Coal Bottom Ash Research Articles

Waste-Based porous materials as water reservoirs for the internal curing of Concrete. A review

This review collates findings from more than 100 scientific publications regarding the performance of several waste-based porous materials (WASPORs) as water reservoirs for the internal curing of concrete. Results obtained by using recycled concrete aggregates, crushed ceramics, coal bottom ash, artificial waste-based aggregates, different powder materials and porous fibres were included. The influence of these WASPORs on the consistence, hydration, setting, microstructure, density, strength, modulus of elasticity, autogenous deformation, drying shrinkage and durability properties of concrete were analysed. General recommendations for suitable characterization of WASPOR and mix design are also given. The differences in water absorption capacity between the different porous materials studied have been used for explaining several of the observed phenomena. A moderate water absorption capacity together with a quick water desorption capacity were found to be among the key factors that define the internal curing efficiency of the proposed WASPORs.

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.

Evaluation of Coal Bottom Ash for clay brick manufacturing: a preliminary study

Currently, industrial, economic, and social growth has produced large amounts of solid waste, which harms the environment and human health. Coal bottom ash (CBA) is a waste produced by burning coal. A preliminary study on CBA, to be used as raw material for the clay bricks manufacture, is presented. CBA was characterized through the Laser Granulometry, X-ray Fluorescence (XRF), X-ray diffraction (XRD) techniques; besides, the real and apparent density and the content of organic matter. Furthermore, the environmental tests Toxicity Characteristic Leaching Procedure (TCLP) and Daphnia Pulex acute toxicity test, were applied. It was found that the CBA is an amorphous material, and is composed of oxides of silica, iron, aluminum, and others, while the environmental tests satisfactorily met the applicable standards. According to the results, it is concluded that the CBA has a great potential to be used in the manufacture of bricks.

Coal bottom ash processing for capitalization according to circular economy concept

This work reports the semiquantitative laboratory chemical procedures developed for some Rare Earth Elements (REE) extraction and concentration from coal bottom ash (BA), including recycling the recovered valuable components. This preliminary assessment applied in case of 25 coal BA samples of Ceplea Valley landfill of Romania describes the chemical methods by using digestion with nitric acid coupled with microemulsion assisted extraction procedure. The enrichment of REE by concentrated nitric acid followed by water washing proved to be an adequate approach since water recovers 29.42% of metals comparing to that extracted by the total phase (ac + aq). The REE concentration process achieved by precipitation with NaOH, at different pH values, shows to be almost completely in the fraction at pH ≈ 0 and 3. The statistical outlook coefficient Coutl shows that evaluation of REE concentration in acid/aqueous solution falls into the “promising” field for their recovery by chemical procedures. Optimal microextraction was obtained by coupling microemulsion Winsor II ternary system consisting in Brij 30/AcOEt:AcOBu/metal ions solution, with citric acid as complexing agent. Results confirm that recovery of lanthanides as nanoparticles from microemulsion system yields over 85%. Optical characterization of oxide nanoparticles suggested applications such as for energy efficient buildings, photo-catalysts for water remediation or thin films for photonic optical devices. The ash residue can be also recycled as an alternative raw material for building materials production.

Use of bottom ash as part replacement of sand for making concrete blocks

Coal-based thermal power plants all over the world facing serious problems of handling and disposal of the ash produced. The productive use of coal Bottom Ash (BA) is the best way to alleviate the problems associated with its disposal. This paper covers the studies on laboratory scale evaluation of vibro compaction concrete blocks using BA I, BA II & BA III collected from three different location of Coal Fed Thermal Power Station. In the present investigation laboratory investigation have been carried to utilize BA as part replacement of sand in concrete. This study cover manufacture of concrete blocks without flyash & with BA using for making solid block as per specification laid down in IS:2185 using vibro compaction machine. Three different sources of BA were used in concrete mix each @ 30%, 40% & 50% replacement by weight of sand were adopted in making concrete blocks. Comparative study of compressive strength of concrete at different age of curing, wet density, drying shrinkage is reported in this study. Wet density is found to be lower in blocks containing BA & dry shrinkage values are found well within the limits of specifications. Concrete Blocks having BA @ 30% by weight of sand are found suitable for use in the manufacture of concrete blocks.

