Coal Bottom Ash Research Articles

Engineering properties of self-compacting concrete incorporating coal bottom ash (CBA) as sustainable materials for green concrete: a review

Engineering properties of self-compacting concrete incorporating coal bottom ash (CBA) as sustainable materials for green concrete: a review

Utilizations of Coal Bottom Ash as Sand replacement to produce sustainable concrete

Utilizations of Coal Bottom Ash as Sand replacement to produce sustainable concrete

Separation and recovery of arsenic, germanium and tungsten from toxic coal ash from lignite by sequential vacuum distillation with disulphide

Large amount of coal ash is produced as industrial waste during the electricity generation through the combustion of lignite. Toxic elements arsenic exists in the coal ash, which hinders the subsequent recycling processes. Moreover, coal ash could be recycled further to retrieve scattered metals germanium and tungsten. It is believed that traditional recycling methods present barriers to scaled application, especially serious secondary pollution, such as toxic residue and waste liquid. In this work, a novel sequential vacuum distillation with disulphide method is proposed to separate arsenic, germanium and tungsten from coal ash. First, arsenic can be volatilized completely out of the reaction system at temperatures below 550 °C. Subsequently, Ge and W volatilized in the form of sulfide in the presence of Na2S2O3. The optimal condition was 1050 °C, the mass ratio of 0.6 with reaction a pressure of 1 Pa and a time duration of 120 min demonstrated the best evaporation ratio. For coal fly ash, chemical species As2S3, GeS, and WOx (x < 3)/WS2 were the main condensed products. For coal bottom ash, As2S3, GeS, and WO3/WS2 were dominant chemical components. Mechanisms for the process of release and evaporation of As, Ge, and W from coal ash, vacuum reaction, evaporation, and condensation were analyzed. In summary, the vacuum distillation method deserves to be further developed as it provides an eco-friendly method to recycle coal ash.

Study on the Use of Coal Bottom Ash as a Raw Material Replacement for the Production of Clay Bricks

Context: Masonry bricks are one of the most widely used building materials in the world, which leads to the overexploitation of its raw materials. Its production consumes a large amount of energy and has a large environmental footprint. The clay brick industry can add residues to its raw materials; among those reported are tea processing waste, brick waste, paper industry residues, waste from coffee mills, and coal ashes. Method: Bottom coal ashes were characterized by X-ray fluorescence, X-ray diffraction, thermogravimetric analysis, electronic microscopy, and particle size analysis. In addition, their density and loss on ignition were determined. The incorporation of ashes in the elaboration of clay bricks was evaluated, with sand replacement percentages of 0, 3, 5, and 7%. Finally, the physical and mechanical properties of the bricks were evaluated. Results: The water absorption and apparent porosity increased, while the compressive strength and bulk density decreased with the incorporation of ash in the brick samples, except for those with a 3% replacement, which showed a better performance in the evaluated properties. Conclusions: Coal bottom ashes have great potential in the manufacturing of clay bricks. The findings of this study indicate that, by incorporating up to 3% ashes, bricks can be obtained which comply with the Colombian regulations.

Compatibility Study between Ceramic Balls and Jatropha Curcas Oil Properties under Long Time Heat Treatment: Potentiality for Thermal Energy Storage

Valorisation of local and low-cost eco-materials have become an imperative for the sustainable development of Concentrating Solar Power (CSP) in West Africa. In this study, the compatibility tests were carried out. These involve the application of jatropha curcas oil (JCCO) and ceramic balls, which were developed from clay coal bottom ash and sands with a focus on Burkina dune sand ceramic. The aim was to assess the applicability of using JCCO as heat transfer fluid in CSPs with direct thermocline thermal energy storage. The tests involve the use of a small container to put in contact with Jatropha oil with ceramic balls for 2160 hours and at 210 °C. From the chemical properties’ analysis, the peroxide value in the oil decreases with aging time while the acidity increase. However, the acidity remains below the limited value that is 25 mg KOH.g-1. Therefore, thermal properties that drive heat transfer and rheological properties (density, thermal conductivity, kinematic viscosity and so on) were not adjusted significantly at the storage temperature (of about 210°C). Thermal stability temperature decreased to 261.93°C for the oil aged alone as against 263.41 °C for the one that was put in contact with filler material. In the nutshell, there is no incompatibility between JCCO, and the new thermal energy storage material (TESM) developed. These couple of materials could be suitable for thermocline energy storage in CSP plant and for other applications like there use in solar cooker box.

