Silica Content Research Articles

Effects of waste glass dust incorporation on the tribological performance of flax-epoxy hybrid composites

Waste glass dust, an industrial waste, generated in the glass-cutting industries, is considered carcinogenic and poses health risks as it is high in silica content. This research essentially explores the alternative use of these waste glass dust as functional fillers in fabricating wear-resistant hybrid polymer composites. It includes fabrication of the hybrid epoxy composites in hand lay-up route with varying weight fractions (0–0.2) of the waste glass dust along with the flax fiber (30 wt. %) and their dry sliding wear behavior is observed. Test sample preparation follows ASTM-G99–05 standard and experiments are conducted considering Taguchi's L25 design. Significant improvement in the wear resistance of the hybrid composites is obtained after incorporating the waste glass dust and flax fibers. Filler content is found to be the most effective factor in affecting the wear rate followed by the sliding velocity during the Taguchi analysis with respective contributions of 54.51% and 38.59% as obtained from the ANOVA analysis of the wear results. Normal load and sliding distance are found to affect marginally the wear rates of the composites. A predictive model is proposed to find the specific wear rate (SWR) using the test results through the regression analysis. The minimum wear rate is obtained for 20 wt. % of filler, 1000 m of sliding distance, 50 cm/sec of sliding velocity, and 10 N of load. The mechanisms predominantly responsible for the wear loss have also been studied using a scanning electron microscope.

Effect of Operational Parameters and Iron Ore Tailings Properties on Filter Cake Porosity

Objective: By evaluating operational filtration conditions, chemical, mineralogical, and particle size properties of the tailings, the study aimed to identify critical variables affecting porosity and provide predictive models for optimizing dewatering operations. Theoretical Framework: This research builds upon existing theories of solid-liquid separation and dewatering processes in mineral processing. Key references include classical works on filtration dynamics, particle size distribution, and cake porosity characterization. The study addresses gaps in literature regarding the relationship between tailings composition and filtration results. Method: The Leaf Test method was employed on 33 fresh slurry samples from the Brucutu plant to simulate industrial filtration conditions. Filtration cycle parameters such as cake formation and drying times were standardized. Porosity was calculated using Grace's equation and correlated with characterization data, including mineralogical composition, true density, and particle size. Statistical methods such as clustering, regression, and Random Forest modeling identified key predictors of porosity. Results and Discussion: The results indicated that porosity correlates strongly with silica content and certain mineralogical attributes, such as the presence of martitic hematite and quartz. Cluster analysis revealed two sample groups with distinct filtration characteristics. While operational parameters showed limited impact on porosity, the statistical models highlighted the significance of ore composition. Research Implications: This research provides a foundation for optimizing iron ore tailings filtration by identifying the key variables influencing porosity. The findings support more efficient dewatering techniques, contributing to sustainable tailings management. Further, the development of predictive models aids industrial operations in minimizing risks associated with tailings disposal. Originality/Value: This study is among the first to integrate statistical modeling and mineralogical characterization in exploring filter cake porosity. The results offer novel insights into the optimization of solid-liquid separation processes in the mining industry.

Enhancing concrete sustainability with spent diatomaceous earth from the wine industry: Long‐term experimental and statistical analysis

AbstractSpent diatomaceous earth, a by‐product of wine filtration, holds significant promise for use in concrete mixtures due to its pozzolanic properties, which enhance concrete performance. This research explores the application of spent calcined diatomaceous earth (SCDE), heat‐treated at 700°C to remove organic content, as a partial substitute for cement or sand in concrete. The high silica content of SCDE contributes to the formation of additional calcium silicate hydrates during the hydration process, leading to improvements in mechanical strength over time. The study includes a preliminary analysis of cement replacements ranging from 5% to 10% and sand replacements from 2.5% to 15%, assessing their effects on workability, density, water absorption, and compressive strength at 7 and 28 days. The testing program focuses on three key compositions: the reference concrete and optimal mixtures with 10% cement and 5% sand replacements. Compressive strength tests are conducted at 7, 28, 90, 180, and 360 days. The results, validated through ANOVA, demonstrate the influence of SCDE on concrete strength over time, with distinctive behavior patterns identified for different mixtures. The strength of concrete with replacements correlates with the reference strength, with a multiplicative factor that varies from 7 to 90 days and then. When SCDE replaces cement, the factor is less than one before 28 days due to the slow pozzolanic reaction, whereas for sand replacement, it always exceeds one because of the initial filler effect. After 90 days, the strength multiplicative factors are 1.13 for cement replacement and 1.30 for sand replacement, demonstrating the potential of SCDE for sustainable concrete manufacturing and its positive long‐term impact on mechanical performance.

