Study of the Morphological Characteristics of Geopolymer concrete based on Eggshell and Bauxite powder

Researchers conducted research into the strength properties of a Geopolymer produced from eggshell powder, bauxite, and flyash with RGL (Reaction generating liquid) and cure for 84 days at ambient temperature. Also studied were changes in products of Morphology, XRD, FTIR studies and SEM images of microstructure. The results indicated that, in various mix proportions, the strength gradually improved from 28 to 84 days. The aged Geopolymer’s lower porosity is attributed to the hardened samples becoming more compact with time due to gradual Geopolymerization to generate the coexisting C-A-S-H and N-A-S-H gels. Both the early-age and long-term Geopolymers had such an X-ray amorphous phase corresponding to Geopolymerization gel, but the aged specimens contain calcite from eggshell powder and alumina from bauxite powder, showing potential improvement in the properties of mechanical and durability properties were examined using various mix proportions in an experimental investigation.


Introduction
A category of solid materials that are created by reacting an aluminosilicate powder with an alkaline solution is termed Geopolymers [1]. Due to the material's lower energy needs and CO 2 emissions than standard OPC, various researchers have been studying the preparation, Geopolymerization, microstructure, performance, and uses of Geopolymers over the past few decades [2]. Numerous earlier studies showed that Geopolymers have a number of desirable performance characteristics, including strong early-age strength [3], protection against chemical attack and insulation from heat [4,5], however, the technology's commercial applications so far are few [1,6]. The inability to predict the durability of concrete containing Geopolymer is one of the two obstacles holding back progress; structural concretes must survive for at least several decades, but information on such time scales is lacking for the newly discovered material [7,8]. A Geopolymer made from eggshell powder and bauxite powder and cured at room temperature was found to have increased strength. However, the strength improves since eggshell powder and bauxite powder were calcined and precipitated, which makes them more resistant to moisture exposure than cement and increases strength and durability [9,10]. The outcomes of solution-based studies have also been helpful in understanding the long-term performance of Geopolymers in addition to the results for air curing that were previously published. Although Geopolymers are considered resistant to chemical attack, long-term acceleration data showed that when samples were exposed to an aggressive solution, degradation took place [11,12]. Geopolymers' microstructure and phases alter as a result of prolonged curing. In alkali-activated slag, the silicate gel produced by the gelation of water-glass was initially largely consumed to form long, linear C-S-H chains, but more Al is likely substituted into the C-S-H to promote further cross-linking [13]. Geopolymers' microstructure and phases alter as a result of prolonged curing. In alkaliactivated slag, the silicate gel produced by the gelation of water glass was initially largely consumed to form long, linear C-S-H chains, but more Al is likely substituted into the C-S-H to promote further cross-linking [14,15]. Given that composition and structure are always important factors 1 3 42 Page 2 of 11 in the evolution of physical properties like strength; these changes unquestionably have an impact on the long-term performance of Geopolymers. The aforementioned experimental findings contribute significantly to the understanding of the service characteristics of Geopolymers, but it is challenging to directly extrapolate laboratory results to estimate the service life of Geopolymers in practical applications due to the stark contrast between laboratory and service conditions. Therefore, numerous attempts have been undertaken to validate their long-term performance under natural circumstances [16,17]. The durability was attributed to the combination of an inner product that underwent continuous hydration via a cyclic process involving carbonate anions and an exterior product that was highly polymerized, comparatively low-Ca, amorphous C-S-H. The Geopolymer's longer service data highlighted its excellent environmental stability. Purdocement, a commercial invention by Arthur Oscar Purdon that uses slag to create concrete, is susceptible to carbonation, yet the residual mechanical strength was still substantial after 60 years [18,19]. This earlier research is solely useful for illustrating how alkali-activated slag performs. More research is necessary before making changes to the initial materials. The beginning materials used in this investigation, such as Flyash, Eggshell powder, and bauxite, are distinct from those used in previous studies. Therefore, investigating the development of strength and microstructure in materials that were cured in the air is required.

Materials
Fly ash: Fly ash is one of the solid residues composed of fine particles that are driven out of the boiler with flue gases in coal-fired power plants. In this study, the fly ash (fineness = 3.550 cm 2 /g, density = 2.18 g/cm 3 ) originated from the power plant. It exhibits chemical properties corresponding to a class-F material as specified in ASTM C 618, with a mean particle size of 15 µm (90% smaller than 57 µm) and with large quantities of reactive oxide 23.118 (%) of silicon dioxide (SiO 2 ) and 17.50(%) aluminium oxide (Al 2 O 3 ), less than 1% of calcium oxide (CaO), and potassium oxide, as shown in Table1. The Si and Al components contribute to the development of the strength of concrete through Al-Si polymerization which occurs due to the use of alkaline activators and high-temperature curing. The mechanical properties and durability can be improved by fine-tuning Si/Al ratios, Rgl solutions, and curing conditions. Fly ash-based geopolymer is expected to be used as a kind of novel green cement. Fly ash-based geopolymer can be used as a class of materials to adsorb. The factors affecting the performances of fly ash-based geopolymer concrete, in the particular aggregate, are discussed. For future studies on fly ash-based geopolymer, further enhancing mechanical performance, scaling up production and exploring new applications are suggested.
