Geopolymer Concrete Mixtures Research Articles

Sustainable Geopolymer Concrete for Pavements: Performance Evaluation of Recycled Concrete Aggregates in Fly Ash-Based Mixtures

This study investigates the feasibility of incorporating recycled concrete aggregates (RCA) into fly ash-based geopolymer concrete for sustainable pavement applications. The research evaluates RCA’s physical and mechanical properties compared to virgin coarse aggregates (VCA) and assesses the performance of geopolymer concrete mixtures with up to 40% RCA replacement. Aggregate characterization revealed that RCA exhibited higher water absorption (4.39%), crushing value (20.9%), impact value (28.2%), and abrasion value (26.1%) compared to VCA, yet these values remained within acceptable limits for pavement applications. Geopolymer concrete specimens were tested for compressive strength, water absorption, abrasion resistance, and chloride ion permeability. Results indicated that increasing RCA content led to a gradual decrease in compressive strength, from 40.16 MPa to 33.52 MPa, while water absorption increased from 5.2% to 6.8%. Abrasion resistance declined as RCA content rose, and chloride ion penetrability increased from 1687 to 2196 coulombs. However, mixtures with up to 20% RCA replacement met the strength and durability criteria required for pavement construction. This study demonstrates the potential for utilizing RCA in geopolymer concrete pavements, offering a sustainable solution for waste management and resource conservation in the construction industry.

Proposed simplified methodological approach for designing geopolymer concrete mixtures

The development of geopolymer concrete offers promising prospects for sustainable construction practices due to its reduced environmental impact compared to conventional Portland cement concrete. However, the complexity involved in geopolymer concrete mix design often poses challenges for engineers and practitioners. In response, this study proposes a simplified approach for designing geopolymer concrete mixtures, drawing upon principles from Portland cement concrete mix design standards and recommended molar ratios of oxides involved in geopolymer synthesis. The proposed methodology aims to streamline the mix design process while optimizing key factors such as chemical composition, alkali activation solution, water content, and curing conditions to achieve desired compressive strength and workability. By leveraging commonalities between Portland cement concrete and geopolymer concrete, this approach seeks to facilitate the adoption of geopolymer concrete in practical construction applications. The proposed mix design guidelines have been validated through examples for concrete cured under different conditions, including outdoor and oven curing. Future research should focus on validating the proposed methodology through experimental studies and exploring cost-effective alternatives for alkali activation solutions to enhance the feasibility and scalability of geopolymer concrete production. Overall, the proposed simplified approach holds promise for advancing the utilization of geopolymer concrete as a sustainable alternative in the construction industry.

Constitutive behavior of CFRP-confined normal- and high-strength geopolymer concrete: Experiments and modelling

The constitutive behavior of geopolymer concrete (GPC), which is essential to the design of GPC structures, has not been well explored, especially in multi-axial stress state. This study therefore performs an investigation on the constitutive behavior of normal- and high-strength GPC confined by carbon fiber-reinforced polymer (CFRP) jacket. A total of 36 CFRP-confined GPC specimens are fabricated, which cover six GPC mixtures and three thickness of CFRP jacket. A dataset comprising of 24 specimens is employed to develop the models for ultimate condition and axial stress-strain curve. Two testing datasets, one consisting of the rest 12 specimens and the other composed of six specimens collected from the literature, are exploited to test the models. A linear function of actual confinement ratio is competent for modelling the compressive strength, whereas a nonlinear function is capable of characterizing the ultimate axial strain. The average absolute error of predicted compressive strengths and ultimate axial strains is less than 8.0 % and 15.0 % for both testing datasets. A single four-parameter function originally proposed for OPCC can be extended to represent the axial stress-strain curve of CFRP-confined GPC by formulating expressions for the parameters. The correlation coefficient between predicted and measured curves is more than 0.96.

