Fly Ash Materials Research Articles

Mechanical performance and co2 footprint analysis: recycled aggregate polypropylene geopolymer concrete compared with conventional concrete

Abstract Geopolymer concrete (GPC) has gained significant awareness in recent years as an eco-friendly alternative to conventional concrete due to its lower CO2 emissions and utilization of industrial waste materials. The cementitious material fly ash (FA), GGBS, silica fume (SF) with incorporation of polypropylene fiber (PF), recycled aggregates (RA) further promote the strength properties of geopolymer concrete, particularly in terms of ductility and crack resistance. Exploratory tests been conducted to assess the effects of various parameters including activator type, curing conditions, fiber content, and aggregate characteristics on the mechanical behaviour and CO2 emissions of geopolymer concrete (GPC). The mechanical performance aspects like as compressive strength(45.7Mpa), flexural strength(4.78Mpa), and split tensile strength(4.12Mpa) were attain by optimum mix design GPC-FG where cement substituted with ratio of FA:GGBS:SF - 40:50:10 and compressive strength(50.4Mpa), flexural strength(5.51Mpa) and split tensile strength(4.99Mpa) were attain by optimum mix design of Polypropylene based GPC-FGP where cement substituted with ratio of FA:GGBS:SF:PF - 40:49:10:1. The optimal mix design GPC-FG and GPC-FGP are compared there is raise in compressive strength of 9.325%, flexural strength of 13.241%,split tensile strength 17.434% of GPC-FGP, along with CO2 of polypropylene fiber-based geopolymer concrete with recycled aggregates as shown 60.01% reduction of CO2 when compared with traditional concrete. The results demonstrate the potential of geopolymer concrete to achieve comparable or superior mechanical performance while significantly reducing CO2 emissions compared to conventional concrete. This research adds to sustainable construction knowledge by showcasing geopolymer concrete’s environmental benefits, mechanical strength, and potential applications in the industry and infrastructure development.

The Use of Waste Materials Red Mud and Fly Ash as Road Embankment Fill

This study provides a comprehensive evaluation of red mud as a sustainable material for road base construction, particularly in combination with bottom ash. Red mud, a by-product of the Bayer process used in alumina extraction, is known for its high alkalinity and heavy metal content. For this reason, this waste material causes environmental challenges. Red mud sourced from the Eti Aluminum Factory in Seydişehir, Konya (Turkey), was stabilized with bottom ash. Then, these waste materials were tested through a number of experiments, such as in relation to their Atterberg limits, compaction characteristics, unconfined compressive strength (UCS), California bearing ratio (CBR), and microstructure through a scanning electron microscopy (SEM) analysis. The results highlight that the UCS of stabilized red mud samples significantly improved with the addition of bottom ash and longer curing periods. Specifically, the UCS values increased from 0.5 MPa to 2.5 MPa after 28 days of curing. Moreover, RM specimens stabilized with 25% bottom ash achieved a CBR value of 146.64% after 28 days, far exceeding Turkey’s road fill material requirement, which mandates a minimum unsoaked CBR value of 15%. These findings indicate that red mud stabilized with bottom ash not only meets but exceeds the structural requirements for road base materials. This approach provides a sustainable solution for the environmental management of red mud while contributing to infrastructure development. Through the recycling of these industrial by-products, this study presents a viable method to reduce waste and support economic and environmental sustainability in road construction projects.

Avenues To Reduce Carbon Emission In Cement Fabrication To Acquire Carbon Credit

The cement industry accounts for roughly 8% of global carbon dioxide emission, and for every tonne of cement procured, a ton of carbon dioxide is released into the air. Cement industry is the backbone of global infrastructure development with no sign of slowing down, as such, it provides the most promising testbed for a carbon credit market to start up. Carbon credit functions as a conversion of money as payment to offset carbon dioxide emission, and can be acquired by reducing carbon emission or its greenhouse equivalents. This carbon credit can then be sold on the carbon market which provides financial incentive for companies to reduce their carbon emission. Acquiring carbon credit can be a viable capital gain strategy in developing nations due to their relatively low labor and overhead costs. This study aims to provide avenues to reduce carbon dioxide emission in cement fabrication as a way to acquire carbon credit for capital gain purposes to developing nations worldwide. This study uses literature review with a descriptive qualitative methodology, with data from relevant books and journals of renowned and reputable publishers online as validity. This study identified three promising avenues to reduce carbon dioxide emission in cement fabrication: alternative cement aggregate material fly ash and bottom ash, carbon capture and storage technology, and alternative fuel in cement fabrication. Three avenues provide pathways for players in the cement industry to adopt according to their capabilities in order to effectively reduce their carbon dioxide emission for acquiring carbon credit.