Parametric analysis and prediction of dry adhesive wear characteristics of waste glass dust filled hemp-epoxy composites

Waste glass dust, an industrial waste, generated in the glass cutting industries, is carcinogenic and possesses health risk due to high silica content. As an attempt to gainfully utilize this, the possibility of using this waste glass dust as a functional filler in wear-resistant polymer composites is explored. It includes fabrication of epoxy composites in hand lay-up route with varying weight fractions (0–0.2) of the waste glass dust along with multiple layers of hemp fiber. The dry sliding wear behavior of these composites under different test conditions are studied. ASTM G99-05 standard is followed for preparing the test samples and experiments are conducted as per Taguchi’s L25 design. Wear resistance is significantly improved with addition of the filler. Among the control parameters, the filler content is the most effective factor influencing the wear rate and next comes the sliding velocity as obtained from the ANOVA and Taguchi analysis. A predictive model is proposed to find the specific wear rate (SWR). The minimum wear rate is obtained for 20 wt. % of filler, 250 m sliding distance, 50 cm/sec sliding velocity and 10 N load. The mechanisms predominantly responsible for the wear loss have also been studied using a scanning electron microscope.

Microstructure Analysis of Different NaOH Molarity Towards Fly Ash Geopolymer for Underwater Concreting Material

Geopolymer concrete is a new sustainable and environmentally friendly composite with great potential to replace conventional concrete that is mostly produced by ordinary Portland cement (OPC). Binders used for geopolymer concrete such as fly ash and blast furnaces are mostly industrial wastes or by -products containing high silica and aluminium content that act as stimulants for geopolymerization. Furthermore, geopolymers also exhibit better durability and corrosion resistance than OPCs. However, material subjected to underwater placement method typically exhibit a decrease in properties. While geopolymer has not been widely used as underwater concreting material, this research is purposed to identify the effect of underwater placement method towards geopolymer in terms of microstructure analysis. Using different molarities of sodium hydroxide (NaOH), the optimum compressive strength will be discussed for underwater concrete while correlating with the microstructure result. For alkaline activators, the ratio used is 2.5 and the ratio for solid to liquid is 2.5. The molarities used for alkaline activators were 8 M, 10 M and 12 M. Using the tremie method for underwater concrete, it is possible to measure the leaching loss with respect to the objective of this research. The best compressive strength result is 12 M. The SEM result support with 12 M molarity had less cavities and lowest density.

One Part Method for Making Geopolymer Paste using Flocculated Sidoarjo Mud

Some efforts have proposed the utilization of Sidoarjo mud for geopolymer paste. However, the original dry mud in geopolymer concrete showed decreased compressive strength and increased required water. In this paper, the one-part method is proposed to reduce the water in the mixture. First, the mud was chemically flocculated. Then, the dry mud was mixed with fly ash, activated geothermal silicate, and sodium hydroxide mixture in solid form before then the distilled water was added. This reduced the required water to 50% compared to the two-part method. The flocculant sedimented heavy metal that resulted in higher compressive strength at a later age. At 28 days, dry flocculated mud showed higher compressive strength than the original dry mud, with a compressive strength of 13 MPa and 11 MPa, respectively. This is because of the increase of silica, alumina, and iron content from 70% in dry LUSI to 75% in dry flocculated mud.

Influence of CFBC Fly Ash Chemical Composition and Mechanical Activation on the Properties of Geopolymer

Circulating fluidized bed combustion (CFBC) fly ash has the potential as a precursor to making geopolymer concrete because of its rich silica and alumina content. However, there is a problem in utilizing CFBC fly ash caused by its chemical and physical properties that differ from the widely used pulverized coal combustion (PCC) fly ash. CFBC fly ash has a higher water requirement than PCC fly ash due to its angular particle shape, and higher sulfur and lime contained also caused a different reaction in the geopolymer system. Mechanical activation by milling the CFBC fly ash could decrease the water requirement in the mixture and make good quality CFBC fly sh-based geopolymer concrete. Three CFBC fly ash samples from different power plants in Indonesia with different chemical compositions were used in this research. The first had a low lime and no sulfur content, the second had high lime and no sulfur content, and the third had high lime and sulfur content. The milling process using a ball mill for two hours decreased the water requirement, as shown in the lower normal consistency of the fly ash. The reactivity also was increased, shown by the faster initial setting time. Besides its higher reactivity, lower water requirement increased the compressive strength of geopolymer mortar produced. This study also showed that the existence of calcium and sulfur content in the CFBC fly ash could cause unexpected results shown by the change of initial setting time, water requirement, and compressive strength.

