Coal Ash Waste Research Articles

Pavement Subgrade Stabilized with Waste coal Ash and Geosynthetics: An Experimental Study and Multiple Regression Modelling

With expansive soils like black cotton soil, subgrade soil stabilisation is a critical step in the pavement construction process. The focus of this research is to use Multiple Regression Analysis (MRA) to evaluate the soil for the optimal addition of coal ash as well as geosynthetics, as well as to develop a model to forecast CBR values. For MRA, data analysis tool in Excel 2020 is used. The input values for this study includes Atterberg’s limits, Optimum Moisture Content (OMC) and percentage of coal ash added by weight which directly affect the CBR value. A model pavement subgrade with the stabilized soil characteristics is designed and economic analysis is done for the designed pavement subgrade.

Recycling of Waste Materials Using Bitumen Emulsion for Road Pavement Stabilized Base Courses: a Laboratory Investigation

The valorisation and reuse of waste materials can enhance the environmental sustainability of road constructions, especially by means of cold recycling techniques, which, moreover, allow to reduce polluting emissions in atmosphere. Among the various technological approaches, the use of bitumen emulsion to stabilize waste materials is very common, especially in case of reclaimed asphalt pavement (RAP) aggregates. However, even other types of waste materials could be considered using a Cold Central Plant Recycling (CCPR) approach. The paper discusses the main results of a laboratory investigation aimed to evaluate the mechanical performance of bitumen emulsion stabilized mixtures for road pavements base courses, prepared with RAP, steel slag, coal ash and glass wastes, used with various percentages. In a first step of the laboratory study, both physical and toxicological properties of each waste material have been investigated, in order to assess their environmental compatibility. Subsequently, an extensive mechanical analysis of the bitumen emulsion stabilized mixtures has been carried out in the laboratory, in terms of indirect tensile strength, indirect tensile stiffness modulus at three temperatures (10°C, 25°C, 40°C) and repeated load axial tests at 30°C. The moisture resistance of the mixes has been also investigated by means of indirect tensile strength tests carried out on soaked specimens. Very good results have been observed, depending on the mix composition: indirect tensile strength at 25 °C on dry specimens up to 0.52 MPa and stiffness modulus up to 4,056 MPa (at 25 °C, for a rise time equal to 124 ms). Therefore, it has been verified that the waste materials considered in the study can be successfully reused to completely substitute conventional aggregates in bitumen emulsion stabilized mixtures for road pavements base courses.

An Overview of Eco-Friendly Alternatives as the Replacement of Cement in Concrete

Due to the global urbanization, economic development, and increasing rate of the world’s population, the construction of new buildings and infrastructure is increasing. The manufacture of concrete has become an essential part of our life all over the world. Emitting 5-8% of carbon dioxide (CO2), the production of concrete becomes the main obstacle to reach global climate action under the Paris 2050 Agreement. Reuse of waste or recycled waste materials in concrete as an environmentally friendly construction material has become highlighted as a feature of achieving sustainability, because of its potential environmental and economic benefits. The focus of this paper is to assess the application of alternative eco- friendly substitutes of cement for an innovative, economically attractive, and environmentally friendly alternative, and the transition towards of circular economy by reducing the number of natural resources consumed. Based on the existing studies, waste material (fly ash, bottom ash, coal ash, tire, steel slag, construction and demolition waste, glass, ceramic) incorporated with concrete accepted performance in the environment and economic perspective by reducing energy consumption, greenhouse gas emissions, costs, and other indicators.

A Review of the Utilization of Coal Bottom Ash (CBA) in the Construction Industry

One effective method to minimize the increasing cost in the construction industry is by using coal bottom ash waste as a substitute material. The high volume of coal bottom ash waste generated each year and the improper disposal methods have raised a grave pollution concern because of the harmful impact of the waste on the environment and human health. Recycling coal bottom ash is an effective way to reduce the problems associated with its disposal. This paper reviews the current physical and chemical and utilization of coal bottom ash as a substitute material in the construction industry. The main objective of this review is to highlight the potential of recycling bottom ash in the field of civil construction. This review encourages and promotes effective recycling of coal bottom ash and identifies the vast range of coal bottom ash applications in the construction industry.