Study on the Reuse of Shield Mud from Clay Stratum in Synchronous Grouting Slurry

The purpose of this study is to investigate the feasibility of replacing the fly ash in synchronous grouting material by reusing the shield mud produced in the clay stratum during the shield construction of Wuhan Rail Transit Line 11. The test utilizes the shield mud from the clay stratum to replace the fly ash material in synchronous grouting at percentages of 20%, 40%, 60%, 80%, and 100%, and research and analyses are conducted on the fluidity, stability, strength, and resistance to water dispersion of the slurry after the replacement; at the same time, improvements in the undesirable phenomenon produced by the synchronous grouting slurry are also examined after the replacement. The results show that, when the fly ash is replaced by shield mud at 80%, the mortar still has good stability and strength performance, but, at the same time, the initial value of consistency and the phenomenon of flow time loss is too large. Through the adjustment of the water–binder ratio and the addition of an appropriate amount of a polycarboxylate superplasticizer agent, the adverse phenomenon of the slurry is effectively improved, and the compressive strength and ease of the slurry are also improved. At the same time, when adding an appropriate amount of hydroxyethyl methyl cellulose (HEMC), the slurry has good water dispersion resistance, but, with the gradual increase in HEMC, the fluidity of the slurry deteriorates and the compressive strength decreases. The test proves that the shield mud in the clay stratum can be used to replace most of the fly ash in an appropriate proportion, which not only solves the problem of the shield mud being difficult to work with, but also provides more valuable insights for tunneling projects.

A novel solution for the in-situ Microcystis aeruginosa capture and flotation removal using fly ash derived buoyant cenospheres

Harmful algal blooms are increasingly prevalent globally, posing significant threats to water safety and ecological health. In this study, a novel positive charged buoyant cenosphere (FABC@CTS) was developed for capturing and floating algal cells using chitosan (CTS) and an easily available waste material—fly ash buoyant cenospheres (FABC). The prepared cell-capturing buoyant cenospheres were characterized by various analytical techniques and tested for the removal of Microcystosa aeruginosa. The results demonstrated that at a FABC-to-CTS mass ratio of 8:1 and an FABC@CTS dosage of 55.5 mg CTS/g algae, the removal efficiency of Microcystis aeruginosa exceeded 95%. XDLVO analysis indicated a significant reduction in the repulsive energy barrier after surface modification due to stronger electrostatic and van der Waals forces. Compared with 108 μm buoyant cenospheres, 50 μm FABC@CTS exhibited higher affinity to algal cells, significantly improved the compactness and floatability of aggregates, enabling the rapid flotation of microalgae in 1 min. The FTIR and XPS analysis results further revealed that the amino and hydroxyl functional groups on the surface of the FABC@CTS could effectively capture microalgae through hydrogen bonding and π–π bonding. Overall, the results of this study provide new insights into developing cost-effective and eco-friendly material for efficiently controlling cyanobacterial blooms and contribute to advancing the comprehensive utilization of fly ash solid waste.

