structural characteristics of flyash-based geopolymers formed using different solid silicate industrial by-products were investigated, which indicated that it is possible to produce geopolymer using solid silicates to replace alkaline silicate solutions, thereby increasing the commercial viability of this material.
Abstract: Previous research on geopolymer technology has made use of alkaline silicate solutions to form geopolymers from solid aluminosilicates such as flyash or metakaolinite. The use of a silicate solution limits the commercial application of the technology due to ease of handling and mix-proportioning concerns. The present work therefore investigates the suitability and structural characteristics of flyash-based geopolymers formed using different solid silicate industrial by-products. XRD results indicate that the glassy phases of flyash are involved in geopolymerisation. FTIR results show a significant peak shift, which has been correlated with a restructuring of the Si-O-Al and Si-O-Si network between unreacted flyash and the geopolymer gel. Differing molar ratios of solid silicate in the samples was seen to have an effect on the FTIR peak position and therefore the network bonding of the reaction products. An increase in compressive strength was observed for samples with effective Si/Al molar ratios of 2.5, compared to a reference sample with effective Si/Al = 1.95. Results of the current work indicate that it is possible to produce geopolymers using solid silicates to replace alkaline silicate solutions, thereby increasing the commercial viability of this material.

01 Jan 2004
TL;DR: In this article, a mathematical model describing the formation of a "geopolymer," one of a class of cementitious aluminosilicate binder materials with a wide variety of potential applications in areas ranging from construction and fire-proofing to waste encapsulation, is presented.
Abstract: A mathematical model describing the formation of a 'geopolymer,' one of a class of cementitious aluminosilicate binder materials with a wide variety of potential applications in areas ranging from construction and fire-proofing to waste encapsulation, is presented. Geopolymers have enormous potential as a replacement for ordinary Portland cement in the construction industry due to the possibilities of waste utilisation and the reductions in Greenhouse emissions obtainable by their use in preference to conventional technologies. The geopolymer modelled in this investigation is synthesised by a hydrothermal technique from metakaolin and sodium silicate solution. A system of differential equations describing chemical reaction kinetics is formulated and solved, providing a simulated heat flow signal. Validation of the model is undertaken by comparison of this signal with data obtained from the literature. This work provides a basis for the optimisation of formulations and synthesis conditions for tailor-made geopolymeric materials suited to specific applications.

Book ChapterDOI
01 Jan 2004
TL;DR: In this article, a pre-composite is proposed to generate a micro-crystalline reinforcing phase during the rotomoulding heating phase to achieve better distribution of reinforcement within the polymer matrix.
Abstract: Rotational moulding has significant advantages over other methods such as injection moulding and blow moulding for the production of large hollow plastic parts but at the same time it is limited by its dependence on the use of polyethylene (PE) as the base resin. Polyethylene is suited for rotomoulding because of its thermal stability, low cost and the low melting point. However, its low mechanical strength and stiffuess must be improved to meet product requirements. Rotational moulding of fibre and/or inorganic powder reinforced polyethylene has proved to be difficult to achieve due to segregation of plastic powder and the reinforcements. In this paper, it is proposed to develop a novel hybrid organic/inorganic resin, in effect a ‘pre-composite’, which will generate a microcrystalline reinforcing phase during the rotomoulding heating phase to achieve better distribution of reinforcement within the polymer matrix. For this investigation, a formulation of inorganic mixture of “Geopolymer” is developed to form a microcrystalline phase under injection moulding with the same heating conditions as those of rotomoulding. The mixing of “Geopolymer” with polyethylene powder is achieved in such a way that the inorganic component is uniformly dispersed in the resin while rotomoulding takes place. The preliminary results show an improvement in mechanical properties of Geopolymer-PE composites. Scanning Electron Microscopy clearly shows the existence of an acicular crystalline structure in nano-scale dimension on the fracture surface of geopolymer-PE composites, which is an interesting finding. This micro-/nano-crystalline phase acts as fibre-like reinforcement that is believed to give the improvement of mechanical properties.

Journal Article
TL;DR: In this article, the effect of activation of kaolinite on geosynthesis was investigated, and the result showed that geosynthetic was occurred when the two kinds of Kaolinite were activated by the compound activator.
Abstract: Kaolinite-based geopolymer was successfully synthesized using compound activator composed of sodium silicate solution and sodium hydroxide solution at room temperature and the pressure of about 4Mpa. Mechanism of geosynthesis was studied by XRD、IR. Shape of geopolymer was observed using SEM. The effect of activation of kaolinite on geosynthesis was investigated. The result shows that geosynthesis was occurred when the two kinds of kaolinite were activated by the compound activator. Geopolymer material derived from kaolinite with high degree activation can be easily identified by XRD pattern, while that low degree activation kaolinite-based has not considerable information on the XRD pattern. SEM images indicate the geopolymer based on the two kinds of kaolinite is layer structure. Geopolymer material produced from kaolinite with high degree activation has better continuity of layer structure and more compact than that of kaolinite with low degree activation.

Journal Article
TL;DR: Inflated pearlite and calcined aluminosilicate (dolomitic mudstone) was used as main materials to prepare lightweight geopolymer with addition of a small quantity of fly ash or calcined kaolin in this article.
Abstract: Inflated pearlite and calcined aluminosilicate(dolomitic mudstone) was used as main materials to prepare lightweight geopolymer with addition of a small quantity of fly ash or calcined kaolin in this study.The product's property achieved Inflated pearlite insulation product China standard(GB/T10303-2001).Influence of several affecting factors such as material blending ratio,forming pressure,granulity gradation and temperature and time of solidifying reaction etc.on product's performance were discussed,It showed that the optimized processing condition was as follows:solid/liquid(in mass)2, pearlite/clinker(in mass) 3 and calcined kaolin/clinker(in mass) 0 or solid/liquid(in mass) 2,pearlite/clinker(in mass) 4 and calcined kaolin/cliner(in mass) 0^4.Infrared spectrum analysis show that the matrix formed by aluminosilicate gel phase probably has the similar microstructure of gelite.