Performance of OPC blended concretes incorporating 25% GGBS and 15% fly ash: hydration, strength, and durability

Building materials are the main products made of coal gangue and coal fly ash. Most of these products contain various heavy metals such as Pb, Cd, Cr, Hg, which are needed to measure in the purpose of safe using and environment protection. In our work, we established a set of method to pre-treat the products by microwave digestion technique and measure the concentration of heavy metals by atomic absorption spectrophotometer. And we measured three products from Shuozhou City, Shanxi Province and found that the content of one or two kinds of heavy metals are high, which should be paid great attention in its application for their high environmental risks.

This research focuses on the chemical properties of coal fly ash (CFA) and coal bottom ash (CBA) obtained from Sultan Azlan Shah Power Plant and compares them with the characteristics of ordinary Portland cement (OPC). Coal has been recognised as a significant fuel source in Malaysia, where it is extensively employed in the creation of steel, cement, and power. When coal is burned to create power, several different types of coal ash are created, including fly ash, bottom ash, boiler slag, and clinker. Fly and bottom ash, however, are the main coal ash waste products that have been created. In an effort to create sustainable concrete from waste, a number of studies have been carried out to ascertain the chemical characteristics of fly and bottom ash. These tests include Energy Disperse X-Ray (EDX), Mineralogy (XRD), and X-Ray Fluorescence (XRF). From the SEM result, fly ash has smaller particles and a spherical, uniform shape than bottom ash and cement. Fly and bottom ash from the Sultan Azlan Shah power plant contain a number of elements, including Silicon (Si), Aluminium (Al), Oxygen (O), Calcium (Ca), Titanium (Ti), Iron (Fe), Magnesium (Mg), Potassium (K), Carbon (C), and Sodium, according to Energy Dispersive X-Ray (EDX) test. The fly ash is primarily an amorphous material, with the presence of quartz crystalline phase (SiO2) at 24.3% and bottom ash at 31.1%, according to X-ray Diffraction (XRD) data. For the mullite phase (3AlO3.2SiO2), fly and bottom ash show results of 24.9% and 14.5%, respectively. According to an X-ray fluorescence (XRF) investigation, the main constituents of fly and bottom ash are silica, iron, and alumina. Fly ash is classified as Class F because it has a high concentration of SiO2, Al2O3, and Fe2O3 while OPC has a high CaO value. With the right composition and material preparation, CFA and CBA from the Sultan Azlan Shah Power Plant can be used as a cement replacement in concrete.

Mass fractions, solubility, speciation and isotopic compositions of iron in coal and municipal waste fly ash.

Design of slurry transportation pipeline for the flow of muti-particulate coal ash suspension

Thermal power plants (TPP) generates wastes (bottom and fly ashes) which become a serious environmental problem in Vietnam. Indeed, although in several countries fly ash can be used for cement industry, fly ash from actual TPP in Vietnam does not have enough good quality for cement production, because the fly ash treatment phase has not yet included in the generations of existing Vietnamese TPP. That is why bottom ash and fly ash purely become wastes and their evacuation is an urgent demand of the society. This paper presents an investigation using fly and bottom ashes in the manufacturing of construction materials. The aim of this study is to propose a possibility to reduce environmental impacts of fly and bottom ashes, and manufacture construction materials having low embodied energy by using less cement. Several proportions of fly ash, cement, gravel, sand and water are tried to manufacture low strength concretes which can be used for non-load-bearing walls. Specimens are tested in uniaxial compressions. Results show that with a reasonable cement amount (4–8% by weight), by replacing cement by fly ash or replacing sand by bottom ash at 10-30%, the obtained materials can be used for non-bearing materials or low strength structural materials.

