Figure 2 - available via license: Creative Commons Attribution 4.0 International
Content may be subject to copyright.
XRD patterns of geopolymers based on volcanic ash with the other raw materials (Fly, Pz, Mk, and Mt).
Source publication
This work studies the feasibility to employ a combination of volcanic ash (natural waste) with different raw materials in the production of geopolymers: fly ash and mining tailing (considered hazardous solid waste), natural pozzolan, and metakaolin. This study compares the properties of geopolymers based on volcanic ash with fly ash, pozzolan, meta...
Similar publications
Construction solid waste and agricultural waste, as renewable resources, have gained increasing attention recently. This research aims to explore the mechanical and thermal properties of recycled-straw insulating concrete commonly made with construction waste and straw in northern Fujian, which can provide useful suggestions for the practical use o...
The efficacy of two machine learning algorithms to predict the concrete compressive strength is investigated in this research. For this objective, a vast amount of experimental data from numerous academic research articles was statically evaluated and modelled. In all, 265 observations were considered in this investigation 70% of the data was used...
Aluminum dross (AD) is a waste product produced during aluminum processing and can be used to prepare mullite ceramic materials. However, the research on the preparation of mullite porous ceramics entirely from solid waste is still in the development stage. In this paper, porous mullite ceramics were successfully fabricated using a solid-phase sint...
It has been proven that it is a feasible treatment method to prepare paste filling material from coal-based solid waste to fill underground goaf. Based on the complexity of the goaf environment, especially the influence of humidity on paste filling materials, this paper prepared paste filling materials with a mass concentration of 80% by using coal...
Most of the previous studies focused on the mechanical characteristics before the stress peak of solid waste cemented backfill, but in the compression process of a solid waste cemented body, the phenomenon of post-peak stress rebound often occurs. Through the uniaxial compression experiment of a solid waste cemented body composed of coal gangue, fl...
Citations
... Volcanic ash deposits are approximately 0.84% (124 million Ha) of the world's land cover, with about 60% of this in tropical countries [42,57]. While volcanic ash has been utilised as a geopolymer precursor material [58], the resulting specimen has shown slightly lower reactivity and slower strength development. It may exhibit swelling and some cracks compared to geopolymers resulting from alternative precursor materials such as fly ash [59]. ...
Due to the expansion of construction activities and the increased threat of fires to civil structures and lives, there has been a need to find alternative fire-resistant materials that meet sustainability and green material standards. This study reports on using Colloidal Nanosilica (CNS) to modify the elevated temperature resistance of Volcanic Ash-Based Geopolymer Mortar (VAGPM). The volcanic ash (VA) locally sourced in Kenya was partially replaced with between 1-5% CNS by mass of VA and activated with sodium or potassium hydroxide and sodium silicate. The workability of the resulting mixtures was determined. Following a curing period of 28 days, the VAGPM specimens were exposed to temperatures ranging from 200-800°C for durations of 1 and 2 hours, and their compressive strengths, mass losses, volumetric changes, visual appearances, and microstructural properties were analysed. Results indicated that replacing VA with CNS up to 5% by mass resulted in a reduction in the flowability of the fresh mortar and that adding 2% CNS improved compressive strength and elevated temperature resistance. In contrast, higher levels did not significantly improve performance. Specimens recorded increased compressive strengths up to 400 and 600°C. Increasing CNS levels decreased mass loss and volume shrinkage. The samples also displayed changes in colour and mineralogical phases after exposure to elevated temperatures. CNS yielded a denser microstructure.
... The first category includes geopolymers and inorganic alkaline polymers, and both may be defined as alkaliactivated binders without OPC. In this class of reactions, zeolitic precipitates and sodium or potassium aluminosilicate hydrate (N-A-S-H) gels are the primary end products [64,65]. A second, less-researched category is mixed cement, which combines OPC with alkaliactivated aluminosilicate binders. ...
Alkali-activated materials are gaining much interest due to their outstanding performance, including their great resistance to chemical corrosion, good thermal characteristics, and ability to val-orise industrial waste materials. Reusing waste glasses in creating alkali-activated materials appears to be a viable option for more effective solid waste utilisation and lower-cost products. However, very little research has been conducted on the suitability of waste glass as a prime precursor for alkali activation. This study examines the reuse of seven different types of waste glasses in the creation of geopolymeric and cementitious concretes as sustainable building materials, focusing in particular on how using waste glasses as the raw material in alkali-activated materials affects the durability, microstructures, hydration products, and fresh and hardened properties in comparison with using traditional raw materials. The impacts of several vital parameters, including the employment of a chemical activator, gel formation, post-fabrication curing procedures, and the distribution of source materials, are carefully considered. This review will offer insight into an in-depth understanding of the manufacturing and performance in promising applications of alkali-activated waste glass in light of future uses. The current study aims to provide a contemporary review of the chemical and structural properties of glasses and the state of research on the utilisation of waste glasses in the creation of alkali-activated materials.
