A PHOSPHOGYPSUM GGBS AND MICRO SILICA BASED GEOPOLYMER CONCRETE

Abstract

The invention discloses a geopolymer concrete composition utilizing phosphogypsum, ground granulated blast furnace slag (GGBS), and micro silica as sustainable alternatives to traditional cement. Phosphogypsum serves as the primary precursor (55-75%), with GGBS fixed at 20% and micro silica (5-25%) enhancing strength and reducing permeability. Activated with an alkali solution (6M-16M), the composition undergoes heat curing at 65°C for 24 hours, achieving a compressive strength of 60.88 MPa and low chloride penetration. This eco-friendly concrete is ideal for durable infrastructure applications, promoting waste utilization and reduced carbon emissions.

Specification

Description:FIELD OF THE INVENTION:
The field of the invention pertains to sustainable construction materials, specifically geopolymer concrete formulations. It involves the use of industrial by-products, including phosphogypsum, ground granulated blast furnace slag, and micro silica, to develop an eco-friendly and high-performance concrete alternative suitable for construction applications with enhanced strength and durability properties.

BACKGROUD OF THE INVENTION:
Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
Geopolymer concrete has emerged as a sustainable and eco-friendly alternative to traditional Portland cement-based concrete, which is widely known for its significant environmental impact. The production of Portland cement contributes substantially to global carbon emissions due to the energy-intensive calcination process. This environmental burden, coupled with the increasing depletion of natural resources, has driven researchers and engineers to explore alternative materials for concrete production. Geopolymer concrete, with its reliance on industrial by-products and waste materials, offers a promising solution to these challenges.
Phosphogypsum, a by-product of the phosphoric acid manufacturing process, is a major industrial waste that poses environmental and storage challenges due to its high volume of production worldwide. Phosphogypsum contains calcium and sulfate, making it a potential precursor for use in geopolymer concrete. However, its utilization in construction materials remains underexplored, particularly when combined with other industrial by-products such as ground granulated blast furnace slag (GGBS) and micro silica (MS). The potential for these materials to collectively contribute to sustainable construction practices forms the basis of this invention.
GGBS is another industrial by-product, generated during the production of iron and steel. Known for its cementitious properties and ability to enhance the mechanical and durability characteristics of concrete, GGBS has been used as a partial replacement for cement in various construction applications. The combination of GGBS with phosphogypsum in geopolymer concrete offers a synergistic effect, utilizing the strengths of both materials to produce a binder that is both effective and environmentally friendly.
Micro silica, also known as silica fume, is a by-product of the production of ferrosilicon alloys. With its fine particle size and high pozzolanic reactivity, micro silica is widely recognized for its ability to improve the performance of concrete. It enhances the compressive strength and reduces the permeability of concrete, making it more resistant to aggressive environmental conditions. The incorporation of micro silica into the geopolymer matrix not only improves mechanical performance but also addresses the durability concerns associated with chloride ion penetration, which is critical for long-term structural stability.
The alkali activation process plays a pivotal role in the development of geopolymer concrete. This process involves the use of alkaline solutions, such as sodium hydroxide or potassium hydroxide, to activate the aluminosilicate precursors in the raw materials. During this chemical reaction, a geopolymer binder is formed, which serves as a strong and durable matrix for the concrete. The invention employs a carefully optimized alkali solution, with precise molar concentrations and alkali-to-binder ratios, to achieve the desired properties in the geopolymer concrete.
The integration of phosphogypsum, GGBS, and micro silica into geopolymer concrete is innovative and offers several advantages. By replacing traditional cement with these industrial by-products, the invention significantly reduces the carbon footprint of concrete production. Additionally, the utilization of phosphogypsum addresses the environmental concerns associated with its disposal, providing a sustainable solution for managing this industrial waste. The inclusion of GGBS and micro silica further enhances the performance of the concrete, resulting in a material that is both environmentally friendly and technically superior.
