Description:FIELD OF THE INVENTION
The present invention pertains to the field of construction, specifically detailing the composition and method of preparation for geopolymer bricks.

BACKGROUND OF THE INVENTION
The rapid pace of industrialization and population growth has significantly strained natural resources, leading to severe environmental challenges such as air and water pollution, soil degradation, and increased waste generation. Industries produce massive amounts of waste, often in hazardous forms, which pose risks to ecosystems and human health. For example:
• Water Pollution: Effluents containing chemicals and untreated waste contaminate water bodies, harming aquatic ecosystems and reducing water quality. Polluted water used for irrigation can degrade soil fertility.
• Soil Contamination: Industrial waste, including heavy metals and toxic chemicals, pollutes soil, affecting its productivity and contributing to environmental imbalance.
The construction industry, as a significant contributor to CO₂ emissions and a major consumer of natural resources, represents a critical area for implementing sustainable practices. The pressing need to mitigate environmental harm and promote circular economy principles has led to innovative research into the use of industrial by-products as alternative materials in construction.
OBJECTS OF THE INVENTION
The primary objective of the present invention is to provide a geopolymer mix composition comprising of red mud, metakaolin, manufactured sand and GGBS along with chemical activators
It is another objective of the present invention to provide a greener solution by providing a geopolymer brick mix composition using by-products.

SUMMARY OF THE INVENTION
The present invention presents a red mud-based geopolymer brick composition designed to enhance sustainability in construction materials. The solid component mix consists of red mud (40-60% w/w), metakaolin (5-15% w/w), manufactured sand (20-25% w/w), and ground granulated blast furnace slag(GGBS)(10-15% w/w). Complementing this, the liquid component involves an alkaline activator solution (25-30% w/w), formulated from a 2M NaOH and Na2SiO3 mix in a 1:2.5 ratio. This alkaline activator serves as a chemical catalyst.

The present invention also discusses the method of preparation of the brick composition comprising steps of mixing of these solid components with a liquid alkaline activator solution, consisting of 2M NaOH and Na2SiO3 in a 1:2.5 ratio, in proportions of 25-30% w/w. This composite mix is cast into molds, followed by demolding, sun drying, and hydration for a minimum of 24 hours. The resultant geopolymer brick demonstrates desirable properties, achieving a compressive strength of at least 14.1 MPa and exhibiting a water absorption rate of 9.15%.

BRIEF DESCRIPTION OF THE FIGURES
Fig.1 shows the Couplet test conducting machine.
Fig.2 illustrates the plan for the Couplet test specimen.
Fig.3 displays the prepared Couplet test specimen.
Fig.4 illustrates the loading of the Triplet specimen. Fig.5 shows the failure pattern after testing by UTM

DETAILED DESCRIPTION OF THE INVENTION
The principles of operation, design configurations, and evaluation values presented herein serve only as illustrative examples of the invention and are not intended to limit its scope. The subsequent detailed descriptions, accompanied by marked references to the drawings, elucidate the various embodiments of the invention, highlighting their essential components. It is imperative to recognize that these embodiments may assume diverse forms and should not be construed as exhaustive or restrictive. The forthcoming sections aim to furnish a comprehensive understanding of the disclosed invention, thereby clarifying its scope for individuals skilled in the relevant field.

The present invention pertains to the advancement of non-conventional composite construction materials, specifically addressing the dual challenge of effectively utilizing industrial by-products while simultaneously mitigating waste disposal issues. This exploration centres on the incorporation of red mud, combined with a substantial array of mineral admixtures, into the formulation of Geopolymer composites. The objective is to fabricate a geopolymer binder and masonry blocks utilizing various combinations of red mud and mineral additives, augmented by specific chemical agents. Furthermore, the methodology for producing the geopolymer mix is meticulously detailed to ensure the resultant bricks meet established quality standards.

This invention presents a red mud-based geopolymer brick composition designed to enhance sustainability in construction materials. The solid component mix consists of red mud (40-60% w/w), metakaolin (5-15% w/w), manufactured sand (20-25% w/w), and ground granulated blast furnace slag (10-15% w/w). Complementing this, the liquid component involves an alkaline activator solution (25-30% w/w), formulated from a 2M NaOH and Na2SiO3 mix in a 1:2.5 ratio. This alkaline activator serves as a chemical catalyst.

The present invention also discusses the method of preparation of the brick composition comprising steps of mixing these solid components with a liquid alkaline activator solution, consisting of 2M NaOH and Na2SiO3 in a 1:2.5 ratio, in proportions of 25-30% with respect to the total mass of the solid mix components. This composite mix is cast into molds, followed by demolding, sun drying, and hydration for a minimum of 24 hours. The resultant geopolymer brick demonstrates desirable properties, achieving a compressive strength of at least 14.1 MPa and exhibiting a water absorption rate of 9.15%.
The different components of the Geopolymer mix discussed and method of preparation of the same is discussed in detail as below:

COMPONENTS OF THE GEOPOLYMER MIX:
The unique blend of geopolymer mix discussed in the 30 present invention include predominantly two components
when mixed can be moulded into bricks and then demoulded, sundried and hydrated before being used.
I. Solid component:
Different solid components in the mix include:

Red Mud: It is a by-product of Bayer’s process, which is obtained from the production of alumina from bauxite ore. 10 Disposal of this waste was the most major problem faced by the alumina industry after the adoption of the Bayer process. The conventional method of disposal of red mud in ponds and pits has put adverse effect on 15 environments.