Use of bottom ash as part replacement of sand for making concrete blocks

Coal-based thermal power plants all over the world facing serious problems of handling and disposal of the ash produced. The productive use of coal Bottom Ash (BA) is the best way to alleviate the problems associated with its disposal. This paper covers the studies on laboratory scale evaluation of vibro compaction concrete blocks using BA I, BA II & BA III collected from three different location of Coal Fed Thermal Power Station. In the present investigation laboratory investigation have been carried to utilize BA as part replacement of sand in concrete. This study cover manufacture of concrete blocks without flyash & with BA using for making solid block as per specification laid down in IS:2185 using vibro compaction machine. Three different sources of BA were used in concrete mix each @ 30%, 40% & 50% replacement by weight of sand were adopted in making concrete blocks. Comparative study of compressive strength of concrete at different age of curing, wet density, drying shrinkage is reported in this study. Wet density is found to be lower in blocks containing BA & dry shrinkage values are found well within the limits of specifications. Concrete Blocks having BA @ 30% by weight of sand are found suitable for use in the manufacture of concrete blocks.

Influence of Lime and Coal Bottom Ash as Partial Cement Replacement Material on Mechanical Properties of Concrete

Coal bottom ash (CBA) is a waste product collected at the bottom of the furnace from the coal operatedpower plants. However, its huge production becomes a major environmental issue that will bring a negative impact on the environment as it will lead to a higher risk of groundwater contamination. In this study selected 10% of CBA based on previous studies,but various percentages (5% to 15%) of lime content were used in this study by weight method. The compressive, tensile, and flexural strength tests were performed at 7 and 28days. Based on the results, the workability of concrete showed a reduction when the cement replacement level increased. The compressive, splitting tensile, and flexural strengths were reduced when cement replacement level increase, but the strength was improved with the increase in curing age. However, the concrete with10% CBA indicated higher splitting tensile strength than the control.

Appraisal of Asphalt Concrete with Coal Bottom Ash as Mineral Filler

This study was conducted to access the performance of asphalt concrete produced with coal bottom ash as partial replacement of cement in the mineral filler. The Marshal Mix design method of hot mix asphalt (HMA) samples preparation and testing was adopted. Fifteen (15) samples of HMA compacted and used for volumetric and stability testing at a varying percentage of bitumen contents (5.0, 5.5, 6.0, 6.5, and 7.0%,) following the Asphalt Institute and Nigeria General Specification for Road and Bridges (NGSRB) approach for determining optimum bitumen content (OBC). An Optimum bitumen content of 5.5 % was obtained and used throughout the study. Another set of 15 samples of the HMA were prepared and compacted at varying percentage replacement of cement with CBA in the order of 15, 20, 25, 30, and 35% by volume of cement to determine the optimum dosage of the coal bottom ash that will satisfy the requirements for the strength and durability of wearing course of flexible pavement. The Marshall Stability, flow, and the volumetric properties test results obtained indicated that the samples prepared with 25% CBA as filler with OBC of 5.5% satisfied the requirements of the NGSRB for wearing course of flexible pavement. Hence, the addition of up to 25% CBA by volume of cement in asphalt concrete can reduce the consumption of cement and provide a proper means of CBA disposal.Keywords- Coal Bottom Ash (CBA), Marshal Stability, Marshal Flow, Mineral filler, Optimum Bitumen Content (OBC)

Influence of coal ash on the concrete properties and its performance under sulphate and chloride conditions.

This study investigated the influence of coal bottom ash (CBA) on the concrete properties and evaluate the effects of combined exposure of sulphate and chloride conditions on the concrete containing CBA. During concrete mixing, cement was replaced with CBA by 10% of cement weight. Initially, concrete samples were kept in normal water for 28days. Next, the specimens were moved to a combined solution of 5% sodium sulphate (Na2SO4) and 5% sodium chloride (NaCl) solution for a further 28 to 180days. The experimental findings demonstrated that the concrete containing 10% CBA (M2) gives 12% higher compressive strength than the water cured normal concrete (M1). However, when it was exposed to a solution of 5% Na2SO4 and 5% NaCl, gives 0.2% greater compressive strength with reference to M1. The presence of 10% CBA decreases the chloride penetration and drying shrinkage around 33.6% and 29.2% respectively at 180days. Hence, this study declared 10% CBA as optimum that can be used for future research.

