THE DEVELOPEMENT OF GEOPOLYMER SCIENCE AND … · Sunday, May 24, 2015 Opening Plenary Speech THE...

Sunday, May 24, 2015 Opening Plenary Speech

THE DEVELOPEMENT OF GEOPOLYMER SCIENCE AND TECHNOLOGIES

Joseph Davidovits, Geopolymer Institute, [email protected]

Key Words: geopolymer science, discovery, terminology, applications. The geopolymer science and technology that I created 36 years ago (1979) seems to be on the rise. Figure 1 shows the evolution of the number of papers published per year on the topic - 1991: 2 scientific publications - 2013: 407 scientific publications (others are claiming 470 publications)

In the late 1970’s, I coined the term “geopolymer” to classify the newly discovered geosynthesis that produces inorganic polymeric materials now used for a number of industrial applications. I also set a logical scientific terminology based on different chemical units, essentially for silicate and aluminosilicate materials. The atomic ratio Si:Al in the poly(sialate) structure determines the properties and application fields. A low ratio Si:Al (1,2,3) initiates a 3D-Network that is very rigid. A high ratio Si:Al, higher than 15, provides polymeric character to the geopolymeric material.

In our development of

geopolymer chemistry, the research was applications driven and generated numerous patents in the 1980-1990's, yet few scientific publications at that time. One third of my book Geopolymer Chemistry and Applications (2008, 3rd ed. 2011), is dedicated to applications. Several products are industrialized and commercialized, some of them since 1985. See at the Geopolymer Institute internet site, the page Who is selling geopolymers: -Geopolymer Precursors: metakaolin, slag, soluble silicates. -Geopolymer Resins, paints, binders, grouts: acid resistant, fire resistant -Geopolymer cement, concrete, waste management, global warming: user-friendly systems- manufacturing of Geopolymer cements emits 80 to 90% less CO2 than Portland Cement. - ideal for environmental applications, such as the permanent encapsulation of radioactive and other hazardous wastes, toxic metals, as well as sealants, capping, barriers, and other structures necessary for remedying toxic waste containment sites. - building and repairing infrastructure with very high early strength, - corrosion resistant (salts), acid resistant, fire resistant (tunnels, etc.). - Geopolymer specialties: non-ferrous industries and metallurgy. - Geopolymer ceramics: - Geopolymer high-tech/ fiber reinforced fire- and heat resistant composites: aeronautic and automobile applications, defense, World champion in Formula 1 racing cars since 2000. 85% of present R&D is focusing on civil engineering, cements and concretes applications, essentially in emerging countries. This explains the exponential increase in publications related to civil-engineering and construction. The other 15% relate to specialized knowledge, niche applications in the field of paints, ceramics, medicinal applications, fire resistance, heat resistance, etc.

Figure 1 – Evolution of scientific papers published per year on geopolymer

http://www.geopolymer.org/about/business-fellows

Monday, May 25, 2015 Keynote

EFFECT OF NON BRIDGING OXYGEN ATOMS OF ALKALINE SOLUTION ON GEOPOLYMER FORMATION

Ameni GHARZOUNI, Science des Procédés Céramiques et de Traitements de Surface (SPCTS), 12 rue

Atlantis, 87068, Limoges Cedex, France [email protected]

Emmanuel JOUSSEIN, Université de Limoges, GRESE, EA 4330, 123 Avenue Albert Thomas, 87060 Limoges, France

Samir BAKLOUTI, Laboratoire de Chimie Industrielle, Ecole Nationale d’Ingénieurs de Sfax, 3038, Sfax, Tunisie

Sylvie ROSSIGNOL, Science des Procédés Céramiques et de Traitements de Surface (SPCTS), 12 rue Atlantis, 87068, Limoges Cedex, France

Key Words: geopolymer, alkaline solution, non bridging oxygen atoms, depolymerization

Over the last decades, geopolymers have gained tremendous interest as promising new binders, environmentally friendly and with good working properties. These ecomaterials result from the activation of an aluminosilicate source by an alkaline solution. Elucidation of the interaction of the alkaline solution with the aluminosilicate source requires a deeper comprehension of the geopolymerization mechanism and the parameters that can affect it. The objective of this work is to study the effect of the alkaline solution reactivity and metakaolin properties on the geopolymer formation. For this purpose, several geopolymer samples were synthesized from various alkaline solutions and metakaolins that differ in term of reactivity. The structural evolution of the reactive mixtures was investigated using FTIR and 27Al NMR spectroscopies during the formation. The measurement of mechanical strength was tested by compression.

The results allow to evidence that the type and the amount of siliceous species and non bridging oxygen atoms controls the alkaline solution reactivity. The effect of metakaolin reactivity is more significant when activated with a poorly reactive alkaline solution. However, the alkaline solution governs the reaction when it is highly reactive. Therefore, the extent of depolymerization of the alkaline solution and the reactivity of the metakaolin are crucial parameters that control the rate of polycondensation and the mechanical properties of the geopolymer materials.

mailto:[email protected]

Monday, May 25, 2015 Session I

CHARACTERIZATION AND CLASSIFICATION OF PRECURSORS FOR ALKALI-ACTIVATED MATERIALS (AAMS)

Caijun Shi*, Lei Jiang, Zhihua Ou, Jian Zhang, Jiake Zhang

College of Civil Engineering, Hunan University, Changsha, China

* Corresponding author: [email protected] Early studies and applications mainly used blast furnace slag, fly ash, and metakaolin as precursors for alkali-activated materials (AAMs). If the precursor has a high content of calcium, it can be used to produce an AAM showing high strength development rate at room temperature. On the other hand, AAMs made with low calcium precursors need elevated temperature curing to achieve desirable strength development rate and ultimate strength. Recent studies have greatly widened the sources and types of precursors used, which include: (1) special metallurgical slag, (2) mineral processing tailings, (3) catalyst residues, (4) coal bottom ash, (5) agricultural ash, (6) waste glass, (7) waste ceramic, (8) sludge ash, and (9) natural minerals. Some of them can be sued directly; some of them may need thermal and/or mechanical activation before being used as precursors. This study analyzed the chemical and physical characteristics of these materials, and proposed relationship between their structural characterization and reactivity in alkali-activated materials, which will be helpful in selection and preparation of proper precursors for AAMs.


USE OF CLAY SEDIMENT AND WATER PURIFICATION SLUDGE IN THE MANUFACTURE OF GEOPOLYMER BUILDING BLOCKS

Claudio Ferone, University Parthenope of Naples, Italy

[email protected] Giuseppina Roviello, University Parthenope of Naples, Italy

Francesco Colangelo, University Parthenope of Naples, Italy Bruno Molino, University of Molise, Italy

Raffaele Cioffi, University Parthenope of Naples, Italy

Key Words: Clay sediment, sludge, reservoir, blocks. In the last decades many scientific papers have been published on the synthesis, characterization and utilization of geopolymer materials based on solid wastes. The manufacture of these materials takes place by alkali-activated polycondensation of the reactive aluminosilicate fraction whose presence often derives from thermal treatment of clay materials at 600-700°C. To improve sustainability of these materials a proper raw materials selection should be carried out. From this point of view, the use of kaolin (that when fired give reactive metakaolin) can be successfully replaced by clay-containing wastes such as lake and reservoir sediments. The management of reservoir sediments is of major relevance from various points of view, especially from the quantitative one. In fact, there are 7,000 large reservoirs in the European Union, of which 564 are located in Italy. In this work reservoir sediment and water purification sludge were collected from the same site locate in Molise (Southern Italy). The wastes have been characterized from chemical and mineralogical point of view. The sediments mainly contain clay minerals, quartz and calcite and the sludge are mainly composed of quartz, calcite, gibbsite and aluminum silicate hydrate. They have both been employed after thermal activation for 2 hours at 750° C. Three mixtures with different sludge/sediment weight ratios have been prepared. Specifically, ratios equal to: 70/30, 50/50 and 30/70 have been studied (Table 1). Two series of polyethylene cylinders containing solid precursors and activation solution have been pre-cured for 24 hours at room temperature and for 24 hour at 60°C, respectively. The hardened specimens have been characterized from chemical and physico-mechanical point of view after 7 and 28 day room temperature curing. Table 1 – Chemical composition of mixtures, wt%

Mixtures (% w/w) % SiO2 % Al2O3 % CaO % Fe2O3 %Na2O

70 sludge/ 30 sediment 48,89 31,09 6,70 6,43 0,45

50 sludge/ 50 sediment 51,35 27,63 7,34 6,66 0,54

30 sludge/ 70 sediment 53,81 24,18 7,97 6,88 0,56 The tested mixture showed promising mechanical strength, ranging between 11 and 22 MPa, even after 7 day curing. The results are of interest for manufacture of preformed building blocks.


CORRECTING FOR ALUMINIUM IN BENTONITE

I. García-Lodeiro1*, N. Cherfa, A. Fernández-Jimenez1 and A. Palomo1

1. Cement and Recycling Materials Department, Instituto Eduardo Torroja (CSIC), Madrid, 28033, Spain

[email protected], Tel +34-913020440 (Ext 337), Fax +34-913020700 The alkaline activation of aluminosilicates, primarily fly ash and metakaolin, is a consolidated methodology that has driven the development of binders that perform as well or better than ordinary Portland cement. The use of these two raw materials is subject to constraints, however: the lack of uniformity in the former and the high cost of the latter. The present study assessed the reactivity of bentonite, an aluminosiliceous material. To that end, bentonites differing in mineralogy and chemical composition were activated with 8-M NaOH at 85 °C for 20 hours. De-hydroxylated bentonites hardened well, giving rise to materials with cementitious properties. The shortfall in reactive aluminium in the original material (high SiO2/Al2O3 ratios) was corrected by adding 10 or 20 wt% sodium aluminate. The addition of this reagent was observed to raise the mechanical strength of the activated bentonite. The primary reaction product was found to be a (N,C)-A-S-H gel in all the cases studied, with zeolites as the secondary products.


INFLUENCE OF GIBBSITE AND QUARTZ IN KAOLIN ON THE PROPERTIES OF METAKAOLIN-BASED GEOPOLYMER CEMENTS

H.K. Tchakoutea,b*, C.H. Rüscher b, J.N.Y. Djoboa, B.B.D. Kennea,, D. Njopwouoa

aLaboratory of Applied Inorganic Chemistry, University of Yaounde I, Faculty of Science, Department of Inorganic Chemistry, B.O. Box 812 Yaounde-Cameroon

bInstitut für Mineralogie, Leibniz Universität Hannover, Callinstrasse 3, D-30167 Hannover, Germany

Three different kaolins (K1, K2, K3) from sources in Cameroon were applied for producing geopolymer cements. The kaolins differ significantly in their gibbsite and quartz contents. Thermal transformation (700°C, 4h) into their metakaolins MK1, MK2, MK3 shows the total loss of crystalline kaolinite and reveal the typically rather broad bump in the X-ray pattern. Gibbsite becomes dehydrated into γ and χ-Al2O3. Geopolymer cements (GP1, GP2, GP3) were obtained using freshly prepared sodium silicate solutions (NWG) with a ratio NWG/MK = 0.87. It could be observed that the initial (60/80/90 min) and final (90/140/160 min) setting time increases and their 28 days compressive strength (49/39/30 MPa) decreases in the course GP1/GP2/GP3. It is discussed that the higher content of quartz in K1 (up to 22 wt%), compared to K2 (10 wt %) and K3 (8 wt%) promotes higher strength values and decreased setting times. Gibbsite not present in K1, but up to 11 wt% in K2 and 28 wt % in K3, transformed in its dehydrated forms remains unreacted during geopolymerization. Therefore, the higher content of gibbsite in the kaolinite could be related with a lower strength. The reacted volumes and compositions of the geopolymer becomes almost the same in all three cases. A content of 30-50% of unreacted metakaolin was proved in all cases. Keywords: Kaolin, gibbsite, metakaolin, γ-and χ-Al2O3, geopolymer, compressive strength Table 1 Initial and final setting times and compressive strength of fresh and hardening geopolymers pastes respectively.

Samples

Initial setting time (min)

Final setting time (min)

Compressive strength (MPa)

GP1 60 90 48.8 ± 2 GP2 80 140 38.7 ± 2 GP3 90 160 30.2 ± 2

Fig. 1. XRD pattern of samples GP1, GP2, GP3 in comparison to heated gibbsite and quartz. I and A denotes

peaks of illite and anatase, respectively. References Favaro, L., Boumaza, A., Roy, P., Ledion, J., Sattonnay, G., Brubach, J.B., Huntz, A.M., Tetot, R., 2010.

Experimental and ab initio infrared study of χ-, k- and α-aluminas formed from gibbsite. Journal of Solid State Chemistry 183, 901–908.

Huertas, F.J., Fiore, S., Linares, J., 1997. Thermal analysis as a tool for determining and defining spherical kaolinite. Clays Clay Miner. 45, 587–590.


27Al AND 29Si MAS-NMR STUDY OF SPECIES DISSOLVED IN ALKALI-ACTIVATED FLY ASH

M. Criado1, A. Palomo2 A. Fernández Jiménez2

1Instituto de Ciencias de Materiales (CSIC), Cantoblanco, 28049 Madrid

2Instituto de Ciencias de la Construcción Eduardo Torroja (CSIC), Serrano Galvache 4, 28033 Madrid In alkali-activated fly ash systems, the condensation reactions between aluminate and silicate species or between silicates may be highly impacted by the concentration and degree of polymerization of the silica used in the alkaline activator (waterglass). In the present study, 29Si and 27Al MAS-NMR techniques were used to explore such condensation and polymerization in the early stages (5 minutes, 1 and 3 hours) of the reaction between the waterglass solution and the ash. To that end, silicate and aluminate species were studied in the liquid phase of fly ash pastes activated with three waterglass solutions (W15 with SiO2/Na2O = 0.19, W50 with SiO2/Na2O = 0.69 and W84 with SiO2/Na2O = 1.17). In system W15, reactions between aluminate and silicate species formed polysialate structures, while in system W50, in addition to the aluminate-silicate species reactions, some of the silicates reacted among themselves, giving rise to poly(sialate-silox) structures. Lastly, in system W84 reactions between silicate species were favored over reactions between aluminates and silicates, with the formation of poly(sialate-disilox) structures.