In this invention, the specific combination of phosphogypsum, GGBS, and micro silica has been thoroughly studied to determine its impact on the mechanical and durability properties of geopolymer concrete. The study involves varying the replacement levels of phosphogypsum with micro silica, while keeping the GGBS content constant. Through systematic experimentation, the optimal proportions of these materials have been identified, leading to the development of a geopolymer concrete composition that achieves high compressive strength and low chloride ion permeability.
The findings of the study demonstrate that replacing 20% of phosphogypsum with micro silica yields the best results in terms of both strength and durability. The compressive strength of the concrete reaches a peak value of 60.88 MPa at this replacement level, while the rapid chloride penetration test (RCPT) values are minimized. This indicates that the concrete is highly resistant to chloride ion penetration, making it suitable for use in aggressive environments such as marine or coastal areas.
The curing process is another critical aspect of this invention. The geopolymer concrete specimens are subjected to heat curing at 65°C for 24 hours to enhance the chemical reactions and ensure the formation of a strong and stable matrix. This curing method contributes to the improved performance of the concrete, particularly in terms of its mechanical properties.
The invention has significant implications for the construction industry. The developed geopolymer concrete can be used in various applications, including pavement construction, where strength and durability are paramount. By utilizing industrial by-products, the invention aligns with the principles of sustainable development, promoting the circular economy and reducing the reliance on virgin materials. Furthermore, the enhanced resistance to chloride ion penetration ensures that the concrete structures maintain their integrity and durability over extended periods, even in harsh environments.
In conclusion, this invention represents a major advancement in the field of sustainable construction materials. By leveraging the potential of phosphogypsum, GGBS, and micro silica, the invention not only addresses the environmental challenges associated with industrial waste disposal but also offers a high-performance alternative to traditional Portland cement-based concrete. The innovative use of alkali activation and optimized material proportions ensures that the resulting geopolymer concrete meets the stringent requirements of modern construction. This invention paves the way for more sustainable and durable infrastructure, contributing to a greener and more resilient built environment.

OBJECTS OF THE INVENTION:
The prime object of the invention is to provide an eco-friendly and sustainable alternative to traditional Portland cement-based concrete by utilizing industrial by-products such as phosphogypsum, ground granulated blast furnace slag, and micro silica. This invention aims to address the environmental concerns associated with cement production, such as high carbon emissions and resource depletion, while offering a durable and high-performance material for construction applications.
Another object of the invention is to effectively utilize industrial waste materials, including phosphogypsum and GGBS, which are often considered environmental liabilities, by incorporating them into the production of geopolymer concrete. This contributes to the reduction of waste disposal issues and promotes sustainable waste management practices in industrial processes.
Yet another object of the invention is to enhance the mechanical properties of geopolymer concrete, particularly its compressive strength, through the strategic replacement of phosphogypsum with micro silica. The invention demonstrates that replacing up to 20% of phosphogypsum with micro silica significantly improves the compressive strength of the concrete, making it suitable for structural and load-bearing applications.
Still another object of the invention is to improve the durability of concrete by reducing its permeability to chloride ions, thereby enhancing its resistance to aggressive environmental conditions such as marine and coastal exposures. The reduction in rapid chloride penetration test (RCPT) values ensures the longevity and structural integrity of the developed concrete.
A further object of the invention is to optimize the alkali activation process, including the molar concentration of the alkaline solution and the alkali-to-binder ratio, to achieve a robust and chemically stable geopolymer matrix. This process ensures efficient chemical activation of the raw materials and results in a high-performance concrete composition.
An additional object of the invention is to demonstrate the feasibility of heat curing at 65°C for 24 hours as an effective method to enhance the geopolymerization process, leading to improved strength and durability properties. This curing technique accelerates the chemical reactions and ensures the development of a strong binder matrix.
Moreover, another object of the invention is to provide a concrete material that is cost-effective and resource-efficient by replacing conventional cement with readily available industrial by-products. This reduces the overall cost of concrete production while minimizing the environmental footprint of the construction industry.
Finally, an object of the invention is to offer a practical solution for infrastructure applications, such as pavements, that require materials with superior strength and durability characteristics. The invention's use of geopolymer concrete ensures that these applications benefit from enhanced performance while contributing to environmental sustainability.