Evaluating the Socio-Economic Effects of Fly Ash and Agricultural Waste on the Construction Sector

The building industry significantly impacts environmental degradation due to its reliance on conventional materials such as cement and concrete, which are associated with high carbon emissions and substantial energy consumption. This study explores the socio-economic impacts of substituting fly ash and agricultural waste for traditional construction materials. A comprehensive review of 50 peer-reviewed papers, industry reports, and online sources reveals that these alternative materials offer considerable benefits. Cost savings average between 15% and 20%, driven by reduced material costs and lower disposal requirements. Environmentally, using fly ash and agricultural waste significantly reduces greenhouse gas emissions, with fly ash cutting emissions by approximately 25% and agricultural waste by about 20%, primarily due to decreased energy consumption. Furthermore, technical assessments show that these materials enhance the strength and durability of concrete, meeting or exceeding conventional standards. The study also highlights broader socio-economic advantages, including support for rural economies through new markets for agricultural by-products and job creation in recycling and construction sectors. These findings suggest integrating fly ash and agricultural waste into construction practices can positively impact economic growth and environmental sustainability. However, the study acknowledges limitations such as reliance on secondary data and potential geographic biases. Future research should prioritize original data collection, long-term performance assessments, and investigation of regional material-use variations. This study underscores the practical and environmental benefits of incorporating these sustainable materials, contributing to a more eco-friendly construction industry.

Experimental investigation on physical properties and early-stage strength of ultrafine fly ash-based geopolymer grouting material

The conventional cement grouting materials possess certain drawbacks that hinder their environmental compatibility. The utilization of geopolymer grouting materials with the raw material of fly ash is anticipated to serve as a proficient approach in mitigating the environmental problem caused by solid wastes. Consequently, this study employed ultrafine fly ash (UFA) and granulated blast furnace slag (GBFS) as composite base materials to fabricate a kind of novel geopolymer grouting material. The addition of 0.05 % − 0.2 wt% graphene oxide (GO) facilitated the preparation of this material, and the physical properties and early-stage strength were experimentally investigated. The micro-analysis was conducted using micro-analysis techniques, including Fourier transform infrared and energy dispersive X-ray spectroscopy, etc. The findings indicated that as the contents of GO and GBFS increased, the flowability slightly decreased; the addition of GBFS and GO can contribute to the elevation of viscosity; the initial and final setting times were decreased. The bleeding rate decreased and increased with increasing GO and GBFS contents. It was also found that the GO and GBFS were beneficial to increase the water retention rate. Furthermore, the inclusion of GO and GBFS significantly enhanced the early-stage compressive strength of the grouting material. The GO and GBFS contents of 0.1 % and 60 % resulted in the attainment of maximum compressive strength of samples, with the value of 15.89 MPa at the first day. The simultaneous utilization of GO and GBFS facilitates the generation of a greater quantity of calcium-alumina-silicate-hydrate gel, thereby substantially enhancing the initial compressive strength of grouting materials. The results of this study could provide valuable perceptions into the production of sustainable grouting materials with low carbon emissions and the recycling utilization of solid wastes.

Comparative Study of the Effects of Conventional, Waste, and Alternative Materials on the Geomechanical Properties of Clayey Soil in the Chemical Soil Stabilisation Technique

This paper presents an extensive comparative analysis of the experimental results of chemical stabilisation of clayey soil in laboratory conditions by comparing the effects of adding conventional stabilisers (lime, cement binder), stabilisers that can be considered as waste material (fly ash, rock flour), as well as alternative chloride-based materials (ferric chloride, calcium chloride, potassium chloride) on the geomechanical properties of the soil. With the aim of determining the stabiliser optimal content in the mixture with the soil, in the first part of the research, the effects of stabilisation of clayey soil of medium plasticity using the considered stabilisers with different percentage share on the change in uniaxial compressive strength (UCS) and pH value of the soil at different time intervals after the treatment were analysed. In the second part of the research, additional tests were conducted on soil samples with optimal content for each of the considered stabilisers by monitoring changes in the physical and mechanical properties of the soil. These include Atterberg’s limits (liquid limit and plasticity limit), modulus of compressibility in the oedometer, California bearing ratio (CBR), and swelling potential at different time intervals after the chemical treatment to determine the durability of stabilisation effects. The results of the conducted research reveal that each of the conventional, waste, and alternative materials considered as chemical stabilisers contributes to the improvement of the geomechanical properties of the clayey soil, primarily in terms of increasing the bearing capacity and reducing the swelling of the treated soil.

