Symposium CJ
ABSTRACTS
Session CJ-1 Synthesis, processing and microstructure
CJ-1:IL01 Processing Options to Create More Sustainable Materials
Y. PONTIKES, KU Leuven, Department of Materials Engineering, Leuven, Belgium
Sustainability remains high on the agenda, and diverse strategies are deployed to develop materials with a smaller environmental footprint. Many of these initiatives seek to produce equivalent products through the use of alternative raw materials and/or process modifications. Others take a more fundamental stance, challenging the very basis of current practices and proposing entirely new approaches to meeting societal needs. This presentation introduces a conceptual framework that categorizes and prioritizes such efforts, integrating technical, market, and regulatory considerations. Bauxite residue is employed as a case study to illustrate the methodology; however, the framework and insights are broadly applicable to other resources, including metallurgical slags, construction and demolition wastes, and clays. The grouping is done following a conceptual process, i.e., how to enhance the reactivity of the raw material, how to deliver a performant binder, and how to deliver a performant monolith. In all cases examined, the processes are powered by electricity. Representative examples include high-temperature melt engineering, mechanochemical activation, CO₂ uptake, and hydrothermal curing, as well as innovative construction practices that enable the reuse of building components.
CJ-1:IL02 Influence of Shaping Process on Geopolymer Microstructure
M.C. BIGNOZZI, G. MASI, C. PACENTE, A. SACCANI, University of Bologna, Department of Civil, Chemical, Environmental and Materials Engineering, Bologna, Italy
Geopolymers are a promising class of materials that exhibit a high versatility in terms of physical-mechanical properties and applications. Geopolymer mix design is typically tailored according to the desired final properties; however, the shaping process also plays an important role in defining the microstructure, which in turn influences the final behavior of the material. Recently, 3D-printing is also emerging as a new technology for shaping process of geopolymers; however, a systematic comparison of the final microstructure of 3D-printed materials with respect to cast and pressed ones has not yet been carried out. In this contribute, open porosity at the micro and nanoscale is investigated and reported for some formulations with minimal variations needed only for making them suitable to the different shaping process. Metakaolin and ceramic waste from the rectification process were used as geopolymer precursors, while sodium silicate and sodium hydroxide solutions were used as activators. The final aim is to understand the advantages and disadvantages of each shaping process, in view of achieving rigorous microstructural control under identical geopolymerization conditions (temperature and relative humidity).
CJ-1:IL03 Soil Stabilization by Alkali Activation
L. ŽIBRET, K. FIFER BIZJAK, V. DUCMAN, Slovenian National Building and Civil Engineering Institute (ZAG), Ljubljana, Slovenia
Traditionally, lime or cement has been used for soil or sediment stabilization. However, alkali activation can utilize waste materials for such applications, which, besides technical benefits, also offer environmental advantages. Alkali-activated binders form strong aluminosilicate gels that enhance the soil’s compressive and shear strength. Within the present study, sediments from the reservoirs of a hydroelectric power plant and a port that are reducing storage volume have been investigated. The sediments obtained in this way have a high moisture content and are therefore unsuitable for direct use in geotechnical embankments. Both sediments (river and marine) were stabilized by the addition of slag, ash and/or metakaolin, and activated by water glass and/or NaOH. The compressive strength of the stabilized soil in laboratory tests increased significantly. But as long-term performance is of utmost importance, pilot field investigations are needed before large-scale application. Field application revealed challenges related to the high moisture content of sediments and slower strength gain due to limitations in establishing optimal curing conditions. The introduction of alkali activation technology into soil stabilization promotes the circular economy and industrial symbiosis.
CJ-1:IL04 Heavy Metals and Anions Encapsulation in Geopolymers: the Role of Chemical Agents
F. GENUA1, M. GIOVINI1, R.E. RUSSO2, M. FATTOBENE2, M. BERRETTONI2, C. LEONELLI1, I. LANCELLOTTI1, 1Department of Engineering “Enzo Ferrari”, University of Modena and Reggio Emilia, Modena, Italy; 2School of Science and Technology, University of Camerino, Camerino, Italy
Geopolymer synthesis involves a polycondensation reaction that forms a complex 3D network of silicon and aluminium atoms that are tetrahedrally coordinated with oxygen. This network is capable of immobilising cations and anions, thus rendering inert an hazardous waste. Galvanic sludge waste poses environmental hazards due to its high concentrations of Cr₂O₃ and NiO. Due to the presence of toxic cations and hazardous anions, this waste is particularly difficult to stabilise and solidify. However, this work demonstrated the efficiency of stabilising and solidifying real galvanic waste using metakaolin-based geopolymers incorporating different types of agents: chelating, reducing and adsorbing. During geopolymerisation, reducing agent create a synthetic redox environment that favours the immobilisation of pollutants. The solidified geopolymers were tested with European standards for their ability to retain hazardous cations and anions. Chelation reduced Ni leaching, the reducing agent decreased Cr release by reducing Cr(VI) to insoluble Cr(III), and the adsorbing agent enhanced Ni retention via cation exchange. This work presents a low-carbon process as alternative to traditional high-temperature treatments for managing hazardous waste.