Cost and CO2 emission of concrete incorporating pretreated coal bottom ash as fine aggregate: A case study

The production cost of concrete using coal bottom ash as a fine aggregate, along with the associated CO2 emissions, was critically assessed through a case study. Two types of reinforced concrete buildings, one with a beam-column rigid frame system and the other with a slab beam-wall frame system, were selected. Structural designs and concrete mix proportions were determined in accordance with domestic standards. The study estimated the total cost and CO2 emissions associated with the production and transportation of concrete for these buildings considering treatment of bottom ash. The advantages of using bottom ash as a fine aggregate, in terms of cost and CO2 emissions, were found to be significantly influenced by various factors, including the handling and treatment processes of ash, as well as the availability of relevant subsidies or incentive.

Numerical investigation of the influence of temperature and composition on the thermophysical properties of an innovative environmentally friendly glass obtained from mineral coal bottom ash

The purpose of this work is to investigate, through numerical simulation, the influence of temperature and chemical composition on the heat capacity, density, and thermal conductivity of a novel eco-friendly glass from mineral coal bottom ash. The modeling used to represent the system is based on the heat transfer in solids with phase-change. The numerical resolution was performed by the finite element method, and the variation of physical properties with temperature and composition was represented by theoretical and empirical equations introduced in the model. After the model is experimentally validated, the behavior of these properties during cooling process was investigated, pointing out higher ash content levels resulted in higher values of heat capacity, and lower values for density and thermal conductivity. Thus, this study brings contributions in the investigation of physical properties of a novel glass obtained by reuse of mineral coal bottom ash from a thermoelectric plant.

Impact of recycled coal bottom ash as mixing ingredient on fresh and mechanical properties of concrete: A review

The expanding use of concrete in the global construction sector requires the exploitation of more main ingredients from nature, such as limestone, stone, sand, and rocks, which leads to an additional degradation of the state of the environment. Recognizing that this approach has negative impacts on plants, animals, and humans, a technique to use industrial byproducts as partial substitutes for concrete mix ingredients would reduce consumption of key resources and make the environment more sustainable. As a result, the huge amounts of coal bottom ash (CBA) produced annually in thermal power plants and their improper management have led to major ecological problems, as the waste has negative effects on the environment and human welfare. This review summarizes the results to date on the use of CBA as an alternative to sand and cement in concrete production. This review also examines the effects of CBA on fresh concrete properties and the mechanical properties of concrete. This paper is intended to help newcomers understand the scope and development of the use of CBA as a mix ingredient in the production of concrete. Overall, the use of CBA in appropriate proportions can improve the fresh and mechanical properties of concrete at replacement ratio up to 30% in the mechanical properties. However, further research is needed to investigate the possibility of using CBA in large quantities to achieve high-performance and durable concrete. Therefore, the inclusion of CBA as a mix ingredient in concrete production is the most effective way to reduce dependence on key ingredients and potentially minimize the negative environmental impacts caused by landfills.

The Synthesis and Characterization of Pahae Natural Zeolite-Coal Bottom Ash Adsorbent for Fe and Mn Purifier in Well Water

Zeolite is a porous crystalline mineral alumina silica tetrahydrate that has an open three-dimensional framework structure that has channels and cavities filled with metal ions, while Bottom ash is also known to have high porosity and surface area. Thus, both zeolite and bottom ash can be used as adsorbents. This study aims to make an adsorbent based on Pahae natural zeolite with a mixture of bottom ash from coal as an adsorbent for iron (Fe) and manganese (Mn) metals in well water. Adsorbent made from Natural Zeolite Pahae-Coal Bottom Ash with a size of 200 mesh (74 µm) which has been chemically activated with 1 M NaOH solution, was prepared with various compositions of (100:0)%, (95:5)%, (90:10)%, (85:15)%, (80:20)%, (75:25)% respectively, then mold using a hydraulic press with a load of 6 tons of weight for 10 minutes. The mold samples were then physically activated with temperature variations of 600°C, 700°C, and 800°C for 4 hours, respectively. The addition of coal bottom ash filler is known to increase the porosity of the adsorbent with the composition of (75:25)% with an activated temperature of 800°C by 10%. The results of the AAS test showed that the adsorbent made from Natural Zeolite Pahae-Coal Bottom Ash reduced the content of Fe and Mn metals by 92.37% and 53.49% in well water, respectively.