Evaluating the durability performance of concrete containing clastic sand and GGBS

The manufacturing process of materials utilized in concrete production has environmental implications. The production of cement releases significant amounts of greenhouse gases, while the extraction of aggregates and sand poses challenges to the natural environment. To minimize the aforementioned challenges researchers are suggested to utilize industrial by-products as a partial alternative for these materials Fly ash, stone dust, GGBS, silica fume, and metakaolin are widely utilized alternatives to construction materials. The specific use of clastic sand as a partial substitute for fine aggregate has recently gained popularity . However, studies on the characteristics of concrete prepared using cementitious materials and clastic sand are very few. In this work, the effect of clastic sand with ground granulated blast furnace slag concrete is being investigated. The GGBS is added in place of cement from 0% to 45%. Further, clastic sand is added in different proportions in GGBS concrete. The electrical resistivity, water absorption, acid attack, and micro-structural studies are carried out on all mixes to know the durability properties. The results confirm that the addition of GGBS as a cementitious material enhances durability. The inclusion of 35% of GGBS as a substitute for cement is optimum for enhancing durability. Further, the inclusion of 35% GGBS as a cement substitute and 20% clastic sand shows a dense matrix and optimum results in enhancing durability. This is due to the pozzolanic activity of GGBS and clastic sand works as filler materials. This investigation suggests utilizing clastic sand along with GGBS as a cementitious material.

Multiscale Dynamic Diffusion Model for Ions in Micro- and Nano-Porous Structures of Fly Ash: Mineralization Experimental Research

The leaching concentration of alkaline ions plays a crucial role in the efficiency of the CO2 mineralization reaction in fly ash. The multi-scale structural characteristics of micro–nano pores in fly ash are the primary factors that control the leaching and diffusion rate of alkaline ions. However, the existing theoretical models do not account for the multi-scale pore structure, leading to challenges in accurately describing the ion diffusion in fly ash and predicting the reaction rate and efficiency of CO2 mineralization. To address this issue, a multi-scale dynamic diffusion model of ions was developed based on the micro–nano pore structure of fly ash. This model established the relationship between the ionic leaching rate and pore structure, as well as macroscopic changes over time, which were validated through experiments. Mineralization experiments with varying soaking times and uniaxial compression experiments on mineralized specimens were conducted to investigate the relationships among soaking time, ion leaching concentration, mineralization degree, and mechanical strength. The results elucidated the impact of alkaline ion concentration on the mineralization degree and mechanical strength of fly ash materials, offering theoretical insights to enhance mineralization and material properties.

Recovery and reuse of phosphogypsum: Effect of ternary cementitious materials on the performance of phosphogypsum pavement base layers

In this paper, the performance of a new type of phosphogypsum (PG) pavement material is studied under the joint action of ternary cementitious materials (cement, mineral powder, and fly ash), CaCl2 and gravel. The experimental results of mechanical properties and durability of the material system, including compressive strength, splitting strength, dry and wet cycle, freeze-thaw cycle, etc., confirm that the material system can meet the design standards for road base material design standards for highways and primary highway sub-base. The test results of SEM, XRD, EDS, contact angle, and solubility of trace elements show that the material system does not cause secondary pollution to the environment, and its strength mainly comes from the C-S-H gel and calcium alumina (AFt) generated by the reaction of the reactive substances in the cementitious materials with PG in an alkaline environment. Finally, the optimal ratio of modified PG: mineral powder: cement: fly ash: gravel: water: CaCl2 was 50:8:3:0:39:11:0.22, and its 7d compressive strength, splitting strength, loss of strength in dry and wet cycles, loss of strength in freezing and thawing cycles, and water absorption were 6.41 MPa, 6.84 MPa, 3.01%, 16.22%, and 8.87%, respectively.