Acknowledgement: PRIN 2022, ACCHA, 2022LKEKJ7
CJ-1:IL05 Mechanical and Microstructural Performance of Geopolymers Synthesized from Agroindustrial Residues in Brazil: Challenges and Future Applications
MS SEYEDSALEHI, D. RIVERA ORJUELA, G. BONINI DE CASTRO, A.C. CONSTÂNCIO TRINDADE, Department of Biosystems Engineering, University of São Paulo, Pirassununga, SP, Brazil
Agro-industrial residues from bamboo, soybean, and corn represent a vast and underutilized biomass stream in Brazil. When properly processed, these residues can be transformed into value-added materials for circular and low-carbon construction. Controlled calcination produces ashes enriched in amorphous silica (SiO₂) and alkalis (K₂O), essential for geopolymer synthesis. In this study, residues were thermally treated to obtain reactive ashes suitable for one-part geopolymer formulations requiring only water addition. The process increased amorphous silica and promoted the in situ formation of potassium carbonate (K₂CO₃), enhancing reactivity and self-activation potential. Comprehensive analyses (XRF, XRD, FTIR, TG/DSC, SEM-EDS, ICP-OES) and mechanical tests assessed composition, phase evolution, and performance. Results showed that the synergistic interaction between K₂O and SiO₂ facilitates early activation, yielding dense matrices with high compressive strength. This approach offers a circular, carbon-efficient route for residue valorization and supports the development of sustainable, regionally tailored geopolymer technologies aligned with Brazil’s bioeconomy goals.
CJ-1:L06 Microstructural Investigation of Alkali Activated Materials Based on Different By-products after Accelerated Carbonation
G. MASI, C. PACENTE, University of Bologna, Department of Civil, Chemical, Environmental and Materials Engineering, Bologna, Italy; S. BANDINI, Certimac, Faenza (RA), Italy; L. CASINI, Centro Ceramico, Sassuolo (MO), Italy; M.C. BIGNOZZI, University of Bologna, Department of Civil, Chemical, Environmental and Materials Engineering, Bologna, Italy
Research in construction sector is currently focusing on the possibility of materials to adsorb CO2 by using suitable SCM and/or during their curing stage and/or their service life, to reduce the carbon footprint related to this sector. This topic has a synergistic effect with other strategies having the same final aim, i.e. the application of different binders rather than cementitious ones, such as alkali activated materials (AAMs) and geopolymers. For this binder typology, investigation of their microstructure is a fundamental step in view of their applications. Thus, this research was aimed at exploring the microstructural changes in terms of porosity of AAMs after accelerated carbonation. It is known that AAMs can carbonate when exposed to atmosphere; however, this process can impair the final properties of the materials, such as mechanical and durability performances. In this study, blends of metakaolin and ceramic waste from tiles rectifying process or wood bottom ash from thermoelectric power plants were used as precursors. Modifications in micro- and nano-porosity were measured before and after accelerated carbonation exposure. It was found that a change in the open porosity occurred depending on the calcium content of the precursors and the time of carbonation exposure.
CJ-1:L07 Immobilization of Hazardous Exhausted Lime in Alkali-Activated Matrices
F. GENUA, C. LEONELLI, I. LANCELLOTTI, Department of Engineering “Enzo Ferrari” - University of Modena and Reggio Emilia, Modena, Italy
The ceramic tile industry of the Emilia-Romagna region, responsible for about 90% of Italy’s production, generates significant amounts of exhausted lime, a hazardous by-product from air emission treatment during firing ≈15 kg per 1000 m² of tiles¹. Unlike other ceramic residues, this waste, mainly composed of Ca(OH)₂, is still not reused due to its fine granulometry, high alkalinity, and presence of fluorides, sulphates, chlorides, and heavy metals. In this study alkali-activated materials were developed for the room-temperature inertization and consolidation of exhausted lime at 5 and 20 wt%. The immobilization efficiency of both cations and anions was assessed by leaching tests, while XRD and FT-IR analyses elucidated the retention mechanisms of F⁻, SO₄²⁻, and Cl⁻ within the geopolymeric network. Various additives were also introduced to enhance anion retention, confirming alkali activation as a promising and sustainable strategy for the circular management of exhausted lime.
[1] Giacomo Boschi et al., 2023. Recycling insight into the ceramic tile manufacturing industry. Open Ceramics16,100471. Acknowledgements: PNRR DM 629/2024 “Transizioni digitali e ambientali”, Missione 4, Componente 1, Investimento 3.4, with GARC AMBIENTE SpA for the PhD grant of F. Genua.