Thermal power plants (TPP) generates wastes (bottom and fly ashes) which become a serious environmental problem in Vietnam. Indeed, although in several countries fly ash can be used for cement industry, fly ash from actual TPP in Vietnam does not have enough good quality for cement production, because the fly ash treatment phase has not yet included in the generations of existing Vietnamese TPP. That is why bottom ash and fly ash purely become wastes and their evacuation is an urgent demand of the society. This paper presents an investigation using fly and bottom ashes in the manufacturing of construction materials. The main aims of this study is to reduce environmental impacts of fly and bottom ashes, and to test another non-conventional binder to replace cement in the manufacture of unburnt bricks. Several proportions of fly ash, bottom ash, cement, gravel, sand and water were tested to manufacture concretes. Then, geopolymer was prepared from the fly ash and an activator. Specimens were tested in uniaxial compressions. Results showed that the cement concrete tested had the compressive strengths which could be used for low rise constructions and the material using geopolymer could be used for non-load-bearing materials (unburnt bricks).

To provide a steam electric station with information regarding the chemical nature of leachate from a proposed dry fly and bottom ash disposal site, accelerated laboratory testing of ash leachability and contaminant adsorption in the site soils was performed. These tests involved sequential batchwise extractions of various combinations of new alkaline and acidic fly ash, aged fly ash, bottom ash, and site soil to simulate leachate from the disposal site. The testing procedure, originally developed by Houle and Long at the Dugway Proving Ground, Dugway, Utah, has been shown to closely simulate leached columns, with the advantage of requiring less time and effort than column tests. These tests allowed the simulation of years of field leaching in a period of several weeks. Three different combinations or scenarios of fly and bottom ash and site soil were chosen for accelerated testing. These scenarios represent variations of potential site conditions. Scenario 1 consists of a combination of new alkaline and acidic fly ash obtained from the precipitator outlet hoppers challenging three layers of site soil. This scenario represents the interaction of a worst-case ash (that is, highest trace metal content) in direct contact with site soil. Scenario 2 consists of the same fly ash combination used to challenge a layer of aged fly ash and then bottom ash. Scenario 3 involves a new composite acidic fly ash layer challenging a layer of aged fly ash and then bottom ash. Scenarios 2 and 3 both yielded a leachate which could be expected from the disposal site given a condition of saturation. Scenario 3 was considered to be an absolute worst-case in that acidic leachate from the ash would cause the maximum solubility of heavy metals. The test procedure involved eight extractions of each ash or soil layer. The ratios of ash to water and soil to water were graded by size to accelerate testing, that is, the volume of each extraction after the second was doubled. Each extraction mixture was slowly agitated with a paddle for a predetermined time period. Conductivity and pH were monitored at intervals throughout the period. At the end of the extraction period, the mixture was filtered in a vacuum. An aliquot of the filtrate was then filtered through a 0.5 Millipore filter and preserved for metals analysis. The filter cake was transferred back to the beaker and mixed with the required volume of water for the next extraction. The test results agreed closely with the types of results expected from saturated column tests, and considering the fine-grained, low permeability of the fly and bottom ash and site soil, took significantly less time. As such, the accelerated testing method provides a good approach to modeling the actual environmental effects of materials disposal. The site soil showed a potential for adsorbing arsenic and selenium from the ash layers, and then desorbing or releasing these metals into solution. The site soil also demonstrated the capacity for complete removal of aluminum, boron, total chromium, iron, and zinc from solution.

A retrofit of the San Francisco Oakland Bay Bridge involves more than 30 different concrete mixes, each of which confers specific advantages.For instance, according to the U.S. EPA, concrete containing more than 50% fly ash resists the cracking and corrosion associated with seawater.