Monday, May 25, 2015 Session II

GEOPOLYMERIZATION FROM LIQUID STATE TO POROUS MATERIAL

Prune Steins, CEA, DEN, DTCD, SPDE, LP2C. [email protected]

Fabien Frizon, CEA, DEN, DTCD, SPDE, LP2C. Arnaud Poulesquen, CEA, DEN, DTCD, SPDE, LP2C. Virginie Benavent, CEA, DEN, DTCD, SPDE, LP2C.

Olivier Diat, CEA, DSM, ICSM

Key Words: Structuration, Porosity, Rheology, Formulation Many studies have shown that the formation of geopolymers proceeds according to a mechanism of dissolution - restructuring - polymerization resulting in a solid material and the present paper aims at propose new insights on these reactions. First, the behaviour of the geopolymer at the liquid state is described by using rheological and small angle X-ray and neutron scattering (SAXS, SANS) techniques. It is shown that the appearance of the percolating network (increase of the viscoelastic modulus, G’ and G’’ in figure 1) essentially depend on the formulation parameters at room temperature. Aggregation phenomenon and spatial arrangement of oligomers will be described by original rheological method named Time-Frequency Resolved Rheology (TF2R). Moreover, as shown in figure 1, the geopolymerization reactions continue several hours after the appearance of the percolating network by the formation and the densification of the mesoporous network. Then the influence of the formulation parameters, and more specifically the alkali cation, on the nature of the mesoporous network is described. The pore size and the specific surface area depend indeed on the chaotrope nature of the alkali cation (the pore size decreases and the surface specific area increases with Cs, K and Na). Solid geopolymers evolve over time due to the composition of the poral solution embedded within the pores. By contrast variation in neutron scattering technique correlated to sorption-desorption isotherms, it is possible to show that closed porosity appear over time.

Figure 1- Evolution of the x-ray and neutron scattering intensity and the viscoelastic parameters as a function of time


EFFECT OF MECHANICAL ACTIVATION OF FLY ASH ON GEOPOLYMER PROPERTIES

Gábor Mucsi, Institute of Raw Material Preparation and Environmental Properties, Hungary [email protected]

Zoltán Molnár, Institute of Raw Material Preparation and Environmental Properties, Hungary Imola Osváth, Institute of Raw Material Preparation and Environmental Properties, Hungary

Sanjay Kumar, CSIR- National Metallurgical Laboratory, India Key Words: fly ash, mechanical activation, geopolymer. Industrial wastes such as fly ash, slag and red mud are produced in huge amount worldwide due to the increasing energy and materials demand. Among these, fly ash is the most abundantly available by-product generated due to combustion of coal in thermal power plants. In practice, fly ash is transported using water and deposited in ash ponds along with bottom ash and other waste of power plants. Thus apart from annual generation, there is huge inventory of deposited fly ash. Majority of the research focus on use of fly ash is directed towards the fresh fly ash. Deposited fly ash, due to its blending with other discharged materials, are often less reactive and has been paid low research attention. In present research a deposited brown coal fly ash was used as raw material for geopolymer. The reactivity of the fly ash was altered using mechanical activation, which is one of the promising methods to improve bulk and surface reactivity. The mechanical activation experiments were carried out in a high energy density mill using 5 m/s circumferential speed and residence times (1, 3, 5, 10 and 15 min). The effect of mechanical activation on particle size distribution was measured by a laser particle size analyzer and structural changes using FT-IR. Geopolymer samples were prepared from mechanically activated fly ash with alkali solution. The progress of geopolymerization was monitored using an Isothermal Conduction Calorimeter. The heat flow curve obtained indicated that reactions were more prominent and started much earlier in the mechanically activated samples. This observation is further supported by the compressive strength results which also improved in geopolymers using mechanically activated fly ash. Based on the obtained results, it can be infer that mechanical activation is a possible way to enhance the reactivity of fly ash and consequently properties of resulting geopolymers.


REACTION KINETICS STUDY OF FLY ASH GEOPOLYMER

Susanta Kumar Nath, CSIR- National Metallurgical Laboratory, Jamshedpur 831007, India Saikat Maitra, Govt. College of Engineering & Ceramic Technology, Kolkata - 700010, India

Siddhartha Mukherjee, Jadavpur University, Kolkata-700032, India Sanjay Kumar, CSIR- National Metallurgical Laboratory, Jamshedpur 831 007, India

Key Words: Fly ash, Geopolymer, Reaction kinetics, Activation energy, Microstructure Geopolymer is a synthetic material consisting of three dimensional networking of alumina and silica tetrahedron. Due to its binding properties, it has been emerged as an alternative to Portland cement in building and construction applications. Out of several natural and synthetic precursors for the preparation of geopolymer, fly ash, which is a byproduct of coal fired power plant, has been proved to be a formidable one. Majority of the studies on the reaction kinetics of geopolymers are based on metakaolin due to its high purity. Geopolymerization of fly ash is relatively complex reaction due to its heterogeneous characteristic which often leads to additional reaction path. In this work, we have made an attempt to study the kinetics parameters using isothermal conduction calorimetry. For obtaining the heat evolution curve the fixed parameter used was alkali concentration of 6M NaOH solution and variable parameter of temperature ranging between 40–60oC. Fly ash powder to alkali solution ratio was fixed as 2:1 for all the experiments. The effect of temperature on the peak behavior such as peak intensity and area under peak was recorded. The shifting of peak towards lesser time, increase in peak intensity and area with temperature clearly indicates the faster and more reaction. From calorimetric data reaction conversion fraction (α) verses time graph was plotted. Kinetic parameters like activation energy (Ea), pre-exponential function (A) and reaction rate (k) was measured. The measurement of activation energy from Arrhenius plot has been presented in Fig. 1 as given below. It has been observed that reaction temperature enhanced the reactivity of fly ash leading to the formation of higher amount of geopolymeric gel. An attempt has been made to correlate the reaction kinetics with mechanical properties and microstructural features.

Figure 1: Arrhenius plot for evaluating kinetic parameters

3.00 3.05 3.10 3.15 3.20

-8.4

-8.0

-7.6

-7.2

-6.8

-6.4

lnk

1000/T (1/K)

Slope = -9.188Ea = 75.65 KJ/mole


NOVEL HYBRID MATERIALS BASED ON POLYSILOXANES AND GEOPOLYMERS

Giuseppina Roviello, Department of Engineering, University of Naples ‘Parthenope’, INSTM Research Group Napoli Parthenope, Centro Direzionale Napoli, Isola C4, Napoli 80143, Italy

[email protected] Costantino Menna, Department of Structures for Engineering and Architecture, University of Naples Federico II,

Napoli 80125, Italy Oreste Tarallo, Department of Chemical Sciences, University of Naples Federico II, Complesso Universitario di

Monte S. Angelo, via Cintia, 80126 Napoli, Italy Laura Ricciotti, University of Naples ‘Parthenope’, INSTM Research Group Napoli Parthenope, Centro

Direzionale Napoli, Isola C4, Napoli 80143, Italy Claudio Ferone, University of Naples ‘Parthenope’, INSTM Research Group Napoli Parthenope, Centro

Direzionale Napoli, Isola C4, Napoli 80143, Italy Francesco Colangelo, INSTM Research Group Napoli Parthenope, Centro Direzionale Napoli, Isola C4, Napoli

80143, Italy Domenico Asprone, Department of Structures for Engineering and Architecture, University of Naples Federico II,

Napoli 80125, Italy Raffaele Cioffi, University of Naples ‘Parthenope’, INSTM Research Group Napoli Parthenope, Centro

Direzionale Napoli, Isola C4, Napoli 80143, Italy

Key Words: hybrid, geopolymer, siloxanes, metakaolin, fire resistance. New hybrid materials with no phase separation up to nanometric level were obtained by performing the in situ co-reticulation of an aluminosilicate source (metakaolin), a mixture of dialkylsiloxane oligomers with different degree of polymerization and an alkaline solution by exploiting their chemical similarity. Microstructural analyses pointed out a structural homogeneity of these materials up to nanometric level, suggesting that, thanks to their chemical similarity, strong interactions are present between siloxane and inorganic geopolymer units. This hybrid structure turned out in significantly enhanced compressive strengths and toughness of the samples in respect to those of neat geopolymers and organic-inorganic geopolymer composites. Moreover, the chemical nature of silicone ensures a good thermal stability and fire resistance to the final

material, despite the high content of dimethylsiloxane units (up to 15% wt). In fact, similarly to the neat geopolymer, these new materials are not flammable and do not produce smoke. At variance from analogous materials obtained by sol-gel approaches, that are much more expensive and require a fine control of the experimental conditions, in the case of the described hybrids materials, the very simple and inexpensive procedure used for their obtainment and the interesting technological properties suggest possible applications for these materials even on a large scale, such as the realization of thermo-resistant and thermo-insulating panels.

Figure 1: Average compressive strength for the tested samples References: Kickelbick, G., 2007. Introduction to Hybrid Materials, in Hybrid Materials: Synthesis, Characterization, and Applications (ed G. Kickelbick), Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, Germany; Ferone, C.; Roviello, G.; Colangelo, F.; Cioffi, R.; Tarallo, O. Novel Hybrid Organic-Geopolymer materials. Appl Clay Sci 2013, 73, 42-50; b) Roviello G., Ricciotti L., Ferone C., Colangelo F., Cioffi R., Tarallo O. Synthesis and Characterization of Novel Epoxy Geopolymer Hybrid Composites Materials 2013, 6, 3943-3962; c) Colangelo F, Roviello G, Ricciotti L, Ferone C, Cioffi R. Preparation and characterization of new geopolymer-epoxy resin hybrid mortars. Materials 2013;6:2989-3006.

Monday, May 25, 2015 Session III

FIRE RESISTANT FLY ASH-BASED GEOPOLYMERS

L Vickers, A van Riessen, W Rickard, Geopolymer Research Group

Curtin University, Perth, 6845, Australia; E-mail: [email protected]

Resistance of geopolymers to fire exposure is managed by the techniques used to control thermal expansion/shrinkage events and loss of volatiles, predominantly water, to leave a post fire material in a serviceable condition.

However, to optimise geopolymer fire resistant products there is a need to first understand the role of fly ash alumino-silicate precursors and activating solution composition in influencing the microstructure and thus ultimately their response to high temperatures. In this paper the influence of Si:Al in controlling the response of geopolymer to elevated temperatures will be discussed. The thermal properties of fly ash based geopolymers will be presented along with a discussion about the impact of the addition of fibers and fillers to control thermal expansion. The thermal expansion of the fillers can be utilized to balance the shrinkage events of the geopolymer at sufficiently high filler loadings. The addition of basalt fibers minimizes macro crack development while wollastonite exhibits a dual role as both filler and microfiber. Geopolymers composites have been optimized with thermal expansion/shrinkage of less than 2% up to 700oC. Fire testing of these same composites resulted in structurally sound specimens after an exposure time of 3 hours for 50 mm thick samples. These results clearly indicate a strong potential for geopolymer based fire resistant products.

Monday, May 25, 2015 Session III

POTENTIAL OF SECONDARY RESOURCES AS ALUMINIUM-SILICATE PRECURSORS FOR GEOPOLYMER SYNTHESIS

S.L.A. Valcke, P. Pipilikaki, H.R. Fischer, TNO, Delft, The Netherlands

Secondary resources containing (calcium) aluminium-silicate phases, e.g., fly ash, slag or bottom ash, can be used as precursor for binders such as geopolymers. Because secondary resources can be highly variable in terms of their potential to dissolve and form reaction products, analytical methods are needed to evaluate their potential as a precursor and to optimize the geopolymer mix design. The most commonly used methods (e.g., XRF, XRD) for measuring the characteristics of source materials which influence binder performance, do not capture heterogeneity between the particles and do not necessarily reveal the key parameter that is most dominant for the binder performance. This presentation therefore discusses techniques that we have investigated to capture inter- and intra-particle variations of aluminium-silicates and to evaluate the potential influence of these variations on geopolymer performance. For this, feature sizing and chemical typing (FS&CT), semi-quantitative FTIR and solid state 29Si NMR were used. FS&CT is an automated technique that enables to simultaneously measure inter particle variations in chemistry (energy dispersive x-ray spectra) and size (shape). Two key variables for application in geopolymers, Si:Al ratio and size, were measured using FS&CT for coal combustion fly ash and its fraction of potentially reactive aluminium-silicate particles. These measurements have been preliminary related to the reactivity of the fly ash in NaOH-solutions with high liquid/solid ratios as well as low liquid/solid ratios (geopolymers). As such the FS&CT method is found to be a useful alternative to commonly used bulk methods such as x-ray fluorescence (XRF) or manually operated electron microscopy that gives just an indication of local heterogeneity. Using semi-quantitative FT-IR and 29Si NMR, the aim was to investigate whether the presence of particular aluminium-silicate phases may have a dominant influence on the strength of a simple geopolymer system. Based on deconvolution of FT-IR and NMR spectra of 9 source materials (fly ash and slag) and their geopolymers, relative amounts of different (aluminium-silicate) phases were estimated and trends with strength were evaluated. A clear trend is observed for both NMR and FT-IR results: the precursors containing a higher amount of ‘active bonds’, predominantly from silicates with a medium amount of aluminium and alkalis incorporated in their framework, result in higher paste strengths. As such, due to its relatively quick and easy measurements, FT-IR for estimating relative amounts of aluminium-silicate phases, can be a useful tool for evaluating geopolymer precursors.