CORRELATION BETWEEN COMPRESSIVE AND TENSILE SPLITTING STRENGTH OF GEOPOLYMER FIBER CONCRETE

Geopolymer concrete mixture contain fine and coarse aggregate, fly ash and activator, composed from sodium silicate and sodium hydroxide. Like normal concrete, geopolymer concrete is weak in terms of tensile strength, so fiber needs to be added to improve the mechanical properties of geopolymer concrete. In this research nylon and steel fiber are added to the geopolymer concrete mixture, with percentage from 0.5%, 0.75%, 1%, 1.5% and 2% of volume. The correlation between compressive and tensile splitting strength of geopolymer steel and nylon fiber concrete were evaluated in this research program. The relationship between tensile splitting strength and compressive strength of geopolymer concrete will be built in a mathematical model using multivariable non-linear regression from SPSS software. The specimens are cylindrical concrete, which have diameter of 100 mm and height of 200 mm. The specimen undergo a curing process in an oven at 60oC for duration of 24 hour. Geopolymer concrete mixture with a fiber percentage of 0.75% have a good workability, since they still meet the slump value requirements (10 + 2 cm). The compressive strength reaches the highest value at 0.75%, for both steel and nylon fibers. The addition of up to 2% steel fiber produces a splitting tensile strength 12.06% higher than geopolymer concrete with nylon fiber. The equation model proposed for geopolymer fiber concrete is fspt = 0.049f'c.exp(0.7p), with the R-square values from 0.722 - 0.715.

Assessing the effects of Na2SO4 and NaCl on the properties of geopolymer concrete subjected to elevated temperatures

AbstractSince concrete is exposed to chemical, mechanical, or physical deteriorating effects simultaneously or successively under environmental conditions, this study focused on the durability of geopolymer concretes containing ground blast furnace slag (GGBFS) and fly ash (FA) under the effects of sulfate and salt after elevated temperatures. For this aim, five FA‐based geopolymer concrete mixtures with different GGBFS contents were produced and cured at 90°C for 72 h. First, the produced samples were exposed to 200, 400, 600, and 800°C for 2 h. Then, the samples were put into 5% sodium sulfate (Na2SO4) and 5% sodium chloride (NaCl) solutions for 30 days. The impacts of elevated temperature + Na2SO4 and elevated temperature + NaCl on geopolymer concrete were investigated by compressive strength, mass loss, visual examination, capillary water absorption, x‐ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FT‐IR). As a result, although cracking or strength decreases in concrete have been observed after only elevated temperatures, it has exhibited significant resistance to the integrated deterioration influences, has not disintegrated, and maintained its integrity under appropriate mix design and curing conditions. Shortly, the results demonstrated the ability of geopolymer concrete subjected to elevated temperatures with acceptable strength and durability under chemical effects, even if left for a short time.

Effect of marble dust blended with recycled coarse aggregate on self-compacting geopolymer concrete

This investigation on the application of marble dust, ground granulated blast furnace slag (GGBS), and recycled coarse aggregate (RCA) in geopolymer concrete is presented in this research report. The study aims to determine whether it is possible to make concrete that is more environmentally friendly and sustainable while maintaining its desirable features. The creation and testing of various GGBS-based geopolymer concrete mixtures utilizing varying ratios of marble dust and RCA in a 12M NaOH solution were part of the research technique. In the experimental study, new concrete qualities were developed and examined by EFNARC requirements. The addition of marble dust and RCA has been found to significantly alter the geopolymer concrete’s characteristics. The study finds that employing RCA, GGBS, and marble dust can be successful.

THE EFFECT OF DIFFERENT DESIGN RATIOS ON THE COMPRESSIVE STRENGTH OF GEOPOLYMER CONCRETE: A PARAMETRIC STUDY USING THE TAGUCHI METHOD

This paper presents the influence of numerous limits on compressive strength of fly ash-based geopolymer concrete mixtures optimized by Taguchi method using Minitab program. The major goal is to find the optimal ratios that may give the greatest compressive strength of geopolymer concrete. A total of twenty fife mixtures of geopolymer concrete with fife mixtures of normal concrete were assessed considering the effect of inclusion of Alkali-Activator to binder ratio (AA/B), NaOH concentration (M), Influence of Na2SiO3 to NaOH ratio (SS/SH) and effect of binder content (B). Different molarities was used in this study: 8, 10, 12, 14, and 16. Flay ash by way of waste material is used in ratios of (15, 17.5, 20, 22.5, and 25) % and substituted via 90 % of ordinary Portland cement to output the geopolymer concrete. Also, sodium silicate to sodium hydroxide are utilized in ratios of 1, 1.5, 2, 2.5, and 3. The alkali activator was made using sodium silicate, sodium hydroxide, and water in ratios of (0.3, 0.35, 0.4, 0.45, and 0.5). One type of locally crushed coarse aggregate was used instead of normal coarse aggregate that has sizes of 19 mm, as well as, fine aggregate. The examined mechanical property is characterized by compressive strength. The outcomes specify that the geopolymer concrete exhibits The highest compressive strength has been reached when the alkali-activator to binder ratio equal to 0.45, NaOH concentrations equal to 16, Na2SiO3 to NaOH ratio equal to 1 and binder content reached to 25 %. Also, the result showed that the compressive increases as the curing age increases. Moreover, scanning electron microscopy was evaluated to show the geopolymer concrete microstructure.