Utilization of Silica from Palm Ash Waste as an Abrasive Material in Brake Friction Composite

The silica element in palm ash has the potential to be an alternative source of silica material to replace mineral silica, making it more environmentally friendly and reducing production costs. This research aims to utilize silica from palm ash waste as an abrasive material in brake friction composites. The silica from palm ash was isolated by a leaching process using 1 M HCl solution at a temperature of 70 °C for 90 minutes. Isolated silica was then characterized by X-ray fluorescence (XRF). The composition of silica was varied by volume fraction (0, 2, 4, and 6%). The mixing process of the powder mixture was conducted using a chopper mixer for 5 minutes, The powder mixture is then hot compressed using uniaxial hot pressing at a pressure of 47 MPa and a temperature of 165 °C for 15 minutes. Post-curing of the samples was carried out at a temperature of 165 °C for 10 hours. The samples were characterized by density, porosity, hardness R-scale, friction coefficient, and specific wear rate. The research results showed that the palm ash was successfully purified with a silica content of 27.3% to 57.2%. Increasing volume fraction of palm ash silica decreases in density and hardness, while porosity increases. The sample with 4% volume of palm ash silica exhibited better friction performance and a lower specific wear rate. Palm ash silica has the potential to replace the silica mineral for brake friction composites.

Fumed Silica in Coconut Oil Based Nanofluids for Cooling and Lubrication in Drilling Applications

Virgin coconut oil (VCO) is an edible vegetable oil that is eco-friendly, biodegradable, and sustainable, with high thermal and chemical stability as a phase change material (PCM). In this work, VCO filled with fumed silica A200 nanoparticles was tested as a cutting fluid in drilling processes. Silica concentrations ranging from 1 to 4 vol% were analyzed. Thermal properties were evaluated by differential scanning calorimetry (DSC) and thermal conductivity measurements at different temperatures and concentrations. Thermal conductivity showed an enhancement with the addition of silica powder and reduced with increasing temperature. Based on thermal and flow properties, VCO-3A200 was found to be the optimal concentration. The thermal images of this nanofluid taken after 60 s of drilling exhibited a reduction of 12 °C with respect to the dry process. The friction coefficient versus shear rate was also measured. With 8% VCO, a reduction in the friction coefficient of 8% compared to the dry test was achieved. The addition of 3 vol% of silica to the base oil reduced the friction coefficient by 16% compared to the dry test. The use of fumed silica dispersed in VCO has proven to be a sustainable, recyclable, and environmentally friendly refrigerant and lubricant cutting fluid.

Wear Behaviour of Nickel Coatings Reinforced by Recycled Quarry Dust: Influence of Current Density

Nickel coatings incorporated with quarry dust were synthesized through direct current electrodeposition from a nickel Watt’s bath. The study explored the effects of varying current densities on the surface morphology and wear behaviour of the nickel-quarry dust (Ni-QD) composite coatings deposited on a high-speed steel (HSS) substrate. Quarry dust was chosen as a reinforcement material due to its high silica and alumina content, which enhance the properties of the coating. To achieve finer particle size, the quarry dust was subjected to ball milling before electrodeposition. The study tested a range of current densities from 2 to 8 A/dm², as different current densities produce different results. The composite coatings were characterized using a Scanning Electron Microscope (SEM) and their wear resistance was evaluated through pin-on-disk test. The results indicated that increasing the current density enhanced the wear resistance of the coatings. Coatings produced at high current densities displayed a colony-like structure, demonstrating the impact of deposition conditions on colony size relative to current density. Ni-QD composite coatings created at 6 and 8 A/dm² resulted in smoother and narrower wear scars with minimal scratching, attributed to the low surface roughness of the coatings.

