Showing papers on "Geopolymer published in 2006"

Effect of Curing Temperature and Silicate Concentration on Fly-Ash-Based Geopolymerization

Abstract: The development of the pore structure of geopolymers synthesized from class F fly ash was studied using electron microscopy and porosimetry. Fly-ash-based geopolymer can be classified as a mesoporous aluminosilicate material, with a Si/Al composition varying from 1.51 to 2.24. The Si/Al composition and pore structure of fly-ash-based geopolymer vary depending on the curing temperature and the silicate ratio of the activating solutions (SiO2/M2O, M = Na or K). A higher Si/Al ratio and finer pores are obtained in geopolymers synthesized at higher temperature and silicate ratios. Elevating the curing temperature increases the extent and rate of reaction, shown through an increase in mesopore volume, surface area, and an accelerated setting time. The kinetics appears to be temperature-controlled only before the material is hardened. Very high silicate ratios (SiO2/M2O ≥ 2.0) are also believed to slow the reactions. The pore structure of K-based geopolymer is more susceptible to change in temperature than that...

Thermal evolution of metakaolin geopolymers: Part 1 – Physical evolution

Abstract: The physical evolution of materials during heating is a critical factor in determining their suitability and performance for applications ranging from construction to refractories and adhesives. The effect of different cations (sodium and potassium) on the physical evolution of geopolymeric materials derived from metakaolin is investigated for a range of specimens with Si/Al ratios between 1.15 and 2.15. It is observed that the effect of potassium is to reduce the thermal shrinkage, while thermal shrinkage increases with increasing Si/Al ratio in the presence of each alkali type. The thermal shrinkage behavior of mixed-alkali specimens is observed to change from a mean of the sodium and potassium specimens at low Si/Al ratio to behave similarly to sodium specimens at high Si/Al ratios. It is clear from this investigation that alkali cations only have a significant effect on thermal shrinkage of geopolymer at low Si/Al ratios (⩽1.65), while both Si/Al ratio and alkali cation have little effect on the extent of thermal shrinkage at Si/Al ⩾ 1.65.

Microstructure of geopolymer materials based on fly ash

Abstract: 4(4Si)and SiQ 4 (3Al) and SiQ 4 (2-3Al). Any presence of the temporary phase with different composition was not found between geopolymer and aggregate as it is at the concretes from Portland cement. Geopolymer composition is almost the same in the close nearness even in the geopolymer matrix. Elastic modulus evaluated for the mixed geopolymeric and C–S–H phase by means of nanoindentation was found to be E= 36.1 ± 5.1 GPa. Such result is comparable (a little bit higher) to ordinary Porland cement pastes.

Thermal Conductivity of Metakaolin Geopolymers Used as a First Approximation for Determining Gel Interconnectivity

Abstract: The thermal conductivities of a systematic series of metakaolin-derived Na, NaK, and K geopolymers have been measured under a range of different environmental conditions, including varied relative humidity (RH) and temperature. The thermal conductivity of geopolymers is closely linked with the specific heat, with little variation in thermal diffusivity observed in different conditions. The thermal transport properties of specimens was found to not change significantly under ambient humidity from 40 to 100 °C. The Hashin−Shtrikman model for conductivity in biphasic solids, with an extension developed by Schilling and Parstzsch, has been applied to determine the thermal conductivity of the intrinsic geopolymer binder and a first approximation of the interconnectivity of the gel.

Impact behavior and microstructural characteristics of PVA fiber reinforced fly ash-geopolymer boards prepared by extrusion technique

Abstract: A short PVA fiber reinforced fly ash-geopolymer boards (SFRFGBs) manufactured by extrusion technique is developed in this study. The effects of fly ash content and fiber volume fraction on the impact behavior of SFRFGBs are also investigated. In order to better understand the impact behaviors of SFRFGBs with different content of fly ash and fiber, Laser particle size analysis (LSA), X-ray diffraction analysis (XRD), Scanning Electron Microscope (SEM), Mercury intrusion porosimetry (MIP) are employed to explore the microstructure and failure mechanism. The experimental results show the addition of PVA fiber changes the impact failure mode from a brittle pattern to ductile pattern, resulting in a great increase in impact toughness for SFRFGBs with high volume fraction of fiber. SFRFGBs without or with low percentage of fly ash possess very high impact strength and stiffness. However, when too much fly ash was incorporated, the impact resistance of SFRFGBs is reduced obviously. This can be explained by the fact that low percentage of fly ash addition significantly improved the extrudability of fresh Geopolymer composites, resulting in a formation of very dense and compacted matrix with high-quality finish. When too much fly ash is added, the Geopolymer product is greatly reduced, resulting in a formation of very poor matrix.