GGBS: It contains silicates and alumino-silicates of calcium and is a by-product of 25 iron manufacturing blast furnaces.

Metakaolin: - Rocks rich in Kaolinite, traditionally known as China clay, when heated to 650-750oc forms a dehydroxylated Kaolin known as Metakaolin.

M-Sand or Manufactured Sand: It is an artificial sand made by crushing hard stones into a fine powder. It's a sustainable alternative to river sand and is used in many construction applications.

II. Liquid component
The liquid component also acts as the chemical activator and includes:
A mixture of NaOH and Na2SiO3 in the ratio of 1: 2.5 where both NaOH and Na2SiO3 are in the 10 concentration of 2 Molar and also acts as chemical activators as well.
• 2 M NaOH solution.
• Sodium silicate in the ratio of 1: 2.5 with NaOH
Activating Solutions:
Sodium Hydroxide (NaOH): A strong alkaline medium to break down the alumina-silicate bonds.
Sodium Silicate: Supplies soluble silica, essential for the formation of polymer chains.

METHOD OF PREPARATION OF GEOPOLYMER BRICK:
Preparation of Solid Mix:
The ingredients of the solid components are hand mixed in said ratio i.e., red mud (40-60% w/w), metakaolin (5-15% w/w), manufactured sand (20-25% w/w), and ground granulated blast furnace slag (10-15% w/w) are dry mixed in for about three minutes.

Preparation of Liquid Mix
1. Preparation of 2M NaOH solution:
To prepare NaOH concentration, NaOH whose Mol weight is 25 40, for 2 M NaOH solution consists of 2x40=80g of NaOH flakes solids per kg of water is taken and mixed until the solid is completely dissolved in distilled water. The solution of NaOH is prepared one day prior to use.
2. Preparation of 2M Na2SiO3 solution:
To prepare 2M sodium silicate (Na2SiO3) solution 2x 122.06 =244.12g of Sodium silicate is taken per kg of water. The sodium silicate solution is added to this solution.
The liquid component also acts as an activator. The liquid mix is prepared by combining / mixing the prepared alkaline solutions i.e., 2M concentration of NaOH and 2M concentration of Na2SiO3 is mixed in the ratio of 1: 2.5 respectively.
The liquid component and solid component are combined proportionately to form a brick of desired size

1. Mixing and Geopolymerisation:
The solid components mixer is combined with the activator solution to initiate geopolymerization, resulting in the formation of a three-dimensional network of polymer chains.

2. Casting And Curing:
The obtained mixture from the blending of solid components and liquid activating solution is poured into molds shaped as prisms or other desired forms. Specimens are left to cure at room temperature for seven days to gain strength.

Advantages of the Present Invention:
Environmental Impact Reduction:
Utilizes industrial byproducts like RM, FA, and GGBS, reducing reliance on traditional materials like Portland cement.
Lowers carbon emissions by eliminating high-temperature calcination processes.
Enhanced Material Properties:
High compressive strength (e.g., 14.1 MPa for mix M4). Improved durability and resistance to water absorption.
Cost-Effectiveness:
Utilizes readily available waste materials, reducing raw material costs.
Sustainability: Promotes circular economy by recycling waste into high-value construction materials.

 
EXAMPLE
An exemplary method of preparation of geopolymer brick comprises mixing of solid component and liquid activator component proportionately is described below:

Component Percentage/Result
Red Mud (RM) 50%
Metakaolin (MK) 10%
M-Sand 25%
Ground Granulated Blast Furnace Slag (GGBS) 15%

The alkaline activator solution is prepared at a specific molarity (e.g., 2M with a 1:2.5 ratio).

The raw materials are combined with the activator solution to begin the process of geopolymerization, resulting in the formation of a three-dimensional network of polymer chains. Once the geopolymer composite is mixed thoroughly, it is immediately poured into molds. After demolding the prepared geopolymer bricks, they undergo a curing period in ambient conditions for 7 days.