Tuesday, May 26, 2015 Keynote

HYDROTHERMAL AND LONG-DURATION AMBIENT CURING OF METAKAOLIN BASED GEOPOLYMERS

John L. Provis1, Susan A. Bernal1, David Brice2, Peter Duxson2, and Jannie S.J. van Deventer2, 3

1Department of Materials Science and Engineering, The University of Sheffield, Sir Robert Hadfield Building, S1 3JD, Sheffield, United Kingdom

2Department of Chemical & Biomolecular Engineering, The University of Melbourne, Victoria 3010, Australia 3Zeobond Pty Ltd, P.O. Box 23450, Docklands, Victoria 8012, Australia

Geopolymer materials, produced from the chemical reaction between a poorly crystalline aluminosilicate source and a highly alkaline solution, have been object of study for over half a century. Metakaolin, derived from the thermal treatment of kaolinite clays, has been one of the primary precursors used for their production 1. The microstructural development, and therefore the performance, of metakaolin geopolymers is strongly dependent on the mix design used, and synthesis conditions adopted. Metakaolin geopolymers are often described as poorly crystalline materials; however, it has been identified that the aluminosilicate geopolymer gel, the main binding phase forming in these binders, develops a short range ordering with a pseudo-zeolitic type structure.2 Formation of crystalline phases in metakaolin geopolymers have been identified, depending on the mix design,3 however, it is significantly slower than the crystallization which takes place under hydrothermal synthesis conditions, which have a notable impact on the kinetics of crystal growth. This study evaluates the correlation between mix design, hydrothermal curing conditions and aging in the crystallization of zeolite originating from the nanocrystalline binder phase forming in geopolymers. The results elucidate that despite the low water content present in the geopolymers studied, these materials harden under both hydrothermal conditions and saturated near-ambient temperature environments. The type of zeolites forming are determined by the chemical composition of the liquid phase (Si and Al concentration), and the alkaline cation supplied by the alkali-activator. Importantly, essentially the same zeolite phases form in systems cured for a short period under hydrothermal conditions and systems held at room temperature for several years, indicating that the nature of the crystal phases formed is controlled by kinetic not equilibrium considerations within this temperature range. The mechanism for zeolite growth in geopolymer systems resembles a gel-solid transformation via association and rearrangement of the precursor structure. Therefore, the rate of dissolution and polycondensation in metakaolin geopolymers are expected to have a significant impact on the zeolite species present and the degree of crystallization. The presence of different alkali metal cations modifies the geopolymerization process, so that Na samples are significantly more crystalline than K-containing samples among the sample set analyzed. This is primarily attributed to the more rapid reduction of mobility of zeolite precursors in K-containing systems. The results of this study provide valuable information to identify which mix designs favor crystallization, and enabling identification of routes for zeolite synthesis using geopolymerization technology. References (1) Duxson P; Fernández-Jiménez A et al., J Mater Sci 2007, 42:2917. (2) Provis JL; Lukey GC; van Deventer JSJ, Chem Mater 2005, 17:3075; Bell JL; Sarin P et al., Chem Mater

2008, 20:4768. (3) De Silva P; Sagoe-Crentsil K, Cem Concr Res 2008, 38:870; Zhang B; MacKenzie KJD; Brown IWM, J

Mater Sci 2009, 44:4668; Fernández-Jiménez A; Monzó M et al., Micropor Mesopor Mater 2008, 108:41.

Tuesday, May 26, 2015 Session IV

EFFECT OF CURING CONDITIONS ON CRYSTALLINE PHASE DEVELOPMENT OF HEAT-TREATED K/CS GEOPOLYMER

Andrew J. Steveson and Waltraud M. Kriven

University of Illinois at Urbana-Champaign, USA

Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Illinois, USA Geopolymers are amorphous analogues of the Group 1 zeolite minerals. In the case of the potassium-based geopolymer, leucite (K2O·Al2O3·4SiO2), which undergoes a deleterious phase transformation in the process of cooling from crystallization temperatures (~1100°C). In the past, cesium has been shown to be an effective dopant for stabilization of the high temperature leucite phase, which prevents the transformation. In this work, we correlate the environmental conditions during the initial solidification of the geopolymer gel to the development of the stabilized leucite phase from subsequent annealing heat treatment. Compositions of K2O(1-x)·Cs2O(x)·Al2O3·4SiO2; where x=0, 0.25, 0.5, 0.75, 1; were cured at 50, 70, and 90°C for 48 hours in sealed containers. Subsequent heat treatments were carried out at 1200°C for 3 hours. Powder X-ray diffractograms were collected and analyzed to identify present phases and determine structural parameters using Reitveld refinement.


WASTE GLASS POWDER AS PARTIAL BINDER PRECURSOR IN GEOPOLYMER PASTE: A STUDY ON GLASS REACTIVITY AND GEL FORMATION

Shizhe Zhang, Delft University of Technology, Faculty of Mechanical, Maritime and Materials Engineering,

Department of Materials Science and Engineering, Delft, The Netherlands [email protected]

Guang Ye, Delft University of Technology, Faculty of Civil Engineering and Geosciences, Department of

Materials and Environment, Delft, The Netherlands [email protected]

Key Words: waste glass powder, alkali-activation, microstructure, geopolymer concrete

Most unrecyclable glass, which is not suitable for packaging stream recycling, eventually goes to landfill and causes environmental problems. A potential utilization of the waste glass is to create construction materials through alkali activation. To better engineer the gel structure of alkali activated materials, characterization of reactivity of waste glass powder and understanding on the gel formation are essential.

This paper deals with reactivity of waste glass powder and presents the investigation results on feasibility of using it as precursor to produce geopolymer paste through alkali activation using NaOH of different concentrations. Waste glass powder serves as major component of precursors, along with fly ash and blast furnace slag to introduce Al and Ca into the gel network. A simultaneous formation of sodium silicate gel, sodium aluminosilicate (N-A-S-H) gel and Aluminium modified C-S-H (C-A-S-H) gel is found. Analysis on element distribution of gel network is carried out using ESEM with EDX. Factors influencing geopolymerization of waste glass powder based binder is studied by microstructure characterization using FTIR and XRD. This work provides a potential solution to handle unrecyclable glass waste and to build up a theoretical basis for mixture design in waste glass based geopolymer concrete.




RECYCLING INFLUENCE ON GEOPOLYMER FORMATION

Najet Essaidi, Science des Procédés Céramiques et de Traitements de Surface (SPCTS) UMR 7315 CNRS, Ecole Nationale Supérieure de Céramique Industrielle, 12 rue Atlantis, 87068 Limoges Cedex, France

[email protected] Emmanuel Joussein, University de Limoges, GRESE EA 4330, 123 avenue Albert Thomas, 87060

Limoges, France Sylvie Rossignol, Science des Procédés Céramiques et de Traitements de Surface (SPCTS) UMR 7315 CNRS,

Ecole Nationale Supérieure de Céramique Industrielle, 12 rue Atlantis, 87068 Limoges Cedex, France

Key Words: Laboratory aluminosilicate waste - FTIR spectroscopy - Compressive test - Si/K ratio Geopolymer materials have a lot of attention as suitable binder because they are environmentally friendly and require less energy during their manufacturing process. These ecomaterials can be synthesized by the alkaline activation of aluminosilicates obtained from calcined clays, natural minerals and industrial wastes at room temperature. The properties of geopolymers are affected by two important factors which are the alkaline solution and the aluminosilicate source. Recycling of wastes as secondary raw materials is becoming progressively more important. Using industrial by products or wastes (fly ash, red mud and furnace slag) for geopolymer synthesis is another advantage of the geopolymer technology, because of the significantly reduced costs and additional environmental benefits, leading to greener manufacturing and global sustainable development. Taking this into account, some studies focused on recycled aggregates incorporation in the geopolymer materials. The aim of the study is to investigate the influence of laboratory waste addition on geopolymer formation in order to minimize the cost and to focus on the life cycle of material. For this, different amounts of laboratory waste were added to geopolymer reactive mixture. The experimental protocol of geopolymer synthesis consists in dissolving potassium hydroxide pellets in a commercial potassium silicate solution in order to maintain the Si/K solution molar ratio to 0.58. Then, laboratory aluminosilicate waste, previously crushed and sieved through 80 μm, and metakaolin were added. The waste proportion ranged from 10 to 30% of total mass. Finlay, the reactive mixtures were placed in open polystyrene molds at room temperature (25°C). This study evidenced the possibility of re-using aluminosilicate laboratory waste to synthesize consolidated materials. It was shown that the laboratory waste addition influences the polycondensation rate as well as the mechanical strength. The low reactivity of these incorporated materials disturbs the geopolymerization reactions and lead to the formation of different networks.


EFFECT OF ALKALINE ACTIVATORS TO IMMOBILIZE LEAD IN FLY ASH-BASED GEOPOLYMERS

Sujeong Lee, Korea Institute of Geoscience and Mineral Resources [email protected]

Chul-Min Chon, Korea Institute of Geoscience and Mineral Resources Nam-Hee Kang, University of Science and Technology

Hyeong-Tae Jou, Korea Institute of Ocean Science and Technology Youn-Joong Kim, Korea Basic Science Institute

Arie van Riessen, Curtin University

Key Words: Geopolymer, activator types, immobilization, lead. Immobilization of heavy metals in geopolymers has attracted attention as a potential means of treating toxic wastes. Lead is known to be effectively immobilized in a geopolymer matrix, but detailed explanation for the mechanisms involved and the specific chemical form of lead are not fully understood. To reveal the effect of the activator types on immobilization of lead in geopolymers, 0.5 and 1.0 wt% lead was mixed with fly ash and alkaline activators. Zeolite was formed in aluminate-activated geopolymers having a Si/Al ratio of 2.0, but the

zeolite crystallization was suppressed as lead content increased. No specific crystalline phase of lead was detected by X-ray diffraction, electron diffraction and FT-IR spectrometry. A sequential extraction procedure for fractionation of heavy metals showed that lead did not exist as an exchangeable ion in geopolymers, regardless of activator type used. About 99% of extracted lead existed in the oxidizing (F IV) and residual (F V) fractions of aluminate-activated geopolymers (J205 and J 210). Even though geopolymer (J510) with a Si/Al ratio of 5.0 and 1.0 wt% lead showed the highest proportion of lead extracted during the residual step, about 30% of lead was extracted during the acido-soluble (F II) and reducible (F III) steps. Aqua regia extraction showed that the aluminosilicate geopolymers were too resistant to be degraded by extractants and the silicate-activated geopolymers were more substantial than the aluminate-activated ones. On the other hand, TEM analysis revealed that lead was evenly distributed with no evidence of formation of a specific lead compound.

Figure 1 – Chemical fractionation patterns of lead in geopolymers. J205 and J210 are aluminate activated while J505 and J510 are silicate activated. F I, exchangeable fraction; F II, acido-soluble fraction; F III, reducible fraction; F IV, oxidizing fraction’ F V, residual fraction.


ASHES FROM BIOMASS INCINERATION AS ALTERNATIVE ACTIVATOR FOR INORGANIC POLYMERS

Hubert Rahier, Vrije Universiteit Brussel, Brussels, Belgium [email protected]

Arne Peys, KU Leuven, Leuven, Belgium Yiannis Pontikes, KU Leuven, Leuven, Belgium

Key Words: plant ashes, kaolinite, metakaolinite, geopolymer, alkali activation, inorganic polymer. Alkali activation is a way to minimize the environmental impact of constructions on our environment. The alkaline activators however need substantial energy for their production and they can be rather expensive, especially for people in developing countries. Ashes from biomass incineration often contain a large proportion of possible activators such as Ca or K oxides or carbonates. These ashes are mostly regarded as waste. The amount of biomass ashes in Europe is growing as biomass is used for producing green electricity. Some ashes were screened and tested on their ability to act as an activator for (meta)kaolinite. Oak/beech, cotton and maize ashes were compared in this study. The chemical composition does not only change largely with the type of plant but also with the part of the plants. To produce inorganic polymers two main options were tried out. The ash was mixed with the dry clay and water was added, or only the soluble content of the ash was used for alkali activation. The first option gave the best results. A compressive strength up to 27 MPa was obtained for compositions were the pure ash was added to metakaolinite (Figure 1 ). The samples proved to be stable in water. A large difference in strength was obtained depending on the origin of the ash. The ashes with more K (maize cob ash) developed a higher strength (see figure). The reactivity of the mixtures was studied with calorimetry. A preliminary study into the structure of the material is made. The typical shift in IR to lower wavenumbers of the Si-O stretching band around 1000cm-1 is observed upon addition of ash to metakaolinite. With SEM the binder phase can be observed. Only a limited number of small cracks were observed this phase.

Figure 1 – Compressive strength of metakaolinite/ash inorganic polymers. Ash mixed with dry metakaolinite, and then water added.

Cured for 48h at 80°C.

Tuesday, May 26, 2015 Session V

RECYCLING MINERAL WOOL WASTE IN GEOPOLYMERS

Paivo Kinnunen, University of Oulu [email protected]

Juho Yliniemi, University of Oulu Bob Talling, Renotech Oy

Mirja Illikainen, University of Oulu Jouko Niinimäki, University of Oulu

Key Words: Rockwool, waste valorization, alkali activation, geopolymer Mineral wool waste is often considered unrecyclable, due to its difficult-to-process physical composition, and potential microbial contamination in the post-consumer products. Total mineral wool waste generated in the EU is growing continuously and is currently over 2.3 million tons annually, volumetrically accounting for largest single waste source in many landfills. Here, we take advantage of the alkali-soluble nature of the rockwool waste, and use a combined mixing and dissolution method to prepare this otherwise unusable waste for geopolymerization, with up to 33% inclusion in the final product. This mixing and dissolution step enables sufficiently high solid content to form a castable cementitious geopolymer paste, which forms a rigid matrix and

a compressive strength of 12.8 MPa, sufficient for structural applications. FESEM and XRD analysis of the formed products were performed to verify geopolymer formation. By using the preparation steps, otherwise unrecyclable mineral wool waste can be turned into a potentially valuable raw material for high tech geopolymer materials.