... Furthermore, the obtained peaks are primarily located between angles of 15 • and 40 • (2θ), which is consistent with zeolite synthesis studies by Rajakrishnamoorthy et al. [38] and Verrecchia et al. [39]. The open halo that was observed suggests thermodynamically metastable amorphous aluminosilicate structures with high pozzolanic activity [40]. The zeolite pattern shows that the peaks of ignimbrite decreased, whereas new peaks appeared. ...
In the present work, a TiO2/zeolite photocatalyst was synthesized by dispersing TiO2 nanoparticles obtained through the sol-gel method onto the surface of natural zeolite derived from ignimbrite residue. The zeolite was obtained from an ignimbrite rubble treatment collected from a quarry in Arequipa City, Peru. The research focused on the effect of zeolite on the TiO2 nanoparticles. The synthesized photocatalysts were characterized using various techniques, including field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray (EDS), X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), and Brunauer–Emmett–Teller surface area analysis (BET). The results revealed that the TiO2/zeolite samples displayed high crystallinity, with TiO2 being present in three phases and zeolite being present in the analcime phase. Furthermore, these samples exhibited a band gap of 3.14 eV and a high surface area compared to that of bare TiO2. Finally, the photocatalytic activity of the TiO2/zeolite composite obtained was evaluated toward the decomposition of 10 ppm and 20 ppm of methyl orange (MO) dye. The TiO2/zeolite samples demonstrated improved photocatalytic activity compared to that of pristine TiO2 under the same experimental conditions. This enhancement is primarily attributed to the increased specific surface area of the TiO2/zeolite samples, making them promising materials for future efficient and sustainable photocatalytic applications.
... In these 70% VFA systems, unlike the previous systems with much higher cement contents, the main band is a broad and asymmetric band located around 1000 cm −1 . This band would again result from the overlapping of different signals, both from phases corresponding to non-reactive anhydrous ash (crystalline phases and remains of the unreacted vitreous component) and from the reaction products (cementitious gels), which, considering the chemical composition of the starting blends, are probably a mixture of C-A-S-H + (N,C)-A-S-H gels [41,42]. ...
... Finally, the FTIR spectrum corresponding to the 100% alkaline AC system ( Figure 6) shows significant differences compared to the original VFA anhydrous ash. The main band of VFA with shoulders at 1058 cm −1 and 975 cm −1 becomes much more intense and sharp, shifting to values around 1000 cm −1 , a characteristic position for T-O (T: Si or Al) vibrations of N-A-S-H type gel (or more likely (N,C)-A-S-H type gel, considering the CaO content of the starting ash) [41,42]. The band at 460 cm −1 , corresponding to the δSi-O deformation vibrations of SiO 4 tetrahedra, also becomes much more intense and sharp. ...
... ), clear differences are observed compared to anhydrous cement (PC). Bands associated with clinker phases (calcium silicates at 923, 521 and 452 cm −1 ) disappear, and two bands at 977 cm −1 and 465 cm −1 appear, attributed to stretching and deformation vibrations of Si-O bonds in the C-S-H gel, respectively[41,42]. The sharp and intense band at 3642 cm −1 corresponds to the asymmetric stretching vibrations of O-H bonds in portlandite. ...
The present work evaluates the feasibility of using volcanic fly ash (VFA) generated by the eruption of the Tajogaite volcano on the island of La Palma (Spain) in 2021, as a precursor in the preparation of cementitious materials with different Portland cement (PC) replacement levels (0%, 30%, 70% and 100%), in the absence (Blended Cement, BC) and presence of an alkaline activator (Hybrid Alkaline Cement, HAC, and Alkaline Cements, AC). Hydration kinetics (isothermal conduction calorimetry), paste mechanical strengths and reaction products were characterised by XRD, FTIR, TG/DTG and BSEM/EDX. The results obtained indicate that the strengths developed by the hybrid alkaline cements (HAC) are higher than those of the blended cements (BC), especially at the age of 2 days, where 25 MPa were obtained with the replacement of 70% PC by VFA. Alkaline cements (AC, 100% VFA) that were prepared with 8 M NaOH solution as the activator reached 40 MPa after 2 days. It was observed that in all the binders, depending on the initial composition of the binder mixture and the percentage of replacement and/or activator, VFA reacts to form cementitious gels, C-A-S-H and N-A-S-H type, which supports its use as a mineral addition to blended cement or as a precursor in the preparation of alkaline and hybrid alkaline cements.