Reactivity of Ground Coal Bottom Ash to Be Used in Portland Cement

Ground coal bottom ash is considered a novel material when used in common cement production as a blended cement. This new application must be evaluated by means of the study of its pozzolanic properties. Coal bottom ash, in some countries, is being used as a replacement for natural sand, but in some others, it is disposed of in a landfill, leading thus to environmental problems. The pozzolanic properties of ground coal bottom ash and coal fly ash cements were investigated in order to assess their pozzolanic performance. Proportions of coal fly ash and ground coal bottom ash in the mixes were 100:0, 90:10, 80:20, 50:50, 0:100. Next, multicomponent cements were formulated using 10%, 25% or 35% of ashes. In general, the pozzolanic performance of the ground coal bottom ash is quite similar to that of the coal fly ash. As expected, the pozzolanic reaction of both of them proceeds slowly at early ages, but the reaction rate increases over time. Ground coal bottom ash is a promising novel material with pozzolanic properties which are comparable to that of coal fly ashes. Then, coal bottom ash subjected to an adequate mechanical grinding is suitable to be used to produce common coal-ash cements.

Effect of local metakaolin developed from natural material soorh and coal bottom ash on fresh, hardened properties and embodied carbon of self-compacting concrete.

The carbon dioxide emissions from Portland cement production have increased significantly, and Portland cement is the main binder used in self-compacting concrete, so there is an urgent need to find environmentally friendly materials as alternative resources. In most developing countries, the availability of huge amounts of agricultural waste has paved the way for studying how these materials can be processed into self-compacting concrete as binders and aggregate compositions. Therefore, this experimental program was carried out to study the properties of self-compacting concrete (SCC) made with local metakaolin and coal bottom ash separately and combined. Total 25 mixes were prepared with four mixes as 5, 10, 15, and 20% replacement of cement with metakaolin; four mixes as 10, 20, 30, and 40% of coal bottom ash as partial replacement of fine aggregates separately; and 16 mixes prepared combined with metakaolin and coal bottom ash. The fresh properties were explored by slump flow, T50 flow, V-funnel, L-box, and J-ring sieve segregation test. Moreover, the hardened properties of concrete were performed for compressive, splitting tensile and flexural strength and permeability of SCC mixtures. Fresh concrete test results show that even if no viscosity modifier is required, satisfactory fresh concrete properties of SCC can be obtained by replacing the fine aggregate with coal bottom ash content. At 15% replacement of cement with local metakaolin is optimum and gave better results as compared to control SCC. At 30% replacement of fine aggregate is optimum and gave better results as compared to control SCC. In the combined mix, 10% replacement of cement with metakaolin combined with 30% replacement of fine aggregate with coal bottom ash is optimum and gave better results as compared to control SCC.

Microstructural and engineering properties investigation of sustainable hybrid concrete produced from industrial wastes

The wastes generated from manufacturing industry are increasing at an alarming rate and causing severe threats to our environment’s sustainability. However, the strategic utilization of industrial waste in construction industry has the potential to solve the problems of waste disposal, unsystematic landfills and it may also reduce the demand for natural resource like river sand. Therefore, this study proposes the novel and sustainable method of concrete production from industrial wastes like coal bottom ash and marble dust. In the present experimental investigation the fine aggregate used for concrete production is fractionally replaced by coal bottom ash and marble dust at 10%, 20% and 30% separately, in the initial stages. Further, a sustainable hybrid concrete is prepared containing coal bottom ash and marble dust together by replacing fine aggregate in the same percentages having equal proportions. The test results shows that the compressive strength is maximum at 20% replacement of marble dust and bottom ash, with fine aggregate, when done individually; whereas in hybrid concrete when prepared with 30% replacement of fine aggregate attains highest 28 days compressive strength of 43.9 ​MPa which is 16.75% higher than control mix. This improved strength is attributed to strength compounds, observed in microstructural investigation, like Calcium silicate hydrate (C-S-H) and Calcium aluminate-silicate hydrate (C-A-S-H) formed in hybrid specimen, prepared in conjunction with silica fume.

Sustainable Fiber Reinforced Self-Compacting Concrete with Carbon and Glass Fiber Addition And Its Economic and Environmental Significance

Concrete is the most popular material in the construction sector and due to its popularity and use it has become the largest contributor to the environment also. This is primarily due to the fact that production of concrete consumes Portland cement which consumes high amount of energy and considerable CO2 emissions. It becomes mandatory to search for suitable alternatives of cement. Different kinds of industrial by-products, such as wood ash, solid waste incinerator bottom ash, solid waste incinerator fly ash, metakaolin, cement kiln dust, graphene oxide, agro-industrial by-products, electric arc furnace dust, and coal bottom ash, may to some extent replace cement and thereby reduce the environmental impact on the planet earth from the use of concrete as a construction material. Self-compacting concrete (SCC) is a flowable concrete mixture which has been given viscosity through adding up of different forms of admixtures that give the composite flexibility. Because of its extremely fluid nature, this concrete can be used in complicated situations as well as around parts of complex strengthening. SCC is an extremely flowable kind of material that does not need the same amount of mechanical vibration to be put as standard concrete. SCC is non-isolating concrete that moves with flexibility under the influence of gravity, with the adjunct of super-plasticizers and viscosity modifiers.