Bauxite: A sedimentary rock with a comparatively high aluminum concentration is called bauxite. It is the principal producer of gallium and aluminum in the world. The main applications for bauxite span a variety of industries, including metallurgy, the chemical sector, and the production of building and road aggregates. The greatest and only material for producing aluminum metal is bauxite. The chemical industry, refractory bricks, abrasives, cement, steel, and petroleum industries all require bauxite. It is frequently mistaken for a mineral when it is actually a rock. The primary mineral of aluminum is bauxite. It is created in tropical areas as a result of silica leaching from rocks containing aluminum and chemical weathering. Bauxite is a type of rock mostly made up of hydrous aluminum oxides. The primary source of aluminum is bauxite. Finding Bauxite is somewhat simpler than finding Aluminum Wire, but it's still risky. Mining iron ore deposits in the red Limestone Spire zone will occasionally provide bauxite. Players have additionally mentioned obtaining a small amount of bauxite via pillaging the NPC bases on the overworld map. Bauxite waste can be used in the manufacture of cement in a variety of ways, such as a raw material in the creation of Portland cement clinker, as a pozzolanic material that is used in mortar or concrete mix, or in some forms of "special" cement. Eggshell powder: A pure calcium dietary supplement. Processed eggshell powder made from hen eggs. It mostly consists of calcium carbonate, a typical calcium type. Protein and other minerals make up the remainder. Dairy products and other meals were rich in calcium and are found in many different foods. Where, Calcium carbonate, which also makes up the bones, teeth, and nails, makes up almost all of an eggshell. Protein, magnesium, selenium, strontium, and other substances thought to be beneficial for bones and joints are also abundant in them. Around the world, enormous amounts of eggshells are produced daily as bio-waste. Eggshells are a byproduct of the fast food and residential construction industries. The disposal of eggshell waste contributes to environmental contamination, and it also involves financial costs and the availability of disposal locations. The eggshell's odour attracts flies and is abrasive. Roughly 91% of the weight of an egg is made up of the eggshell, which weighs about 11% of the entire egg. This study sought to apply Eggshell Powder to concrete situations as a waste product while being calcium-rich and chemically similar to limestone. Therefore, it is necessary to comprehend the qualities of concrete created with it before using waste to substitute cement in concrete. Therefore, the main goal of this research was to comprehend the practical applications and Systematic research was done into how well concretes performed in terms of their strength and durability characteristics. Tests on the control and Eggshell powder replaced concrete lasted 7, 28, 56, and 84 days respectively. This influence of curing age on the properties of concrete was discussed in light of the test findings.
Reaction generating liquid: It is a mix of sodium hydroxide pellets and sodium silicate solution including water is known as RGL (Reaction Generating Liquid) solution. These Geopolymeric source materials of which Flyash, Groundgranulated blast furnace slag, Eggshell powder and Bauxite are the most prevalent examples, are powdery and have an oxide composition of Al 2 O 3 and SiO 2 . For the purpose of starting the binding action-creating process known as Geopolymerisation, a liquid known as Reaction General Liquid (RGL)-is introduced to this powder mixture. In order to develop polymerization reactions for Geo polymeric source materials manufactured primarily from various combinations for a variety of applications, the employees working in the field of Geopolymer technology currently have access to one optimized RGL (Reaction Generating Liquid) formulation.
The features listed above are mainly illustrative, and their true worth depends on ambient temperature and humidity conditions. The RGL stored in the drums and other storage vessels should not be exposed directly, at any time, to the atmosphere since the RGL is prone to carbonation reaction due to CO 2 available in the atmosphere.
CaO was the primary oxide in Eggshell powder (Table 1). Bauxite and eggshell powder were given the names Bauxite and Eggshell powder, respectively. RGL solution was a mixture of sodium hydroxide, sodium silicate solution and water (Density: 0.05-1.20 kg/m 3 ). The solution's SiO 2 /Na 2 O ratio ranged from 0.5 to 1.5 the combination of Flyash, Eggshell powder and bauxite powder, with different mix proportions being tested in the lab at ambient temperature.