CJ-1:L08 Microstructural and Mechanical Behavior of Geopolymers Incorporating Phosphate Waste Rocks
A. HAIDA, S. MANSOURI, Y. TAMRAOUI, J. ALAMI, Benguerir, Morocco
Phosphate mining generates large quantities of waste rocks that pose significant environmental challenges. This study explores the valorization of phosphate mine waste (PMW) as a reactive precursor in the synthesis of sustainable geopolymers. Metakaolin was partially substituted by PMW and activated with sodium hydroxide and sodium silicate solutions to produce eco-efficient binders. The effects of PMW incorporation and activator composition on the geopolymerization process and material performance were systematically examined. Microstructural characterization using XRD, FTIR, and SEM-EDS revealed that phosphate waste contributes to the formation of amorphous N–A–S–H and (N,C)–A–S–H gels, enhancing the microstructural compactness of the matrix. The findings demonstrate that phosphate mine waste can effectively participate in geopolymer reactions, reducing raw material consumption and environmental impact. This work offers a sustainable route for converting mining residues into low-carbon construction materials and supports circular economy objectives in phosphate-producing regions.
CJ-1:IL09 Role of Nanomaterials in the Synthesis of Functional Porous Matrices
F.A.N. NGASSA1, Y. BOGNE1, I.F. GILDAS1, A.P. YEPSEU1, G.A. TIGWERE1, L.D. NYAMEN1, N. REVAPRASADU2, P.T. NDIFON1, 1Department of Inorganic Chemistry, University of Yaoundé 1, Cameroon; 2Department of Chemistry, University of Zululand, South Africa
The integration of nanomaterials in the synthesis of structural and functional porous matrices has opened new frontiers in material science, enabling the design of advanced systems with tailored structural, physicochemical, and catalytic properties. Here, we explore the pivotal role of nanomaterials as templates, modifiers, and active components in fabricating porous architectures with enhanced properties and performance. The discussion also highlights the use of eco-friendly and sustainable raw materials, such as essential oils as biosurfactants. The study emphasizes on how nanostructured particles contribute to controlled porosity, surface area optimization, and functional versatility. Furthermore, we review the influence of nanomaterial characteristics—size, morphology, and surface chemistry—on the resulting matrix properties and their applications in catalysis, adsorption, energy storage, and environmental remediation. The findings demonstrate that nanomaterial-assisted synthesis not only advances material functionality but also supports the development of sustainable and high-performance systems for emerging technological applications. Thus, contributing to Sustainable Development Goals, mainly SDG 3, SDG 6, SDG 7 and SDG13.
CJ-1:IL10 Cold-sintering of Fe-based Aluminosilicates
E. KAMSEU1,2, M. BIESUZ3, C. LEONELLI1, V.M SGLAVO3, 1Department of Engineering “Enzo Ferrari”, University of Modena and Reggio Emilia, Modena, Italy; 2Laboratorty EEPER-MD, Local Materials Promotion Authority/MIPROMALO, Nkolbikok, Yaounde, Cameroon; 3Department of Industrial Engineering, University of Trento, Povo, Trento, Italy
The need to reduce toxic emissions and energy of firing has favours the emerging of new synthesis techniques (climate technologies) called cold-sintering. This is performed using high pressure and transient liquid phase which enhance grain contact, grain boundary and surface diffusion as well as mass transport. Based on the findings of Gallup, 1990 and Davidovidts 1989, it is was successfully hypothized that geopolymerization of natural iron-rich aluminosilicates (laterites) would combine the synthesis of ferrisilicates. Both consolidated reactions taking place at relatively low temperature (< 200C). Cold-sintered composites is developed using alkaline silicate solution as transient liquid and biomass as source of soluble silicate. Allowing the design of low porosity, high strength and high performance structural and functionnal composites with low energy and sustainable process. The Absence of high temperature sintering unlocks grain boundary design to a significant extend, opening new route for the development of structural and functional matrices.
CJ-1:L11 Layered Double Hydroxides With Immobilized Porphyrin Compounds - Synthesis and Study of Properties
A. LIPKE, D. SOKOL, A. KAREIVA, Institute of Chemistry, Faculty of Chemistry and Geosciences, Vilnius University, Vilnius, Lithuania; A. LIPKE, A. GŁADYSZ-PŁASKA, M. MAJDAN, Institute of Chemical Sciences, Faculty of Chemistry, Maria Curie-Skłodowska University in Lublin, Lublin, Poland
Porphyrins, owing to their unique light absorption and emission properties and redox capabilities, are widely used in environmental chemistry. Their practical applications can be further expanded through immobilization in inorganic matrices such as layered double hydroxides (LDHs). In this study, the layered double hydroxide containing four metal cations (Cu, Zn, Mg, Al) with a M2+:M3+ ratio of 3:1 was synthesized and used as a matrix for immobilization of three porphyrin compounds: two tetraphenylporphyrins bearing carboxyl or sulfonate groups, and a chlorophyll derivative. The LDH materials were prepared by a co-precipitation method. Porphyrins were incorporated into the LDH either during its synthesis or via anion-exchange in the solution of the corresponding porphyrin. The resulting composites were characterized using UV-Vis absorption spectroscopy, Vis-NIR spectrofluorimetry, XRD, FTIR-ATR, and SEM analyses. The data showed that the porphyrins interacted with the matrix in different ways, depending on their structure and synthesis route, which affected their localization within the LDH lattice and the optical properties of the composites.
Research is funded by the Lithuanian Science Council under the Postdoctoral Internship Project No. S-PD-24-145.
