Recycling of coal dust and fly ash as replacement of fine aggregate and cement for manufacturing of sustainable construction material

Abstract

This invention presents a sustainable concrete composition that incorporates coal dust and fly ash, two byproducts of coal production, as partial replacements for fine aggregate and cement, respectively. The objective is to reduce dependency on natural resources and address environmental issues associated with coal waste disposal. In this composition, fine aggregate is replaced by coal dust at levels of 5%, 10%, and 15%, while cement is replaced by 22% fly ash. Laboratory tests, including slump tests and compressive strength tests conducted as per IS standards, validate that this modified concrete mix achieves desirable workability and strength across various curing periods (7, 14, and 28 days). This innovation offers a cost-effective, eco-friendly solution for the construction industry, supporting waste management while conserving natural resources. The invention has the potential to address material shortages in construction, promote the efficient use of industrial byproducts, and reduce the environmental impact of concrete production.

Specification

Description:

Field of the Invention
[001] The field of this invention lies in sustainable construction materials, specifically focusing on the recycling and repurposing of industrial byproducts from coal production. Coal remains a significant energy source globally, particularly in nations with high coal reserves. This reliance on coal generates a substantial amount of waste, including coal gangue, coal dust, coal bottom ash, and fly ash, which present environmental and health challenges if not properly managed. By incorporating these coal industry byproducts as partial replacements for fine aggregate and cement in concrete manufacturing, the invention seeks to reduce reliance on natural resources, mitigate waste, and lessen the environmental footprint of both coal production and the construction sector. This approach not only supports sustainability but also enhances the performance of building materials, presenting a viable alternative to traditional resources while promoting eco-friendly construction practices.

Background of the invention and the related Prior Art
[002] The background of this invention centers on the increasing demand for sustainable construction materials, driven by environmental concerns and the depletion of natural resources. The construction industry, particularly in countries like India, faces a shortage of river sand, which is crucial for concrete production, leading to a search for alternative materials. Simultaneously, the coal industry generates vast quantities of waste, such as coal dust, coal gangue, coal bottom ash, and fly ash, which can pose severe environmental and health risks when disposed of improperly. Efforts have been made to utilize these byproducts, such as using fly ash as a cement additive, but the potential of other coal residues remains underexplored. The innovation in this area involves recycling these byproducts into concrete, replacing traditional components like fine aggregates and cement. By transforming coal waste into construction material, the invention aims to address issues of waste management, conserve natural resources, and reduce environmental impacts, all while meeting the construction industry's needs.
[003] A patent document KR101148655B1 discloses a cement mixed soil composition using fly ash and bottom ash as main component comprises cement, soil, bottom ash, and fly ash. A mixing ratio of fly ash: bottom ash: soil is 1:4:5. The cement is contained 4-10 weight% based on the total weight of the cement. The cement mixed soil composition comprises 9-9.6 weight% of fly ash, 36-38.4 weight% of bottom ash, and45-48 weight% of soil. A manufacturing method of cement mixed soil composition using fly ash and bottom ash as main component comprises the following steps: The manufacturing method of the cement mixed soil composition comprises next steps: mixing 9-9.6 weight% of fly ash, 36-38.4 weight% of bottom ash, and 45-48 weight% of soil in order to accomplish a mixing ratio of 1:4:5; and adding 4-10 weight% of cement based on total weight the cement.
[004] Another patent document KR960029277A relates to a concrete produced by mixing coal ash, crushing a bottom ash (Bottom Ash) of coal ash to less than about 25mm in diameter and mixing the pulverized coal ash with cement but with a weight ratio of cement 100: coal ash 10 ~ 800 To mix. Coal ash may be mixed with cement and supplied in dry mortar state, and coal ash and cement may be mixed with an appropriate amount of water and supplied to ready-mixed concrete. Since coal ash has many fine pores formed therein, the concrete mixed with coal ash has the effect of insulation, insulation, sound insulation, and weight reduction, and recycling coal ash, which is industrial waste, is the greatest effect.
[005] A document KR20040051459A discloses a cement admixture composition which reduces the amount of cement and production cost of secondary cement products, decreases hydration heat and prevents deterioration of early strength by using coal as main materials. The cement admixture composition is characterized by containing 84-96wt.% of coal ash with a fineness of 4000-10000cm¬2/g, wherein the coal ash is obtained by grinding and classifying coal ash, bottom ash with a size of 0.3-2.5mm and fly ash with a size of 3000-4000cm¬2/g, generated from steam power plants. The cement admixture replaces as much as 30% cement in concrete.
[006] Another document KR101271369B1 relates to a coal ash block and a manufacturing method, and more specifically, to a concrete body by mixing one type of fly ash in the fly ash (Fly ash) of coal ash, the block body having an inner space portion open to the upper side, the bottom of coal ash It is made of ash (Bottom ash), the sludge part received in the bottom of the inner space of the block body, the fly ash of the coal ash mixed with two kinds of fly ash of the concrete poured, the block to be stacked on the upper side of the sludge part The intermediate part is located in the inner space of the body, and the concrete is poured by mixing one kind of fly ash of the fly ash of coal ash, it is laminated to the upper side and comprises a stopper for sealing the inner space of the block body The inner space of the block body in which the sludge part is stored is sequentially made by the intermediate part and the stopper part. As it is sealed in the furnace is embedded in the inner space of the block body so that the sludge portion is not exposed to the outside.
According to the present invention as described above, as well as recycling one and two kinds of fly ash, it is possible to reduce the amount of concrete used, and by eliminating the conventional treatment process by embedding the bottom ash therein, the cost and time can be reduced. Of course, the environment can be improved.
[007] A patent document KR20100060928A discloses a method for manufacturing highly fluidized soil that is provided to supplement economical, environmental, and technical problems by utilizing environment-friendly solidifier, construction residual soil, and fly ash and to reduce noise and vibration.
[008] None of these above patents, however alone or in combination, disclose the present invention. The invention consists of certain novel features and a combination of parts hereinafter fully described, illustrated in the accompanying drawings, and particularly pointed out in the appended claims, it being understood that various changes in the details may be made without departing from the spirit, or sacrificing any of the advantages of the present invention.