From the above Fig. 1 represents the Table 2, the results on the peak values were showing for that each and every mineral was formed between 2θ to the intensity at various angles were formed for the Flyash, Eggshell powder and Bauxite powder. It has been observed that the peak values of XRD results showing on flyash are 24.3°, Eggshell powder is 29.2° and Bauxite powder is 24.6 0 .
From the below Table 3 and Fig. 2, plotting the FTIRimages of Flyash, Eggshell powder and Bauxite powder explained the wavenumber (cm −1 ) to transmittance (%) for forming the bond to the functional group.
The changes induced in response to the above-mentioned physical and chemical process in the FTIR spectra are shown in Fig. 2. The spectra of each and every material were shown in different wavelengths to transmittance forming the bond and functional group for different materials. In the flyash, FTIR Spectroscopy of broad absorption bands at approximately ranges from 2978.14 cm −1 and 1083.08 cm −1 were formed to C-H stretch to the functional group of Alkanes and C-H stretch to the functional group of Alkanes. The different variable ranges of FTIR Spectroscopy absorption bandwidth of remaining ranges were 556.34 cm −1 , 786.30 cm −1 were formed the C-Cl stretch bond to the functional group of Alkyl halides and the remaining 951.65 cm −1 were formed the = C-H bend formed to the functional group of Alkenes. Whereas for the bauxite powder has recorded that the absorption rate of FTIR Spectroscopy is attributed to the different ranges of wavelength were seen as 539.65 cm −1 are C-Br stretch of functional groups named Alkyl halides and for another wavelength of 734.99 cm −1 are C-Cl stretch bond of formation to the functional group was Alkyl halides. The other various wavelengths of this mineral were absorbed to the different ranges as 1540.72 cm −1 , 1745.32 cm −1 and 2933.23 cm −1 that was bonded to the N-O asymmetric stretch of Nitro compounds, C=O stretch of Esters, Saturated aliphatic and C-H stretch of Alkanes were formed. Finally, for the Eggshell powder FTIR Spectroscopy ranges for the absorption rate of wavelength (cm −1 ) to transmittance (%) were ranges to 710.11 cm −1 and 874.29 cm −1 forming the C-H "oop" bond to the functional group of aromatics. The other broad absorption rate of spectroscopy ranges was formed to 1416.56 cm −1 , 2977.16 cm −1 corresponds to C-C stretch to the formation of a functional group named as Aromatic and C-H stretch to the Alkanes.

Test results
The Mix proportion ratio of Geo-Polymer concrete using the draft code of IS 17452: 2020, identifies the basic properties of each material used for the Geo-polymer concrete. Now, from the research side, observed the most of literature surveys have been conducted on the mixed proportion of Geo-polymer on (40:30:30) whereas the other terms in the form like units (kg) say it as 160 kg: 120 kg: 120 kg and that mix proportions with best results like basic properties and fresh properties to choose Flyash: Bauxite: Eggshell powder.  The below tables and figures represents about the combination of Flyash, Eggshell powder and Bauxite powder represents about the combination used for making the Geopolymer concrete using the mix design following the drafted code.
From, Fig. 3 and Table 4 Table 7 were shown the absorption rate on different mix proportions. In the Tables 3, 4 and 5 MPa represents to strength      values is in the units of Kilopascal. Whereas, Fig. 6 represents about the durability test conducted on the test specimens in the water tanks with two different solutions named HCL and H 2 SO 4 were shown. • In the various mix proportion of Sio 2 /Na 2 o, the test conducted results water absorption tests on Geo-polymer concrete of Fly ash: bauxite: eggshell was got the highest value of 1.4 is 2.61% and the lowest value of 0.8 is 2.80(%) of gain percentage and the total average percentage for water absorption ratio is 2.642(%)

Test discussions
From the above Figs. 3, 4 and 5 of Geo-polymer concrete of mix pastes were related to mechanical properties and from the above Fig. 6 of Geo-polymer concrete mix pastes were from durability studies using HCL and H 2 So 4 , identifying the SEM images on it and it is observing the microstructure and morphological behavior of the concrete specimens on the various mix proportions on Sio 2 /Na 2 o = 0.5-1.5. The pastes all have similar morphology with the porous gels, but it indicates that the early-age pastes have higher porosity on the scale of a micrometer than that of the long-term pastes [20,21]. SEM images of pastes that were cured for varying ages are shown. According to the assessment of the pore structure, the progressive reaction is thought to periodically fill the pores with gels, and that is why the large pores tend to partially disappear with maturity. Long-term, the progressive reaction leads to an increase in the surface area and pore volume smaller than 1 μm specimen as a product of the gels' interconnectivity to create capillary holes, as depicted. In general, the polymerization reaction in the low calcium and high silicon/aluminum system advances slowly at room temperature. When sodium silicate-activated Geopolymer is dried at 27 °C for 28 days, there is indeed a substantial number of fly ash left around 34.8%. [22,23]. Even after curing at 85 °C for 7 days, the residual fly ash in sodium hydroxide-activated Geopolymer exhibits a high value of 35.5%, despite the fact that the reaction rate may be considerably accelerated at higher temperatures [24,25]. Eggshell powder is one of these beginning materials that exhibit calcium characteristics based on composition. Also, fly ash-based Geopolymer and bauxite-based Geopolymer Fig. 6 Studies on H 2 SO 4 and HCL Solutions both demonstrate a similar hardening behavior at room temperature. What's more, both Geopolymers based on fly ash and eggshell powder, and bauxite powder follow the same reaction pathway, which includes gel nucleation, dissolution, and solidification. [26,27]. The rate of polymerization of eggshell powder-based Geopolymer may therefore be similar to and low compared to that of fly ash-based Geopolymer [28,29]. It allows to detect powder, which has a platelet-like morphology and is enmeshed in the surrounding gels, in 7, 28, 56 and 84 day pastes, as depicted in Fig. 4. In early-age individuals, the porous structure is partly due to this loose structure of geopolymer concrete.