Influence of setting time and compressive strength for coal bottom ash as partial cement replacement in mortar

Environmental degradation from forestry practices to extract limestone from mountains, as well as subsequent calcination in cement factories and dumping of coal bottom ash (CBA) waste from thermal power plants, are among the wastes from industry. However, it is essential for the construction industry to look for sustainable solutions to mitigate the negative impact on the environment. In order to promote an environmentally friendly and sustainable ecosystem, the use of recycled CBA waste as a partial substitute for cement in the manufacturing process has significant potential to mitigate the environmental damage caused by the two distinct sectors of cement and waste management. A series of six mortar preparations were prepared, each containing varying percentages of CBA as a partial substitute for cement. The percentages used ranged from 0% to 50% by weight of cement. The time tests were performed on freshly prepared pastes. All samples were cured with water until the respective test time was reached. The experiment included the evaluation of the compressive strength of hardened mortar cubes at three different time intervals: 7, 14 and 28 days. The findings of the study demonstrate that the incorporation of CBA as a partial substitute for cement affects both the setting time and the compressive strength of the mortar. It has been shown that the use of up to 20% CBA as a cement replacement effectively increases the compressive strength of the mortar. Conclusively, the successful use of CBA as a partial substitute for cement in the manufacture of mortar has the potential to reduce the amount of cement consumed, eliminate the need for landfill space for waste disposal, and contribute to the production of a more sustainable environment, thereby promoting a better lifestyle for the surrounding population.

Characterisation of Ground Coal Bottom Ash With Different Grinding Times

The physical and chemical composition of Ground Coal Bottom Ash (GCBA) exposed to varying grinding periods is discussed in this article. CBA was pulverised for 20 hours, 30 hours, and 40 hours in a ball mill machine. Particle Size Analyzer (PSA) and X-ray Fluorescence (XRF) instrument were used to characterise GCBA. According to the results of the tests, GCBA with a grinding duration of 40 hours generates the largest percentage of the finest particle (50-1000 nm) at 4%, the specific surface area is 13528.18 cm2/cm3, and the specific gravity (SG) is 2.54. According to the XRF results, there are no significant variations in the chemical compositions of the CBA with varying grinding periods. At 20, 30, and 40 hours grinding time, the primary oxide element for SiO2 is 51.5%, 53.8%, and 52.3%, while Al2O3 is 14.3%, 15.1%, and 14.6%, and Fe2O3 is 5.08%, 5.27%, and 5.07% respectively. The sum of three primary oxide constituents surpasses the 70% ASTM C618 limit for pozzolanic material Class F fly ash.

Remediation of Pb–Cd contaminated soil using coal bottom ash-based geopolymer and coir: Soil remodeling and mechanism

Stabilizing heavy metal-contaminated soil with solid waste-based materials is a sustainable approach. This study synthesized a coal bottom ash-based geopolymer and coir for the treatment of Cd- and Pb-contaminated soil. The results demonstrated that adding 10% geopolymer stabilized over 95% of Cd and Pb in contaminated soil, with the maximum compressive strength of soil reaching 634 kPa after curing. Geochemical model simulations revealed that Pb and Cd primarily converted to precipitated mineral forms (Cd4(OH)6SO4, Pb4(OH)6SO4, Litharge, and larnakite) when the system pH exceeded 5. From a mechanical perspective, the combination of coir and coal bottom ash-based geopolymers effectively solidified heavy metals while improving soil frost resistance, compression resistance, and shear resistance. The mineral recombination of coal bottom ash was successfully achieved, and it was prepared as an amorphous cementitious material. This study unveils the mechanism of geopolymer-cemented heavy metals and their structural strengthening, providing new technologies for addressing land resource pollution and realizing the green, sustainable, and clean reuse of industrial solid waste.

Utilization of coal bottom ash from thermal power plants as a cement replacement for building: A promising sustainable practice

Coal bottom ash (CBA) is claimed to carry some pozzolanic qualities that can be stimulated by pre-treatment. This study investigates the feasibility of partially replacing ordinary Portland cement (OPC) with ground CBA to produce CBA-cement paste. A thorough experimental program was designed to explore the effect of the CBA source and particle size, liquid-to-binder ratio (l/b), and superplasticizer (SP) on the 28-day compressive strength of CBA-cement paste. The CBA source with a high SiO2/Al2O3 ratio (approximately 3.6) and CaO content (5.3%) yielded higher compressive strengths. Grinding breaks down the large raw CBA particles and enhances their reactivity with water and pozzolanic character. Specimens with 50% ground CBA attained a 28-day compressive strength of up to 51 MPa at l/b of 0.225. The low pozzolanic nature combined with the porous texture of CBA necessitates the incorporation of a superplasticizer to enhance workability at low l/b. A 28-day strength of 61 MPa was achieved at 30% cement replacement with 150 μm CBA at l/b of 0.25 using 1% SP. In view of this, partial replacement of cement with ground CBA has proven to be a viable and sustainable construction option.