Microstructure and Phase Characterization of Alkali-Activated Slag–Fly Ash Materials with Tetrasodium of 1-Hydroxy Ethylidene-1, 1-Diphosphonic Acid (HEDP·4Na)

The effect of tetrasodium of 1-hydroxy ethylidene-1, 1-diphosphonic acid (HEDP·4Na) on the microstructure and phase characterization of alkali-activated fly ash–slag (AAFS) materials is not clear or well documented. In this study, XRD, DTG, TAM-air, and SEM analyses of AAFS were used to identify the microstructural changes in AAFS made with HEDP·4Na. Meanwhile, the workability and compressive strength of AAFS were evaluated. The results demonstrated that the early-age alkaline-activated reactions were retarded due to the addition of HEDP·4Na in the AAFS mixture. However, the degree of gel formation was relatively increased at a later age in the AAFS made with HEDP·4Na compared to the plain AAFS mixture. Additionally, in comparison to the control group, the incorporation of HEDP·4Na in AAFS specimens resulted in improved flowability, with increments of 5%, 15%, and 24% for concentrations of 0.1%, 0.2%, and 0.3%, respectively. The initial and final setting times were prolonged by 5% to 50%, indicating a beneficial impact on the rheological properties of the AAFS fresh mixture. Furthermore, the addition of HEDP·4Na led to an improvement in compressive strength in the AAFS mixtures, with enhancements ranging from 13% to 16% at 28 days compared to the control group. With the presence of HEDP·4Na, the increase in the degree of reactions shifted to the formation of gel phases, like C-S-H, through the combined measurement of TGA, XRD, and SEM, resulting in a denser microstructure in the AAFS matrix. This study presents novel insights into the intricate compatibility between the properties of AAFS mixtures and HEDP·4Na, facilitating a more profound comprehension of the potential improvements in the sustainable development of AAFS systems.

Detecting Moisture in Building Materials and Commercial Food adducts by 2-Hydroxy-naphthaldehyde Derived Chromo-Fluorogenic Chemosensor.

A great deal of effort has been put into developing a novel and cost-effective molecular probe for selective and sensitive recognition of trace amounts of water in organic solvents due to their tremendous advantages in industrial, pharmaceutical, and laboratory-scale chemistry. Herein, a cost-effective chemosensor L has been designed and studied for the detection of trace amounts of water. The addition of water to the DMSO solution of L exhibited an enhancement of fluorescence emission at 460nm along with a color change from green to colorless. The spectral and color changes occurred due to the self-aggregation of L. The interaction between water and L was performed by dynamic light scattering (DLS), scanning electron microscope (SEM) and finally complemented by quantum mechanical calculation. The detection limit was found to be 0.0093 wt% in DMSO. The L also exhibits a fast visual response and is effectively applied to detect trace amounts of moisture in various food materials (salt, sugar, wheat and honey) and building materials (cement, fly ash, limestone and sand).

Prediction and interpretation of concrete corrosion induced by carbon dioxide using machine learning

The CO2-induced corrosion of concrete containing solid waste materials (slag and fly ash) rich in Ca, Si, Al, Fe, and Mg oxides is investigated. In this work, more than 1700 samples are extracted, each accompanied by 29 feature data points. Subsequently, 8 key supervised machine learning (ML) algorithms were explored to predict the concrete corrosion induced by CO2, including Decision Tree (DT), Random Forest (RF), AdaBoost, CatBoost, and XGBoost, as well as K-Nearest Neighbors (KNN), Support Vector Regression (SVR), and Multilayer Perceptron (MLP). Filling the gap in the research of the ML model in predicting the carbonation depth of concrete incorporating solid waste materials. After optimizing the hyperparameters, the XGBoost model exhibits the best prediction accuracy and generalization ability, with MSE, RMSE, MAE, and R2 values of 7.94, 2.82, 1.83, and 0.92, respectively. Based on the optimally trained XGBoost model, Shapley Additive exPlans (SHAP) and Partial dependency plots (PDP) were used to evaluate the independent impacts of ‘carbonation time’, ‘water’, ‘aggregate’, and each raw material, as well as the interactive effects between features and oxide components.

