Mineral processing and characterization of coal waste to be used as fine aggregates for concrete paving blocks (original) (raw)

Use of Coal Waste as Fine Aggregates in Concrete Blocks for Paving

10th International Conference on Concrete Block Paving Shanghai, Peoples Republic of China, 2012

Brazilian run-of-mine (ROM) coal contains high levels of impurities (rock minerals and pyrite). Thus, it requires concentration methods to reach the conventional Brazilians power station's standards, which require coals containing 43% of ash and 2.3% of sulphur. Approximately, 65% of the ROM material is discharged in waste deposits. It is estimated that more than 300 million tons of coal waste exists in the south of Brazil, generating AMD with the well-known environmental impacts and economic costs.

Use of Coal Waste as Fine Aggregates in Concrete Paving Blocks

The aim of this work was to study the use of coal waste to produce concrete paving blocks. The methodology considered the following steps: sampling of a coal mining waste; gravity separation of the fraction with specific gravity between 2.4 and 2.8; comminution of the material and particle size analysis; technological characterization of the material and the production of concrete paving blocks. The results showed that the coal waste considered in this work can be used to replace conventional sand as a fine aggregate for concrete paving blocks. This practice can collaborate in a cleaner coal production.

Waste from the coal extraction process as raw material for the construction industry

Ecology and the Environment, 2007

During mineral mining, huge quantities of waste are produced. This waste is usually placed in the open air, near the deposits, with the environmental consequences this situation implies. The construction industry and its auxiliaries can receive waste and by-products. As these industries handle materials on a large scale they can include an important percentage of waste in their compositions. In the present work the feasibility of utilization by the construction industry of waste originating during the coal extraction process as a raw material was studied. The materials, as received from the mine, were characterized as usual. From analysis of the results it is concluded that the waste can be used without any additives, but subject to a previous milling process in order to reduce the bigger pieces so as to prepare adequate mixtures for the compacting process. In a previous work some waste from the process was analyzed: ashes, mud and sterile material. As the stored quantity of the sterile material is noticeably higher and its characterization shows the possibility of using it to produce dense bodies, only this residue is studied in this work. The "steriles" were ground and mixtures with different particle size distribution were prepared. These powders, with 12% H 2 O and without other additives, were uniaxially pressed in order to obtain samples that were heat treated at 850°C. The samples obtained had good properties related to color, edges and surface finish. They were characterized by several techniques.

Coal bottom ash as sand replacement in concrete: A review

Construction and Building Materials, 2020

There is a need to improve the sustainability of concrete by incorporating waste by-products and at the same time controlling the use of precious river sand as well as invaluable land from becoming waste disposal area. Coal bottom ash (CBA) is one such by products that can be used as river sand substitute in concrete. The present study investigates the effects of CBA on fresh, mechanical, and durability properties of concrete as reported in literature. The chemical and physical properties of CBA are diverse from various sources and years of investigation as it is influenced by the coal combustion system. Being rich in silica, CBA has pozzolanic characteristic. Many experimental works revealed that CBA can be used in appropriate proportion to enjoy the benefits of workability, enhanced concrete strength and durability. Almost all the researchers promote the idea of turning variety of wastes to wealth to save valuable green area for better use rather than dumpsite and reduce high dependency on river sand mining supply to ensure the sustainability of green river environment for prosperity of all the nations.

Properties of concrete containing high volumes of coal bottom ash as fine aggregate

Journal of Cleaner Production, 2015

Coal fired thermal plants in India produce about 131 million tons of coal ash, which comprises about 25 million tons of coal bottom ash. Utilization of coal bottom ash has environmental advantages also which are of great importance in the present context of sustainability of natural resources. The replacement of river sand with industrial by-products such as coal bottom ash in concrete can prove both technically and economically beneficial to the construction industry. In this study, laboratory tests were conducted to assess the possibility of the use of coal bottom ash as a substitute material of river sand in concrete. River sand was substituted with coal bottom ash by mass in concrete at 0, 30, 50, 75 and 100% replacement level. The test results show that 28 d compressive strength and pulse velocity through concrete were not affected on the use of coal bottom ash in concrete. Water absorption and initial rate of absorption of water by capillary action increased on incorporation of coal bottom ash in concrete manufacturing. However, the secondary rate of absorption of water was constant for all concrete mixtures. Water absorption varied between 4.68 and 5.56% for all concrete mixtures at curing period of 28 d. With increasing age, bottom ash concrete mixtures showed significant reduction in permeable pore space and water absorption. Abrasion resistance was measured in terms of average depth of wear. Bottom ash concrete mixtures displayed marginally lesser resistance to abrasion than control concrete. All the concrete mixtures showed decrease in the average depth of wear with increasing age, in other words increase in resistance to abrasion.