CJ-1:L12 Influence of the Chemistry of Various Volcanic Ash on their Use as Cement Replacement in Cameroon
I. NGASSAM, Civil and Architecture Engineering Department, University of Buea, Buea, Cameroon
Cameroon has a mountain chain, which crosses the country from the North to the South, hence various regions. Volcanic emissions can be found as rocks or ash, depending on their location. Moreover, their use also depends on the location; while the volcanic rocks are not used in the south-West region, the volcanic ash are traditionally used in the West region mainly to reduce the cost of construction by partially replace cement. This study was carried out to optimize these use of volcanic products as cement replacement. To do this the volcanic products were extracted from different regions of Cameroun. Then, they were characterized to determine their chemical composition and their crystallinity. Finally, the fine powder of each of these volcanic products were used to replace cement in the formulation a mortar reference. The outcomes of this study will help in the selection and the formulation of volcanic products based on their location, their chemistry and the use of these local materials to replace will lead to affordable and eco-friendly cementitious materials in construction.
CJ-1:IL13 Clay-Based Porous Geopolymers: Influence of Raw Materials, Curing, and Processing
E. PRUD'HOMME, L. GREMILLARD, MATEIS, INSA Lyon, France; O. SORE, LaCER, Université Nazi BONI, Burkinsa Faso; C. ZOUDE, INISMa-CRIBC (BCRC), Belgium; A. MESSAN, P. NSHIMIYIMANA, LEMHaD, Institut 2iE Gilles Escadaillas, LMDC, INSA Toulouse, France
Clay-based geopolymer materials are being developed for an increasing range of applications, requiring a high degree of adaptability in terms of their properties. As with many materials, their properties depend on the source of the raw materials, the formulation, and the curing conditions, all of which can lead to variations in robustness. For civil engineering applications, for example, using local resources is a significant challenge. However, significant variations in mechanical properties and durability are caused by differences in physical properties, composition and mineralogy between geological deposits. Tests carried out on different soils have shown that, despite the important role of clay content, it is the nature, rate and composition of the amorphous phase that control the reactivity of the binder. In the context of technical shaping, such as additive manufacturing, the curing conditions are also a fundamental parameter in ensuring that geopolymerisation reactions take place. Therefore, the mechanical durability of materials is greatly affected during curing at low relative humidity, leading to significant changes in mechanical behaviour when humidity increases sharply. These works support advanced technological applications of geopolymers in construction.
CJ-1:L14 Development of Porous Biochar-Alkaline Activated Hybrid Materials for Water Remediation
S. BUENO, R. VICO-LUJANO, P. DELGADO-PLANA, D. ELICHE-QUESADA, L. PÉREZ-VILLAREJO, Chemical, Environmental and Materials Department. University of Jaén, Jaén, Spain
The removal of emerging pollutants and heavy metals from water remains a critical challenge. This research explores the development of low-cost, sustainable hybrid adsorbents based on alkaline activated materials (AAMs) functionalized with biochar, valorizing both industrial and biomass wastes. The primary goal is to create AAM-biochar composites with controlled hierarchical porosity to maximize specific surface area and active sites for enhanced contaminant adsorption. Metakaolin and fly ash-based AAMs incorporating 0-20 wt.% biochar are synthesized and characterized (XRD, SEM, N2-BET) to understand their microstructure and pore distribution. A key innovation is the study of the fresh paste rheology to assess suitability for additive manufacturing (Direct Ink Writing) of optimized adsorbent monoliths. Preliminary adsorption performance using model pollutants or methylene blue will be presented. We hypothesize a synergistic effect where biochar creates a micro-porous network within the AAM matrix, significantly enhancing adsorption kinetics and capacity. This study aims to demonstrate the potential of these AAM-biochar composites as robust, 3D-printable materials for next-generation water treatment systems.
CJ-1:L15 Alkali-Activated Natural Zeolite Geopolymers: Insights into the Mechanical Properties of Mortars
N. ULLOA1, K. VACA1, G. VACA1, H. BAYKARA2, C. PAREDES2, M. CORNEJO2, 1Escuela Superior Politécnica de Chimborazo - ESPOCH, Riobamba, Equador; 2Escuela Superior Politécnica del Litoral - ESPOL, Equador
In the present study, samples of geopolymer mortar based on natural zeolites (GMZ) were prepared, in which the compressive strength of different samples synthesized was evaluated. In addition, the design of the mixture was optimized using two alkaline activators (NaOH 14M and Na2SiO3) in different proportions, river sand as fine aggregate, curing time and temperature. All GMZ samples were characterized by quantitative X-ray diffraction, SEM-EDS, simultaneous TGA-DSC analysis and FTIR spectrometry. According to the highest mechanical resistance obtained after 28 days of resting of the synthesized specimens, the mixture best and curing temperature was obtained, corresponding to: activator / zeolite: 0.5, Na2SiO3/NaOH: 3 and 60 ° C, the same that reached 18 MPa.