Summary of the invention
[009] The invention provides a sustainable approach to concrete production by incorporating coal industry byproducts-specifically, coal dust and fly ash-as partial replacements for traditional fine aggregate and cement. This method addresses two major issues: managing coal waste and reducing reliance on natural resources in the construction industry. In this approach, varying percentages of coal dust (5%, 10%, and 15%) are substituted for fine aggregate, while fly ash replaces 22% of cement, forming a mix that maintains desirable properties for concrete applications. Laboratory tests, including slump and compressive strength tests, confirmed the concrete's workability and strength across curing intervals of 7, 14, and 28 days, aligning with IS standards. This innovative use of industrial byproducts not only reduces environmental hazards associated with coal waste but also supports the construction sector's need for sustainable materials, paving the way for eco-friendly practices and helping alleviate the shortage of natural construction materials.
Detailed Description of the Invention with Accompanying Drawings:
[010] For the purpose of facilitating an understanding of the invention, there is illustrated in the accompanying drawing a preferred embodiment thereof, from an inspection of which, when considered in connection with the following description, the invention, its preparation, and many of its advantages should be readily understood and appreciated.
[011] The principal object of the invention is to develop recycling of coal dust and fly ash as replacement of fine aggregate and cement for manufacturing of sustainable construction material. The invention involves the sustainable production of concrete by partially substituting fine aggregate with waste coal dust and replacing a portion of cement with fly ash, both of which are industrial byproducts from coal production. This approach aims to utilize coal dust and fly ash to produce concrete that meets necessary workability and strength criteria, while reducing environmental impact. To develop this sustainable concrete, three types of concrete specimens were prepared with varying levels of coal dust replacement for fine aggregate (5%, 10%, and 15%) and a constant 22% replacement of cement with fly ash.
[012] Laboratory testing was conducted on these concrete specimens to assess their performance. The tests included the Slump Test, to evaluate workability, and the Compressive Strength Test, to determine the strength of the concrete. The Slump Test followed IS:1199-1959 guidelines, while the Compressive Strength Test was conducted in line with IS:516-1959, using a compressive testing machine on 150 mm concrete cubes. These cubes were tested after 7 days, 14 days, and 28 days of curing.
[013] The results of these tests demonstrated that concrete with coal dust and fly ash substitutions achieved satisfactory workability and compressive strength, meeting standard performance criteria. While an increase in coal dust content led to a slight reduction in workability, this was within acceptable limits for practical applications. The findings indicate that by substituting conventional materials with waste coal dust and fly ash, it is possible to produce durable, high-performing concrete, which supports sustainable practices by reducing dependency on natural resources and managing industrial waste more effectively. This innovation opens pathways for environmentally conscious construction methods, potentially addressing material shortages and promoting the use of industrial byproducts in the construction industry.