SUMMARY OF THE INVENTION:
The present invention relates to a geopolymer concrete composition formulated using industrial by-products such as phosphogypsum (PG), ground granulated blast furnace slag (GGBS), and micro silica (MS). This invention provides an eco-friendly and sustainable alternative to conventional Portland cement concrete by leveraging the unique properties of these materials. Phosphogypsum serves as the primary aluminosilicate precursor, while GGBS enhances cementitious behavior, and micro silica improves pozzolanic activity and reduces permeability. The composition reduces the environmental impact of cement production and offers superior strength and durability.
The composition includes phosphogypsum at 55-75% of the binder content, which acts as the principal material for the geopolymerization process. Ground granulated blast furnace slag is fixed at 20% of the binder content, contributing significantly to the mechanical and durability characteristics of the geopolymer concrete. Micro silica, with its fine particle size and high pozzolanic reactivity, is included at 5-25% of the binder content, replacing phosphogypsum in varying proportions. The alkali solution, primarily sodium hydroxide, is prepared with molar concentrations ranging from 6M to 16M, with an alkali-to-binder ratio fixed at 0.4. Fine and coarse aggregates are also proportionally incorporated to ensure desired workability and strength. Heat curing at 65°C for 24 hours is employed to enhance the geopolymerization process and strengthen the concrete matrix.
An inventive aspect of the invention is to provide a sustainable and innovative use for phosphogypsum, a commonly discarded industrial by-product, as a primary binder material in the production of geopolymer concrete. By utilizing phosphogypsum, the invention addresses both the environmental burden of waste disposal and the reduction of carbon emissions associated with traditional cement.
Another inventive aspect of the invention is the integration of ground granulated blast furnace slag, which significantly improves the mechanical properties and durability of the concrete. The inclusion of GGBS ensures a robust matrix, contributing to the long-term performance and stability of the geopolymer concrete. This utilization further emphasizes the eco-friendly nature of the invention by repurposing another industrial by-product.
Yet another inventive aspect of the invention is the partial replacement of phosphogypsum with micro silica, demonstrating that replacing up to 20% of phosphogypsum with micro silica results in optimal performance. This replacement enhances compressive strength, achieving a maximum value of 60.88 MPa, and significantly reduces the rapid chloride penetration test values, ensuring resistance to chloride ion ingress and enhancing durability, especially in aggressive environments.
Still another inventive aspect of the invention is the optimization of the alkali activation process. The carefully controlled alkali-to-binder ratio of 0.4 and sodium hydroxide molarity ranging from 6M to 16M ensures efficient activation of the aluminosilicate materials. This results in a chemically stable geopolymer matrix, enhancing the structural integrity and overall performance of the concrete.
A further inventive aspect of the invention is the incorporation of heat curing at 65°C for 24 hours, which accelerates the geopolymerization process and significantly enhances the mechanical and chemical properties of the concrete. This curing technique ensures the formation of a strong and durable binder matrix within a short time frame, making the process efficient and effective.
Moreover, an inventive aspect of the invention is the reduction of chloride ion permeability with increasing micro silica content. The invention demonstrates that as micro silica content increases, the rapid chloride penetration test values decrease, improving the concrete's resistance to chloride ingress. This feature makes the geopolymer concrete ideal for applications in marine or coastal environments, where resistance to aggressive ions is critical.
An additional inventive aspect of the invention is the cost-effectiveness and resource efficiency of the composition. By replacing conventional cement with phosphogypsum, GGBS, and micro silica, the overall production costs are reduced while simultaneously addressing environmental concerns. This dual benefit of cost reduction and environmental sustainability highlights the practical value of the invention.
Finally, an inventive aspect of the invention is the development of a high-performance concrete composition suitable for infrastructure applications such as pavements. The composition offers superior strength and durability, meeting the rigorous demands of modern construction while maintaining a low environmental footprint. The innovative use of industrial by-products ensures that the invention contributes significantly to sustainable development in the construction industry.