Experimental investigation on the mixture optimization and failure mechanism of cemented backfill with coal gangue and fly ash

Using coal gangue and fly ash for mining backfill materials can create a win-win situation for safe mining and waste disposal, with the critical challenge being the optimization of coal gangue grading and fly ash proportions. Uniaxial compression tests and scanning electron microscopy (SEM) observation were conducted on backfill specimens with different coal gangue grading and fly ash proportions, and in-situ monitoring of acoustic emission (AE) parameters and infrared radiation temperatures (IRT) was carried out. The elastic modulus, uniaxial compressive strength (UCS), failure pattern, infrared temperature, AE ringing count and energy evolution of the backfill were discussed. Further, the b-value and entropy-value of AE during the loading were analyzed. The results show that the UCS and elastic modulus decrease with the increase in the proportions of fly ash and large-size gangue. Tensile cracks generally dominate the failure of specimen under unaxial compressive load but shear cracks are more prone to occur for specimens with high proportions of fly ash and large-size gangue. The inner defects and weak interfaces between large-size gangue and cement pastes significantly affect the mechanical performance for specimens with high proportions of fly ash and large-size gangue. A sudden drop of the b-value occurs before the peak stress while the AE entropy-value reaches maximum at the peak stress. The methods and findings can guide the mixture optimization and mechanical failure analysis for backfill mining.

Waste Management of Red Mud and Fly Ash to Utilize in Road Subgrade Material

Red mud (RM) is a waste material obtained during the production of aluminum from bauxite minerals. RM causes environmental pollution due to its high alkaline properties. Therefore, RM materials are stored in waste reservoirs. As production continues, the number of required waste reservoirs increases day by day. This study aims to utilize RM waste material in construction structures to contribute to the economy. The research investigates the potential use of RM waste material as road fill material. RM was improved using another waste material of fly ash (FA) since RM has low strength. Atterberg limit tests, compaction tests, unconfined compression tests, CBR tests, and SEM analyses were conducted on stabilized RM samples. In the physical properties of stabilized RM, Atterberg limits and optimum moisture content increase and density decreases since FA content increases. In the mechanical properties of stabilized RM, unconfined compressive strength, initial and secant modulus of elasticity, and California bearing ratio increase and maximum peak strain decreases since FA content and curing period increase. SEM images prove the increase in mechanical properties due to the cementation products (CSH and CAH gels) formed in the microstructure of stabilized RM. The results showed that RM waste stabilized with FA can be used as road subgrade material.

Characteristics of carbide-slag-activated GGBS–fly ash materials: Strength, hydration mechanism, microstructure, and sustainability

To improve the reuse of industrial solid wastes, this study investigates alkali-activated material (AAM) consisting of ground granulated blast-furnace slag (GGBS) and fly ash (FA) activated by carbide slag (CS). A separation treatment process was introduced to obtain reactive ultrafine GGBS and FA (RUGGBS and RUFA). The compressive strength is used to differentiate between representative specimens for exploring the hydration mechanism in terms of hydration process, hydrate types, and pore-structure characteristics. Finally, the environmental and economic benefits of these materials are calculated and analyzed based on the material sustainability indicators (MSIs). The results show that the separation of GGBS and FA reduces their particle size and enhances their hydration activity. Although using RUGGBS and RUFA delays the setting time of AAM, it results in lower hydration heat release and increases compressive strength after aging for 3 days. RUGGBS and RUFA synergistically promote polymerization reactions in CS-activated GGBS-FA systems, which results in more hydrates, including C–S–H gel, C–A–S–H gel, and hydrotalcite-like hydrates, helping to optimize the pore structure and strengthen the material. These findings suggest that separating industrial solid wastes can promote the use of AAMs in construction engineering by significantly reducing their environmental impact.

Wastewater Treatment Utilizing Industrial Waste Fly Ash as a Low-Cost Adsorbent for Heavy Metal Removal: Literature Review