CJ-1:L16 Cold Sintering of Etna Volcanic Ash for Sustainable Building Material Production
L. KARACASULU, P. PAZERAUSKAITE, M. KERMANI, V.M. SGLAVO, M. BIESUZ, Department of Industrial Engineering, University of Trento, Trento, Italy; D. DI GENOVA, CNR-ISSMC, Institute of Science, Technology and Sustainability for Ceramic Materials, Rome, Italy
Traditional ceramic manufacturing can be improved by exploring alternative raw materials to enhance sustainability. Etna volcanic ash, abundantly available yet underutilized in Sicily (Italy), shows great promise for construction-related applications owing to its favorable chemical and mineralogical composition. In this study, volcanic ash from Etna was investigated as a sustainable precursor for the fabrication of porous ceramics via the cold sintering process (CSP). The influence of CSP parameters was systematically examined with respect to densification behavior and microstructural development. The resulting materials exhibited relatively low thermal conductivity, comparable to conventional bricks, along with good mechanical strength. In conclusion, Etna volcanic ash demonstrates strong potential as an alternative raw material, supporting resource efficiency and waste valorization in the ceramics sector.
CJ-1:L17 Study of Hybrid Binders with Fly Ash, Ground Granulated Blast Furnace Slag and Silica Fume in a Calcium Sulfoaluminate Cement Matrix
L.I. RODRÍGUEZ-BARBOZA, L.Y. GÓMEZ-ZAMORANO, Universidad Autónoma de Nuevo León, Facultad de Ingeniería Mecánica y Eléctrica, Centro de Investigacion y Desarrollo Tecnologico, Ciudad Universitaria, San Nicolás, Nuevo León, México
Nowadays, low-CO2 cements are presented as an option to mitigate the environmental impact of cement production by partially replacing conventional cement and allowing the use of potentially polluting industrial wastes. In this research, the mechanical properties and hydraulic behavior of hybrid cementitious pastes based on a calcium sulfoaluminate cement with alkaline activated supplementary cementitious materials (SCMs) were examined. The main innovation of this study lies in the use of 30% sulfoaluminous cement clinker as the base of a hybrid cement using substitutions of up to 70% of materials such as fly ash (FA) and ground granulated blast furnace slag (GGBFS) and using water glass, Na2SO4, K2SO4 and Ca(OH)2 as activators. The incorporation of alkaline activators, as well as the addition of silica fume (SF), contributed to improve the properties of the hybrid cements and thus broaden their possible applications. The pastes were cured for up to 90 days at 23°C in relative humidity. Compressive strength values above 30 MPa were observed for all systems, with the ones with water glass and Na2SO4 showing better performance. Also, the systems with GGBFS and SF improved both compressive strength and hydration product formation as evidenced by XRD and SEM analysis.
Session CJ-2 Properties
CJ-2:L19 Development of Low-Cost Geopolymer Matrix Composites (GMCs) for Helicopter Firewalls
P. VIERHAUS, Fraunhofer Centre HTL, Bayreuth, Germany
In the framework of the LuFo project NEUTRON, we developed cost-effective Ceramic Matrix Composites (CMCs) with geopolymer-based matrices and silica, glass, and basalt fibers. These Geopolymer Matrix Composites (GMCs) are designed as firewalls for helicopters, specifically to separate the passenger cabin from the turbine compartment, providing protection against fire, oil, and fuel leakage. The material must maintain integrity under temperatures of up to 1100 °C for 15 minutes and remain impermeable to oils and kerosene. Various metakaolins and water glasses were optimized to produce geopolymer matrices, which were reinforced with different fiber types. The resulting GMCs were systematically characterized for their thermal and mechanical properties. While the goal of thermal resistance and mechanical stability was partially achieved, additional sealing measures were required to ensure impermeability. This study showcases a promising approach to lightweight, low-cost aerospace fire protection materials, while also addressing the technical challenges associated with geopolymer-based composites for stringent safety applications.
CJ-2:IL20 Geopolymers and their Potential Applications
W.M. KRIVEN, University of Illinois at Urbana-Champaign, Materials Science and Engineering Department, Urbana, IL, USA
Geopolymers are new, interdisciplinary, inorganic polymers consisting of silicate or aluminate tetrahedra. The chemical definition of geopolymers is based on their molecular bonding. They can be alkali-activated or acid activated, where both families achieve charge balance. Other new, geopolymer chemistries have been identified. Geopolymers are also compared with cements, but geopolymers are chemically stable up to 1,000°C, after which they crystallize into a ceramic. Cements, on the other hand, contain significantly more water and so steadily decompose with increasing temperature, losing their mechanical strength by 500°C-700°C. Thus metakaolin-based geopolymers can be made like a cement but behave more like a ceramic. Potential applications of geopolymer composites include: fire resistant coatings and fire breaker panels; nuclear radiation shielding against gamma rays and neutron rays with ~98 % attenuation for 0.5 to ~0.7 cubic meters of composite, respectively; low level radioactive waste encapsulation; corrosion and acid resistant coatings; refractory adhesives between stainless steel, metals, glass, ceramics and wood to at least 1150°C; thermal shock resistant coatings having tailorable thermal expansion coefficients; porous insulators and refractories having tailorable porosity; alternative and scalable processing routes to iso-chemical ceramics made with organic alkalis; scalable molten salt containment for thermal energy storage; coatings e.g. as roof tiles; fire breaker panels; alternatives to cements for geothermal wells; a potential partial solution to global warming as a potential replacement for Portland cement when made from revalorized mine tailings; removal of heavy metals (As, Hg) or PFAS from water; UV, X-ray and neutron-responding luminescent composites; porous panels for CO2 encapsulation.