Cementitious composites of pulverised fuel ash and blast furnace slag activated by sodium silicate: effect of Na2O concentration and modulus

Abstract: Pastes of pulverised fly ash (PFA) and blast furnace slag (BFS) in proportions of 100–0, 75–25, 50–50, 25–75 and 0–100 (wt-%) were chemically activated using sodium silicate with modulus (SiO2/Na2O...

39K NMR of Free Potassium in Geopolymers

Abstract: Nuclear magnetic resonance (NMR) studies of geopolymer gels have shown directly that free Na cations are present in the pore solution of some specimens. Furthermore, it has been suggested previously but not directly proven that potassium is incorporated into these materials, in preference to sodium. Here, the presence of free potassium in the pore solution of geopolymeric gels prepared without sodium hydroxide was confirmed by 39K NMR. The preferential incorporation of potassium was directly shown by the absence of free potassium in the mixed-alkali geopolymer gel.

Geopolymer composition and application in oilfield industry

Abstract: The invention provides geopolymeric compositions, which have controllable thickening and setting times for a wide range of temperatures and a large range of geopolymer slurry densities. The geopolymer slurry compositions have good mixability and pumpability, while the set materials develop good compressive strength and permeability. The invention discloses a method for preparing geopolymer for oilfield cementing applications. The geopolymeric compositions according to the invention comprises a suspension comprising an aluminosilicate source, a metal silicate, an alkali activator, lightweight or heavyweight fillers and a carrier fluid wherein the suspension of said geopolymeric composition is pumped in a well and allowed to set.

The structure and thermal evolution of metakaolin geopolymers

Abstract: ........................................................................................................................i Declaration .................................................................................................................. iii Acknowledgements ......................................................................................................v Publications from the Thesis .......................................................................................ix Table of