Effect of adding coal ashes and oxide mixtures on CO2 gasification reactivity of petcoke at high temperature

Strength properties and micro-structural properties of concrete containing coal bottom ash as partial replacement of fine aggregate

A review of rare earth elements and yttrium in coal ash: Content, modes of occurrences, combustion behavior, and extraction methods

Fly ash can include toxins from high levels of bottom ash in some circumstances, such as burning of solid waste to generate power (resource recovery facilities or waste-to-energy conversion), and combining fly ash and bottom ash together delivers corresponding quantities of contaminants. Under some conditions, fly ash can be classified as non-hazardous waste, but if it is not blended, it can be classified as hazardous waste. The goal of this research was to find out about the differences between fly and bottom ash, as well as the influence of fly ash on bottom ash in terms of avoiding abrasion. In addition, the study's goal was to see how fly ash affected coconut fiber's resistance to abrasion. This study employed a quantitative technique in which the researcher used primary data sources such as questionnaires and observations, as well as secondary data sources such as prior studies. The findings revealed that fly ash had no effect on bottom ash in terms of avoiding abrasion. Furthermore, it is well known that neither fly ash nor bottom ash are effective against coconut fiber. Fly ash has a coarser texture than bottom ash, according to the findings. The regression test revealed that there was no difference between fly ash and bottom ash, as well as coconut coir, in terms of reducing abrasion

Chemical and petrographical characterization of feed coal, fly ash and bottom ash from the Figueira Power Plant, Paraná, Brazil

At presently there are five operating power plants in the central energy system of Mongolia which generate both heat and electricity. Together these burn about 5-6 million tonnes of coal resulting in more than 600,000 tonnes of coal combustion by-products per year. Three thermal power plants are located in Ulaanbaatar city and produce more than 80% of the total electricity in Mongolia. Within these plants, the 4th thermal power plant generates around 300,000 tonnes of fly and bottom ash and the 3rd thermal power plant around 100,000 tonnes of bottom ash. The thermal power plants in Ulaanbaatar city use coal from the Baganuur and Shivee-ovoo deposits. The chemical composition of these fly ashes indicate they belong to class C fly ashes. The physical and chemical characteristics of fly ash and boiler slags determine the how to make of use them. The physical properties of these residues will be determined by the technology, design and operational conditions of the power stations. The chemical composition of the fly ash and slags depends completely on the inorganic matter within the source coal deposits and the composition of the slags and fly ashes cannot be controlled. Comprehensive characterization of coal combustion by products were performed using XRD, XRF, SEM and gamma-spectroscopy methods. A novel geopolymer type binder was prepared using Baganuur and Shivee ovoo fly ashes from the 4th Thermal power plant. Sodium hydroxide solutions with a different molarity were used as the activating solutions. It was found that an alkali concentration increase resulted in an increase in the compressive strength of the geopolymer paste. Compressive strengths of greater than 20 MPa was achieved with Shivee ovoo fly ash based geopolymer while with Baganuur fly ash it was more than 30 MPa.

In present condition to full-fill the demand of sustainable construction, concrete made with different materials is the best choice for the construction industry. Generally, we use materials which are required for conventional concrete and addition to those we replace the low-cost materials such as bottom ash in this project we replace the coal bottom ash & quarry dust to the fine aggregate by variable percentages. Coal bottom ash is the by-product of coal combustion. The rock detritus filled in the fishers of coal become separator from the coal during pulverization. In the furnace, carbon, other combustible matter burns, & the non-combustible matter result in coal ash. The coal ash collector from the electro static precipitators is called fly ash. coal bottom ash constitutes about 20% of coal ash and the result is fly ash. The perfect substitute for reverse sand is quarry dust it is the one of the ingredients in manufacture of concrete the crusher dust is known as quarry dust can be used as alternative material to the river sand. quarry dust possesses similar properties as that of river sand, hence accepted as a building material. The aggregate replaced with concrete in various percentages as both BA and QD (10%,20%&30%). All replacements where done to the m30 grade of concrete. the concrete has been replaced by coal bottom ash accordingly to the percentage, and fine aggregate has been replaced by quarry dust in percentage. concrete mixtures where produced, tested & compared in terms of compressive strength, tensile, flexural strength are evaluated. The curing of cubes, cylinders, & beams is 7days 28days & 90days.