Regression Modeling of Elasticity Modulus of Concrete with Coal Bottom Ash as Partial Replacement of Sand

Regression Modeling of Elasticity Modulus of Concrete with Coal Bottom Ash as Partial Replacement of Sand

Properties and microstructure development of alkali- activated coal bottom ash and titanium- extraction tailing slag binder

In this study, ground coal bottom ash (CBA) and titanium-extraction tailing slag (TS) were used as source materials to prepare alkali- activated materials (AAMs). The effects of grinding time on the properties of CBA and TS were investigated, and it was found that the optimum reactivity of CBA and TS appeared at specific surface areas of 700 ∼ 800 m2/kg. The influence of alkali content and modulus of water glass, water–solid mass (w/b) ratios and TS content on the fresh and hardening properties of AAMs were investigated. Furthermore, the reaction process of the binder was conducted by using XRD, FT-IR, SEM and hydration heat. Results showed that increasing the alkali content, reducing modulus of water glass, and adding TS into system could promote the reaction of AAM. A binder with more desirable properties was prepared at alkali content of 12%, water glass modulus of 1.2, w/b ratio of 0.45 and TS content of 20%. Its compressive strength at 7 d and 28 d was 20.8 MPa and 25.9 MPa, respectively. Microstructure analysis showed that the reaction products of binder contained AFm, N-A-S-H gel, C-S-H gel and C-A-S-H gel. This research tried to provide a fundamental basis for preparing clinker-free cement concrete from local industrial wastes to achieve sustainable development.

Adsorption of Phosphate from Aqueous Solution by Calcination of Silicified Coal: Kinetic and Isotherm Studies

Silicified coal (SC) consisting of SiO2 is promising raw material for adsorbent. The present study aimed to utilize the adsorbent of silicified coal bottom ash (SCBA) by calcination of the SC at the temperature of 600, 800 and 1000 oC for 1 hour. The FTIR result showed that the SCBA-600, SCBA-800 and SCBA-1000 had chemical functional groups such as the asymmetric Si-O-Si, the symmetric Si-O-Si and Si-O-Si bond rocking for adsorption of phosphate (PO43−) with the lowest percentage of transmittance of SCBA-1000. The adsorption test showed that a rapid adsorption occurred in the first 10-min of contact time, and it did not change significantly for the rest of contact time until reaching an equilibrium time of 30 min. The PO43− adsorption efficiency and capacity fluctuated over initial PO43− in solution in the range of 60.02–480.29 mg/L. The highest PO43− adsorption efficiency and capacity was at 480.29 mg/L, which was 95.49 % and 45.86 mg/g, respectively using the SCBA-1000. The adsorption kinetic fitted better to pseudo second-order kinetics model (average R2 = 0.999) with the adsorption capacity of 45.454, 45.662 and 45.872 for the SCBA_600, SCBA_800 and SCBA_1000, respectively, and the PO43− adsorption rate was 0.0007, 0.0008 and 0.001 g/mg.min, respectively. The adsorption isotherm followed Langmuir model (average R2 = 0.873) with the adsorption capacity being 2.357, 1.198 and 8.196 mg/g, respectively, and the pore volume being 0.0316, 0.0364 and 0.2103 L/mg, respectively

Influence of densified silica fume on engineering properties of concrete containing coal bottom ash aggregate.

Coal bottom ash (CBA) is a significant waste produced by the coal manufacturing power plant, harming the environment. CBA has been used in many studies to replace sand in cementitious materials. However, few studies have investigated the use of CBA in concrete as a sand replacement with densified silica fume (DSF) as a cement replacement. DSF is a potential supplementary cementitious material (SCM) to combat the engineering properties of concrete that are typically decreased when CBA is used as a replacement for natural aggregate. Therefore, the present study aimed to evaluate the influence of DSF on the engineering properties of concrete containing different content of CBA as a partial replacement for natural sand. The mix design of the ordinary Portland cement (OPC) and binary blended concrete comprised 90% OPC and 10% DSF by total binder’s weight. The CBA as the fine aggregate replacement was used at 25%, 50%, 75%, and 100% by total aggregate volume. The mechanical, porosity, absorption performance of DSF and CBA (DSF+CBA) concrete containing CBA as partial aggregate replacement material were investigated. DSF+CBA with 50% CBA replacement showed improved mechanical strength performance than control by 15% at 28d and 5.6% at 56d of curing. However, the total porosity performance for DSF+CBA concrete decrease as CBA content increases. In conclusion, the DSF as SCM in binary blended concrete with CBA content up to 50% achieved a better performance in terms of mechanical properties even though the porosity was marginally increased.