BRIEF DESCRIPTION OF DRAWINGS:
The accompanying drawing illustrates an embodiment of "A Phosphogypsum GGBS and Micro Silica Based Geopolymer Concrete," highlighting key aspects of its composition and preparation. This figure is intended for illustrative purposes to aid in understanding the invention and is not meant to limit its scope.
FIG. 1 depicts a block diagram of the geopolymer concrete composition, showing the integration of phosphogypsum, ground granulated blast furnace slag, micro silica, alkali solution, and aggregates, according to an embodiment of the present invention.
The drawing provided will be further described in detail in the following sections. It offers a visual representation of the composition and preparation methodology of the geopolymer concrete, helping to clarify and support the detailed description of the invention.

DETAILED DESCRIPTION OF THE INVENTION:
In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that the embodiments may be combined, or that other embodiments may be utilized and that structural and logical changes may be made without departing from the spirit and scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims and their equivalents.
The present invention is described in brief with reference to the accompanying drawings. Now, refer in more detail to the exemplary drawings for the purposes of illustrating non-limiting embodiments of the present invention.
As used herein, the term "comprising" and its derivatives including "comprises" and "comprise" include each of the stated integers or elements but does not exclude the inclusion of one or more further integers or elements.
As used herein, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. For example, reference to "a device" encompasses a single device as well as two or more devices, and the like.
As used herein, the terms "for example", "like", "such as", or "including" are meant to introduce examples that further clarify more general subject matter. Unless otherwise specified, these examples are provided only as an aid for understanding the applications illustrated in the present disclosure, and are not meant to be limiting in any fashion.
As used herein, the terms ""may", "can", "could", or "might" be included or have a characteristic, that particular component or feature is not required to be included or have the characteristic.
Exemplary embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments are shown. These exemplary embodiments are provided only for illustrative purposes and so that this disclosure will be thorough and complete and will fully convey the scope of the invention to those of ordinary skill in the art. The invention disclosed may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.
Various modifications will be readily apparent to persons skilled in the art. The general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the invention. Moreover, all statements herein reciting embodiments of the invention, as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents as well as equivalents developed in the future (i.e., any elements developed that perform the same function, regardless of structure). Also, the terminology and phraseology used is for the purpose of describing exemplary embodiments and should not be considered limiting. Thus, the present invention is to be accorded the widest scope encompassing numerous alternatives, modifications and equivalents consistent with the principles and features disclosed. For purpose of clarity, details relating to technical material that is known in the technical fields related to the invention have not been described in detail so as not to unnecessarily obscure the present invention.
Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references below to the "invention" may in some cases refer to certain specific embodiments only. In other cases, it will be recognized that references to the "invention" will refer to subject matter recited in one or more, but not necessarily all, of the claims.
All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., "such as") provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.
Various terms as used herein are shown below. To the extent a term used in a claim is not defined below, it should be given the broadest definition and persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing.
Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all groups used in the appended claims.
With reference to FIG. 1, in an embodiment of the present invention, the invention pertains to a geopolymer concrete composition that incorporates industrial by-products, including phosphogypsum, ground granulated blast furnace slag, and micro silica, as key components. This innovative composition provides a sustainable alternative to conventional Portland cement concrete while offering superior mechanical properties and durability. Phosphogypsum serves as the primary aluminosilicate precursor, making up 55-75% of the binder content. Its role is central to the geopolymerization process, as it undergoes chemical activation through an alkali solution to form a stable and robust binder matrix. By utilizing phosphogypsum, a waste material generated in large quantities during phosphoric acid production, the composition addresses both environmental and resource efficiency concerns.
Ground granulated blast furnace slag is incorporated into the composition at a fixed 20% of the binder content. This material, a by-product of iron and steel production, contributes significantly to the mechanical and durability characteristics of the concrete. Its cementitious properties enhance the structural integrity of the final product, ensuring long-term performance in demanding applications. The combination of phosphogypsum and GGBS creates a synergistic effect, leveraging their complementary properties to produce a high-performance binder.