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.

Constitutive Model of Uniaxial Compressive Behavior for Roller-Compacted Concrete Using Coal Bottom Ash Entirely as Fine Aggregate

Coal bottom ash (CBA) is one of the by-products that can be employed as fine aggregate to replace natural sand in concrete. Owing to the very low water demand, roller-compacted concrete (RCC) has the potential to use CBA as fine aggregate at a high proportion. However, little research about RCC using CBA entirely as fine aggregate has been conducted. In this study, the uniaxial compressive strength, deformation, stress–strain curves, and splitting tensile strength of CBA-containing RCC (CBA RCC) were studied to bridge this gap. The compressive strength, elasticity modulus, and splitting tensile strength of all mixtures decreased with increasing CBA content. The relationship between compressive strength and splitting tensile strength of CBA RCC was proposed, which is very close to that recommended by the CEB-FIP code. The uniaxial compressive constitutive model based on the continuum damage theory can well illustrate the stress–strain relationship of CBA RCC. The growth process of damage variable demonstrates the hybrid effect of coarse aggregate, cement, and compacting load on delaying damage under uniaxial compression. The theoretical formula can also accurately illustrate the stress–strain curves of RCC presented in the literature studies.

Eco-friendly immobilization of dithizone on coal bottom ash for the adsorption of lead(II) ion from water

Coal bottom ash is one of coal combustion wastes which mainly contains metal oxides of alumina and silica, thus it can be potentially used as adsorbent for heavy metal removal in aquatic environment. We have developed a new approach of eco-friendy immobilization of dithizone on activated coal bottom ash (CBA-Act) in water medium to yield dithizone-immobilized coal bottom ash (CBA-Dtz). The immobilization process in water medium is intended to replace previous method that uses more toxic organic solvents of toluene or carbon tetrachloride. Dithizone immobilization on CBA-Act is aimed to increase the selectivity and capacity of the adsorbent towards heavy metal ions. Characterization of the materials by FTIR (Fourier Transform Infra-Red), SEM-EDX (Scanning Electron Microscopy-Energy Dispersive X-Ray), TEM (Transmission Electron Microscope), XRD (X-Ray Diffraction) and DSC/TGA (Differential Scanning Calorimetry/Thermogravimetric Analysis) confirms that dithizone immobilization on CBA-Act in water medium has successfully accomplished and the new approach has proved to be twice more effective than that done in toxic organic media. Application of the original and modified CBA-Act in the adsorption of lead(II) ion from water suggests that the adsorption capacity of CBA-Dtz increases approximately three times as much as that of CBA-Act. The adsorption on both adsorbents follows pseudo-2nd order kinetic and can be best described by either Langmuir or BET isotherm adsorption models. Sequential desorption experiments reveal that lead(II) adsorption on CBA-Act is mostly governed by electrostatic and hydrogen bond interactions. However, upon immobilization of dithizone as found in CBA-Dtz, electrostatic interaction decreases while hydrogen bond interaction increases significantly.

GEOPOLYMERS SYNTHESIZED FROM PHILIPPINE COAL ASH AS SUSTAINABLE ALTERNATIVE LOW HEAT TRANSMISSION AND FIRE-RESISTANT MATERIAL FOR BUILDINGS

Geopolymers are formed from alumina and silica rich materials by alkali dissolution and subsequent polycondensation into a polymeric network. Geopolymerization technology presents a great potential for positive environmental impact since many alumina- and silica- rich industrial waste materials, such as coal ashes, blast furnace slags, mine tailings, etc., can be used as its precursor materials in a process that requires less energy and gives up less emissions vis-à-vis the current conventional OPC (ordinary Portland cement) technology. In this study, geopolymer samples were prepared using an 85% coal fly ash (CFA) - 10% coal bottom ash (CBA) - 5% rice hull ash (RHA) wt/wt mix proportion and activated using an alkali solution of NaOH-Na2SiO3 at an 80%-20% wt/wt solid-to-liquid ratio. With this mix proportion, two types of specimens were used, a slab type with 50 mm thickness, and a cube type, 50 mm x 50 mm x 50 mm. The slab type specimens were used for evaluating fire resistance using ASTM E119, Standard Test Methods for Fire Tests of Building Construction and Materials, and the cube type specimens were used to study the effect of foaming agents on the strength and thermal conductivity of the geopolymers formed. Two types of foaming agents, hydrogen peroxide and sodium perborate, at an amount of 0.1% to 0.4% of dry mass mixture, were used. Results from the foamed geopolymers gave compressive strength values ranging from 0.37 to 0.71 MPa and densities of 1430-1560 kg/m3 at 0.3% to 0.4% peroxide added. Values of thermal conductivity of the foamed geopolymers were within 0.033-0.037 W/m-K for all foamed geopolymer samples tested which is a significant reduction compared to the thermal conductivity of the unfoamed geopolymer sample at 0.48 W/m-K. The fire resistance tests show that the unfoamed geopolymer samples perform better than OPC concrete. However, the foamed geopolymers have very low strength compared to the unfoamed sample compressive strength of 18.1 MPa and, thus, are suitable for non-load bearing, insulation applications.