CJ-2:IL21 Durability Aspect of Geopolymers and Alkali Activated Materials
V. DUCMAN, ZAG, Ljubljana, Slovenia; A. TESOVNIK, ZAG, Ljubljana, Slovenia
The durability of building products is a critical factor in determining their long-term applicability in the construction sector. Alkali-activated materials (AAM) are emerging building products and are therefore extensively assessed for various aspects of durability. In addition to compressive strength, which may be a good predictor of long-term performance, there are several exposures to which durable materials should successfully respond. Depending on the final use, these include wear resistance, freeze-thaw resistance (with and without de-icing salts), resistance to elevated temperatures, and chemical resistance (e.g. sulphate resistance, alkali-silica reactivity). Additionally, as they influence the corrosion of steel reinforcement, carbonation resistance and chloride penetration are also important factors when assessing the durability of AAM. The most studied precursors to date are metakaolin, class F fly ash, and ground granulated blast furnace slag, but other precursors are also being investigated. The variety in chemistry and mineralogy thus makes it more difficult to provide robust mixture design that would guarantee their long-term durability. Therefore, development and technical assessment of AAM from various precursors should be made on a case-by-case basis.
CJ-2:L22 The Effect of Mechanical Activation on the Properties of Geopolymer Properties
E. FIDANCHEVSKI1, D. PANIAS2, I.P. GIANNOPOULOU2, V. JOVANOV1, B. ANGJUSHEVA1, 1Ss. Cyril and Methodius University in Skopje, Faculty of Technology and Metallurgy, Skopje, Republic of North Macedonia; 2Section of Metallurgy and Materials Technology, School of Mining and Metallurgical Engineering, National Technical University of Athens, Athens, Greece
The construction industry is increasingly focused on developing environmentally friendly materials to reduce CO₂ emissions. Geopolymers, particularly those derived from fly ash and metakaolin, have emerged as promising alternatives to Ordinary Portland Cement (OPC) due to their lower carbon footprint and excellent mechanical performance. This study investigates the synthesis and characterization of geopolymers produced from raw and mechanically activated fly ash (FA) and metakaolin (MK) as aluminosilicate precursors. Mechanical activation was carried out in a planetary mill to enhance precursor reactivity by increasing surface area, disrupting crystalline phases, and raising the amorphous content, thereby accelerating geopolymerization kinetics. The mixtures were activated with alkaline solutions of sodium silicate and sodium hydroxide, with variations in the solid-to-liquid ratio and curing conditions. Comprehensive characterization techniques (XRF, XRD, FTIR, DTA/TG, SEM/EDS) were employed to examine both the raw and activated precursors, as well as the resulting geopolymers. The results demonstrated that geopolymers synthesized from mechanically activated precursors exhibited significantly improved mechanical strength and a denser microstructure compared to those based on untreated materials. Notably, the compressive strength of geopolymers prepared from mechanically activated fly ash increased to 28.60 MPa in comparison to the raw fly ash, 6.14 MPa, thus confirming the effectiveness of mechanical activation in enhancing geopolymer performance.
CJ-2:IL23 Zeta Potential a Tool to Explain Properties in Relation with Drastic Applications
S. ROSSIGNOL, IRCER Limoges University, Limoges, France
The purpose of this work is to evaluate the resistance of different geopolymer formulations under severe conditions, particularly acidic environments, high temperatures (1700 °C), or during casting and consolidation in water, allowing simultaneous exposure to these conditions. To achieve this goal, different geopolymer formulations were prepared using different metakaolins and alkaline solutions with different alkali cation concentrations [M]. The K+ concentration controls the working properties; all the samples exhibit thermal resistance up to 1200 °C, and only the low M concentration withstand a temperature of 1700 °C. The high M concentration samples are pourable and undergo consolidation underwater. The compressive strength increases with increasing alkaline cation concentration, with values of 50 to 75 MPa. Finally, zeta potential values can be used to predict the performance properties (acid and temperature resistance, as well as underwater consolidation).
CJ-2:L24 Freeze–thaw Resistance of Metakaolin Geopolymer Pavers
A. TESOVNIK, V. DUCMAN, Slovenian National Building and Civil Engineering Institute, Laboratory for Cements, Mortars and Ceramics, Ljubljana, Slovenia
Geopolymers, as environmentally friendly binders, offer a sustainable alternative to conventional binders through reduced CO₂ emissions and the ability to utilize industrial waste or natural precursors. Despite their promising mechanical and chemical properties, some aspects of the durability of metakaolin-based geopolymers under harsh environmental conditions remains insufficiently explored. In particular, degradation during freeze–thaw in the presence of deicing salt represents a research area that must be addressed to ensure reliable implementation of geopolymer technology in real-world construction applications, especially in cold climates. In this study, several metakaolin-based geopolymer mixtures were prepared with varying activator dosages and mix designs to investigate their performance under freeze–thaw and freeze–thaw with de-icing salt exposure. Paver-shaped specimens were tested to evaluate changes in surface hardness, surface scaling, and microstructure after cyclic exposure to moist freezing simulating real world conditions. The surface hardness was measured before and after testing to correlate mechanical properties with observed durability behavior. Microstructural changes were further examined using scanning electron microscopy and mercury porosimetry.