Aluminium Tertiary Industry Waste and Ashes Samples for Development of Zeolitic Material Synthesis

Wastes generated in large amounts have been recognized as sustainable sources of raw materials for the synthesis of adsorbents. The synthesis of zeolite through wastes recycling of two different ash sources (coal bottom ash and sugarcane waste ash) and industrial aluminum waste was evaluated. The molar ratio of SiO2/Al2O3 for zeolite 4A formation was achieved by the addition of aluminum waste from tertiary industry as aluminum source. Coal bottom ash and sugarcane waste ash were used as a source of both silica and alumina. The synthesized materials were characterized using X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and cation exchange capacity (CEC). The analysis of the properties of the products demonstrates that the by-products can be used to produce zeolite A. The utilization of synthesized zeolites as adsorbent for cadmium removal from aqueous solution was conducted following the concept of implementation of utilization of waste materials as a component of the circular economy in the wastewater sector.

Pengaruh Perbandingan Komposisi Media Tanah Pasca Tambang dengan Pembenah Tanah Faba terhadap Kemasaman Tanah dan Pertumbuhan Land Cover Crop (Pueraria javanicum)

The higher the use of coal in the industry, the higher the waste produced. This causes environmental problems such as air, soil, water pollution and a decrease in the quality of ecosystems and public health in industrial environments. For this reason, it is necessary to make efforts to utilize coal waste so that unwanted things do not occur, one of which is by using coal ash waste as a soil repairer to improve soil quality in post-mining land. This experiment was carried at the Faculty of Agriculture screenhouse, Winaya Mukti University, Tanjungsari, Sumedang Regency on the altitude of 850 M above sea level. The trial period is from Jully to August 2020. The experiment aims to determine the effect of comparisons of post-mining soil media composition with Faba fixer on the value of growth of Pueraria javanicum plants. The experimental design used was a randomized block design (RBD) which consisted of five treatments and was repeated five times. Treatment is the ratio of Fla Ash Bottom Ash soil repairer and post-mining soil with the following dosages; A = 100% post-mining soil, B = 25% Faba soil repairer + 75% post-mining soil, C = 50% Faba soil repairer + 50% post-mining soil, D = 75% Faba soil repairer + 25% post-mining soil, E = 100% Faba soil repairer. The results showed that treatment C (50% Faba soil repairer + 50% soil) had a good effect on plant height and shoot wet weight, treatment D (75% Faba soil repairer + 25% soil) had a good effect on the number of leaves, root length, number of effective nodules, and root wet weight of Pueraria javanicum plants.

The Facts of Science & the Values of Social Justice

The Facts of Science & the Values of Social Justice

The potential of cenospheres production from Malaysian coal power plants

Coal Combustion Waste (CCW) fly ash, main component of coal ash waste generated at the Coal-Fired Power Plant throughout the year that causes the presents of toxic metals in the ash. Hence, pose significant health threats towards humans and environment. Cenosphere is a coal combustion by-product obtained from fly ash in boilers of coal fired power plants. The properties of cenosphere including spherical, lightweight, good thermal stability, chemical proof, heat resistance making it to have improved insulation. The aim of this research was to investigate the potential of cenospheres production from three different coal fired power plants in Malaysia namely Jimah, Kapar and Manjung. The wet method was used for cenospheres separation from the fly ash. The percentages of cenospheres ranged from 1 to 1.2% of every 1000 gram of fly ash. The mean sizes were 95.86μm 88.64μm, 49.04μm for Jimah, Kapar and Manjung respectively. Cenosphere evacuated by utilizing water as a medium, it will expend a lot of water and lead to water contamination cause of leaching of toxic material while extracting the cenosphere from fly ash. Nevertheless, any health and environmental impacts from the value-added physical application of cenospheres in civil engineering materials must be screened via strict monitoring and legislated guidelines.

Effect of Different Waste Coal Ash (WCA) Loading to Dynamic Load Application of Chloroprene Rubber

This study seeks to address the effect of waste coal ash collected from burnt charcoal after human recreational activities to the chloroprene rubber’s dynamic property specifically in cyclic load. Waste coal ash was chosen due to their availability, low cost, and recyclability. The waste coal ash was incorporated into chloroprene rubber via melt compounding process using an internal mixer. The compounding formulation of the chloroprene rubber compound and coal ash were based on 100 phr of the chloroprene rubber. The loading of waste coal ash were varied at 5, 10, 20, 30 and 40 phr. Waste coal ash exhibits the highest reinforcing property at 40 phr loading. The fatigue test was done to determine the peak stress value and stress softening effect and found that at 5 – 30 phr waste coal ash had a detrimental effect on CR compound while at 40phr, the rubber compound exhibit positive result with an increase of 30% of the peak stress. Morphological study using scanning electron microscopy (SEM) showed degrees of agglomeration of the waste coal ash in the chloroprene rubber matrices. The dispersion of waste coal ash agglomerates and morphology of failures were in good agreement with the observed dynamic properties.