Coal bottom ash derived zeolite (SSZ-13) for the sorption of synthetic anion Alizarin Red S (ARS) dye

SSZ-13 zeolite was successfully synthesized from coal bottom ash (CBA) upon hydrothermal treatment for selective sorption of Alizarin Red S (ARS) dye. The characterization of CBA, and SSZ-13 were performed using BET, SEM, FTIR, XRF, and XRD techniques. The optimal fusion ratio (CBA: NaOH) was identified as 1:3, resulting zeolite SSZ-13 with a specific surface area of 206.6 m2/g, compared to raw CBA (7.81 m2/g). The kinetics, isotherms, and thermodynamics of the ARS adsorption onto the SSZ-13, and CBA were assessed under various conditions. The results indicated that the adsorption phenomenon is optimal under acidic medium (pH = 2 for CBA, pH = 3 for SSZ-13); at ambient room temperature of 298 K; adsorbent dosage of 0.03 g, contact time of 120 min. Further, the equilibrium data fitted well to Langmuir isotherm (qe = 210.75 mg/g), following pseudo-second-order kinetics. Moreover, the chemisorption phenomenon is clearly described using Elovich kinetic model. Various thermodynamic parameters signifies the adsorption phenomenon is spontaneous, and endothermic in nature. Finally, regeneration studies revealed the sensitivity of SSZ-13 zeolite towards 0.1 M NaOH/EtOH eluent in recovery and the possibility of reuse to five successive adsorption/desorption cycles. Thus, hydrothermal treatment of CBA has potential in producing zeolites suitable to adsorption.

Pilot-scale biomass gasification system for hydrogen production from palm kernel shell (part A): steady-state simulation

Hydrogen (H2) production via biomass gasification has demonstrated to be a viable method to obtain environmental-friendly fuel. In this paper, steady-state modeling of palm kernel shell (PKS) steam gasification pilot-plant is developed and validated using experimental data. The process optimization study for the gasification of PKS utilizing the coal bottom ash as a catalyst is conducted in the continuous advanced fluidized bed technology pilot-scale gasification plant to determine the optimum conditions to produce maximum H2 and syngas composition. The optimum conditions for maximum H2 and syngas composition are a temperature of 625 °C, PKS particle size of 1–2 mm, and coal bottom ash to PKS percentage of 7.5 %. The optimum operating condition results are then validated in the pilot-scale gasification system. Steady-state simulation of the pilot scale biomass gasification plant is then developed using Aspen Plus® and validated using the experimental data.

Microstructural characteristics and carbonation resistance of coal bottom ash based concrete mixtures

The combined use of coal bottom ash (CBA) and ground CBA (GCBA) as partial replacement of fine natural aggregate (FNA) and Portland cement, respectively, was investigated for the production of concrete mixtures. Five concrete mixtures incorporating GCBA at 20 wt% replacement of binder and CBA at 0, 25, 50, 75 and 100 wt% replacement of FNA were produced and tested for strength, microstructural characteristics and carbonation resistance. A base concrete mixture made of conventional concrete was also produced as a reference concrete mixture. Test results showed that the combined use of GCBA and CBA in concrete mixtures results in enhancement of the microstructure, carbonation resistance and compressive strength of the resulting concrete mixtures. Scanning electron microscopy and X-ray diffraction analyses pointed at the occurrence of pozzolanic reaction and pore-filling effect of GCBA and CBA in the resulting concrete mixtures. It was observed that 25 wt% replacement of FNA with CBA is an optimum dosage considering its effects on the later age strength and durability characteristics of the resulting concrete mixtures.