CJ-2:L25 Ceramic Waste as a Sustainable Binder Component in Cement-based Mortars
T. KRONBERG, J-E. ERIKSSON, T. MANNISTO, L. HUPA, Åbo Akademi University, Turku, Finland
Recycling ceramic construction and demolition waste offers a promising pathway toward a circular economy. However, its current utilisation remains limited due to the absence of systematic collection and separation processes. Typically, ceramic waste is mixed with other demolition materials, such as concrete and bricks, which complicates its reuse. In this study, ceramic waste was collected, milled, and sieved into three different particle size fractions. Mortar mixtures were prepared by partially substituting cement with 5-20% of ceramic waste while maintaining constant sand and water contents. Compressive strength was measured after 7, 28, and 91 days of curing. The microstructure and chemical composition of the samples were analysed using SEM/EDS. The results revealed that the reactivity of ceramic waste strongly depends on both particle size and phase composition. Strength development in ceramic-containing mortars was initially lower after 7 days but improved significantly with longer curing times. Ceramic wastes with higher amorphous content exhibited greater pozzolanic activity. Overall, the findings indicate that 15–20% of cement can be effectively replaced by ceramic waste without major loss in mechanical performance.
Session CJ-3 Structural and functional applications
CJ-3:IL26 New Strategies to Reduce and Store CO2 Emissions in Building Materials Using Inorganic Polymers
C.H. RÜSCHER, S. TOME, Institut für Erdsystemwissenschaften, Leibniz Universität Hannover, Hannover, Germany
The alkali activation technology (AAT) for inorganic polymer formation is a mature technology and hopefully penetrating the market. This will strongly reduce the CO2 emission compared to the use of Portland cement. The AAT is using sodium or potassium-silicate solution mostly with metakaolin and waste materials like fly ash or slag. These ingredients form the cement for obtaining mortars and concrete. It has been shown that the addition of slag significantly increases the flexural and compressive strength in the range of typical high performance applications. However, there are strong arguments put forward by the “Portland cement suppliers” that their CO2 footprint becomes much better for CEM-based mortars and concrete with the additions like slag, fly ash and metakaolin, i.e. calcined clay. Moreover, they could use fine crashed waste concrete as substitute in part for sand and gravel. And even the crashed waste concrete is already used for sequestrating significant contents of CO2. Therefore, it seems worthwhile to investigate in some more detail the ability of CO2 sequestration of waste concrete and the use of such material for the alkali activation technology, too.
CJ-3:IL27 Potassium Metakaolin-based Geopolymers Containing Microwave Susceptible SiC
P. KEANE1,2, F. BRUNO1, W. SAW2, 1Future Industries Institute, University of South Australia, Mawson Lake, Australia; 2School of Chemical Engineering, University of Adelaide, Australia
Amorphous self-healing geopolymer composites (ASH-G) were previously synthesized from a potassium metakaolin-based geopolymer, incorporating alumina platelets and low-melting-temperature glass particulates. Sintering this green body via a liquid phase process at 900°C—with heating and cooling rates of 1-2.5°C/min and a five-hour dwell time—produced a homogenous microstructure. A key feature of this material is the formation of a uniform, 50-250 µm thick surface glaze of glass, which enables the sintered composite to withstand subsequent rapid thermal cycling. Our new research explores the feasibility of incorporating or replacing the alumina platelets with microwave-susceptible silicon carbide particulates. The primary objective is to develop a novel ASH-G composite that can be rapidly and efficiently heated using microwave energy, significantly advancing its processing and application potential.