Wastewater discharges from industrial processes typically include elevated concentrations of contaminants, which largely consist of potentially harmful chemicals such as heavy metals. These contaminants are characterized by their slow rate of decomposition. Hence, the removal of these metallic ions from effluents poses a challenge. Among different treatments, the adsorption approach has considerable potential due to its ability to effectively eliminate both soluble and insoluble pollutants from effluent, even at lower levels of concentration. Of various wastes, fly ash (FA) material has been the subject of attention because it is abundant, has favorable qualities, and contains a high percentage of minerals. This review investigates multiple facets, with a specific focus on the application of FA, an industrial byproduct, as an adsorbent in removing heavy metals. A comprehensive examination was conducted on a range of concerns pertaining to the pollution caused by metallic ions, including the underlying causes, levels of contamination, health implications of heavy metals, and removal methods. Multiple factors were found to affect the adsorption process. Of all the factors, the pH value considerably influences the elimination of heavy metals. An acidic pH range of 2.5–4.5 was found to be optimal for achieving the highest possible elimination of As(V), Cu(II), Hg(II), and Cr(VI). The latter elimination rate reached 89% at the optimal pH level. Most heavy metals’ adsorption isotherms conformed to the Langmuir or Freundlich models, while the pseudo-second-order kinetics provided a satisfactory match for their removal. Using a raw FA, adsorption capacities were achieved in the removal of metallic ions, Ni(II), Pb(II), and Cr(VI), that ranged from 14.0 to 23.9 mg g−1. Meanwhile, the FA-zeolite showed a remarkable capacity to adsorb ions Mn(II), Ni(II), Cd(II), Cu(II), and Pb(II), with values ranging from about 31 to 66 mg g−1. The cost analysis showed that the treatment of FA is economically advantageous and may result in significant cost reductions in comparison to commercial adsorbents. In summary, FA is an inexpensive waste material with potential for water treatment applications and several other purposes due to its excellent chemical and mineralogical composition.

Effect of Source Type on Pore Structure and Properties of Aerated Geopolymer Concrete

A study has been carried out to produce environmentally friendly lightweight concrete by substituting cement with alternative geopolymer binders. Fly ash and silica fume (waste materials) were used as source materials and their effect on pore structure and properties of aerated geopolymer concrete was evaluated. Autoclaved aerated concrete, locally known as thermostone, was supplied from the market and tested as a reference mix. Three aerated geopolymer concrete mixes (around 550 kg/m3 density) were produced by mixing source materials (fly ash and silica fume), activator solution (sodium silicate and sodium hydroxide), and aeration agent (aluminum powder). It was found that by not only enhancing the pore structure but also improving the binder medium, the aerated geopolymer mixes were stronger and less absorbed than the autoclaved aerated concrete mix. However, the thermal insulation of the aerated concrete mix was better than those of aerated geopolymer concrete mixes. In terms of the source material, it was found that usage of fly ash helped in enhancing the strength by about 100% of autoclaved aerated concrete. In addition, unless its lowest density, aerated geopolymer mix made with fly ash and silica fume in combination absorbed less water than the other investigated mixes. Adding superplasticizer to the geopolymer mix helped in enhancing its pore structure by making the pores smaller, their irregularity lesser, and their number higher. In general, an environmentally friendly lightweight material with strength and absorption better than those of autoclaved aerated concrete was produced by adopting a geopolymerization process.

ANALYSIS OF THE EXPERIENCE OF USING ASH SLAG MATERIALS OF THERMAL POWER PLANTS IN ROAD MATERIALS MADE BY COLD RECYCLING TECHNOLOGY

Summary. This scientific text examines the analysis of domestic and world experience of using ash slag materials of thermal power plants in road materials produced by cold recycling technology. Coal is the most important primary source of energy in Ukraine. In 2019, its share accounted for 28.9% of all energy resources. There are 15 coal-fired power plants in Ukraine, the total capacity of which is 30-40% of the total installed power generation capacity in the country. As a result of the operation of thermal power plants (TPP), a significant amount of large-tonnage waste - ash and slag materials (ZShM) is generated. 360 million tons of ash slag are accumulated in TPP ash dumps. About 5-10 million tons of ash and slag are produced annually. Therefore, there is a question of reducing waste materials as materials for road construction. In Ukraine, the main method of using fly ash materials is their use in the production of cement. But at the current level of cement production, the potential of using slag in this industry has been exhausted. Therefore, the question of using ash slag materials in other industries arises. As an option, it is the use of ZSHM in road construction. Key words: road, road clothing, ash and slag materials, hydroremoval ash, takeaway ash, recycling.