Plasticity and compaction characteristics on soft clay stabilised with coal ash and cement

This paper aims to determine the compaction and plasticity properties of marine clay stabilized with increasing percentages and different ratios of coal ash with cement. Coal ash with different ratio of bottom ash and fly ash (70:30, 50:50, and 30:70) were prepared at increasing percentages. Limited amount of ordinary Portland cement of 2% was added. The percentage of additives added to the marine clay were 5%, 8%, 10%, 15%, 20% and 25%, respectively. Standard Proctor test was done to determine the compaction characteristics while Atterberg limits was executed to acquire the plasticity characteristics of treated marine clay soil. In terms of plasticity, by increasing the additives percentages, the marine clay approaches CL group of plasticity which shows improvement in soil’s plasticity. For compaction, the values of MDD of treated marine clay is higher while the OMC is lower when compare to untreated. Hence, with the addition of coal ash waste there is improvement in terms of soil’s plasticity for all three ratios whilst for compaction values of treated marine clay does not change significantly between ratios.

Stabilization of Peat Soil Using Fly Ash, Bottom Ash and Portland Cement: Soil Improvement and Coal Ash Waste Reduction Approach

Peat soil is very compressible, which leads to an excessive settlement. Stabilization of peat soil is the way to improve the engineering properties of peat soil through mixing peat with supplementary cementation materials. Therefore, this study aims to investigate the stabilization of peat soil using fly ash, bottom ash and ordinary Portland cement (OPC) to improve the engineering properties of peat soil. Also to examine the possibility of fly ash and bottom ash waste reduction through using them as a binder of the mixture in soil improvement application. In this study, fly ash and bottom ash were collected from generation wastes at coal- fired electric power and stabilization of peat soil was done by mixing peat soil with fly ash, bottom ash and OPC. Unconfined compressive strength (UCS) and Fourier transform scanning electron microscope (FESEM) was conducted before and after the stabilization of peat soil. Also, some essential physicochemical properties of a mixture have identified before the mixing process. The findings of the compressive strength of peat soil were equal to 5 kPa at its natural state and after stabilization strength of peat soil was equal to 47 kPa. FESEM micrographs have shown ultrastructure of peat stabilization appears as inherent and coherent while the ultrastructure of original peat appears as incoherent and sporadic. The findings have revealed the effectiveness of fly ash and bottom ash to improve the strength of peat and the applicability of the utilization of coal ash waste as binder materials.

Synthesis of in-situ Al3+-defected iron oxide nanoflakes from coal ash: A detailed study on the structure, evolution mechanism and application to water remediation

The recovery of value-added materials from coal ash waste is of highly economic value and sustainable significance. However, researches on the synthesis of defect-engineering nanomaterials from coal ash are still blank. Herein, iron oxide (Fe1.72Al0.28O3, simplified as FAO) nanoflakes were successfully synthesized from a brown coal fly ash (BCFA) waste. The obtained FAO nanoflakes possess a round-shape morphology with a diameter of around 300 nm and 50 nm in thickness. With the progress of hydrothermal treatment, the impure Al3+ gradually replaced part of the Fe3+ in the α-Fe2O3 crystal. Specifically, Al3+ was preferentially adsorbed on the (001) facet, hindering the growth of Fe3+ on the [001] direction and thus causing the flattening of the resultant FAO. The introduced Al3+ also serves as the disordered defects on the hematite surface, leading to decreased crystal parameters for hematite, the formation of a compact first shell and a reduced periodical symmetry for the central cation Fe3+. The defects were also found to significantly improve the adsorption capacity of the resultant FAO for Cr(VI), As(V), As(III) and Congo red in waste water, with the maximum adsorption capacity of 68.3, 80.6, 61.1 and 213.8 mg g−1, respectively. Cyclic tests also confirmed a relatively strong stability for the as-synthesised adsorbents.

Investigating the Influence of Replacing Two Biomass Ashes with Conventional Filler on High and Intermediate Temperature Performance of Mastic and Mixture