Test Results:
Table 1: Test result data for Concrete with 5% coal dust as a replacement of fine Aggregate and 22% fly ash as a replacement of Cement

Days Compressive Strength Test Data (MPa) Slump Test Data (mm)
7 Days Compressive Strength 16.02
33
14 Days Compressive Strength 18.96
28 Days Compressive Strength 24.01

Table 2: Test result data for Concrete with 10% coal dust as a replacement of fine aggregate and 22% fly ash as a replacement of cement

Days Compressive Strength Test Data (MPa) Slump Test Data (mm)
7 Days Compressive Strength 17.30 37
14 Days Compressive Strength 20.34
28 Days Compressive Strength 25.82

Table 3: Test result data for Concrete with 15% coal dust as a replacement of fine aggregate and 22% fly ash as a replacement of cement

Days Compressive Strength Test Data (MPa) Slump Test Data (mm)
7 Days Compressive Strength 17.70 42
14 Days Compressive Strength 20.87
28 Days Compressive Strength 26.42

[014] Without further elaboration, the foregoing will so fully illustrate my invention, that others may, by applying current of future knowledge, readily adapt the same for use under various conditions of service. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention.


Advantages over the prior art
[015] Recycling of coal dust and fly ash as replacement of fine aggregate and cement for manufacturing of sustainable construction material proposed by the present invention has the following advantages over the prior art:
1. Environmental Benefits: By utilizing coal dust and fly ash, this invention helps reduce industrial waste and minimizes the environmental hazards associated with their disposal, such as air and water pollution. This promotes a cleaner, healthier environment.
2. Resource Conservation: Replacing fine aggregate and cement with coal byproducts decreases reliance on natural resources like river sand and limestone, which are finite and increasingly scarce. This conservation effort helps preserve natural landscapes and ecosystems.
3. Cost-Effective: Coal dust and fly ash are often available as low-cost or waste materials. Using them as concrete substitutes can reduce material costs in construction, making it economically viable, especially in regions with high coal production.
4. Enhanced Concrete Properties: Properly formulated, the addition of fly ash can improve the durability and longevity of concrete by enhancing resistance to chemical attacks and reducing permeability, leading to more durable infrastructure.
5. Energy Savings: By reducing the need for traditional cement production, which is energy-intensive, this invention helps lower greenhouse gas emissions associated with cement manufacturing, contributing to energy savings and a reduced carbon footprint.
6. Waste Management Solution: This method provides a productive use for coal byproducts that would otherwise require disposal, offering a practical waste management solution and helping to mitigate the risks associated with coal industry waste storage and disposal.
7. Alignment with Sustainability Goals: The use of industrial byproducts in concrete aligns with global sustainability and circular economy goals by promoting waste reuse, reducing raw material demand, and supporting environmentally friendly construction practices.
8. Potential to Address Material Shortages: With construction booms in countries like India, shortages of natural materials such as river sand are impacting the industry. This invention provides an alternative that can alleviate these shortages and ensure a steady supply of concrete materials.

[016] In the preceding specification, the invention has been described with reference to specific exemplary embodiments thereof. It will be evident that various modifications and changes may be made thereunto without departing from the broader spirit and scope of the invention as set forth in the claims that follow. The specification and drawings are accordingly to be regarded in an illustrative rather than restrictive sense. Therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of the invention. The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only and not as a limitation. The actual scope of the invention is intended to be defined in the following claims when viewed in their proper perspective based on the prior art.
, Claims:We claim:
1. Recycling of coal dust and fly ash as replacement of fine aggregate and cement for manufacturing of sustainable construction material which consists of:
- waste coal dust , fly ash;
2. A concrete mix as claimed in Claim 1, wherein fine aggregate is replaced by coal dust in the range of 5% to 15% by weight, providing desired workability and compressive strength for construction.
3. A concrete mix as claimed in Claim 1, wherein cement is replaced by fly ash at a rate of 22% by weight, enhancing the durability and reducing the carbon footprint of the concrete.
4. A method of producing sustainable concrete consists of:
- replacing 5% to 15% of fine aggregate with coal dust;
- replacing 22% of cement with fly ash, thereby creating a durable, eco-friendly concrete mix;
5. A method for assessing the compressive strength of the concrete composition as claimed in Claim 1, wherein concrete specimens are cured for 7, 14, and 28 days and tested as per IS:516-1959 standards, confirming structural performance.
6. A method of determining the workability of the concrete mix claimed in Claim 1, using the slump test per IS:1199-1959 guidelines, ensuring the optimum coal dust content for practical applications.
7. A concrete composition as claimed in Claim 1, wherein the replacement of 22% of cement with fly ash increases durability by enhancing resistance to chemical attacks and reducing permeability, suitable for long-lasting construction.
8. A method for producing cost-effective concrete by using coal dust and fly ash as partial substitutes for fine aggregate and cement, respectively, lowering material costs while providing a sustainable alternative for the construction industry.
9. The use of coal dust and fly ash in concrete manufacturing, as claimed in Claim 1, as a solution for industrial waste management, reducing disposal needs and minimizing environmental impact from coal industry byproducts.
10. A method of producing eco-friendly concrete as claimed in Claim 1, wherein the partial replacement of natural fine aggregate and cement with coal dust and fly ash reduces the environmental footprint associated with traditional concrete production.

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