Micro silica is included at 5-25% of the binder content, replacing a portion of phosphogypsum. This replacement is critical for enhancing the compressive strength and reducing the permeability of the concrete. Micro silica, also known as silica fume, is a fine material with high pozzolanic reactivity, which reacts with calcium hydroxide to form additional calcium silicate hydrate (C-S-H) gel. This reaction improves the density and strength of the concrete while reducing its porosity. The invention demonstrates that replacing 20% of phosphogypsum with micro silica results in optimal performance, achieving a compressive strength of 60.88 MPa and significantly lowering rapid chloride penetration test values.
The alkali solution used in the composition is a critical component for activating the aluminosilicate precursors. Sodium hydroxide is employed at molar concentrations ranging from 6M to 16M, with an alkali-to-binder ratio fixed at 0.4. The preparation of the alkali solution 24 hours prior to mixing ensures optimal activation of the precursors, promoting efficient geopolymerization. This process results in the formation of a chemically stable and durable geopolymer matrix, capable of withstanding mechanical stresses and environmental degradation.
Fine and coarse aggregates are proportionally adjusted in the composition to achieve the desired workability and mechanical properties. These aggregates play a vital role in determining the final properties of the concrete, including its strength, durability, and overall performance. The careful selection and proportioning of aggregates ensure that the geopolymer concrete meets the specific requirements of various construction applications.
The invention also emphasizes the importance of the curing process in achieving superior properties. The concrete is subjected to heat curing at 65°C for 24 hours, which accelerates the geopolymerization process and enhances the mechanical and chemical properties of the material. This curing method ensures the formation of a strong and durable binder matrix within a relatively short time frame, making the process efficient and suitable for practical applications.
One of the key advantages of the invention is its ability to reduce rapid chloride penetration test values with increasing micro silica content. This reduction in permeability is critical for enhancing the durability of the concrete, particularly in aggressive environments such as marine or coastal conditions. The decreased chloride ion ingress protects the steel reinforcement in the concrete from corrosion, ensuring the longevity of the structure.
The optimized composition of phosphogypsum, ground granulated blast furnace slag, and micro silica offers a cost-effective and environmentally friendly alternative to traditional Portland cement. By replacing cement with these industrial by-products, the composition significantly reduces carbon emissions and addresses the environmental challenges associated with the disposal of phosphogypsum and other waste materials. This dual benefit of environmental sustainability and cost efficiency makes the composition highly advantageous for modern construction practices.
The method for preparing the geopolymer concrete involves several well-defined steps to ensure optimal performance. The process begins with the preparation of an alkali solution using sodium hydroxide at the specified molar concentration, which is stored for 24 hours prior to mixing. The binder materials, including phosphogypsum, ground granulated blast furnace slag, and micro silica, are mixed in the specified proportions. Fine and coarse aggregates are then added, followed by thorough mixing with the alkali solution to form a homogeneous mixture.
The prepared mixture is poured into molds and subjected to heat curing at 65°C for 24 hours. This curing step accelerates the chemical reactions within the mixture, resulting in a strong and durable geopolymer matrix. The method is efficient and ensures consistent results, making it suitable for large-scale production.
The invention is particularly well-suited for pavement construction due to its superior strength and durability characteristics. The high compressive strength and low permeability of the geopolymer concrete make it ideal for applications requiring long-term performance and resistance to environmental degradation. Additionally, the use of industrial by-products in the composition aligns with sustainable construction practices, promoting the circular economy and reducing reliance on virgin materials.
The use of phosphogypsum, ground granulated blast furnace slag, and micro silica in the geopolymer concrete composition not only addresses environmental concerns but also offers technical advantages. Phosphogypsum provides a readily available and cost-effective source of aluminosilicate material, while ground granulated blast furnace slag enhances the mechanical properties of the concrete. Micro silica, with its high pozzolanic activity, improves the density and durability of the material, making it suitable for a wide range of applications.
The invention demonstrates that the replacement of 20% phosphogypsum with micro silica results in the highest compressive strength and the lowest rapid chloride penetration test values. This finding highlights the importance of optimizing the proportions of the components to achieve the desired performance. The careful selection and proportioning of the ingredients ensure that the geopolymer concrete meets the stringent requirements of modern construction.