Modelling the formation of geopolymers

Abstract: Geopolymers are a class of X-ray amorphous alkali aluminosilicate gel binder materials with potential applications in a wide range of areas. In particular, geopolymers can provide significant improvements over traditional Portland cement technology in applications requiring resistance to acid or salt attack, or thermal stability at temperatures up to 1000°C. The quasi-zeolitic nature of some of the phases formed during geopolymerization is also of significant interest in immobilization of cationic waste streams. However, it is only recently that the structures and synthesis mechanisms of geopolymers have begun to be modeled. Microto nanostructural information has been obtained by MAS-NMR, microscopy and synchrotron pair distribution function analysis, which together have provided for the first time the ability to analyze both framework and non-framework cation sites and ordering within the geopolymer gel binder phase in detail. Comparison between the results of an empirical reaction kinetic model and data obtained by in situ energy dispersive synchrotron X-ray diffractometry is presented, and insight into the geopolymerization process and its influence on the microstructure of geopolymers is undertaken. The results presented will have significance in determining the performance of geopolymers in applications requiring controlled setting rates and rheology, or where long-term chemical stability is important. Introduction Geopolymeric materials show significant potential for utilization in a wide range of applications, including as a replacement for traditional Portland cements, as a possible encapsulant for toxic and/or radioactive wastes, and also as a relatively inexpensive yet heatresistant ceramic material [1]. However, due to their primarily X-ray amorphous nature and the high levels of impurities introduced by the use of waste materials as a solid aluminosilicate source for geopolymerization, detailed analysis of the structure and reactivity of geopolymers has historically been somewhat elusive [2]. The development of such an understanding is central to the future widespread utilization of geopolymers, particularly in waste immobilization applications where extreme durability is required, but also (and no less importantly) in the construction industry, where the ability to predict whether or not a material will retain its structural integrity over a 50 year service life under loaded conditions is critical. The experience of 200 years’ usage of Portland cements cannot be replicated in the short term in the laboratory, so the only way to persuade industry that geopolymer technology is sufficiently mature for use in construction applications is to develop a more complete, theoretically sound understanding of geopolymer properties and performance. An intensive recent research effort has provided some very significant advances in the development of such an understanding by the use of simplified model systems and the development of appropriate experimental techniques [3, 4]. Some of the results of these investigations, and their consequences for the understanding of geopolymer structure and synthesis, are discussed here. Raw Material Sources for Geopolymerization Geopolymers are formed by reaction of an alkaline solution (usually containing very high levels of dissolved hydroxide and/or silicate) with a solid aluminosilicate powder, forming an alkali-aluminosilicate gel phase with inclusions comprising unreacted solid precursor particles and/or any added fillers, for example aggregates [5, 6] or fibers [7-10]. Metakaolin, coal fly ash and blast furnace slag are the three aluminosilicate sources most commonly investigated – metakaolin primarily for higher-value ceramic-type applications due to its cost, and fly ash and slag for larger-scale concrete replacement applications. However, the calcium present in some fly ashes and in slags can greatly complicate the analysis of these systems. Synthetic aluminosilicate precursors are also used when a very high-purity raw material is necessary for analytical purposes or specific applications. Some of the analytical work presented here utilizes an aluminosilicate powder synthesized by the PVA-steric entrapment method [11], however the bulk of the results presented are for metakaolin-based systems. Extension of the results presented here to the analysis of fly ash systems is ongoing [1, 12], although modifications to some of the experimental techniques used are necessary to account for the different rheology and high impurity levels of fly ash geopolymers. The Geopolymerization Reaction Process Geopolymerization takes place via a complex multistep mechanism. The initial dissolution of the solid aluminosilicate source releases small silicate and aluminate species into the surrounding solution. These species are highly labile, and so undergo a series of rapid exchange and oligomerization reactions, also involving any silicate species that are initially present in the activating solution. As larger and larger oligomers form due to the very low water content and therefore the strong driving force for polymerization present in the system, the solution phase undergoes a gelation process. This greatly hinders the diffusive transport of dissolved species from the solid particle surfaces to the bulk of the geopolymer, meaning that in most cases unreacted aluminosilicate source particles will be present as inclusions in the binder. The structure of the gel continues to evolve and harden, eventually becoming a predominantly fully coordinated (Q) aluminosilicate network [13, 14], which is what is described as the ‘geopolymeric binder’ phase. This is clearly visible in Figure 1, which is a SEM micrograph of a polished metakaolin-based geopolymer specimen, showing the smooth binder phase, with voids where the very soft unreacted metakaolin particles have been removed during polishing. Figure 1. SEM micrograph of a geopolymer with overall (superficial) SiO2/Al2O3 = 3.90, synthesized by mixing metakaolin with sodium silicate solution. From [3]. Figure 2 presents a simplified conceptual model of some of the chemical processes occurring during the initial setting and later structural evolution of geopolymers. Figure 2. Processes occurring during geopolymerization. To develop a detailed description of the process of geopolymerization, an understanding of each of these individual steps is highly desirable, however separating the effects of a single step from the others that are happening simultaneously, in a highly constrained and rapidly-solidifying system, is quite challenging. Initial work in this field has focused on the use of model systems, in particular aluminosilicate hydrogels [15] and zeolite synthesis systems [4], to describe certain aspects of the chemistry and rheology of reacting geopolymer slurries. However, to ensure that the full range of competitive and synergistic effects between the different processes is able to be analyzed, a means of examining the process of geopolymerization as a whole – from both experimental and computational viewpoints – is necessary. Energy Dispersive X-ray Diffractometry Energy dispersive X-ray diffractometry has been carried out in situ using white-beam synchrotron radiation on a laboratory-sized geopolymer sample, characterizing the rate of geopolymerization during the first 3 hours of the reaction process. By carrying out the reactions at a temperature (~40°C) where the geopolymer is just completing the solidification step shown in Figure 2, the rate of formation of this initial geopolymeric gel phase is able to be described. It must be noted that this phase will differ structurally from the final geopolymer gel observed after extended curing, as the presence of moisture and warmth allows the gel to continue rearranging itself into a more thermodynamically favorable form, involving very high degrees of crosslinking and also the formation of nanosized crystallites. These two stages of gel evolution, Dissolution of solid aluminosilicate source Rearrangement and exchange between dissolved units Silicate species in activating solution