BASALT CHOPPED FIBER, FELT AND WEAVE REINFORCED GEOPOLYMER COMPOSITES

Daniel R. Ribero, Elias Koehler, Gregory Kutyla, Sean S. Musil and Waltraud M Kriven Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign,

Illinois, USA

Geopolymers of nominal chemical composition is M2O.Al2O3.4SiO2.11H2O where M was Na or K were made. The ceramic-like, cross-linked product shares the brittle nature of ceramics, but can be reinforced with chopped or unidirectional fibers, felts or fiber weaves to yield strong and tough composites. Chopped basalt fibers of 6.35 mm and 12.7 mm were made and their flexure strength tested to 800 °C. Basalt felts consisting of randomly oriented 4 inch long fibers as well as more easily impregnable basalt strand mat were dispersed in potassium and sodium geopolymer matrix, respectively. In addition layers of basalt weaves were pressed in a potassium geopolymer matrix to yield panels for tensile and four-point flexure testing under ambient temperatures. The room temperature flexure strength of basalt felt composites was 22 MPa, while that of basalt weave reinforced geopolymer composites reached 41 MPa. The geopolymer composites were then heat treated at temperatures up to 600 °C, and tested in 4-point flexure in situ up to 600 °C, beyond which the basalt reinforcement softened and melted. The mechanical properties of composites appeared to improve with the increasing dimensions of the reinforcements such that weave > felt> chopped fibers.


SHORT CARBON FIBER-REINFORCED, POTASSIUM GEOPOLYMER COMPOSITES

Shinhu Cho1, Robert D. Schmidt2, Eldon D. Case2, Waltraud M. Kriven3, 4 1 Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana,

Illinois 61801 2 Chemical Engineering and Materials Science, Michigan State University, East Lansing, Michigan, 48824

3 Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign 4 Affiliate Professor, Department of Mechanical Science and Engineering, University of Illinois at Urbana-

Champaign The processes and microstructures of potassium-based geopolymer (K2O ∙ Al2O3 ∙ 4SiO2 ∙ 11H2O) have been studied by many researchers with various techniques. However, the brittleness and relatively lower strength limited the use of geopolymer in certain applications. Therefore, short carbon fibers (60 and 100 µm) have been introduced to reinforce the mechanical properties of potassium based geopolymer. The proper mixing and drying conditions of carbon fiber reinforced potassium geopolymer (Cf KGP) were determined since the mechanical properties varied in wide range depending on the drying conditions. Various static mechanical tests (flexure, uniaxial compression, hardness, toughness and biaxial tensile tests) and statistical analysis of brittle fractures (Weibull distribution) have been performed to investigate the optimal mechanical strengths of Cf KGP composites. In addition to the static measurements, the Young’s and shear moduli of Cf KGP have been measured by dynamic methods such as impulse excitation (IE) and resonant ultrasound spectroscopy (RUS) and compared with various theoretical models.


LIGNOCELLULOSIC FIBERS AS REINFORCEMENTS IN GEOPOLYMERS

Kaushik Sankar and Waltraud M. Kriven Department of Material Science and Engineering, University of Illinois at Urbana-Champaign

Urbana, IL, USA Geopolymers are inorganic polysialates that have excellent compressive and flexure strength with low carbon footprint. However, pure geopolymers are weak in tension and have low fracture toughness. On the other hand, lignocellulosic natural fibers are cheap, bio-degradable and have excellent tensile strength. Hence, they can be used to reinforce geopolymers to make low cost structural material. In this study, the mechanical properties of as-received and alkali-treated jute (Corchorus olitorius), fique (Furcraea macrophylla), malva (Malva sylvestris) and curaua (Ananas erectifolius) fiber reinforced geopolymers were studied through tensile, flexure and impact testing according to ASTM standards. Scanning electron microscopy and energy dispersive x-ray spectroscopy was performed to probe the microstructure and investigate the Si/Al ratio. X-ray diffraction was performed to confirm the presence of geopolymers and cellulose I in the natural fibers. Thermogravimetry was done to confirm the removal of hemicellulose in the fibers.


GEOPOLYMERS USING GLASS PRODUCED FROM THE DC PLASMA TREATMENT OF AIR POLLUTION CONTROL (APC) RESIDUES: OVERVIEW AND CHALLENGES

Ioanna Kourti*, Department of Civil and Environmental Engineering, Imperial College London, UK

[email protected] Aldo R. Boccaccini, Department of Materials Science and Engineering, University of Erlangen-Nuremberg, DE

Christopher Cheeseman, Department of Civil and Environmental Engineering, Imperial College London, UK

(*Currently at Amec Foster Wheeler UK Ltd) Keywords: APC residues; plasma treatment; MSW incineration; waste management; hazardous waste Air pollution control (APC) residues are a hazardous waste produced from cleaning gaseous emissions at energy-from-waste (EFW) facilities processing municipal solid waste (MSW). APC residues have been blended with glass-forming additives and treated using DC plasma technology to produce a high calcium aluminosilicate glass (APC glass). This paper provides an overview of the research work that has been completed and includes:

• Optimization of the properties of geopolymers prepared from this glass: Work has shown that high strength geopolymers can be formed and that NaOH concentration of the activating solution significantly affects the properties. The broad particle size distribution of the APC residue glass used in these experiments results in a microstructure that contains un-reacted APC residue glass particles included within a geopolymer binder phase. The high calcium content of APC residues may cause the formation of some amorphous calcium silicate hydrate (C-S-H) gel. A mix prepared with S/L = 3.4, Si/Al = 2.6 and [NaOH] = 6M in the activating solution, produced high strength geopolymers with compressive strengths of ~130 MPa. This material had high density (2070 kg/m3) and low porosity.

• Properties and characterization of the binder phase: Geopolymer-APC glass composites produced

with APC glass exhibit high strength and density, low porosity, low water absorption, low leaching, high acid resistance and good freeze/thaw resistance. The composites have a microstructure consisting of un-reacted residual APC glass particles imbedded in a complex geopolymer and C-S-H gel binder phase, and behave as particle reinforced composites.

• Comparison with metakaolin and GGBFS geopolymers: APC glass, metakaolin and ground granulated blast furnace slag (GGBFS) geopolymers have also been prepared and compared. The compressive strengths, density, water absorption, and porosity were evaluated. Samples were also characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). Results show that APC glass geopolymers have excellent mechanical properties compared with other geopolymer materials with high density, low porosity, and particularly high compressive strength.

• Carbon footprint of APC glass geopolymers: The carbon footprints of two reuse applications for APC glass (geopolymers and pozzolanic additive to cement) were compared with the carbon footprint of a similar material prepared with Portland cement. Results showed that APC glass geopolymer has the lowest carbon footprint of the two APC glass reuse applications and the reuse of APC glass in blended cement pastes, in laboratory scale, does not provide benefits related to climate change. The reuse of APC glass in geopolymers is beneficial as it provides a significant reduction in CO2 emissions compared to similar materials prepared with Portland cement. Both reuse applications however have a very important advantage which is related to savings of natural resources that they provide.

The research has demonstrated for the first time that glass derived from DC plasma treatment of APC residues can be used to form high strength geopolymer-glass composites that have potential use in a range of applications. Overall the work presents an effective way of managing APC residues, a particularly problematic waste generated by EfW facilities that minimizes waste and maximizes resource efficiency.

Tuesday, May 26, 2015 Session VI

Fe-Al SUBSTITUTION IN INORGANIC POLYMERS DERIVED FROM VITREOUS PRECURSORS

Lieven Machiels Tim Goetschalckx

Lukas Arnout Aart W. Van Vuure

Bart Blanpain Yiannis Pontikes

KU Leuven, Department of Materials Engineering [email protected]; [email protected]

Key Words: Fe-rich inorganic polymers, vitreous precursors, glass, Na-silicate The current work investigates the inorganic polymerization of Fe-rich vitreous precursors, i.e. glasses. To investigate the role of Fe in the inorganic polymer (IP) network and the influence of Al-Fe substitution, glasses of the following composition were synthesized (in wt.%): 47 SiO2, 20 CaO, 5 K2O, 3 MgO, total (Fe2O3 + Al2O3) 25, with Fe2O3 and Al2O3 varying between 0 and 25 wt%. The glasses were milled to a similar specific surface and IP pastes were prepared by blending the powders with a Na-silicate solution at different glass/activator ratios. Curing was performed at room temperature under different levels of humidity. After 28 days of curing, all IP samples produced were insoluble in water and delivered substantial strength. When comparing Al and Fe-rich samples, differences in compressive strength are relatively small, with slightly higher values for IPs from Fe-rich glasses (Figure 1 – left). A large difference in flexural strength is apparent when comparing Al and Fe-rich samples, especially after curing at high relative humidity (Figure 2 – right). A range of complementary analytical techniques is performed on the IP’s to explain these differences in mechanical properties, i.e. determination of the mineralogy of the IP pastes, the IP structure and water content through QXRD, FTIR, TGA-DSC; an analysis of the microstructure and morphology of the IP micelle morphology using nanoSEM; a microchemical analysis using EPMA; an analysis of porosity and cracks using gas pycnometry, BET and X-ray computed tomography; and analysis of the reaction kinetics using calorimetry. Important differences in IP nanostructure, porosity and chemistry are found that could result in the differing properties.

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Figure 1 – Left: Compressive strength; Right: Flexural strength of IP’s prepared from glasses of varying Fe and Al content, with sample GP1 the pure Al end-member (no Fe) and GP5 the pure Fe end-member (no Al).


GEOPOLYMER PREPARATION THROUGH WASTE GLASS AS NEW ALTERNATIVE ALKALINE ACTIVATOR. MECHANICAL AND MICROSTRUCTURAL BEHAVIOUR

Manuel Torres-Carrasco, Eduardo Torroja Institute for Construction Sciences, Madrid, Spain

[email protected] Francisca Puertas, Eduardo Torroja Institute for Construction Sciences, Madrid, Spain

[email protected]

Key Words: waste glass, alternative alkaline activator, geopolymer, The term "geopolymer" was coined in the 1970s by the French scientist and engineer Prof. Joseph Davidovits, and applied to a class of solid materials synthesised by the reaction of an aluminosilicate powder with an alkaline solution. The primary area of application of geopolymer technology is currently in the development of reduced-CO2 construction materials as an alternative to Portland-based cements. This work explores the feasibility of generating geopolymers from fly ash using waste glass as an alkaline activator. Urban and industrial waste glass are mainly composed of SiO2, CaO and Na2O, and previous studies by some of the authors1,2 have demonstrated that it is possible to produce sodium silicates from this waste via chemical attack in highly alkaline media. The mechanical properties of the cementitious geopolymers obtained by alkali-activating fly ash with three solutions were determined. NaOH 8M (AAFA N8), NaOH 10M +15% of waterglass (AAFA WG) and NaOH 10M + 15g of waste glass (AAFA N10-15) were used. The microstructure (by FTIR, XRD, 29Si and 27Al NMR and BSEM/EDX) and mechanical performance of these materials was evaluated. The main reaction product in all systems studied was the alkaline aluminosilicate hydrate gel (N-A-S-H gel) to which geopolymers owes their mechanical properties. Gels formed when the system contained an extra source of silicon (AAFA WG and AAFA N10-15 samples) showed a microstructure and a chemical composition (Si/Al and Na/Al ratios) very similar, confirming the available of waste glass as an alternative activator in geopolymer formation. This study demonstrates that alkali-activation technology is a viable way to promote recycling of urban and industrial waste glass for the development of highly valuable zero-waste cements3. 1 Torres-Carrasco, M. et al. 2014., Materiales de Construcción, 64(314) 2 Puertas, F. and Torres-Carrasco, M., 2014, Cement and Concrete Research, 57: 95-104 3Torres-Carrasco, M. and Puertas, F., 2014, Journal of Cleaner Production (in press)




DESIGN AND CHARACTERIZATION OF FLY ASH-BASED GEOPOLYMER CONCRETES FOR A ROUND-ROBIN DURABILITY TESTING PROGRAM

Gregor J. G. Gluth1, William Rickard2

1 Division 7.4 Technology of Construction Materials, BAM Federal Institute for Materials Research and Testing, Berlin, Germany

2 Geopolymer Research Group, Curtin University, Perth, Australia

Seven fly ash-based geopolymer concretes were designed and characterized with the aim to select two suitable, sufficiently different mix-designs for the use in a round robin durability testing program, organized and conducted by RILEM Technical Committee 247-DTA ‘Durability testing of alkali-activated materials’. The reactive components of the employed fly ash were determined using chemical analysis and Rietveld phase quantification. Based on the obtained data activator composition was optimized to yield good strength, workability, and setting behavior of the paste. Fly ash-content, total water content and grading curves of the aggregates were varied for the concretes; curing was conducted at 23 °C. Concrete testing comprised flow diameter, air void content, density, compressive strength etc. Optimum paste (fly ash + activator) composition was found to be Si/Al = 3.0 (molar), Na/Al = 1.1 (molar) and total water content = 20 wt.-%. Despite the limited variation of fly ash content in the concretes, water content of the pastes and grading curves of the aggregates, the flow diameters of the concretes ranged from 290 mm to 500 mm (flow classes F1 to F4) and the workability from “very poor” to “flowable”, i.e. the rheological properties of the concretes were notably sensitive to changes in the mix-design. As expected, coarser grading curves and more water generally caused a better workability. In addition, it was found that for the tested set of concretes the flow diameter and the flow class were not a good representation of the actual workability as assessed by visual observation. Concrete strengths reached up to 86 MPa and were significantly higher than corresponding paste strengths. Strength development was different for pastes and mortars on the one hand and for concretes on the other hand: while for pastes and mortars strength increased roughly linear between 7 and 56 days of curing, the major part of strength development of the concretes occurred until 28 days of curing and strength development slowed down afterwards. Two concretes, both with sufficient workability but significantly different grading curve, water content and strength could be identified for the round-robin program.