Abstract The aim of this research was to evaluate the rheological properties of mastics and performance of mixtures consisting of two biomass ashes named as coal waste ash (CWA) and rice husk ash (RHA) used as a replacement of limestone filler at different concentrations. The high and intermediate temperature behavior of binders was evaluated through multiple stress creep recovery (MSCR) and linear amplitude sweep (LAS) tests. Moreover, Marshall stability, resilient modulus, dynamic creep, moisture susceptibility, wheel track, indirect tensile strength, and four-point beam fatigue tests were implemented to investigate the mechanical performance of mixtures. Based on MSCR test results utilization of RHA led to improve the rutting resistance of binders, while CWA decreases the rutting resistance of binders. LAS test results indicated that addition of RHA to original binder increase the fatigue life of binder, while CWA decreases the fatigue behavior of mastics. Based on the results, the addition of styrene-butadiene-styrene (SBS) increases the fatigue life of mastics. Results revealed that the addition of RHA improves the Marshall stability, resilient modulus, rutting properties, moisture resistance, and tensile strength of asphalt mixtures, while CWA has negative impact. In general, the obtained results from this study indicated that reuse of RHA and CWA waste materials in the northern part of Iran, where there are lots of RHA and CWA materials, especially RHA, in pavement engineering, has two main effects. First, environmental problems are reduced. Second, the performance properties of mixtures are enhanced.

Coal ash use as a cement replacement in concrete production

Ordinary Portland cement (OPC) is the main contributor of concrete CO2 emissions amongst concrete constituents. Use of alternative cementitious materials is highly encouraged to lower environmental footprint of concrete production. Local waste materials could be a feasible approach in terms of economic and environmental sustainability due to local availability. In this study, coal ash waste was used as a Portland cement replacement by 10% and 20% for the production concrete mix concrete mix with 28-day design strength of 45 N/mm2. Developed mixes were tested against various engineering properties including workability, bulk density, compressive strength, sound permeability, thermal conductivity, water permeability and porosity. Results showed that coal ash incorporated mixes had slightly lower slump values with slightly lower fresh density. Hardened properties including bulk density and compressive cube strength were reduced slightly for CA mixes. Other hardened properties showed that CA mixes had more compact structures compared to conventional mix. Therefore, CA mixes showed enhanced sound permeability, thermal conductivity, water permeability and porosity.

Coal Ash Waste Utilization for Environmentally Friendly Road Pavement Materials

Indonesia is boosting electricity supply, where coal fired power plants are most widely used. Burning coal activity will produce Fly Ash Bottom Ash (FABA) that categorized as Hazardous and Toxic Substances. The production of FABA are 6.598.493 tons (2019) and will increase along with the 35, 000MW program. The research purpose is to study the utilization of FABA from PLTU Labuan Angin as road pavement material that not only fulfill required specifications, but has better performance and environmentally safe. The experimental method was chosen by laboratory testing. Criteria for utilization of FABA as road pavement material, must be carried out with the use of material that capable to binding FABA so that it doesn’t disintegrate Test results showed that FA is type F with CaO levels <10% and LoI 4.27%. Characteristics testing also showed results such as specific gravity of FA 2.64 and BA 2.56, absorption 3.24%, sand equivalent 95.35%. Utilization for base layers with a composition of 75% BA, 25% FA, and 9% PCC produce γd 1.71%, Wopt 5.84%, and UCS 33.05kg/cm2. This utilization is the most effective, because it absorbs more volumes, binding cement, and compaction with heavy equipment can also prevent FABA from released so it is environmentally safe.

An Integrative Approach to International Technology Transfer for Recycling Vietnam Coal Ash with Consideration of the Technological, Legal, and Network Perspectives

The rapid economic growth of Vietnam has increased the amount of coal ash waste during electricity generation from coal-fired thermal power plants. This waste is being dumped even though the capacity of dumping sites will not be sufficient in the future. Accordingly, Korean technologies of recycling ashes, modifying them into a valuable product, and fixing carbon dioxide via carbon mineralization, can be an alternative to dumping. In this study, we aimed to investigate the feasibility of deploying carbon mineralization technology to Vietnam while considering technological, legal, and network perspectives. The material properties of coal ash and the applicability of coal ash recycling technology were briefly investigated in Vietnam. Legislation has progressed, focusing on recycling coal ash as a building material, with supportive measures on investment and international cooperation. Meanwhile, a bilateral network between Vietnam and the Republic of Korea at the institutional and governmental levels strengthened the implementation of practical technology cooperation. In conclusion, we considered various perspectives in terms of the technology transfer of recycling coal ash. This technology transfer model can contribute to enhancing the possibility of successful technology cooperation for solving the environmental problems of coal ash.

Research on the preparation of a new type steel slag ceramics with steel slag and coal ash

Along with our rapid development of steel industry, the output of steel slag was increasing these yesrs. But all kinds of industrial waste emissions increased rapidly too. Application of good solid wastes such as coal ash and mineral powder is under low utilization rate, a large number of accumulation is serious threat to the environment and other issues. Therefore, research on the preparation of a new type steel slag ceramics with steel slag and coal ash is important to improve the industrial solid waste resource utilization. In this paper, the new type of steel slag ceramics was prepared by industrial waste steel slag and industrial waste coal ash, and the new type of steel slag ceramics was prepared by appropriate sintering process system. Meanwhile, the performance indexes of ceramic bricks were tested to determine the influence of different factors on the performance of the new type of steel slag ceramics.