Quality Control and Testing:
The evaluation of material performance encompasses several critical metrics, including compressive strength, water absorption, bond strength assessed through cross-couplet and triplet tests, and durability.
These parameters are essential for determining the structural integrity and longevity of the material in practical applications. Compressive strength provides insight into the material's ability to withstand axial loads, while water absorption indicates its permeability and susceptibility to environmental factors. Bond strength tests further elucidate the interfacial properties between components, and durability assessments ensure the material's resilience against aging and degradation over time.
Strength:
The wet compressive strength of 8 MPa indicates a medium-performance mix, suitable for specific construction applications like paver blocks or non-load-bearing elements.
Water Absorption:
A value of 6.7% is within acceptable limits for medium-durability requirements.
Bond Strength:
The Cross Couplet Test value (0.020 MPa) and Triplet Test value (0.328 MPa) indicate moderate adhesive properties between layers, important for cohesive performance in composite materials.
This mix design balances strength, water resistance, and bonding characteristics, aligning with the goals of sustainable construction. It demonstrates effective utilization of industrial byproducts while maintaining functional performance.
Couplet test:
Referring to Figure.1, One technique to assess strength of the b/w mortar with masonry units is the couplet test on bricks. This procedure assesses the bond strength b/w mortar with bricks. Two bricks are placed in a crossed configuration, with their faces touching each other. A layer of mortar of 10mm thickness is applied between the bricks. Tensile force is then applied to pull the bricks apart. The bond between them is tested for direct tensile strength. The purpose of this test is to determine how well mortar adheres to masonry units. This is a detailed explanation. To determine the bond strength, which is crucial for durability of structures, the mortar acts as the bonding material. A tensile force (pulling force) is applied to the couplet (the two bonded masonry units). The mortar bond is gradually broken by increasing the strain. Either the mortar or the mortar itself fails, depending on where the failure happens. It is noted how much force, or tensile load, is needed to break the bond. The direct tensile strength of the bond for unit is represented by this force. The test yields key details regarding the mortar's quality and the efficacy
Factors Affecting Bond Strength
Several factors influence bond strength:
• Mortar Composition: The type of mortar affects the bond.
• Surface Condition: The cleanliness and roughness of unit surfaces impact bonding.
• Drying: Proper drying affects its strength.
• Joint Thickness: Thicker joints may weaken the bond.
• Unit Absorption: Highly absorbent units may draw moisture from the mortar, affecting bond strength.
Interpretation
• Higher tensile strength indicates better bonding.
• If the bond fails within the mortar, it suggests that the mortar itself is weak.
• If the bond fails at the interface, it indicates poor adhesion b/w mortar and masonry. unit.

Couplet Test
Preparation of couplet test specimen:
Referring to fig.2, and figure.3, Two bricks are placed in a crossed configuration with their faces touching each other. A layer of produced geopolymer mortar of 10mm thickness is applied between the bricks uniformly. This specimen was dried for 7 days. Thus, ensures that the geopolymer binder supports its structural integrity and dimensional accuracy.

Triplet Test:
Referring to Figure 4 and Figure 5,unlike the couplet test (which involves two masonry units), the triplet test focuses on a single brick-mortar interface. It is used to find shear bond strength b/w mortar and unit. Understanding it is crucial for designing safe and durable masonry structures. A single brick is selected for the test. Three layers are involved. Top layer: a horizontal layer of mortar applied on top of the brick. Middle layer: the brick itself. Bottom layer: another horizontal layer of mortar beneath the brick. The three layers together form the “triplet.” A shear force is applied horizontally to the middle layer (the brick). The force gradually increased until the bond between them fails. The failure occurs in 2 ways, first within mortar, second at brick-mortar interface. Highet shear force required to break bond is recorded, strength is represented by this force. The test provides insights into the quality of the mortar and the effectiveness of the bond.

Interpretation
Higher strength indicates better adhesion between the brick and the mortar. If the bond fails within the mortar, it suggests weak mortar properties. If the bond fails at the interface, it may indicate poor adhesion.
Test Results Table Summary
The table provides details about the composition and properties of a specific geopolymer binder mix using Red Mud (RM), Metakaolin (MK), M-Sand, and GGBS, along with performance metrics like compressive strength, water absorption, and bond strength for 2 molarity concentration of activators.
Wet Compressive Strength 14.1Pa
Water Absorption 9.15%
Bond Strength (Cross Couplet Test) 0.020 MPa
Bond Strength (Triplet Test) 0.328 MPa

 
, Claims:We Claim,

1. A red mud-based geopolymer bricks composition, comprising:
i. solid component mix comprising:
a) red mud in the range of 40-60% w/w;
b) Metakaolin (MK) in the range of 5-15% w/w;
c) M (Manufactured) sand in the range of 20-25% w/w;
d) ground granulated blast furnace slag (GGBS) in the range of 10-15% w/w; and
ii. liquid component mix comprising:
a) alkaline activator solution in the range of 25-30% with respect to the total mass of the solid components mix.

2. The composition as claimed in claim 1, wherein said alkaline activator solution is liquid component mix made of 2M NaOH and Na2SiO3 in the ratio of 1:2.5.

3. The geopolymer brick composition as claimed in claim 2, wherein alkaline activator solution acts as chemical activator.

4. The geopolymer brick as claimed in claim 3 has a compressive strength of at least 14.1 MPa.

5. The geopolymer brick as claimed in claim 4 has a water absorption of 9.15%.
 

6. A method of preparation of geopolymer brick comprising steps of:
i. mixing red mud, Metakaolin (MK), M (Manufactured) sand, and Ground Granulated Blast Furnace Slag (GGBS) in the ratio of 40-60%; 5-15%; 20-25%; and 10-15%, respectively,
ii. adding 2M NaOH and Na2 S iO3 in the ratio of 1: 2.5 to the above mix to make composite geopolymer mix;
iii. casting the mix into moulds; and
iv. demoulding, sun drying and hydrating the cast for at least 24 hours before use.