ON THE DURABILITY OF STEEL REINFORCED GEOPOLYMER CONCRETE IN MARINE ENVIRONMENTS

Mahdi Babaee, Centre for Infrastructure Engineering and Safety, School of Civil and Environment Engineering, University of New South Wales, Sydney, NSW, 2052, Australia.

[email protected] Arnaud Castel, Centre for Infrastructure Engineering and Safety, School of Civil and Environment Engineering,

University of New South Wales, Sydney, NSW, 2052, Australia.

Key Words: Geopolymer Concrete, Low-Calcium Fly Ash, Durability, Corrosion. Geopolymer concrete (GPC) is considered as a potential sustainable, low-embodied carbon alternative for Ordinary Portland Cement (OPC) concrete. While during the production of each tone of OPC, almost one tone of CO2 is released as the result of calcination of limestone and combustion of fossil fuels, an 80% reduction in carbon emission can be achieved using Geopolymeric binders instead. However; as a rather new engineering material, there are some concerns over the durability aspects and the long term performance of these types of concretes and further investigation of phenomena such as corrosion of reinforcing bars as one of the major causes of the premature failure of concrete structures is needed. In the current paper, performance of chloride contaminated reinforced GPC specimens which are made up of a blended slag and class F fly ash cement is investigated by doing a set of corrosion experiments during the propagation phase of corrosion. Applicability of electrochemical test methods such as Tafel test and Linear Polarization Resistance (LPR) test which are commonly used to monitor active steel corrosion in OPC concrete is evaluated for low calcium fly ash GPC. Performance of low calcium fly ash GPC during the propagation phase of corrosion is investigated by long term monitoring of corrosion parameters such as free corrosion potential, polarization resistance and Tafel coefficients and the results are compared to the reported values for OPC concrete. Direct mass loss measurement was carried out as well, as a way to verify the results of the corrosion tests. Results show that in general, low calcium fly ash GPC can perform as well as OPC concrete in propagation phase of corrosion, and the available electrochemical test methods and protocols can be applied to evaluate the state of corrosion in low calcium fly ash GPC.


Wednesday, May 27, 2015 Keynote

INFLUENCE OF VISCOSITY ON GEOPOLYMER POROSITY

Marcello Romagnoli, Università di Modena e Reggio Emilia [email protected]

Cristina Leonelli, Università di Modena e Reggio Emilia Elie Kamseu, Università di Modena e Reggio Emilia

Magdalena Gualtieri, Università di Modena e Reggio Emilia

Key Words: porous geopolymer, viscosity, total porosity, pore size dimension The rheological properties of a fresh geopolymeric paste are critical for pore generation, evolution and coalescence. The relationship between the rheology of the suspensions and their final porosity is not deeply studied. This paper wants to contribute to the deeper knowledge about this topic. The interdependency of porosity and viscosity of the fresh paste has been tested using a rotational rheometer. The compositions show a

non-Newtonian behavior (figure 1) and a time dependency. The presence of a porogent additive jointly with the consolidation of the 3D structural bonding network generate a complex system which requires a statistical approach to be properly investigated. The final materials which can be obtained starting from alkali activation of metakaolin or other second raw materials have total porosity around 25-35% (figure 2).

Their complete characterization leads to interesting values for apparent density and thermal conductivity. The results show a strong correlation between viscosity, total porosity (figure 3) and pore dimension. On the contrary, shape and number of pores per unit area seem statistically not affected by the viscosity at least in the analyzed range. Because of the non-Newtonian behavior of the suspension, the viscosities must be measured at very specific shear rates to be significantly related with the characteristics of the pores. The study provides a useful analysis on the viscosity values suitable to obtain tailored total porosities and pore distribution. It shows that its appropriate control is fundamental to design this important parameter in the obtaining of geopolymer with engineered properties.

Figure 1 – Example of non-Newtonian behavior of geopolymer suspensions

Figure 2 – Example of porous geopolymer

Figure 3 – Porosity (%) versus viscosity

Wednesday, May 27, 2015 Session VII

RHEOLOGICAL BEHAVIOR OF A Na-GEOPOLYMER

Arnaud Poulesquen, CEA, DEN, DTCD/SPDE/LP2C, Marcoule, Bagnols-sur-Cèze F-30207, France [email protected]

Prune Steins, CEA, DEN, DTCD/SPDE/LP2C, Marcoule, Bagnols-sur-Cèze F-30207, France Julien Rouyer, CEA, DEN, DTCD/SPDE/LP2C, Marcoule, Bagnols-sur-Cèze F-30207, France Thomas Piallat, CEA, DEN, DTCD/SPDE/LP2C, Marcoule, Bagnols-sur-Cèze F-30207, France Fabien Frizon, CEA, DEN, DTCD/SPDE/LP2C, Marcoule, Bagnols-sur-Cèze F-30207, France

Key Words: Rheology, mixing, master curve, Sodium geopolymer The aim of this study is to evaluate the influence of mixing on a sodium geopolymer (the metakaolin is used as alumino-silicate source) at fresh state by using rheological techniques. By rheology, it is possible to obtain the evolution of the macroscopic viscosity as a function of time (during the geopolymerization reactions) and as a function of the shear rate. Moreover, the use of the oscillatory mode allows to measure in the linear domain, the evolution of the viscoelastic parameters (elastic, viscous modulus and complex viscosity) during the reactions. Lastly, an original rheological method named Time Frequency Resolved Rheology (TF2R) which consists in a continuous frequency strain solicitation in a short duration, is used to rigorously determine the gelling time and the fractal dimension at the sol/gel transition. The results show that the macroscopic and the complex viscosity decrease when the shear rate or the angular frequency increase respectively. This is a classical shear-thinning behaviour. Furthermore, the Cox-Merz rule, which is an empirical method to correlate dynamic and steady shear rheological data, was not applicable as for aggregated or complex food systems. However, by using a shift factor on the angular frequency in the Cox-Merz rule, a master curve is obtained which is very useful to predict the steady shear properties from dynamic shear data. Another results show that the gelling time decreases when the shear rate increases which is confirm by steady shear rheology and TF2R method by using the Winter and Chambon criterion (when G’ and G’’ becomes parallel in a frequency range). Finally, the fractal dimension determined at the sol/gel transition is lower when the shear rate is high. Indeed, the fractal dimension is around 2 when the viscoelastic parameters are measured in the linear domain and decrease to around 1,4 when the geopolymer paste is pre-mixed at 50 s-1. The work is in progress in order to study the influence of formulation parameters such as water or silica content by using the same methodology previously explain.


EXPERIMENTAL STUDY OF WORKABILITY OF GEOPOLYMER CONCRETES MADE OF FLY ASH AND BLAST FURNACE SLAG

Kamel Arbi Ghanmi, Delft University of Technology, Faculty of Civil Engineering and Geosciences, Delft, The Netherlands, [email protected]

Marija Nedeljković, Delft University of Technology, Faculty of Civil Engineering and Geosciences, Delft, The Netherlands

Yibing Zuo, Delft University of Technology, Faculty of Civil Engineering and Geosciences, Delft, The Netherlands

Guang Ye, Delft University of Technology, Faculty of Civil Engineering and Geosciences, Delft, The Netherlands

Key Words: Fly ash, blast furnace slag, geopolymer concrete, workability, admixtures

In recent years, industry by-products, like fly ash (FA) and/or blast furnace slag (BFS), are widely used as precursors in producing geopolymer concrete. The engineering properties of geopolymer concrete, like compressive strength, can be designed by altering the proportion of fly ash and blast furnace slag in concrete mixtures. However, the flowability of fresh concrete is very difficult to control for all mixtures to meet a desired workability, due to the difference on the nature of the particle shape and the water demand between fly ash and blast furnace slag. This paper presents an investigation on workability of geopolymer concrete made of a class F fly ash and blast furnace slag and a mixed alkali activator consisting of sodium silicate and sodium hydroxide solution. The FA:BFS ratios were 0:100, 30:70, 40:60, 50:50, 60:40, 70:30 and 100:0. Slump test was performed to measure flowability. The workability of geopolymer concrete is controlled by using different types and percentages of admixtures. The commercially available naphthalene-based superplasticizer, polycarboxilate based superplasticizer and retarder were used. Experimental results show when alkali activating solution to binder ratio is fixed for all mixtures, the mixtures with FA:BFS no less than 70:30 can reach a desirable workability with slump in the range from 22 cm to 24 cm without using superplasticizer, while the mixtures with FA:BFS of 50:50 and 60:40 need around 2% of polycarboxilate based superplasticizer and the rest with FA:BFS of 30:70 and 0:100 need more superplasticizer and extra water to reach the same desirable workability. During the tests, the slag rich mixtures harden very fast, which confirms that slag has a higher reactivity than that of fly ash. When a combination of retarder and naphthalene based superplasticizer was added into the mixtures, all mixtures have shown a good workability with slump value in the range from 21 cm to 24 cm. For slag rich mixtures with FA:BFS 30:70 and 0:100, only increasing dosage of superplasticizer is not as effective as using retarder simultaneously. Based on the tested workability and mechanical properties an optimal range of each type of superplasticizer and retarder dosages is introduced for geopolymer concrete made of fly ash and /or blast furnace slag.



INFLUENCE OF FORMULATION PARAMETERS AND EVOLUTION OF GEOPOLYMER POROSITY

Virginie Benavent, CEA/DEN/DTCD/SPDE/LP2C [email protected]

Arnaud Poulesquen, CEA/DEN/DTCD/SPDE/LP2C Fabien Frizon, CEA/DEN/DTCD/SPDE/LP2C

Key Words: Porosity, Aging, Interstitial Solution In materiel science, porosity is a key parameter because it controls a lot of properties, like thermal and mechanical properties. Besides, the interconnected pores are responsible for water and ionic transport through the material. Therefore, the deep knowledge of porosity is essential. In this study, we extensively studied the role of formulation parameters on geopolymer mesoporosity, i.e. the water molar ratio H2O/M2O and the silica molar ratio SiO2/M2O, where M is either Na or K. We showed by N2 adsorption-desorption that the water ratio had a bigger impact on pore size and pore volume than the silica ratio. Aging time had also an influence on the measured pore size and pore volume. Typically, the pore size increased and the pore volume decreased with time. A complementary SAXS study did not show an increase in pore size with time and a chemical equilibrium seemed to be reached in the interstitial solution after 7 days. All these results may be explained by a possible dissolution-precipitation mechanism occurring at the pore surface, accompanied by a partial closure of porosity with time. To confirm our hypothesis, SANS experiments using the contrast variation technique will be held in order to find the proportion of closed porosity in our geopolymers.

Figure 1 - Pore diameter evolution calculated from the N2 desorption isotherm

of a geopolymer with H2O/Na2O = 13 and SiO2/Na2O = 4

Wednesday, May 27, 2015 Keynote

INORGANIC POLYMERS FROM RESIDUES OF HIGH TEMPERATURE PROCESSES: GOING BEYOND THE ALUMINOSILICATES

Yiannis Pontikes, S. Onisei, L. Machiels, R. Iacobescu, L. Kriskova, L. Arnout, A. Peys, P.T. Jones, B. Blanpain

KU Leuven, Department of Materials Engineering, Kasteelpark Arenberg 44, 3001 Leuven, Belgium Key Words: residues, metallurgy, high temperature process Most inorganic polymers described in the literature are formed from aluminosilicate precursors and a substantial level of understanding has been obtained in the interplay between processing, microstructure and properties. In the present work however the focus is placed elsewhere. A summary of results is provided for approximately twenty non-traditional inorganic polymer candidate precursors, originating from ferrous, non-ferrous as well as other high temperature industrial processes. These residues are typically semi-vitreous and include substantial levels of Fe. Dissolution experiments were conducted to assess their reactivity and in conjunction with indicative physico-mechanical properties for the pastes, the most promising precursors were identified. One of them was secondary copper slag, and three examples of final inorganic polymers are presented in greater depth: a) a dense, high strength, b) a porous and c) a heat resistant material. Emphasis is given on the different processing routes followed and the properties obtained, accompanied by viscosity, calorimetry, spectroscopy and microscopy data. The work is closing with a presentation of communication actions, events and installations that take place in Flanders, aiming to present these new materials and contribute in performance-based (as opposed to chemistry or perception-based) materials selection.

Wednesday, May 27, 2015 Session VIII

UTILIZATION OF SUSTAINABLE MATERIALS FOR SOIL STABILIZATION: STATE-OF-THE-ART

Prathyusha N.V. Jayanthia and D.N. Singhb

aResearch scholar, Department of Civil Engineering, Indian Institute of Technology Bombay, Powai, Mumbai-400076, India, [email protected]

bProfessor, Department of Civil Engineering, Indian Institute of Technology Bombay, Powai, Mumbai-400076, India, [email protected]

Corresponding author. Tel.: +91-22-2576-7340; fax: +91-22-2576-7302 Most of the challenging soil deposits, necessitate their stabilization either by adopting mechanical modification which includes soil replacement, compaction, surcharge loading and piling or chemical alteration by using lime, cement and chemical additives. These methods of stabilization are oriented towards improving certain defined properties such as plasticity, swell potential, strength and density of the soil mass. Besides, one of the most crucial challenges that is faced is ‘stabilization induced cracking failure of the fine-grained soils’, which turns out to be the basic reason for the failure of the soil mass and subsequent failure of the structures. However, concerns such as non-availability of the ideal soil for replacement of the native soil and even inaccessibility of the site and laborious soil-stabilizer mixing methods necessitates exploring suitable alternatives for stabilization of such soil deposits that adds up to the vows of practicing engineers. A few other pressing issues, which need to be addressed, are the adverse effects caused by these additives on the environment (viz., release of greenhouse gases and/or subsequent leaching of chemicals into the ground water). In such a scenario, application of materials that are manmade and are mainly by-product of an industrial process, find a special place in modern-day soil stabilization and modification exercise. These materials (viz., fly ash, cement kiln dust, blast furnace slag, rice husk ash, silica fumes and fibers) known as ‘sustainable materials’ are environment friendly and are easily available courtesy modern day industrialization. Keeping this in view, a critical synthesis of the literature has been presented in this paper, which showcases superiority of the sustainable materials over the conventionally used soil stabilizers and the need for conducting further research to make these materials an easy and choicest replacement over the former.