... EGC exhibits significant chloride resistance, which translates to minimal mutilation during winter especially upon application of salt for dissolving ice. The outstanding capability of EGC to resist chloride corrosion makes it a viable option for utilization in concrete structures exposed to saltwater environments, such as coastal bridges, underwater concrete supports, and piers (Zhao et al., 2020;Churata et al., 2022;Tanu and Unnikrishnan, 2023). According to Yang et al. (2008), geopolymer concrete manufactured using slag can attain strength if cured at room temperature. ...
Engineered cementitious composites (ECC) exhibits impressive tensile strength but has significant environmental drawbacks due to high cement consumption. Recently, engineered geopolymer composites (EGC) have gained attention as a potential ECC alternative. This comprehensive study reviews the latest EGC advancements, encompassing mix design, design theory, engineering properties, environmental benefits, and durability. It emphasizes how factors like activators, precursors, fibers, additives, and aggregates impact EGC properties, making it a cost-effective material for fire, chemical resistance, and dynamic loads. To address limitations in traditional literature reviews, innovative research methods, including scientometric analysis, were employed to provide a cohesive analysis. This review aims to facilitate knowledge dissemination and collaboration by summarizing EGC advances and highlighting remaining challenges in developing practical applications. It is revealed from the review that various manufacturing methods enhance geopolymers, especially in geopolymer concrete, where replacing 50% of ordinary Portland cement with fly ash boosts strength. Geopolymer concrete excels in pre-cast applications, offering durability and resistance to harsh conditions as an eco-friendly alternative to Portland cement. It suits highway pavement, walls, marine coatings, and tiles, reducing carbon emissions and promoting efficient waste management. EGCs find broad use in construction due to their strong, durable, and eco-friendly qualities, supporting sustainable infrastructure development.
... Additionally, the formation of these binders is impacted by a group of factors that distinguish the precursors, such as the size and morphology of the constituent particles, which contribute to affecting the viscosity of the mixture in the fresh stage [23]. For example, when talking about a ternary blend, the characteristics of the singular starting precursors can be optimally leveraged via the interactions among the source materials, which result in improved compressive strength, durability, and stability [24]. Further factors that may influence the synthesis are linked to the microstructure and chemical structure of the raw product [25]. ...
This study focuses on the application of mixture design as a novel approach to developing a geopolymer paste with optimized mechanical properties. It also aims to utilize the abundance of natural or industrial alumino-silicate precursors through their combination for synthesizing high-performance geopolymers. The synthesis factors studied are kaolin (K), metakaolin (MK), and fly ash (FA) as aluminosilicate sources. Different mixture proportions were prepared by adopting an augmented simplex-centroid design. Twelve geopolymer pastes were synthesized by activating the mixtures with an alkaline solution of sodium hydroxide and sodium silicate. After 28 days of solidification under ambient conditions, the compressive strength (MPa) and bulk density (g/cm 3) of the geopolymer samples were measured. The structural and microstructural properties of the raw and elaborated materials were analyzed using a range of physicochemical techniques, including X-ray Fluorescence (XRF) spectroscopy, X-ray Diffraction (XRD), Fourier Transform Infra-Red (FTIR) spectroscopy, Scanning Electron Microscopy combined with Energy Dispersive Spectroscopy (SEM/EDS), and Transmission Electron Microscopy (TEM). The results showed that the compressive strength and bulk density of the geopolymeric pastes ranged from 7.59 to 19.48 MPa and from 1.52 to 1.82 g/cm 3 , respectively. According to the validated special cubic models and optimization results, the optimum mixture of FA (75 %) and MK (25 %) was found to develop the optimized geopolymer (GPO) paste with the best performance. The optimized geopolymer matrix had a non-porous structure mainly formed by a dense amorphous sodium aluminosilicate gel, which gave excellent mechanical properties (1.82 g/cm 3 and 20.80 MPa). The practical application of the results of this study includes the development of an efficient geopolymer paste with excellent mechanical properties that can be employed in construction and civil engineering applications. The significance of this work lies in its potential to reduce environmental impacts and minimize waste disposal by utilizing abundant natural resources and industrial waste in the formulation of practical and efficient products. Overall, this study provides valuable insights into the development of an improved geopolymer paste through the application of a mixture design methodology, which can have a significant impact on the construction and civil engineering industries.
... To date, various wastes have been incorporated with more or less success within the geopolymeric matrix, e.g., waste glass, volcanic fly ash, blast furnace slag [21][22][23][24]. ...