Engineering properties of geopolymer concrete composites incorporated recycled plastic aggregates modified with nano-silica

The novel approach of reusing recycled plastic in construction instead of landfilling has gained recognition. However, the inclusion of recycled plastic aggregates (RPA) tends to have a negative impact on various concrete properties. Previous studies have explored surface treatment techniques to mitigate these effects. Nevertheless, there is limited research on enhancing the properties of RPA geopolymer concrete (GPC) through the addition of nano-silica (NS) particles in to the GPC mixtures. This study aims to experimentally investigate the properties of GPC incorporating RPAs modified with NS particles. The experimental program consists of seventeen mixtures divided into three stages. In the first stage, the effect of NS addition on the performance of GPC mixtures was evaluated. Moreover, the effect of different percentages of RPAs was investigated in the second phase. In the third stage, the optimum percentage of NS particles found in the first stage was utilized to improve the performance of GPC mixtures which aggravated in the second stage. The total binder content for all mixtures was 450 kg/m3 which contained 90% of ground granulated blast furnace slag (GGBFS) and 10% silica fume. In the first stage the GGBFS was replaced by 1%, 2%, 3%, and 4% NS particles, while, in the second stage, the natural fine aggregate was replaced by RPAs at six volume fractions (5%, 10%, 20%, 30%, 40%, and 50%). The fresh behaviour of all GPC mixtures was investigated to assess the flowability, setting and cohesiveness of the mixtures. The mechanical behaviour was evaluated for compressive strength, splitting tensile strength, modulus of elasticity, flexural strength, and stress-strain behaviour. Moreover, the microstructure characteristics were investigated to illustrate the modifications that occurred in the microstructure scale. The results indicated that the addition of an optimum percentage of NS particles can significantly restore most properties of RPA-GPC which were degraded due to the addition of RPAs. This technique can help the construction industry to safely use the RPAs in the GPC mixtures without concern about their negative impact on concrete performance.

Effect of Slag Sand on Mechanical Strengths and Fatigue Performance of Paving Grade Geopolymer Concrete

AbstractGeopolymer concrete with time is gaining recognition as a sustainable alternative to Portland cement concrete, offering lower carbon emissions and utilising industrial by-products. While prior research focussed on its mechanical properties for structural purposes, this study explores its potential for paving applications. A unique geopolymer concrete mixture suitable for paving, referred to as paving quality geopolymer concrete (PQGC), was developed by incorporating slag sand (SS) as a substitute for river sand (RS). The investigation primarily assessed fatigue life PQGC mixes. The findings demonstrate that the inclusion of SS in PQGC has no significant impact on its setting times or workability. However, PQGC formulated with 100% SS, w.r.t PQGC containing RS, exhibited enhanced mechanical strength of 7% in compression, 16.7% in flexure and 8.3% in split tensile tests at 28 days of open-air curing. Following a 14-day period of curing, PQGC achieved a compressive strength of 46 MPa, surpassing the minimum requirement of 40 MPa as per IRC:58 2015 for pavement quality concrete (PQC) by 15%. To evaluate fatigue performance, PQGC beam specimens were subjected to repeated loading at stress levels ranging from 0.9 to 0.6. The resulting fatigue data were employed to develop stress-fatigue life (SN) and Weibull two-parameter fatigue failure models. Comparative analysis with fatigue failure models such as Indian Road Congress (IRC) and Darter revealed that PQGC exhibits superior fatigue resistance and longer life expectancy compared to PQGC. In conclusion, this study confirms that PQGC incorporating SS is an efficient and eco-friendly choice for constructing rigid pavements with advantages such as curing without water, enabling early opening of roadways to traffic, and excellent resilience under cyclic loads.