METAKAOLIN AND FLY ASH BASED GEOPOLYMERS COMPARED WITH CEMENTITIOUS MORTARS OF THE SAME STRENGTH CLASS: PERFORMANCES AND CORROSION BEHAVIOUR OF BLACK AND

GALVANIZED STEEL BARS

Alessandra Mobili, Department of Materials, Environmental Sciences and Urban Planning, Università Politecnica delle Marche, Ancona, Italy

[email protected] Chiara Giosuè, Department of Materials, Environmental Sciences and Urban Planning, Università Politecnica

delle Marche, Ancona, Italy Alberto Belli, Department of Materials, Environmental Sciences and Urban Planning, Università Politecnica delle

Marche, Ancona, Italy Tiziano Bellezze, Department of Materials, Environmental Sciences and Urban Planning, Università Politecnica

delle Marche, Ancona, Italy Francesca Tittarelli, Department of Materials, Environmental Sciences and Urban Planning, Università

Politecnica delle Marche, Ancona, Italy Key Words: Mortar, Geopolymer, Durability, Metakaolin, Fly Ash. Mechanical, morphological and durability aspects of three types of geopolymer mortars were compared with those of traditional cementitious mortars of comparable compressive strength . To this aim, mortars belonging to three mechanical strength classes (R1 ≥ 10 MPa, R2 ≥ 15 MPa and R3 ≥ 25 MPa according to EN 1504-3:2005) were tested and compared. Geopolymers were obtained with fly ash and metakaolin as precursors and a mixture of sodium silicate and NaOH or KOH as liquid activators. In order to obtain R1, R2 and R3 mortars cementitious mixtures were prepared by partial substitution of Portland cement with hydraulic lime, while geopolymers were prepared by varying the concentration of NaOH or KOH with a waterglass/hydroxide ratio always equal to 1. The obtained samples were characterized both in the fresh and in the hardened state. The first was evaluated by workability and density of the fresh mortar, the latter by compressive strength, dynamic modulus of elasticity, adhesive strength on ceramic surface, free and restrained shrinkage and by microstructural analysis such as SEM and mercury porosimetry. Durability aspects were also investigated through water vapor permeability, capillary water absorption, resistance to salt crystallization and corrosion of possible embedded rebars. Corrosion tests were carried out by measuring corrosion potential and corrosion rates of black and galvanized steel bars during both the curing period and wet-dry cycles in a chloride solution. At the same mechanical strength class, geopolymers shrink more than cementitious mortars if free while their low modulus of elasticity causes a lower shrinkage if mortars are restrained with bars. Pore dimensions affect the water vapor permeability, which resulted to be more pronounced in geopolymers than in cement mortars, and capillary water absorption with low values especially for fly ash geopolymers. During the first month of curing, the higher alkalinity of geopolymers matrix prolongs the active state of both black and galvanized steel bars. However, when exposed to a chloride solution, fly ash based geopolymers offer a higher protection to reinforcements than cementitious mortars.


ALKALI ACTIVATION OF INDUSTRIAL BY - PRODUCTS WITH HIGH LIME CONTENT

Ioanna Papayianni, Laboratory of Building Materials, Dept. of Civil Engineering, Aristotle University of Thessaloniki (AUTH), Thessaloniki, Greece

[email protected] Stavroula Konopisi, Laboratory of Building Materials, Dept. of Civil Engineering, Aristotle University of

Thessaloniki (AUTH), Thessaloniki, Greece Kiriaki Datsiou, Laboratory of Building Materials, Dept. of Civil Engineering, Aristotle University of Thessaloniki

(AUTH), Thessaloniki, Greece Fotini Kesikidou, Laboratory of Building Materials, Dept. of Civil Engineering, Aristotle University of Thessaloniki

(AUTH), Thessaloniki, Greece

Keywords: Alkali activation, calcareous Fly Ash, Ladle Furnace Slag, glass cullet, mechanical strength, physicochemical properties. The alkali activation of industrial waste contributes to the problem of managing them by creating new materials with characteristic properties, low cost and environmentally friendly. One such product is the Fly Ash produced in Greece which is rich in calcium oxide with pozzolanic and / or hydraulic properties. The calcareous Fly Ash used in this study is a by-product of the combustion of lignite power plant of PPC in the north. The content of total calcium oxide is 35-40% wt. A second by-product is Ladle Furnace Slag, resulting of the steelmaking process of the metallurgical industry of the country and its chemical composition is largely dependent on the quality of steel. The ratio of CaO/SiO2 of the slag used is about 1.5 to 2. Other materials, such as recycled glass cullet, may also contribute to the mechanism of alkali activation. In this paper, alkali-activated mixtures of Fly Ash and mixtures of Ladle Furnace Slag with or without the addition of glass cullet are investigated and in particular, the physicochemical and mechanical characteristics. The main effort is to upgrade the properties of the above materials that could find numerous applications in the construction. The specimens (40x40x160 mm) were matured at 65 °C for 2 days and were cured in a humid environment (RH 95 ± 5%). Afterwards, control tests were done concerning mechanical strength at the age of 7, 28 and 90 days. Additionally, the open porosity and volume deformation of specimens were measured. The presence of hydrated calcium-silicon phases (CSH) and the growth of the phases of the geopolymeric gel studied through techniques XRD, SEM/EDS and FTIR. In conclusion, an early strength development was observed, which over time was maintained, possibly because of by – products’ hydraulic properties. The addition of cullet helped to further increase of the strength. Specifically, the compressive strength of the 90-d age fly ash mortars reached the level of 21 MPa. Meanwhile, the corresponding value in compression of slag mortars was 13.3 MPa.


Thursday, May 28, 2015 Keynote

MICROSTRUCTURAL INVESTIGATION OF CARBOTHERMALLY REACTED GEOPOLYMER COMPOSITES, MADE UNDER SPECIFIC ALKALINE CONDITIONS

C. Bagci,1,2 G. P. Kutyla1 W. M. Kriven1

1 University of Illinois at Urbana-Champaign, Urbana, IL USA, 2 Hitit University of Turkey

A series of geopolymers were prepared using both KOH, CsOH alkaline solution by mixing metakaolin (Al2O3•2SiO2) and then a carbon source was added these geopolymers. Geopolymer test samples were hand fabricated to determine the best composition for carbothermal reduction, with and without carbon. The viscous and homogenous slurries was poured into a mold to obtain bar samples at ambient temperature and cured in a constant 50 °C temperature humidity oven for 24 h. After determining the best composition for K and Cs-based geopolymer, these geopolymer compositions were carbothermally reacted under argon and nitrogen gas flow. The carbothermal reduction processes of the samples were carried out in an atmosphere controlled, tube furnace under argon and nitrogen flow of 5 cm3.min-1at temperatures varying between 1400-1550 °C for 2 h. XRD and SEM analyses were used to determine transformation and morphology of all the products after carbothermal reduction. The results were briefly discussed with respect to the possibility of conversion of specific geopolymer composition into their carbide and nitride analogues.

Thursday, May 28, 2015 Session IX

TRANSFORMATION OF THE GEOPOLYMER GELS TO CRYSTALLINE BONDS IN COLD-SETTING REFRACTORY CONCRETES: PORE EVOLUTION, MECHANICAL STRENGTH AND MICROSTRUCTURE

Elie Kamseu1,3*, Chantale Djangang2, Paolo Veronesi1, Andreola Fernanda1, Uphie Chinje2,3 Melo, Vincenzo

Mario Sglavo4, Cristina Leonelli1 1Department of Engineering “Enzo Ferrari”, University of Modena and Reggio Emilia, Modena, Italy.

2Department of Inorganic Chemistry, University of Yaounde I, PO Box: 812 Yaounde, Cameroon 3LAM, Local Materials Promotion Authority/MIPROMALO, PO Box: 2396 Nkolbikok, Yaoundé, Cameroon.

4Department of Materials Engineering and Industrial Technologies, University of Trento, Via Mesiano 77, 38050 Trento, Italy

Keywords: Grain-bond microstructure, kyanite, cold-setting, flexural strength, elastic modulus, porosity. Two K2O-MgO-Al2O3-SiO2 based geopolymer gels with bulk chemical composition corresponding to cordierite (Co) and 1:1 mullite-cordierite (MuCo) were successful transformed to crystalline bonds in high temperature service of cold-setting made refractory concretes. Kyanite aggregates changed the flexural strength of the gels from 11 to 28 MPa due to the development of good adhesive bonds. Under thermal cycles, up to 1250°C, the cumulative pore volume remained at 0.09 mL/g, as from the absence of important densification/shrinkage. However, the behavior of the cumulative pore volume curves changed from that of a matrix with a wide range of distribution of pore sizes to that of matrix consisting of relatively coarse grains exhibiting a rise at 10 µm as void spaces created around the contact points among the coarse kyanite grains and that at 0.054 µm as pores within the crystalline phases (cordierite, kalsilite, leucite, mullite, enstatite) formed. The microstructural observations confirmed the transformation of gel pores (size around 0.01 µm) to interparticle and intergranular pores due to the crystallization. The flexural strength increased from 28 MPa to 40 MPa in agreement with the increase in the elastic modulus from 9 to 30 GPa. The crystallization was enhanced by the MgO content (being important in Co compared to MuCo) and the kyanite concentration as particles of kyanite effectively acted as phase separation and nucleation sites.


DEVELOPMENT OF LIGHTWEIGHT INSULATING BUILDING MATERIALS

Georgia-Maria Tsaousi, National Technical University of Athens [email protected]

Konstantinos Sakkas, National Technical University of Athens Iliana Douni, National Technical University of Athens

Maria Taxiarchou, National Technical University of Athens Dimitrios Panias, National Technical University of Athens

Key Words: Geopolymerization, foaming, inorganic, surfactant, lightweight This paper deals with the development of foamed geopolymeric boards, using as raw material perlitic wastes from comminution operations of perlite exploitation. This new state of the art type of lightweight materials is based on the combination of geopolymerization technology and foaming process. The basic mechanism of foaming is to generate air, which is captured by the geopolymeric matrix in the form of individual bubbles or an interconnected series of voids. In this study the addition of two foaming agents was investigated, an inorganic and an organic one. In the first case, the foaming agent was hydrogen peroxide (H2O2) that was added into the initial paste (by mixing) in different content. Apart from H2O2, an organic surfactant was also studied as a blowing agent. The materials that came out were porous, with different type of microstructure, depending on the selected foaming agent and the foaming agent’s content. They also obtained low apparent density and thermal conductivity values. According to these results, the synthesized lightweight insulating materials, provides the opportunity to reduce the environmental footprint of construction materials in terms of raw materials and operational energy, while at the same time they present similar or even better thermal properties than the current concrete porous materials, such as Autoclaved Aerated Concrete and Aerated Concrete.


COMPARISON OF FIBERS IN GEOPOLYMER MATRIX FOR STRUCTURAL REINFORCMENT OF MASONRY (FRGP): COMPATIBILITY, REACTIVITY, DURABILITY

Sergio Tamburini, IENI-CNR-Padova, Italy

[email protected] Natali Marco, IENI-CNR-Padova, Italy

Enrico Garbin, CIRCe - University of Padova, Italy, Maria Rosa Valluzzi, DBC – University of Padova, Italy,

Gilberto Artioli, Geoscience Dept. and CIRCe – University of Padova, Italy Key Words: geopolymers, fibers, reinforcement, durability, alkali-resistance New continuous maintenance processes are required to endure the effects of extreme natural events on built heritage and existing masonry buildings and mitigate those promoting activities of structural repair and restoration. The application of Externally Bonded Fiber Reinforced Polymers (EB-FRP) has become a widespread solution for existing masonry buildings, also those belonging to the Cultural Heritage where interventions need to meet strict restoration requirements [1]. Recently, inorganic matrices like cement or lime based mortars have been proposed as an alternative choice to epoxy resin, being considered more compatible with masonry substrates, complying with traditional craftsmanship and displaying a better behavior under high temperatures. Nevertheless, traditional inorganic mortars, especially lime based ones, often present low adhesion to the parent substrate and between the composite layers. Geopolymers have better fire resistance and improved compatibility with restoration requirements compared to organic and cement based matrices and provides better mechanical strength and adhesion to fibers and brittle substrates than lime-based mortars. Fibers currently used for EB-FRP with organic and cement based matrices include steel, carbon, aramid, basalt, AR-glass fibers as well as polymer fibers. For geopolymer matrices, the main factor that may limit the use of some fibers is corrosive attack under the alkaline conditions required for the geopolymer synthesis. While Carbon, steel and AR-glass fibers are stable under the alkaline conditions found in Portland cement and geopolymers [2,3] the alkali resistance of basalt fibers, while better than for E-glass fibers [4], is lower than for AR-glass [3]. The purpose of the present work is to investigate the effectiveness of Externally Bonded Fiber Reinforced Geopolymers (EB-FRGP) for reinforcement of brick masonry. Nets of steel, AR-glass, carbon and basalt fibers were first tested for alkali resistance by accelerated ageing tests in different alkaline solutions followed by Scanning electron microscopy (SEM) inspection and tensile tests, confirming largely the available literature data. EB-FRGPs reinforcements were then applied on one side of soft mud bricks and strong extruded bricks and subject to mechanical tests, including three

point bending tests to evaluate the degree of reinforcement of the bricks and pull-off tests to evaluate adhesion of EB-FRGP on the bricks. SEM inspection of the matrix composites before and after fracture was used to evaluate the microscopic fracture activation. As geopolymeric matrix a formulation was chosen based on metakaolin, blast furnace slag, Na and/or K silicate, wollastonite and sand. Freeze-thaw cycle testing was used to evaluate the durability of the EB-FRGPs. [1]”The use of fiber reinforced polymers to improve seismic resistance of masonry”. Shrive, N. G.: Construction and Building Materials, 20 (2006) 269-277. [2] “Unidirectional fiber reinforced geopolymer matrix composites”, Welter M., PhD thesis, Victoria University of Wellington 2013.