Assessment of Kalimantan Coal Ash Properties and Potential as Sustainable Construction Material

This study analyzes the physical and chemical characteristics of Fly Ash and Bottom Ash (FABA) from Kalimantan's coal-fired power plants to assess their effectiveness and potential as sustainable construction materials. The characterization was conducted through a series of tests following ASTM C311 standards, while the mechanical properties of mortars incorporating Fly Ash (FA) were evaluated following ASTM C618 standards. The results indicate that all FA samples meet the ASTM C618 Fineness requirements, with particle sizes below 45 μm, confirming their suitability as pozzolanic materials. In contrast, Bottom Ash (BA) samples do not meet the Fineness standard but still show potential for use in other construction applications. Chemical analysis utilizing X-ray Fluorescence (XRF) further supports the potential use of FABA from Kalimantan, revealing a high content of reactive oxides, SiO2, Al2O3, Fe2O3, which justify the classification as Class F for PLTU Asam-Asam (AA) and PLTU Bengkayang (BK), and the classification as Class C for PLTU Pulang Pisau (PP). X-Ray Diffraction (XRD) analysis also validates the high silica (SiO2) content and low levels of deleterious compounds. Additionally, the mechanical properties confirm the effectiveness of FA from PLTU AA with a Strength Activity Index (SAI) value exceeding 100%. The findings of this research provide strong evidence for the potential of Kalimantan FABA as a sustainable material while contributing to enhanced compressive strength and durability in concrete application.

Impact of Physical Processes and Temperatures on the Composition, Microstructure, and Pozzolanic Properties of Oil Palm Kernel Ash

In recent decades, the global use of ashes derived from agro-industrial by-products, such as oil palm kernel shells, which are widely cultivated in Colombia and other tropical regions of the world, has increased. However, the application of these ashes in engineering remains limited due to their heterogeneity and variability. This study utilized scanning electron microscopy (SEM) to assess the influence of calcination temperatures, ranging from 500 °C to 1000 °C, as well as the physical processes of cutting, grinding, and crushing, on the silica content of the studied ashes. Specifically, the sample labeled M18A-c-m-T600°C-t1.5h-tr1h, which was subjected to a calcination temperature of 600 °C and underwent cutting and grinding before calcination, followed by post-calcination crushing, exhibited the highest silica concentration. Complementary techniques such as X-ray fluorescence (XRF) and X-ray diffraction (XRD), were applied to this sample to evaluate its feasibility as an additive or partial replacement for cement in concrete. XRF analysis revealed a composition of 71.24% SiO2, 9.39% Al2O3, and 2.65% Fe2O3, thus, meeting the minimum oxide content established by ASTM C 618 for the classification as a pozzolanic material. Furthermore, XRD analysis confirmed that the sample M18A-c-m-T600°C-t1.5h-tr1h is in an amorphous state, which is the only state in which silica can chemically react with calcium hydroxide resulting from the hydration reactions of cement, forming stable cementitious products with strong mechanical properties.

Polyamide 6 Recycled Fishing Nets Modified with Biochar Fillers: an Effort Toward Sustainability and Circularity

In a further research effort toward sustainability and circularity, this work demonstrates the possibility of designing and producing novel blends derived from recycled polyamide 6 (PA6) fishing net, incorporating two biochars, i.e., carbonaceous materials obtained from the controlled pyrolysis of vegetable biomasses, at different loadings (namely 5, 10, and 15wt.%). The biochar derived from lignocellulosic biomass enhanced both the mechanical properties and moisture resistance of the recycled polyamide, increasing the elastic modulus from 2.6 to 4.5GPa and reducing water uptake from 3.6 to 1.8%. Interestingly, thanks to its high silica content, the biochar derived from rice husk accounted for an increase in the activation energy for combustion of the polymer matrix (from 43.6 to 70.9kJ/mol). However, it also showed a detrimental effect on the water uptake and the mechanical behaviour of the blends. Besides, the possibility of replacing up to 15wt.% of petroleum-derived carbon black pigments with the biochars decreased the overall cost of PA6 blends. Also considering the biochar densities that are lower than those of traditional carbon fillers, the proposed blends may pave the way for the design, development, and exploitation of novel sustainable materials suitable for lightweight applications.