Geopolymers' XRD patterns are depicted in Fig 8a, b, additionally, crystalline phases that were initially present in the replacements (Flyash, Bauxite and Eggshell powder) were detected with peaks that were either weaker than expected or overlapped, making it difficult to detect any changes in the concrete with the durability properties in the involved to HCL and H 2 SO 4 solution. So, in these Figs 8a, b, explained about the Geopolymer concrete dissolved into the solution. Samples of Sio2/Na 2 0 range from 1.1 to 1.5, sample Sio 2 /Na 2 o ranges from 0.6 to 0.8 lacked a new peak at 17.2 (2θ) in their spectrum. Additionally, there was a stronger peak at 54.5 and a new peak at 25 (2 h) in the spectrum of Sio2/Na20 = 1.5. (2θ). In Fig. In sample Sio2/Na 2 0 = 0.6-0.8's spectra, there was a new peak at 50.9 (2θ) that wasn't present in the other samples. Sio2/Na20 = 1.5. On the other hand, the broad hump that was present between 19 and 38 (2θ) in the XRD patterns of Flyash, Bauxite and Eggshell powder ash (Fig.1), extended between 18 and 45 (2θ) in the Geopolymers' patterns (Fig 8a, b). This was a sign that the amorphous phase of aluminum silicate had disintegrated and a new one had formed in Geopolymers [30,31]. All of this coincided with the consensus that, in general, only the reactive and mostly amorphous phase of aluminum silicate is involved in the production of Geopolymers [32]. Furthermore, it was difficult to identify the new crystalline phases that were created due to the intricacy of the XRD spectra and the few new peaks that showed in them. The variations between the XRD spectra of the Geopolymers made with 5% HCL and 5% H 2 SO 4 solution and those made with a sign of potential differences among certain of their features. On the other hand, the discrepancies between the Geopolymer concrete pastes with the spectra of the two types of mixtures (Fig 8a, b) were primarily due to the makeup of the replacements for the geopolymer concrete.

Conclusions
1. The curing of a Geopolymer that was made from 40% Flyash, 30% Eggshell powder and 30% bauxite powder and activated by an RGL (Reaction Generating Liquid) solution showed a progressive improvement in strength. This rise was caused by age-related cohabitation of C-A-S-H and N-A-S-H gels and gradual Geopolymerization, which resulted in the creation of a denser matrix. It is thought that ongoing Geopolymerization is the cause of the aged Geopolymer's decreased porosity and more compact microstructure. 2. Both early-age and long-term Geopolymers showed an X-ray amorphous phase from Geopolymerization gels, which is a sign of the gel's durability. Calcite and aluminum, however, were found in the aged specimen, particularly in the 84 days paste, which shows that the examined Geopolymer is susceptible to carbonation in an atmospheric environment because of the long-term lower humidity curing. 3. Microcrack-containing carbonation zones were not found. This result is seen because N-A-S-H type gels, which predominate in relatively low-calcium Geopolymers, prevent the carbonation process from degrading the cross-linked structure. Future work should go into great detail on the causes of preferred calcite precipitation in big pores and holes.
4. In the overview, my research work represents that Class F Flyash used for siliceous and aluminous purposes will be found, bauxite powder represents magnesium and calcium in it and Eggshell powder is used for the presence of Cao(lime) in it improves the binding property of the concrete. Thus, the combination of all three trios is used for the incredible improvement of the mechanical and durable properties of Geo-polymer concrete.