Geopolymer formation and its unique properties

Abstract: The characteristic property of naturally-occurring geopolymers is a high content of humic materials that are recognized by the nitrogen function Through a simulated geopolymerization, biopolymers with non-nitrogen function, such as xanthan gum, were found to have the characteristics of humic acid by means of UV–Vis spectrometry This fact ascertains that any kind of biopolymer may naturally transform to a geopolymer A geopolymer is a type of crosslinked long-chain compound, built in three-dimensional structures whose property is immune to microbial degradation A crosslinked biopolymer was shown to have the same characterization as a geopolymer that has a long life due to its crosslinking capacity and anti-microbial properties In this study, the formation of petroleum-based geopolymers (eg, kerogen) was introduced This study may elucidate the structure of geomacromolecules and the mechanism of their formation, closely related with crosslink reaction between inorganic and organic molecules This will further change the conventional definition of geopolymer that involves only the inorganic geopolymer

Fixation of heavy metals in geopolymeric materials based on brown coal fly ash

Abstract: The alkali-activated brown coal fly ash - geopolymer - can be used as a matrix for the fixation of heavy metals. The addition of heavy metals does not result in any substantial extension of the setting time as this happens in the case of Portland cement. The materials prepared by the alkali activation of fly ashes exhibit measurable properties in contrast to some cement mixes containing heavy metals. In contrast to the Portland cement mixes, the strength values ofAAfly ashes containing metal admixtures (Zn 2+ , Cu 2+ , Cr 3+ , Cd 2+ and Pb 2+ ) do not drop in the time horizon of 180-520 days. The IR and NMR spectroscopy corroborate the penetration of aluminium ions into the original Si-O-Si structure (AlQ 4 (4Si), AlQ 2-3 (2-3Si) and Si(3Al) units). The salts of heavy metals are distributed uniformly within the geopolymer body. The leaching values characterizing the mixes containing salts of heavy metals are not the same for the individual investigated metals (Zn 2+ , Cu 2+ , Cr 3+ , Cd 2+ and Pb 2+ ) and they vary within the ranges of the 1 st -3 rd class of durability (as per regulations valid in the Czech Republic). The best results could be achieved for the zinc fixation when the solidification in Portland cement was practically impossible. The resistance ofAAfly ashes to leaching is influenced significantly by the presence of calcium ions in the geopolymer matrix.

Adhesion of glass to steel using a geopolymer

Abstract: Many potential and actual uses for geopolymers (GPs) have been listed, such as waste encapsulation, refractories, fire resistant paneling, sewer pipes, building products, and acid-resistant coatings [1]. Other proposed technical uses include fire protection coatings as applied to concrete [2]. Understanding the nature of bonding of GPs to other materials is desirable if GPs are to be applied as protective coatings or adhesives. Two common methods of making GPs are to add fly ash or metakaolinite (MK: kaolinite heated to ∼750 ◦C to render it amorphous) to concentrated alkali solutions for reaction and subsequent polymerization to take place. The GPs produced consist of amorphous to semi-crystalline three-dimensional aluminosilicate networks [3]. For industrial applications, the use of fly ash as a precursor gives a cost advantage over MK. However to understand the science of the polymerization process, the use of the latter is preferred. It has been reported that ball milling the aluminosilicate precursors up to 4 hr improves the compressive strength of GPs [4]. In the present work, we attrition-milled the MK, which is a more effective method of milling than ball milling, to determine the effect on the compressive strength. Furthermore, we examined the adhesion of stainless steel to glass using GPs derived from the milled MK and determined the interfacial fracture energy by a fracture mechanics approach. The MK was produced by heating kaolinite (Kingwhite 80, Unimin, Australia) at 750 ◦C for 15 hr in air. An MKwater slurry was attrition-milled at 300 rpm with 5 mm zirconia balls for 30, 60 and 120 min. The milled slurry was dried in a stainless steel pan at 40 ◦C for 5 days. The particle size distributions of each batch, including the unmilled sample were determined using laser diffraction techniques (Mastersizer 2000, Malvern Instruments Ltd., UK) and are shown in Fig. 1. The MK exhibits a bimodal distribution and the amount of fines (∼0.18 μm) increased with milling time. The 30 min milling time reduced the coarse particle size from 8.7 to 4.4 μm and doubled the volumes of fines. A further 30 min again reduced the coarse particles to 2.9 μm and increased the fines. Additional milling for 60 min did not

Cementitious materials including slag and geopolymers

Abstract: Cementitious materials including 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 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.