Burning wood is estimated to produce about 6–10% of ash. Despite the possibility of recycling wood ash (WA), approximately 70% of the wood ash generated is landfilled, causing costs as well as environmental pollution. This study aims to recycle WA in an alternative way by inserting it as filler in geopolymeric materials. Here, metakaolin, NaOH, sodium silicate, and WA are used to realize geopolymers. Geopolymers without and with 10, 20 and 30% of WA are synthesized and characterized after 7, 14, 28 and 56 days. The article’s study methods are related to geopolymers’ chemical, biological and mechanical properties. The geopolymers synthesized are compact and solid. The pH and conductivity tests and the integrity and weight loss tests have demonstrated the stability of materials. The FT-IR study and boiling water test have confirmed the successful geopolymerization in all samples. The antibacterial analysis, the moss growing test and the compressive strength test have given a first idea about the durability of the materials synthesized. Furthermore, the compressive strength test result has allowed the comparison from the literature of the specimens obtained with the Portland cement (PC). The results obtained bode well for the future of this material.
... At the same age, the intensity of C3S diffraction peaks tends to increase with the increase of added IOT, while the highest diffraction peak of SiO2 tends to decrease with the admixture of tailings. AFt, Ca(OH)2, and CaCO3 are the main components of cement hydration products, and the relative content of hydration products can be indirectly determined by their peak strengths [36][37][38]. Numerous research studies have concluded that AFt and CaCO3 have a significant influence on the mechanical behavior of cement and cement mortar [39][40][41]. For the diffraction peak at 9.1°, tailings incorporation and longer curing age enhance AFt's diffraction peak intensity, with the highest peak of WIM1 reaching 749, but the overall variation is insignificant. ...
In order to study the feasibility and sand substitution mechanism of cement mortar mixed with iron ore tailings (IOT), iron ore tailings cement mortars (referred to as IOTC) with IOT content of 0%, 25%, and 50% were made and tested. First, the basic properties of IOT used were measured to verify the theoretical feasibility. Second, the uniaxial compressive and tensile strengths, as well as the crack resistance performance of IOTC under different curing ages and different sand substitution rates were tested. Third, the techniques of inductively coupled plasma atomic emission spectrometry (ICP-OES), X-ray diffraction (XRD), nuclear magnetic resonance (NMR), scanning electron microscopy and energy-dispersive spectroscopy (SEM-EDS) were used to study the influence of curing age and different sand substitution rates on the chemical, mineralogical, and microstructural characteristics of IOTC. The sand substitution mechanism of IOT was then discussed. The research results proved the feasibility of using IOT to substitute standard sand in cement mortar. Within substitution rate of 0–50%, the mechanical properties increased with the increase of substitution rate. Though limited chemical effects were found by adding IOT, in comparison with standard sand mortar, more hydration products were found and the pore size distribution was changed for IOTC, which corresponds to its mechanical improvement.
... Currently, the use of lava and volcanic ash has been evaluated by different authors for use as construction material; the main applications have been as ceramic material, geopolymers, cement, and concrete [17][18][19][20]. Zhang et al. [21], manufactured and analysed bricks fired with a mixture of volcanic ash and black cotton soil between 1000-1050 °C, showing good compressive strength (60MPa), a small percentage of dimensional variation, and similar bulk density to conventional brick. ...
In the last quarter of 2021, there was a very significant eruption of the Cumbre Vieja volcano on the island of La Palma, belonging to the Canary Islands, Spain. It generated a large amount of pyroclastic volcanic materials, which must be studied for their possible applicability. This work studies the properties and applicability of the lava and volcanic ash generated in this process. The need for reconstruction of the areas of the island that suffered from this environmental catastrophe is considered in this study from the point of view of the valuation of the waste generated. For this purpose, the possibility of using the fine fraction of ashes and lava as a supplementary cement material (SCM) in the manufacture of cement is investigated. The volcanic material showed a chemical composition and atomic structure suitable for replacing clinker in the manufacture of Portland cement. In this study, the cementing and pozzolanic reaction characteristics of unprocessed volcanic materials and those processed by crushing procedures are analysed. To evaluate the cementitious potential by analysing the mechanical behaviour, a comparison with other types of mineral additions (fly ash, silica fume, and limestone filler) commonly used in cement manufacture or previously studied was carried out. The results of this study show that volcanic materials are feasible to be used in the manufacture of cement, with up to a 22% increase in pozzolanicity from 28 to 90 days, showing the high potential as a long-term supplementary cementitious material in cement manufacturing, though it is necessary to carry out crushing processes that improve their pozzolanic behaviour.