Crustal silica content of East China: A seismological perspective and its significance

East China has experienced multiple periods of tectonic movements, which have contributed to the composition and rheological properties of its present crust. Estimating the composition of the crust is crucial for understanding the tectonic processes. Based on the teleseismic receiver functions with data from the National Seismic Network of China, we applied the H-κ-c method to obtain the crustal bulk VP/VS ratio and to constrain the SiO2 content in the crust. We estimated the SiO2 content to range from 50.89 wt% to 73.51 wt%, with an average value of 65.87 wt%, indicating a predominant felsic composition of the East China's crust. Our study suggests that the North-South Gravity Lineament (NSGL) is an approximate delimitator of the felsic and mafic crust in East China, hinting at a widespread deficiency of mafic lower crust in the east of the NSGL. The mafic crust is extensively distributed in the Taihang orogenic region (TSR) and WuLingshan gravity gradient belts (WLG), particularly in the Datong volcanic area, which manifests the mantle materials intraplating. The scatteredly distributed mafic crust at the east of the NSGL is mainly concentrated in the southeast coast of China and in the intersection region of the Tanlu Fault (TLF) and Sulu region. In Sulu region, the TLF may primarily provide a channel for the thermal intrusion from the underlying mantle lithosphere, which has increased the mafic content. The Pacific/Philippine Sea plate subduction has triggered a significant amount of crust-mantle material exchange below southeast China that resulted in a high degree of mafic crustal composition.

Effects of Silicon Concentration and Synthesis Duration on Lignin Structure: A Spectroscopic and Microscopic Study.

Silicon (Si) is a highly abundant mineral in Earth's crust. It plays a vital role in plant growth, providing mechanical support, enhancing grain yield, facilitating mineral nutrition, and aiding stress response mechanisms. The intricate relationship between silicification and lignin chemistry significantly impacts cell wall structure. Yet, the precise influence of Si on lignin synthesis remains elusive. This study investigated the interaction between Si and lignin model compounds during invitro synthesis. Employing spectroscopic and microscopic analyses, we delineated how Si concentrations modulate lignin polymerization dynamics, particularly affecting molecular conformation and aggregation behavior over time. Fluctuations in the polymer structure are directly related to both the synthesis time and the concentration of silica. Our results demonstrate that lower Si concentrations promote the aggregation of lignin oligomers into larger particles, while higher concentrations increase the possibility of oligomer repulsion, thus preventing particle growth. These findings elucidate the intricate interplay between Si and lignin, which is crucial for understanding plant cell wall structure and stress resilience. Moreover, the results provide insights for developing lignin-silica materials with increasing applications in industry and medicine.

Utilization of Waste Glass in Cement Clinker Production: Impacts on Quality, Process Efficiency and Environmental Benefits

The incorporation of waste glass as a component in clinker production presents a sustainable approach to addressing critical challenges in the cement industry, including the reduction of CO2 emissions and effective waste management. Waste glass, characterized by its high silica content and alkali properties, can serve as an alternative alkali source in clinker manufacturing, replacing traditional raw materials and regulating the alkali-sulphur ratio. This dual functionality not only optimizes the chemical balance in the kiln process but also enhances clinker quality by controlling phase formation. The utilization of waste materials in industrial processes is increasingly significant in promoting circular economy principles. Integrating waste glass reduces the dependence on natural raw materials such as limestone and clay, which are associated with high energy and CO2 emission intensities during production. Furthermore, waste glass contributes to a reduction in the carbon footprint of cement production by facilitating lower-temperature clinkering, thus cutting energy consumption and greenhouse gas emissions. This study highlights the potential of waste glass as a viable alternative in clinker production, emphasizing its importance in achieving sustainability goals. Beyond the environmental benefits, adopting waste materials in industrial applications contributes to waste diversion from landfills, resource conservation, and cost efficiencies, aligning with global efforts to mitigate climate change and promote sustainable development.