[3] “Durability of fibers in aggressive alkaline environment” A. Coricciati, P. Corvaglia, G. Mosheyev, ICCM17 conference, 27-31 July Edinburgh, UK (2009). [4] “Investigation of Chemically Treated Basalt and Glass Fibres”, Friedrich, M., Schulze, A., Prosch, G., et al., Microchim. Acta, 2000, vol. 133, pp. 171.


IN-SITU THERMO-MECHANICAL TESTING OF FLY ASH GEOPOLYMER CONCRETES MADE WITH QUARTZ AND EXPANDED CLAY AGGREGATES

William Rickard1,2, Gregor Gluth2 and Klaus Pistol2

1 Curtin University, Perth, Australia 2 BAM Federal Institute for Materials Research and Testing, Berlin, Germany

The thermal properties of geopolymer pastes have been investigated extensively in the literature. Recently, there has been an increased focus on foamed and composite geopolymers. Geopolymer based materials that are to be used in large scale applications such as structural members or tunnel linings are likely to be in the form of concretes and as such will contain significant amounts of aggregates. Knowledge of the engineering properties of geopolymer concretes and the behavior of common aggregate types is critical in order to gain a better understanding of the mechanical and microstructural changes that occur during elevated temperature exposure. The presented work will summarize the results from a project which involved synthesizing a range of geopolymer concretes and analyzing the changes in their mechanical and microstructural properties before, during and after high temperature exposure. Fly ash based geopolymer concretes with either quartz aggregate or expanded clay aggregate were exposed to various temperatures up to 750 °C using a thermo-mechanical testing apparatus. Tests were performed on 300 mm (height) by 100 mm (diameter) cylinders according to RILEM TC 129-MHT recommendations. Thermal expansion and mechanical strength changes under various loading regimes were monitored in order to quantify the structural changes in the material. Microstructural investigations were also undertaken to better understand the measured changes in the mechanical properties. It was found that dehydration of capillary water caused strength losses at temperatures < 300 °C. At higher temperatures sintering promoted strength increases. At temperatures > 500°C geopolymer concretes exhibited significant advantages when compared with reported values for conventional materials. As expected, the quartz aggregate concrete was more severely affected by the differential expansion with the paste phase.

Thursday, May 28, 2015 Session X

LOW COST SYNTHESIS of SIALON TYPE CERAMIC POWDERS FROM Na, K or Cs GEOPOLYMER

Cengiz Bagcia,b, Greg P. Kutylaa and Waltraud. M. Krivena

aDepartment of Material Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA

bDepartment of Metallurgical and Materials Engineering, Faculty of Engineering, Hitit University, Corum, 19030, TURKEY

Sialon type ceramic powders were synthesized from geopolymer carbon precursors (1:1:4.5:12+9C)

prepared different alkaline conditions by carbothermal reduction and nitridation. NaOH, KOH, or CsOH alkaline solutions were used to make NaGP, KGP and CsGP resins by mixing metakaolin (Al2O3.2SiO2), respectively. NaGP9C, KGP9C and CsGP9C resins were prepared by mixing 9 moles of carbon nano-powder with GP resins. The viscous and homogenous slurries was poured into a Teflon mold to obtain bar samples at ambient temperature and cured in a humidity controlled, constant temperature oven at 50 °C for 24 h. The GP9C compacts were powdered by following additional drying in an open air furnace at 300 °C for 1 h. Also, the GP9C powders were planetary milled with a ball to powder ratio of 5:1 for 10 min to increase their reactivity. Therefore, the GP9C precursors were carbothermally reacted in an atmosphere controlled tube furnace at temperatures of 1400°, 1500° and 1600 °C for 2 hours with high purity nitrogen (99.99%) under dynamic conditions. XRD, Rietveld refinement and SEM-EDS analyses were made to determine transformation and morphology of all the products after carbothermal reduction and nitridation. Depending on the alkaline conditions of the GPs, phase pure or multiple types sialon compounds were examined.


HT MECHANICAL PROPERTIES OF ALUMINA OR MULLITE FIBER REINFORCED GEOPOLYMER COMPOSITES

S. S. Musil1, A. A. Kolchin2, S. T. Mileiko2 and W. M. Kriven1,*

1 Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL,

USA and

2 Solid State Physics Institute, Russian Academy of Sciences, Chemogolovka, Moscow District, Russia

Geopolymers an attractive choice as a matrix material for elevated temperature composites. This body of research investigated numerous different reinforcement possibilities and variants of geopolymer matrix material and characterized their mechanical performance in tension, flexure and flexural creep. This study incorporated unidirectional fiber and woven fiber reinforcements. Sodium, potassium, and cesium based geopolymer matrices were evaluated with cesium-based geopolymer showing great promise as a high temperature matrix material. It showed the best strength retention at elevated temperature, as well as a very low coefficient of thermal expansion when crystallized into pollucite. These qualities made cesium geopolymer the best choice for creep resistant applications. Cesium geopolymer binders were combined with unidirectional continuous polycrystalline mullite fibers (Nextel™ 720) and single crystal mullite fibers, after which the matrix was crystallized to form cubic pollucite. Single crystal mullite fibers were obtained by the internal crystallization method and showed excellent creep resistance up to 1400oC. High temperature flexural strength and flexural creep resistance of pollucite and polycrystalline/single-crystal fibers was evaluated at 1000 to 1400oC.


THE EFFECT OF HEAT-CURING ON MECHANICAL PROPERTIES OF SLAG BLENDED FLY ASH BASED GEOPOLYMER CONCRETE

Amin Noushini, University of New South Wales, Australia

[email protected] Mahdi Babaee, University of New South Wales, Australia Arnaud Castel, University of New South Wales, Australia

Key Words: Geopolymer concrete; heat curing; internal curing; compressive strength. In current study, the effect of various heat-curing conditions on mechanical properties of low-calcium fly ash-based geopolymer concrete (GPC) including 10% ground granulated blast furnace slag (GGBFS) has been investigated. Compressive strength, modulus of elasticity and Poisson’s ratio are considered as the basic mechanical properties. GPC samples and their ordinary Portland cement (OPC) concrete counterparts (having the same amount of binder and aggregate) have been cured under twelve different heat-curing regimes as well as in ambient condition. The heat curing regimes include 3 temperatures of 60, 75 and 90 degree Celsius as well as 4 different curing lengths of 8, 12, 18 and 24 hours. The results obtained are cross compared between GPCs and their counterpart OPC concrete and a summary of which are as below. In contrast to the OPC concrete, the compressive strength of fly ash-based GPCs does not increase significantly over time when cured at high temperature (75 to 90 °C), specifically for a longer curing period of 18 to 24 h. The compressive strength of fly ash-based GPCs increases with increase in the curing temperature from 60 to 90 °C when cured for 8 to 12 h. However, for a longer period of heat-curing (18 to 24 h) the optimum strength is achieved at 75 °C and beyond this temperature the geopolymer concretes are losing strength. The fly ash-based GPC samples having 10% GGBFS cured at ambient temperature showed a very low strength at early ages (fc,1 = 2.9 MPa), however, they had a reasonable strength development rate resulting in a 28-day compressive strength of 41.7 MPa. Therefore, for application which are not sensitive to the high short-term strength (<7 days) and requiring a lower heat of hydration, the ambient curing could be considered as a sensible curing method since it is very much less expensive than the heat-curing method and is resulting in a 40 MPa plus compressive strength after 28 days. For applications requiring high early-age strength such as precast concrete industry, the geopolymer concrete is a very much better material than the traditional Portland cement concrete. GPC could be considered as an ideal material for precast concrete structural members. The results of the current study showed that GPC could achieve 78% higher short-term compressive strength and 21% higher long-term compressive strength comparing to its counterpart OPC concrete cured under the same heat-curing condition.

Figure 1 - Ratio of 1-day to 28-day compressive strength of GPCs versus OPCCs

0

20

40

60

80

100

120

IAC 8h 12h 18h 24h 8h 12h 18h 24h 8h 12h 18h 24h

f c,1/f

c,28

[%]

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90 °C 75 °C 60 °C

OPCC

GPC


IS MORE R&D REQUIRED FOR COMMERCIAL ADOPTION OF GEOPOLYMERS?

Jannie S.J. van Deventer1,2

1Department of Chemical & Biomolecular Engineering, The University of Melbourne, Victoria 3010, Australia 2Zeobond Pty Ltd, P.O. Box 23450, Docklands, Victoria 8012, Australia

Demand pull by a carbon conscious market continues to be the main driver for the short term uptake of geopolymer cement in Australia. There are indications that regulatory pressure to add value to waste fly ash and slag in some countries will become an additional driver for adoption of geopolymers. The scale-up from the laboratory to the real-world is technically challenging but achievable, leaving the core challenge as the scale-up of industry participation and acceptance of geopolymers. High profile application projects in Australia have demonstrated the vast regulatory, asset management, liability and industry stakeholder engagement process required to commercialize geopolymers. It is important for commercial producers of geopolymer cements and concretes to work closely with research partners to develop testing methods for accelerated durability, especially as longer term in-service testing data become available. Substantial progress has been made in Australia, where the local road authority has recognized geopolymer concrete as equivalent to Portland concrete. In the absence of a long in-service track record, R&D is required to validate durability testing methods and improve geopolymer technology. The fact that all concrete standards are based on Portland cement remains an obstacle to the commercial adoption of geopolymers. Even when asset owners and specifiers such as government, architects and design engineers accept the results of durability testing of geopolymers, the main barrier to entry of these new materials into an established market is access to a suitable supply of source materials including fly ash, granulated blast furnace slag and alkaline activators. These issues are seldom appreciated by researchers, governments or the ultimate users of concrete. Tests for the durability of Portland concrete have been validated against its long track record and may not be applicable to geopolymer cement. Geopolymer concrete usually has high resistance to acid, fire, freeze-thaw, chloride diffusion and sulphate, but shows higher porosity in tests that require boiling of the concrete. Standard accelerated carbonation tests are not appropriate for geopolymer concrete, which displays satisfactory carbonation rates in-service in contrast to poor laboratory testing. It has been shown that the mode of drying has a major effect on the microcracking of geopolymer gels, which explains why some tests are inappropriate for geopolymers. It has also been shown that a higher MgO content in slag enhances reactions and reduces Al incorporation into the C-A-S-H due to the formation of hydrotalcite which reduces carbonation. Most research on geopolymers has been done using metakaolin, fly ash and blast furnace slag as precursors. A case can be made for using other sources of solid silica, such as rice husk ash or sugar cane bagasse ash, or natural pozzalans as precursors, often in addition to fly ash or metallurgical slags. R&D is required in this field to underpin commercial development in this field.

Thursday, May 28, 2015 Session XI

GEOPOLYMER CONCRETE: A PRACTICAL APPROACH

Cyril Attwell, Murray & Roberts (Pty) Ltd [email protected]

Key Words: geopolymer, abrasion resistance, shrinkage, durability.

High production costs of concrete in combination with the high CO2 footprint of cement has instigated the research, development and application of concrete utilizing by-products and wastes as partial or entire binder replacements. The literature research progressed through the myriad of definitions and theses available to define two distinct paths of activation, notably alkali- and acid-activations. The alkali-activated path was chosen as the operating risks with alkali materials within the construction industry are known. Experimental work progressed in the laboratory using this base concept to achieve a predictable material with properties similar to both resin and concrete systems depending on the balance of chemistry. The experimentally-defined chemical system has being applied in trials for paver plants and concrete slabs to view the properties in dry and wet plastic states and their respective hardened properties. The hardened properties tested include shrinkage, abrasion resistance, compressive and flexural strengths under different curing regimes. Plastic properties were reviewed through the placing, consolidation and finishing of the products. Differences in consolidation and finishing were established with dry- and wet-plastic applications. The majority of hardened state properties were improved except for a marginal decrease of flexural strength. Due to the benefits in the plastic and hardened state of the geopolymer concrete, further applications on several sites with improvements to the chemical process are being considered to evaluate the viability of replacing conventional Portland cement concrete with the geopolymer concrete on a structural basis.


Thursday, May 28, 2015 Session XI

GEOMATERIAL FOR INDUSTRIAL SANITARY USE

David Kpogbemabou1* and Sylvie Rossignol1 1 CEC, Science des Procédés Céramiques et de Traitements de Surface (SPCTS-UMR CNRS 7315), 12 rue

Atlantis, 87068 Limoges, France *[email protected]

Keywords: sink, sanitary, silica gel, durability, clays, geomaterial Geopolymers are amorphous three-dimensional alumino-silicate binder materials which may be synthesized at slightly lower temperature by alkaline activation of alumino-silicates. This kind of material displays high mechanical properties and efficient thermal behavior, which allow considering their use in building area. However, building materials are currently tightly followed according to their organic volatile compounds, durability and heat behavior. In this condition, a geomaterial with high properties and no organic compounds emission will be very attractive for use in sanitary ware. The aim of this work deals with the preparation of high density or quasi-dense geomaterials based on alkaline silicate, alkaline hydroxide, metakaolin and additives. Natures of alkaline element, quantity of inputs and additives such as for colour or surface aspect were followed. In fact, theses modify the aspect, nature and property of geomaterials. In a second hand, the possibility of perform complex shapes was studied. To compare material performances in terms of mechanical properties, shrinkage and porosity, different studies have been done. In first approach, different formulations were studies and compared. Weight, shrinkage, FTIR and SEM measurements are performed in order to evaluate material behavior and especially microstructure. In order to test the material durability, samples are immersed in various solutions. Alteration was evaluated by visual aspect, SEM measurements and FTIR, which put in evidence the stability of geomaterial. In second way, complex shapes were obtained such as cup and sink. These results confirmed the possibility of using geopolymer in sanitary ware. This behavior is very attractive and gives an opportunity and possibilities to be used as in building area.