CJ-3:IL28 Performance of Geopolymer Granules on Acoustic Insulation Properties
N. KABIR, P. PERUMAL, University of Oulu, Oulu, Finland
Noise pollution remains one of the most persistent challenges in modern urban environments, demanding sustainable materials capable of enhancing acoustic comfort. Geopolymers have emerged as promising alternatives to conventional polymer-based absorbers due to their low environmental footprint, fire resistance, and structural versatility. When developed as porous granules, geopolymer systems can dissipate sound energy efficiently through viscous and thermal interactions within interconnected pore networks. This study investigates the influence of porosity, introduced via hydrogen peroxide (H2O2), on the acoustic and mechanical performance of heat-consolidated geopolymer granule panels through alkali activation. Granules were synthesized from metakaolin as precursor and consolidated at 60 °C using 1-5 wt% H2O2 solutions to generate pore connectivity. The reference panel prepared with deionized water exhibited resonator-like behavior, whereas increasing H2O2 concentration shifted the response toward classic porous absorption. Panels displayed broad pore size distributions (10 nm-7 mm), with mid-sized pores (14-200 µm) identified as critical for achieving high absorption coefficients (α ≈ 0.6-0.8) over 1500-4300 Hz. Panels prepared with 4-5 wt% H2O2 achieved broadband absorption fro
CJ-3:L29 Alkali-Activated Fly Ash as Matrix Material for Carbon Fiber Textile Reinforcement in Concrete
R. FÜRST, P. HLAVACEK, G. HÜSKEN, Bundesanstalt für Materialforschung und -prüfung (BAM), Berlin, Germany
Modern civil engineering increasingly replaces traditional reinforcement materials with non-metallic composites, commonly based on glass and carbon fibers. To enhance their mechanical performance, these fibers are impregnated with synthetic matrices. These reinforcements show excellent mechanical performance at ambient conditions. However, elevated temperatures exposure as in the case of a fire, they rapidly lose their mechanical properties due to thermal degradation of the synthetic matrix. Therefore, their application in load-bearing structures is limited. This study investigates the use of fly ash–based impregnated carbon fibers as a temperature-stable alternative to synthetic matrix materials. An indicative experiment series was conducted, including tensile tests of textile reinforcements and four-point bending tests of composite specimens incorporating the reinforcement within high-performance concrete. The Digital Image Correlation was used to monitor strain distribution and crack evolution during test, providing detailed insights into the deformation behavior. In addition, microscopic analysis was carried out to assess the depth and uniformity of the impregnation within carbon yarn, which is crucial for effective interaction between materials and composite integrity.
CJ-3:IL30 Development of High Early-strength Precast Concrete Products through Geopolymer Technology
WEI-HAO LEE, Institute of Mineral Resources Engineering, National Taipei University of Technology, Taipei City, Taiwan
Traditional reinforced concrete is cast on-site, making it vulnerable to weather and labor constraints. In contrast, precast concrete is factory-produced and assembled on-site, reducing time, cost, and CO₂ emissions by 10–25%. However, Portland cement-based precast concrete requires energy-intensive steam curing for early strength. Geopolymer materials, characterized by high early strength and a cement-free composition, can harden rapidly at ambient temperatures while reducing CO₂ emissions by approximately 40%. Considering Taiwan’s cold spells that hinder curing, this study investigated the reaction and strength of high-early-strength geopolymer concrete under low temperatures. Ground granulated blast-furnace slag (GGBFS) was used as the primary binder, supplemented with minor amounts of fly ash. The optimal mix (95% GGBFS, 5% fly ash) formed C-A-S-H and N-A-S-H gels, confirmed by XRD, FT-IR, and NMR. The mix set within 20–30 min and achieved 30 MPa in 8 h and 46 MPa after 1 day. Precast geopolymer concrete shows superior strength and up to 67% lower CO₂ emissions, providing a sustainable, low-temperature alternative for green construction.
CJ-3:IL31 Advances in Geopolymer Coatings for Diverse Applications: The Contribution of Artificial Intelligence
A. GHARZOUNI, A. BOUZID, S. ROSSIGNOL, IRCER UMR 7315 CNRS, Limoges, France
Coatings can have different functionalities such as protection to improve durability and longevity and prevention from fire, corrosion and environmental constraints. The objective of this study is to demonstrate the suitability of geopolymer coatings for different applications such corrosion prevention and fire resistance. For this, geopolymer coatings on different substrates (mineral substrates, stainless steel, polymer) were investigated. Moreover, given the wide range of properties involved, another challenge lies in the integration of artificial intelligence (AI) models capable of suggesting the optimal geopolymer formulation that will lead to the target properties. To this end, a high-quality in-house experimental database of geopolymer formulations and their properties has been built. Moreover, a customly trained machine learning framework has been developed. It was demonstrated that the geopolymer coating can be successfully applied by airbrush with a thickness varying between 340 and 650 µm. This thickness is related to the coating features such as viscosity, liquid to solid ratio and the substrate surface roughness. The highest adhesive strength was obtained for mineral substrates. For stainless steel, the adhesive strength is about 3 MPa.
CJ-3:IL32 Dynamic and Blast-Resistant Behavior of Fiber-Reinforced Geopolymer Composites for Sustainable Military Infrastructure
YING-KUAN TSAI, National Yang Ming Chiao Tung University, Hsinchu City, Taiwan
The advancement of sustainable and high-performance construction materials has become a strategic priority in modern military engineering. Structures must be capable of withstanding severe loading conditions such as explosions, impacts, and dynamic stress waves, while also supporting global goals for carbon reduction and environmental resilience. Geopolymers, which are alkali-activated aluminosilicate binders produced mainly from industrial byproducts such as ground granulated blast furnace slag (GGBS) and fly ash, provide a promising alternative to traditional Portland cement. These materials demonstrate high early strength, excellent durability, low permeability, and, most importantly, a significantly lower carbon footprint. The present study integrates a comprehensive series of experimental and numerical investigations to evaluate the feasibility and performance of geopolymer materials for protective and rapid repair applications in military engineering.