Coal Mixed Waste Aggregates- An Alternate for Natural Aggregates

India is a developing country which is leading aggressively towards industrial and global development. Construction of roads with premium technology and low rates is necessary. The road and transportation sectors are one of the most valuable and important amongst all others. Although road sector is highly costly but the cost reduction can be done up to some extent without compromising the quality of the pavements. It will be of very beneficial if both quality and cost are optimized. The incorporation for utilization of waste products in road construction is increasing day-by-day to minimize the waste heaps as well as to conserve the natural resources. One of the well-known waste product which can be utilized is coal mixed waste aggregate, which is available in abundance at different thermal power plants. The coal, after mining, when supplied to thermal power plants, contains both coal and stones. The material which has less percentage of coal in the material is rejected and left out as a dump in the premises of power plants. This coal mixed aggregate can be utilized as a replacement for natural aggregates in road construction and maintenance works which will not only minimize the stock of waste material but also quarrying of natural aggregates will be minimized. Test properties indicated that Coal Mix Waste aggregates is suitable for to be use in pavement construction right from, Granular Sub-Base (GSB) and base course layer i.e. wet mix macadam(WMM) as a replacement of natural aggregate as well as in bituminous layers. Based on laboratory studies it is recommended for its use as an alternative to natural aggregate in road construction works. Utilization of this coal mixed waste aggregates will also minimize the overall cost for aggregates procurement from quarries.

Material Characterization and Optimum Usage of Coal Bottom Ash (CBA) as Sand Replacement in Concrete

International Journal of Integrated Engineering, 2020

Recently, the deficiency of natural sand is considered one of the most important thoughtful issues in the construction industry as it is one of the raw materials of concrete. The use of industrial waste by-products as an alternative material in concrete production is one solution to natural sand depletion. Therefore, the aim of this study is to investigate the properties of the concrete containing Coal Bottom Ash (CBA) produced by coal-based power plants as sand replacement material. Initially, physical, chemical, microstructural properties like specific gravity, density, sieve analysis, X-ray fluorescence and scanning electron microscopic were investigated. Then, the optimum replacement of sand with CBA was determined based on the workability, compressive and splitting tensile test. The results displayed that the physical properties of CBA are similar to sand. Moreover, CBA was classified chemically as Class-F ash. It was found that the optimum replacement dosage of CBA with sand i...

ASSESSMENT OF COAL MINE OVERBURDEN SAND FOR USE IN CONCRETE MAKING AS FINE AGGREGATE

This paper presents a study carried out to assess the suitability of sand recovered from a coal mine overburden as an alternate to river sand. The overburden consists of weathered sandstone sludge. The sand particles were recovered by washing the overburden and separating sand particles by sedimentation and decantation method. To assess the suitability of the sand for making concrete, tests as recommended in Indian standard code IS:383 -2016 were carried out. The recovered sand named CMOB sand was found suitable for making concrete. The recovered sand was fine grained having fineness modulus of 2.24 and falls in zone III. Saturated and surface dry loose and compacted bulk density was found to be 1499.44 kg/m 3 and 1696.67 kg/m 3 respectively. The specific gravity was found to be 2.6 and water absorption 1.2%. The chief constituents in CMOB sand were SiO 2 about 90.00% and Al 2 O 3 about 4.00%. No deleterious material was found beyond the limit prescribed in the IS code.

Environmental Viability for Material Developed from Coal Bottom Ash for Highways Under Construction

Revista de Ciências Ambientais, 2019

e increase of the quality of life of the contemporary Man also leads to the increase of the generation of energy. Many alternative sources of energy have been explored, but coal is still an important input, contributing around 29% of the world's energy matrix, despite environmental controversies about its use. Its burning in thermal plants generates the solid bottom ash residue, a material with little application and with potential to generate environmental damages in the places where they accumulate. e Southern Region of Brazil is a region producing coal and the bottom ash generated in its burning is not being used, generating a large environmental liability in the courtyard of the companies producing the input. e present study developed with the cited residue had as objective to defi ne a technological product for its application in the construction of highways and to fi nd a way for the economic and environmental use of the bottom ash. As the authors consider that the goal was achieved, they understand that the importance of the present study is centered in this fact. A product with 87% bottom ash, 5% fl y ash and 8% Portland cement was developed, with adequate mechanical resistance to its application on base and sub-base of road pavement, proving itself a commercial and environmentally sustainable alternative for the use of the residue. Leaching and solubilization tests indicated that the product is chemically inert according to Brazilian environmental standards.

Sustainable Solution for Industrial Waste at the Coal Mining Site

International Journal of Advanced Trends in Computer Science and Engineering, 2020

The environmental impact of the coal industry includes many issues, and one of them is waste management that affects human life crucially. This paper proposes the sustainable solution for the industrial waste at the coal mining site. As an example, this waste is produced with the amount of about 200 million cubic meter per year at the northeast area of Vietnam, where gathers a lot of coal mining site, and more importantly this makes the landfill becoming longer and higher. This waste can be manufactured and turned into aggregates used effectively for construction. The industrial sand, which is one of the products from the coal mining waste, is used for concrete production in this paper. Two types of concrete of strength class 30MPa, such as conventional concrete (need of vibration) and self-compacting concrete (lack of vibration), were considered. The industrial sand replaces totally natural sand that usually involved into concrete mix design. Different specimens of different types and sizes were prepared in order to determine compressive strength, flexural strength and elastic modulus. The experimental test showed that both of concretes achieved strength class as designed. The average compressive strength at 3 and 7 days was about 57% and 76% that at 28 days. Also, the average flexural strength is about 10% the corresponding compressive strength. Lastly, the average elastic modulus at 28 days showed the result of 25 GPa, which complies with the one prescribed in Eurocode for concrete of this type of strength class.