Geopolymer composites and structures formed therefrom

Abstract: Geopolymer composite materials having low coefficient of thermal expansion are disclosed. The materials are useful in high temperature applications due to their low coefficient of thermal expansion and high strength. Also disclosed is a boron modified water glass geopolymer composition that is compatible with ceramic particulate material such as cordierite and fused silica. The geopolymer composite may be extruded to form structures such as honeycomb monoliths, flow filters or used as a plugging or skinning cement and may be fired at temperatures at or below 1100° C. Both the structures and the cement have high green and fired strength, a low coefficient of thermal expansion, and good acid durability. The cost of manufacturing objects using the material of the present invention is substantially reduced, in comparison with typically production methods of cordierite based bodies, due to the substantially shortened firing times.

Immobilization of Cs and Sr in geopolymers with Si/Al molar ratio of ∼ 2

Abstract: Geopolymers with Si/Al ∼ 2 were made by dissolving fly ash or metakaolinite in alkali solutions and polymerizing them by curing below 90°C. 1 and 5 wt% Cs and Sr were added as the nitrates or hydroxides separately. The geopolymers were characterized by X-ray diffraction analysis, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). PCT tests were carried out on selected materials which were heated to temperatures as high as 900°C. Many of the materials passed the PCT test and the most leachable ions were Na and K, with Cs and Sr being considerably more resistant. Fly ash-containing geopolymers can immobilize 1 wt% Cs and Sr effectively and this applies also when they are heated from ambient to as high as 900°C. The Na leach rates of the unheated samples just exceed the limit of 13.5 g/L specified in the PCT- B test. However, metakaolinite-based geopolymers have much lower leach rates for Na and K (< 6.9 g/L). Also the leach rates for Cs and Sr are also much lower (< 1.3 g/L) than than those for the fly ash based geopolymers. Most of the Cs was incorporated into the amorphous geopolymer matrix for the geopolymer with 5 wt% addition as shown by SEM/EDS.

Radioactive Metal Isotopes Stabilized in a Geopolymer Matrix: Determination of a Leaching Extract by a Radiotracer Method

Abstract: The stabilization of radioactive metal ions in inorganic polymer matrices of aluminum silicates, also called geopolymers, is demonstrated. The strength of the metal–ion bonds was then tested by leaching in water and sulfuric-acid solutions. The experiments were carried out by the radioactive-tracer method with 152Eu, 134Cs, 60Co, and 59Fe isotopes.

Study on Abilities of Mineral Admixtures and Geopolymer to Restrain ASR

Abstract: This paper deals with the effect of mineral admixtures and Geopolymer on preventing excessive expansion due to alkali-silica reaction (ASR). The test method used was ASTM C 441-97. Expansions of mortar-bars were measured at 14, 56, 90 days. The results prove that mineral admixtures can effectively restrain ASR. When three kinds of mineral admixtures, silica fume, fly ash, and ground granulated blast-furnace slag (GGBS), were used together, they bring about a compound effect which is more effective to restrain ASR. Mortar expansion can be reduced 81.9 % by this compound effect. Chemical analysis of the pore solution shows that mineral admixtures reduced concentrations of hydroxyl, potassium and sodium ion, so that damages from ASR decreases. Geopolymer, an amorphous inorganic material, was prepared with metakaolin and other mineral admixtures in the condition of high pH. Alkalis fixed in the framework of Geopolymer, there are no enough alkalis to react with active aggregates. Geopolymer does not generate any dangerous alkali-silica reaction even with alkali contents as high as 12.1 %.

Nano- and Microporosity in Geopolymer Gels

Abstract: Extended abstract of a paper presented at Microscopy and Microanalysis 2006 in Chicago, Illinois, USA, July 30 – August 3, 2005

Geopolymer dry powder regenerated polystyrene heat preservation and heat insulating mortar

Abstract: The heat insulating mortar consists of earth polymer powder 48-54 wt%, regenerated polystyrene grain 5-8 wt%, flyash 28-30 wt%, latex powder 8-10 wt%, polypropylene fiber 020-035 wt%, and functional additive 3-4 wt% The present invention adopts earth polymer powder to replace Portland cement as inorganic cementing material, and the heat insulating mortar has high strength, low shrinkage, high resistance to acid and alkali corrosion, environment friendship and other advantages