Properties of Concrete Containing Large Volumes of Ground Granulated Blast Furnace Slag and Ground Coal Bottom Ash with Lime Kiln Dust

Currently, there is no report on the combined use of ground coal bottom ash (GCBA) and ground granulated blast furnace slag (GGBS) as supplementary cementitious material (SCM) with lime kiln dust (LKD) as an additive in mortar. Hence, the current work aimed to investigate the impact of the addition of LKD on the properties of ternary blended cement mortar consisting of a large volume of GCBA and GGBS as SCM. The total substitution level of cement was up to 80%, where 50% of GGBS was combined with 0 to 30% of ground CBA. LKD was used with a content of 0%, 4% and 8%. A polycarboxylate-ether-based superplasticiser was used to achieve the mortar’s flow diameter of 200 ± 10 mm. Also, the fine aggregate-to-binder and water-to-binder ratios were fixed at 3.0 and 0.4, respectively. The result revealed that the setting time of the mortar increased by increasing the cement replacement level by GCBA. Besides, the setting time was reduced with increased LKD content. All the mortar mixtures are considered good quality according to the ultrasonic pulse velocity (UPV) results. The UPV values decrease with the increased GCBA replacement ratio but increase with extended curing ages. The mortar incorporating up to 15% GCBA achieved comparable or greater strength than the control mortar (50% OPC and 50% GGBS) at a curing age beyond 28 days. Moreover, increased strength performance was noticed with increased LKD content from 0% to 8%.

Performance of High Strength Concrete Containing Treated Fine Metakaolin, Palm Oil Fuel Ash, and Coal Bottom Ash as Substitute Materials Toward Compressive Strength and Flexural Strength Test

The annual increase in cement use has a detrimental effect on the environment. To lessen the harmful effects on the environment, concrete production now incorporates industrial waste from power plants such as coal bottom ash and palm oil fuel ash (POFA). In order to create more environmentally friendly concrete, this study used metakaolin (MK), palm oil fuel ash (POFA), and coal bottom ash (CBA). The purpose of this study is to determine how these substitute materials affect the compressive and tensile strengths of concrete. MK and POFA are partial cement replacements, whereas CBA is a partial sand replacement. The compressive and flexural strengths of the concrete were assessed to determine the impact of these materials on its strength. The trials used 20% MK and 10% CBA as the constants and 5%, 10%, 15%, and 20% POFA as cement substitutions for the variables. The concrete with a 10% POFA replacement had the highest compressive strength (78 MPa) and flexural strength (7.5 MPa) among the other concrete mixes while having the best workability.

Experimental Validation of Reinforced Concrete Beam Incorporating Coal Fly Ash and Coal Bottom Ash Using Numerical Analysis

The environmental deterioration affected by the disposal of Coal Bottom Ash (CBA) from power stations has worsened as the energy demand has increased. In addition, the increased demand for concrete leads to an increase in aggregate consumption, which contributing to the depletion of natural resources. To prevent the immense amount of CBA waste and the destruction of natural resources, an initiative has been implemented to replace aggregate with CBA in concrete. The Reinforced Concrete (RC) beams underwent a four-pointbending test. The test was done after 28 days of curingage. Therefore, this study was conducted to study the performance of RC beam incorporating CBA as fine and coarse aggregate replacement. The deflection, maximum load and cracking pattern of RC beam were determined. Beam with 100% coarse coal bottom ash 100% fine coal bottom ash resulted to the maximum load at 88 kN with maximum deflection at 18.87 mm. The RC beams were redesigned using the three-dimensional nonlinear simulation software ABAQUS in enable to identify and compare the simulation and experimental findings. The FEA result shows that ultimate load of FEA waswithin 5% range with the experimental results. The simulation results demonstrated that the proposed finite element model accurately predicted the RC beam’s damage behaviour.