Quantitative Relationship Between Strength and Porosity of Nano-Silica-Modified Mortar Based on Fractal Theory

Nano-silica (NS) is an ideal modifier for mortar materials, and exploring the evolution of the fractal dimension of the pore structure in NS-modified mortar is crucial for elucidating the mechanism by which NS enhances mortar strength. In this study, NS reinforced mortar was prepared using an NS sol solution, which inhibited the aggregation of NS particles. The relationship between the strength and pore structure of NS-modified mortar was quantitatively analyzed based on fractal dimension theory and gray correlation degree. The experimental system evaluated the mortar strength, pore structure distribution, and micro-morphology. Based on this evaluation, the fractal dimension of the mortar pore volume was calculated in detail. Subsequently, models for mortar strength and NS content were further established using grey analysis. The results indicate that NS significantly enhances the strength of mortar while also increasing its porosity due to reduced fluidity. NS can improve the compressive strength of mortar by up to 35%. The curve fitting of volume fractal dimension and box dimension is effective and can accurately reflect the complexity of the pore structure. The calculation of the grey correlation analysis model shows that the impact of varying silica content on the mechanical properties of mortar specimens is not linear; the distribution and quantity of bubbles are the main factors affecting the strength of the specimen.

Geochemical Characteristics of Melts from the Eastern Volcanic Belt and Sredinny Range of Kamchatka: Analysis of Evidence from Melt Inclusions

We analyzed sets of published data on the composition of glasses from melt inclusions in minerals of volcanics from the Eastern Volcanic Front and Sredinny Range of Kamchatka. A significant difference was revealed between the distribution of silica contents in the rocks and melts: intermediate compositions are most common among the rocks, whereas the melts are dominantly silicic. The distribution of major and trace element was analyzed. It was shown that the contents of some elements are environment-specific (e. g., Nb and light REE). We distinguished trace element ratios in melts that most strongly correlate with the geodynamic setting.

Hydrodynamics and Response Analysis of a Cutting-Edge Pulse Bed Mineral Scrubber (PBMS) Featuring U-Type Motion, Pulsation Bed, and Fluidization for Low-Grade Iron Ore Processing

ABSTRACT A novel compact and efficient pulse bed mineral scrubber (PBMS) has been designed. The scrubber has a hybrid design incorporating a U-type particle flow path, bed pulsation like a jig and fluidization. The hydrodynamic characteristics and response of this scrubber for the scrubbing of low-grade iron ore fines have been reported in this article. The response methodology with a central composite design was used to evaluate the hydrodynamics of the PBMS hutch section. The results indicate that the hydrostatic head increases with an increase in solid percentage in the hutch section and decreases with an increase in pulsation frequency. The pressure and load model prediction matched the experimental data well. The model predicts that at 54 rpm pulsation frequency and a 25% solid percentage, the pressure will be 0.0285 bar and the motor load 25.54 W. The R2 of the pressure and load model are 0.9536 and 0.9936, respectively. Scrubbing performance on −10 mm iron ore fines with 54.17% Fe, 8.15% SiO2 and 12.75% Al2O3 at 10, 15, and 20 l/min water rate has been validated with characterization of products after scrubbing. The desliming efficiency of the particle in the range of 0.045–0.3 mm is ± 88% at a water rate above 15 l/min. The best cleaning and segregation of fines are reported at a 15 l/min water rate. The Fe value of clean coarse products increases from 54% to 59%. The scrubbing improves the grade of ore, and the alumina and silica content reduction is 19% and 40%, respectively.

Eco-Pozzolans as Raw Material for Sustainable Construction Industry: Comparative Evaluation of Reactivity Through Direct and Indirect Methods

A solution to reduce the consumption of raw materials and the generation of greenhouse gases is the partial replacement of clinker (the main constituent of cement) with supplementary cementitious materials. This study aimed to compare the reactivity of ten supplementary cementitious materials—synthetic/commercial ones and those from industrial and agricultural waste (eco-pozzolans). The characterization of the raw materials was carried out using X-ray fluorescence, the loss on ignition, X-ray diffraction, and the determination of the amorphous silica content and particle size distribution. The pozzolanicity assessment was carried out using the Frattini test (direct method) and electrical conductivity and pH tests (indirect method), with the latter presenting greater sensitivity and precision, enabling us to classify the pozzolan reactivity. Although synthetic/commercial pozzolans have higher silica content, the eco-pozzolans showed excellent reactivity results, thus indicating their use as sustainable pozzolans, presenting characteristics that enhance the performance of cement matrices and reduce the environmental impacts of production. Nyasil and rice leaf ash were the pozzolans that presented the greatest reactivity among those studied. The obtained results suggest that using industrial/agricultural waste like reactive pozzolans can help to mitigate the adverse impacts of cement production, address natural resource shortages, and promote a circular economy.