The innovative use of industrial by-products in the composition also contributes to the reduction of waste and the conservation of natural resources. By repurposing materials that would otherwise be discarded, the invention aligns with the principles of sustainable development and promotes environmentally responsible construction practices. The composition offers a practical solution to the challenges of waste management and resource conservation, making it a valuable contribution to the field of construction materials.
The geopolymer concrete composition provides a durable and high-performance material for a variety of construction applications. Its superior mechanical properties, enhanced durability, and environmentally friendly nature make it an ideal choice for infrastructure projects, particularly in aggressive environments. The invention represents a significant advancement in the field of sustainable construction materials, offering a viable alternative to traditional Portland cement concrete.

The working of the invention revolves around the careful formulation, preparation, and curing of a geopolymer concrete composition that leverages industrial by-products such as phosphogypsum, ground granulated blast furnace slag, and micro silica. The invention's functionality is derived from the chemical and physical interactions of these components, activated by an alkali solution, to form a robust and durable binder matrix.
The process begins with the preparation of the alkali solution, primarily consisting of sodium hydroxide (NaOH), with a molar concentration ranging from 6M to 16M. The alkali solution plays a crucial role in activating the aluminosilicate precursors present in phosphogypsum, ground granulated blast furnace slag, and micro silica. To ensure optimal activation, the alkali solution is prepared 24 hours in advance, allowing it to stabilize before use.
Phosphogypsum serves as the primary aluminosilicate precursor in the composition, constituting 55-75% of the binder content. This material reacts with the alkali solution during the mixing process to form a geopolymer gel, which acts as the binding matrix in the concrete. The addition of ground granulated blast furnace slag, fixed at 20% of the binder content, further enhances the mechanical properties and durability of the binder matrix due to its cementitious nature.
Micro silica, added in varying proportions of 5-25% by replacing a portion of phosphogypsum, improves the compressive strength and reduces the permeability of the concrete. Micro silica reacts with the calcium hydroxide formed during the geopolymerization process to produce additional calcium silicate hydrate (C-S-H) gel, which fills the voids within the matrix, improving its density and strength. The optimized replacement of 20% phosphogypsum with micro silica yields the best results, achieving a compressive strength of 60.88 MPa and significantly reducing rapid chloride penetration test (RCPT) values.
The prepared alkali solution is combined with the binder components (phosphogypsum, ground granulated blast furnace slag, and micro silica) in specified proportions. This mixture is then thoroughly mixed with fine and coarse aggregates to achieve a homogeneous consistency. The aggregates provide structural stability and workability, ensuring that the final concrete mixture can be easily handled and molded into the desired shapes.
Once the mixing process is complete, the geopolymer concrete mixture is poured into molds for casting. The molds are then subjected to heat curing at a controlled temperature of 65°C for a duration of 24 hours. This curing process accelerates the geopolymerization reactions, facilitating the formation of a chemically stable and durable matrix. Heat curing also enhances the mechanical properties of the concrete, ensuring its suitability for demanding applications.
The geopolymer concrete exhibits exceptional resistance to chloride ion ingress, as demonstrated by its low RCPT values. This property is particularly beneficial for applications in aggressive environments, such as marine or coastal areas, where concrete structures are exposed to corrosive elements. The dense matrix formed by the geopolymer gel and additional C-S-H gel provides excellent protection against permeability and corrosion, ensuring the longevity of the material.
The final product is a high-performance geopolymer concrete with superior compressive strength, enhanced durability, and reduced environmental impact. The composition's reliance on industrial by-products such as phosphogypsum, ground granulated blast furnace slag, and micro silica not only addresses waste management challenges but also reduces the carbon footprint associated with traditional Portland cement production.
In practical applications, the geopolymer concrete is particularly suitable for use in infrastructure projects, such as pavements, where strength, durability, and resistance to environmental degradation are critical. The material's ability to withstand aggressive conditions and maintain structural integrity over time makes it an ideal choice for modern construction practices. The working of the invention demonstrates the potential of geopolymer technology to revolutionize the construction industry by offering a sustainable and high-performance alternative to conventional concrete.