Study on the Solidification of Heavy Metals by Fly Ash Based Geopolymers

Abstract: By using fly ash as basic ingredient, a series of fly ash based geopolymeric matrices were synthesized and some experimental evidences about immobilization efficiencies of heavy metals such as Cu(Ⅱ),Zn(Ⅱ),Pb(Ⅱ),Cd(Ⅱ),Cr(Ⅲ) and Ni(Ⅱ) were presented. According to the toxicity characteristic leaching procedure (TCLP), it is found that these heavy metals can be effectively solidified into the geopolymeric matrices. Through the results of X-ray diffraction (XRD), scanning electron microscopy (SEM) and infrared spectroscopy (FTIR), it is concluded that the solidification mechanism of geopolymer to these heavy metals is a combination of chemical bond and physical encapsulation.

A process for the production of reactive blast furnace slag

Abstract: The invention particularly relates to a process for increasing the reactivity of ground granulated blast furnace slag using surface activation through short mechanical activation time (10-60 min) and it starts to hydrate in short time (48 h or less) when mixed with water without any chemical additive and completely hydrates in maximum 28 days forming cementitious product. The products produced by the process of present invention may be of different particle sizes and shapes, different specific surface areas, different surface charge (Zeta potential) and different reactivity. The reactive blast furnace slag shall be useful in Portland Slag Cement (PSC), Geopolymer, immobilisation and stabilisation of toxic wastes and newer nano-composite materials.

Dynamic mechanical properties of geopolymer-polymer composites

Abstract: Dynamic mechanical properties and rheology of the organic polymer modified inorganic polymer systems synthesized from metakaolin were studied and evaluated. These inorganic polymers, popularly known as geopolymers, possess a set of excellent characteristics which includes high compressive strength, high temperature and fire resistance, acid resistance, heavy ion fixation, low temperature curing, good surface finish, low cost raw materials and are environment friendly. Geopolymers are a relatively new class of engineering materials and are in the process of finding their way to industrial products. A few of the problems that are holding back the development of these materials are the control of curing rime, enhancement of their workability and knowledge of the dynamic mechanical properties of these systems. In this project the control of curing time, improvement in the workability and modification of the rheology was achieved by addition of organic polymers including poly (ethylene glycol) and carboxy methyl cellulose, to the geopolymer system. The dynamic mechanical properties of these systems were evaluated using dynamic mechanical analysis for the cured systems in the plaque form and a rheometer for the uncured systems as slurries. The effect of organic polymers on the geopolymer system was quantified using the same techniques. Poly (ethylene glycol) is commercially used as a plasticizer to increase the lubricity of the ceramic mass and has excellent spreading properties. Carboxy methyl cellulose, a modified polysaccharide, is commercially used as a viscosity modifier and has an excellent water retention capacity. These two organic polymers were added to the geopolymer system with an aim ofmodification of rheology, processability and dynamic mechanical properties before and after curing. Addition of these polymers to the geopolymer system varies the curing time of these systems in the range of 4 hours to 72 hours. Also the rheology of the uncured slurries is changed. This was quantified using the theological studies that show increase in the elastic and viscous moduli of the slurries after addition of the organic polymers. The elastic modulus varied between the range of 7 Pa to 54,600 Pa depending on the polymer and water content. Similarly, the viscous modulus also varied between 1 6 Pa and 25,400 Pa. The increase in the elastic modulus of the uncured slurry is significantly more than that of viscous modulus. The viscosity of these systems with respect to time and shear rate was also observed and showed change after addition of organic polymers. The viscosity varied within the range of 4 Pa.s to 580 Pa.s depending on polymer and water content. The composite slurry exhibited thixotropic behavior. These uncured slurries were cured to form cheesecloth-reinforced plaques. These plaques were used to study their elastic and viscous moduli with respect to temperature using the dynamic mechanical analysis technique. The results are encouraging and showed improvement in the moduli of the systems after addition of organic polymers for a selective loading range. But largely addition of organic polymers had a negative impact on the dynamic mechanical properties of geopolymer system. Addition of organic polymers also imparted flexibility to the cured samples opposing to the brittle nature of the pure geopolymer systems.

Formation of Nanocrystalline Zeolites in Geopolymer Gels

Abstract: Extended abstract of a paper presented at Microscopy and Microanalysis 2006 in Chicago, Illinois, USA, July 30 – August 3, 2005