Friday, May 29, 2015 Keynote

APPLICABILITY OF ALKALI ACTIVATED CEMENTS FOR IMMOBILIZATION OF LOW-LEVEL RADIOACTIVE ION EXCHANGE RESINS

Pavel Krivenko, Kiev National University of Civil Engineering and Architecture, Scientific Research Institute for

Binders and Materials, [email protected] Hailin Cao, Advanced Materials Research Institute, Shenzhen Academy of Aerospace Technology

Oleg Petropavlovsky, Kiev National University of Civil Engineering and Architecture, Scientific Research Institute for Binders and Materials

Luqian Weng, Advanced Materials Research Institute, Shenzhen Academy of Aerospace Technology

Key Words: Alkali activated cement, immobilization, ion exchange resin, long-term disposal, radioactive waste, zeolite. All generated and collected low-level radioactive wastes (LRW) should be processed into final products for long-term disposal without loss of their properties. Worldwide, a cementation is the most widely used technology for immobilization of nuclear wastes. Due to many varieties of LRW some of these wastes can be incompatible with the process of hydration and hardening of a cement matrix and require optimization of a cement applied and immobilization technologies. This paper presents and discusses the results of development of recipes of multi-component alkali activated cements intended for a complex processing technology of liquid low-level radioactive ion exchange resins. Radioactive wastes to be immobilized covered two types of ion-exchange resins: cation – and anion exchange resins taken as 2:1 with pH=12 and anion-exchange resin with pH=5. Analysis of the obtained results suggested to show that the developed optimal recipes of the final products in their properties were in compliance and in some case even exceeded those set in the standards of the PR China: GB 7023 and GB 14569. High efficiency of the alkali activated cement matrices for immobilization of radioactive wastes is attributed to their ability to bind radionuclides not only mechanically and adsorptionally, as it happens in case of traditional cement matrices, but chemically within the zeolite-like hydration products of the R2O∙MeO∙Al2O3∙nSiO2mH2O or R2O∙Al2O3∙nSiO2mH2O types, where: R-Na, K, Cs; Me-Ca, Mg, Sr.

Friday, May 29, 2015 Session XII

STRUCTURATION OF AN ORGANIC LIQUID OIL/GEOPOLYMER COMPOSITE

Vincent Cantarel CEA/DEN/DTCD [email protected]

David Lambertin, CEA/DEN/DTCD Arnaud Poulesquen, CEA/DEN/DTCD

Fabrice Leroux, Institut de chimie de Clermont Ferrand Guillaume Renaudin, Institut de chimie de Clermont Ferrand

Fabien Frizon, CEA/DEN/DTCD

Key Words: Geopolymer, composite, emulsion, organic oil.

Geopolymers are a class of binders with unique hardening chemistry and potentially specifics areas of application. Cement Portland shows poor compatibility with liquid oil organic waste, therefore we have explored the potentiality of using metakaolin based geopolymer to encapsulate those wastes and obtained geopolymer/oil solid composite. Those geopolymers/oil composites were obtained by adding oily waste to the alkaline activating solution under mechanical stirring, leading to a stable emulsion. Metakaolin was then added to this emulsion as a final step. Obtained composites possessed compressive strength around 30 MPa. This presentation aims to clarify the phenomena affecting the oil dispersion and the emulsion stabilization. Characterizations of the final composite structure will also be presented. Geopolymers composites were synthesized with different water contents. Anionic, cationic or non-ionic surfactants were used to control the emulsion and hexadecane was used as model oil. The emulsification process is the key for composite preparation and is governed by the interfacial tension (IFT) between the alkaline activating solution and hexadecane. IFT measured on our systems were always low, even without added surfactant molecules. Hence increasing the surface between our two components demands little energy and an emulsion state can easily be reached. To control the emulsification process, the activating solution viscosity can be tuned. It was found to be significantly sensitive to modification in the water content and temperature, varying over two decades.

The emulsion stability was explained by rheology method. The measurement of higher elastic modulus of the paste after metakaolin addition to the emulsion demonstrates the existence of strong interactions between the geopolymer paste and the organic compound. We noticed that this phenomenon was particularly marked when cationic or non-ionic surfactants were used. Organic compounds dispersion in the composite was observed by MEB (figure 2) and quantified by µtomography . Organic prints have been observed and it was found that during the matrix hardening, oil kept a droplet shape with a diameter ranging from a few to 100 µm. As porosity and the intrinsic bulk heterogeneity of composites may serve as migration path for the oil, composites were also analyzed by porosimetry and impedance spectroscopy to explain the low leaching properties of our composite. Those studies showed that although the oil droplets are connected with the geopolymers native porous systems, the organic compound doesn’t modify transport mechanisms in the geopolymer in term of time constant.

Figure 1 - oil waste/geopolymer composite sample

Figure 2 - SEM micrograph of a calcinated composite


APPLYING GEOPOLYMER TECHNOLOGY TO SOIL INJECTION GROUTS

Anass Cherki El Idrissi, Ecole Centrale Nantes [email protected]

Emmanuel Rozière, Ecole Centrale Nantes Ahmed Loukili, Ecole Centrale Nantes

Sabine Darson-Balleur, Solétanche Bachy France

Key Words: Geopolymer, grout, water, precursor.

The applications of geopolymers are numerous and cover various fields. Soil injection grouts are among the fields that the geopolymer research has not fully covered yet. Aside from some works done on in situ reinforcement of pozzolanic soils [1][2], little has been done as far as the production of injectable geopolymer grouts. This may be due to the challenges that this application raises.

These challenges include the lack of functional superplasticizers for geopolymer materials, the ambiguity yet surrounding the role of water in the geopolymerization process without forgetting the rest of the issues that are encountered when manufacturing a geopolymer mix: safety precautions, variability of the raw materials [3] and the lack of knowledge of the chemical reactions involved. In this study, we tried to look into the possibility of using geopolymer materials as soil injection grouts. Having established their potential as a replacement of cement grouts, the properties of geopolymer grouts have been further investigated in order to determine the factors influencing their behavior. Mechanical properties (compressive strength, elastic modulus…), rheological properties (Marsh funnel viscosity, workability, density) have been measured, in parallel with a microstructural study (thermogravimetric analysis, mercury porosimetry, SEM/EDS imaging, isothermal calorimetry). This allowed for an optimization of the formulas as well as a better understanding of the effect of some parameters, e.g. water content, type of precursor and their combination, nature of the alkali used and the Si/Al ratio. References

[1] L. Verdolotti, S. Iannace, M. Lavorgna, and R. Lamanna, “Geopolymerization reaction to consolidate incoherent pozzolanic soil,” J. Mater. Sci., vol. 43, no. 3, pp. 865–873, Oct. 2007.

[2] N. Cristelo, A. T. Pinto, and S. Glendinning, “Advances in Soft Soil Improvement by Alkaline Activation,” 2005.

[3] P. Duxson and J. L. Provis, “Designing precursors for geopolymer cements,” J. Am. Ceram. Soc., vol. 91, no. 12, pp. 3864–3869, Dec. 2008.

Figure 1 – Compressive strength comparison between cement grouts and geopolymer grouts


GEOPOLYMERS: A NEW ROUTE TO INERTIZE CHROMIUM LIQUID WASTE EXPLOITING ITS WATER CONTENT

Isabella Lancellotti, University of Modena and Reggio Emilia, Department of Engineering “Enzo Ferrari”,

Modena, Italy, [email protected] Chiara Ponzoni, University of Modena and Reggio Emilia, Department of Engineering “Enzo Ferrari”, Modena,

Italy Francesco Armetta, University of Palermo, Department STEBICEF, Palermo, Italy

Luisa Barbieri, University of Modena and Reggio Emilia, Department of Engineering “Enzo Ferrari”, Modena, Italy

Eugenio Caponetti, University of Palermo, Department STEBICEF, Palermo, Italy Cristina Leonelli, University of Modena and Reggio Emilia, Department of Engineering “Enzo Ferrari”, Modena,

Italy

Key Words: chromium liquid waste, inertization, leaching test, ss MAS NMR geopolymers, mechanical strength In this study an industrial liquid waste containing an amount of chromium of ≈ 2.3 wt% in the forms of metallorganic salts is inertized into a metakaolin based geopolymer matrix. One of the innovative aspects is the exploitation of the water contained in the waste for the geopolymerization process. This avoided any drying treatment, a common step in the management of liquid hazardous waste. The evolution of the process of different geopolymers containing a waste amount ranging from 3 to 20% wt and their capability to ineritize chromium cations were studied by: i) the leaching tests, according to the EN 12457 regulation, at different curing times (15, 28, 90 and 540 days) monitoring releases of chromium ions (Cr(III) and Cr(VI)) and the cations constituting the alluminosilicatic matrix (Na, Si, Al); ii) the humidity variation for different curing times (15 and 540 days); iii) SEM characterization at different curing times (28 and 540 days); iv) the trend of the solution conductivity and pH during the leaching test; v) the characterization of the short-range ordering in terms of T-O-T bonds (where T is Al or Si) by 29Si and 27Al solid state magic-angle spinning nuclear magnetic resonance (ss MAS NMR) for geopolymers containing high amounts of waste (10-20% wt). The results show the formation of a stable matrix after only 15 days independently on the waste amount introduced; the longer curing times increase the matrices stabilities and their ability to immobilize chromium cations. The maximum amount of waste that can be inertized is around 10 wt% after a curing time of 28 days. The obtained materials containing the chromium liquid waste ranging from 0 to 10%wt are also characterized from a mechanical point of view. The chromium-based geopolymers exhibit a progressive improvement of compressive strength increasing the chromium liquid waste concentration. In particular the standard geopolymer without waste shows a compressive strength around 25-26 MPa but inserting 10 wt% of waste the materials reaches 41-42 MPa at the same curing time (15days).

Figure 1 – Leached Cr as a function of curing time compared to total chromium in the inorganic polymer.


INNOVATIVE MATERIALS FOR PASSIVE FIRE PROTECTION OF TUNNELS

Konstantinos – Miltiadis Sakkas, National Technical University of Athens [email protected]

Alexandros Sofianos, National Technical University of Athens Pavlos Nomikos, National Technical University of Athens Dimitrios Panias, National Technical University of Athens

Key Words: passive fire protection, fire resistant, geopolymers, RWS curve.

An essential element of tunnel design is to ensure that the structural elements will not fail due to the high temperatures, which may be developed during a fire. For this problem, three different methods of passive fire protection have been developed: (a) Spraying with cementitious mortars; (b) Lining with non-combustible boards; and (c) Lining with concrete containing polypropylene fibers. However there is always a need for developing a new material with improved fire resistance properties and low cost. The geopolymerization technology seems to be very attractive in developing effective fire resistant materials. The slag that was used for the process of the geopolymerization was provided by the metallurgical plant of the Greek company LARCO G.M.M.S.A. that treats laterites to produce ferronickel. Then using this slag as a raw material and a highly alkaline solution (NaOH or KOH) two different geopolymers were produced, which differ in their synthesis. The mechanical (compressive and flexural strength), physical (setting time and water absorption) and thermal properties (thermal conductivity) of the produced materials were measured and their technical data are presented. The results indicate that the produced materials have adequate mechanical, physical and thermal properties similar or superior than the commercial available fire resistant materials. Then, the materials were tested for their resistance under high temperatures (up to 1350 oC) according to E.F.N.A.R.C specifications and guidelines. From the tests results it is concluded that these geopolymers perform well under various fire scenarios without yielding or spalling, according to the standard fire temperature curves employed in international norms, and that may occur during a real fire incident either in a building or in a tunnel. Also as it is shown in figure 1, they can withstand all requirements concerning both the temperature in the interface of the concrete and material and the temperature at the back surface of concrete. Further, it is shown that they are very cost-effective materials, taking into account that the basic raw material is a by-product not used otherwise. The cost of these geopolymers is extremely competitive compared to the existing materials used today for passive fire protection systems.

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Figure 1 – Results of the passive fire protection tests


POTASSIUM GEOPOLYMER REINFORCED WITH GRANITE POWDER

Daniel Roper Material Science and Engineering, University of Illinois at Urbana-Champaign

[email protected] Sean Musil, Gregory P. Kutyla, Waltraud Kriven

Material Science and Engineering, University of Illinois at Urbana-Champaign [email protected]

Key Words: Geopolymer, Granite, Powder

Granite powder is a waste product at many quarries and stone processing plants all over the globe. This waste powder, when properly sieved into an appropriate size distribution, can be used as suitable reinforcement for geopolymers. The goal of this design was to create a sustainable, cost-effective and reliable geopolymer composite utilizing resources that are easily attained worldwide. Its properties and viability as a structural material were determined through four-point flexure testing according to ASTM standards and analyzed by Weibull statistics. Its refractory properties were tested by exposing samples to various temperatures, then testing for shrinkage and flexure strengths. Scanning electron microscopy (SEM) was used to characterize the size and geometries of the granite powder, and to determine its viability as a reinforcement for potassium geopolymer.


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