ADVANTAGES OF THE INVENTION:
The prime advantage of the invention is to provide an eco-friendly alternative to Portland cement-based concrete, significantly reducing carbon emissions and promoting the use of industrial by-products, which addresses environmental and sustainability challenges effectively.
Another advantage of the invention is its ability to utilize phosphogypsum, a widely available industrial waste, as a primary aluminosilicate precursor, thereby reducing the burden of waste disposal and encouraging circular economy practices.
Yet another advantage of the invention is the incorporation of ground granulated blast furnace slag, which enhances the mechanical and durability properties of the geopolymer concrete, ensuring long-term structural stability in various applications.
Still another advantage of the invention is the inclusion of micro silica, which improves compressive strength and reduces chloride ion permeability, making the concrete highly resistant to aggressive environments such as marine or coastal conditions.
A further advantage of the invention is its optimized alkali activation process, which ensures efficient chemical reactions, resulting in a chemically stable geopolymer matrix with superior strength and durability characteristics.
Moreover, another advantage of the invention is its heat curing process at 65°C for 24 hours, which accelerates geopolymerization and enhances the overall mechanical performance of the concrete within a short timeframe.
Additionally, an advantage of the invention is its cost-effectiveness, as it replaces expensive Portland cement with readily available industrial by-products, lowering production costs while maintaining high-quality performance in construction applications.
Finally, the invention offers the advantage of providing a durable and high-strength material suitable for infrastructure projects such as pavements, ensuring resilience and extended service life in demanding conditions.
, Claims:CLAIM(S):
We Claim:
1. A geopolymer concrete composition, comprising:
a. Phosphogypsum (PG) as the primary aluminosilicate precursor, constituting 55-75% of the binder content;
b. Ground granulated blast furnace slag (GGBS) fixed at 20% of the binder content to enhance mechanical and durability properties;
c. Micro silica (MS) included at 5-25% of the binder content, replacing a portion of PG to improve compressive strength and reduce permeability;
d. An alkali solution prepared with sodium hydroxide (NaOH) at molar concentrations ranging from 6M to 16M, with an alkali-to-binder ratio fixed at 0.4;
e. Fine and coarse aggregates proportionally adjusted to achieve the desired workability and mechanical properties.
2. The geopolymer concrete composition of claim 1, wherein the replacement of 20% PG with micro silica achieves a compressive strength of 60.88 MPa and reduces rapid chloride penetration test (RCPT) values, enhancing resistance to chloride ion ingress.
3. The geopolymer concrete composition of claim 1, wherein the alkali solution is prepared 24 hours before mixing to ensure optimal activation of the aluminosilicate precursors.
4. The geopolymer concrete composition of claim 1, further comprising heat curing of the concrete at 65°C for 24 hours to accelerate geopolymerization and enhance the mechanical and chemical properties of the concrete.
5. The geopolymer concrete composition of claim 1, wherein the reduction in RCPT values with increasing micro silica content improves the concrete's durability in aggressive environments such as marine or coastal conditions.
6. The geopolymer concrete composition of claim 1, wherein the optimized composition of PG, GGBS, and MS provides a cost-effective and environmentally friendly alternative to traditional Portland cement.
7. A method for preparing geopolymer concrete, comprising:
a. Preparing an alkali solution with sodium hydroxide at a molar concentration of 6M to 16M, stored for 24 hours;
b. Mixing PG, GGBS, and MS at specified proportions (55-75% PG, 20% GGBS, and 5-25% MS);
c. Adding fine and coarse aggregates to the mixture, followed by thorough mixing with the alkali solution;
d. Pouring the mixture into molds and subjecting it to heat curing at 65°C for 24 hours.
8. The method of claim 7, wherein the replacement of 20% PG with micro silica results in the highest compressive strength and lowest RCPT values.
9. The geopolymer concrete composition of claim 1, wherein the composition is used for pavement construction due to its superior strength and durability characteristics.
10. The geopolymer concrete composition of claim 1, wherein the use of industrial by-products such as phosphogypsum, GGBS, and micro silica promotes sustainable construction practices by reducing carbon emissions and waste disposal issues.

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