Coal fly ash derived zeolite for highly efficient removal of Ni2+ inwaste water

A novel efficient Ni2+ adsorbent A-type zeolite is successfully synthesized. It is worth noting that the raw material used is the waste coal ash produced by local power plants. The ability of A-type zeolite to remove Ni2+ from wastewater is up to 94%. In the study, the physical properties of zeolite are systematically characterized. In addition, we study in detail the effect of the external environment on the adsorption capacity of A-type zeolite. Moreover, the pseudo secondary kinetic model and Langmuir isothermal model evaluate the kinetic performance and isothermal equilibrium adsorption ability are better. The synthetic zeolite not only effectively uses the coal fly ash, but also realizes the sewage recycling. Therefore, the use of power plant coal fly ash to make adsorbent zeolite has potential practical significance.

Laboratory evaluation of the effect of coal waste ash (CWA) and rice husk ash (RHA) on performance of asphalt mastics and Stone matrix asphalt (SMA) mixture

Current study assessed the performance of mastics and SMA mixture containing coal waste ash (CWA) and rice husk ash (RHA) in different mass fractions (0%, 25%, 50%, 75% and 100%) as a substitution of limestone powder (LP) as conventional filler. For this purpose, the Multiple Stress Creep Recovery (MSCR) and linear Amplitude Sweep (LAS) tests were performed to investigate the rutting and fatigue performance of asphalt mastics with different fillers and concentrations. Moreover, Marshall stability, resilient modulus, dynamic creep, moisture susceptibility, wheel track, Indirect tensile strength tests were implemented to investigate the mechanical performance of mixtures. The MSCR test results revealed that addition of RHA to original binder led to decrease in strain of binder and hence rutting strength of original binder increases at both stress levels. While the CWA additive has adverse effect in comparison with RHA. Based on the obtained results from LAS test, addition of RHA to original binder increase the fatigue life of binder. Adversely, CWA is incapable of improving the fatigue behavior of mastics. Also modification of mastics with SBS improve the fatigue behavior of modified asphalt binders. Results indicated that replacement of RHA by conventional filler enhances the Marshall stability, resilient modulus, rutting properties, moisture resistance and tensile strength of asphalt mixtures. Adversely, the modification of asphalt binder by CWA resulting in reducing the mentioned performance properties of mixtures, except moisture resistance. In general, the obtained results from this study indicated that reuse of RHA and CWA waste materials in north part of Iran where there are lots of RHA and CWA materials especially RHA in pavement engineering, has two main effects. First, reduce environmental problems. Second, enhance the performance properties of mixtures.

Influence of a Two-Stage Sintering Process on Characteristics of Porous Ceramics Produced with Sewage Sludge and Coal Ash as Low-Cost Raw Materials

In this paper, the two-stage sintering process as a promising strategy has been adopted to prepare high-performance porous ceramics with high porosity. Sewage sludge and waste coal ash were used as raw materials and added were starch and CaCO3 as a mixed foaming agent. The chemical composition of the raw materials and mixed foaming agents were analyzed by standard techniques. All mixtures were prepared from fixed solid materials mixed at a ratio of 48 : 32 : 10 : 10 (wt.%) for coal ash, sludge, starch, and CaCO3, respectively, followed by granular molding, aging, sintering and property survey tests. The influence of heating rate, holding time, and heating temperature of the two stages on the characteristics of the as-obtained porous ceramics was deeply investigated. The properties investigated are apparent porosity, bulk density, compressive strength, and linear shrinkage. On the one hand, the results show that the major content of the raw materials is silica (SiO2). On the other hand, the results show that the first-stage sintering process had minimal influence on the properties, whereas the second-stage sintering process had a significant influence on the properties of the porous ceramics. With the optimized sintering parameters (temperature, heating rate, and holding time) of the first stage and second stage, we obtained a high-performance porous ceramic product with an apparent porosity up to 51.3%, bulk density up to 1.22 g/cm3, linear shrinkage up to 14.3%, and compressive strength up to 25.1 MPa. Also, the results of the phase composition and microstructure revolution showed sufficient glassy phases and feldspar (Ca, Na) (Si, Al)4O8, which are known to enhance bending strength of ceramics. A comparison of these properties and characteristics with those of standard porous ceramics revealed that the product developed in this study would compete favorably for real applications.