RETRACTED: Fresh and mechanical performances of recycled plastic aggregate geopolymer concrete modified with Nano-silica: Experimental and computational investigation

Concerning environmental concerns, it has become crucial to invent and develop alternative construction materials that can replace ordinary Portland cement and use waste materials instead of natural aggregates in the production of concrete. An important advancement in this area is the utilization of recycled plastics to create geopolymer concrete, which helps reduce plastic waste and minimize the environmental impact of construction materials. Since plastics have become a significant environmental issue, it is imperative to find ways to recycle them for a sustainable future. Thus, this study was conducted involving the preparation of seventeen different mixtures of geopolymer concrete (GPC) in three stages. In the first stage, five GPC mixes were created with varying amounts of nano-silica (NS) ranging from 0 % to 4 %. The main objective of this stage was to determine the optimal NS content that could enhance the performance of the GPC matrix. In the second stage, recycled plastic aggregates (RPA) were introduced to replace a portion of the fine aggregates, ranging from 0.05 to 0.5 volume percentages. This aimed to assess the impact of RPAs on the fresh GPC and its mechanical properties. The third stage involved an analysis to improve the performance of the GPC compound incorporating RPAs. The optimal NS content identified in the first stage was utilized for all mixtures with RPA. Lastly, several modeling techniques, including artificial neural network, M5P tree, multiple linear regression, full quadratic, multi-expression programming, and linear regression, were employed to predict the compressive strength of the GPC compound. The results demonstrated that the addition of nano-silica increased the compressive strength of the GPC mixtures by 6.3 %, 13.4 %, 20.5 %, 21 %, and 21.9 % at curing ages of 3, 7, 28, 90, and 180 days, respectively, when using 3 % NS content compared to the control GPC mixture. However, the inclusion of NS had a negative impact on the workability of the GPC mixes. Furthermore, incorporating RPAs reduced both the workability and compressive strength of the GPC compound. In the end, the results obtained from the modeling analysis revealed that the compressive strength of GPC could be predicted with a high degree of accuracy by taking into account the mixture proportions of its constituents. Among the various techniques used, it was found that the artificial neural network model outperformed other methods in accurately forecasting the compressive strength of GPC. This indicates that the neural network model is a superior and reliable approach for estimating the strength characteristics of GPC, providing valuable insights for optimizing its composition and enhancing its overall performance.

Strength, life cycle analysis, embodied energy and cost-sensitivity assessment of sugarcane bagasse ash-based ternary blends of geopolymer concrete

The sustainability of cement concrete is always a subject of concern and hence, less polluting concrete alternatives are being explored. Geopolymer concrete can be an alternative, which may be partly or fully cement-free. However, there exists a huge gap in the knowledge of quantification for ecological advancements that can be achieved. This study reports on the life cycle assessment (LCA) of five different geopolymer concrete mixes made up of ternary blends of sugarcane bagasse ash, blast furnace slag and fly ash. The results coupled with 28-day mechanical test results were compared with traditional cement concrete of similar grade. Correlation analysis was carried out among the obtained results to determine Pearson’s coefficient and Spearman’s rho factor. The aspect of cost and embodied energy was also studied simultaneously. The analyses showed that conventional concrete is more harmful in all ecological impact categories as compared to other alternative concretes except majorly Ozone layer depletion, Carcinogens and Mineral extraction. The sugarcane bagasse ash-based geopolymer concrete mixtures were also found to be cost and embodied energy-effective as compared to traditional concrete.

Understanding the potential role of precursor content in the geopolymer concrete strength development

A common pozzolanic admixture used by several studies is agricultural waste ashes. An amorphousaluminosilicate substance is knownas pozzolanic admixture, which may not be inherently cementitious but combines with water and calcium hydroxide to produce cementitious substances.As precursors, fly ash and ground-granulated blast furnace slag (GGBS), industrial by-products, have been employed as raw materials in geopolymer concrete. However, a significant prerequisite for the development of geopolymer concrete, aluminosilicate sources are abundant in agricultural waste ashes as well. Therefore, this experimental work aimed to create a geopolymer using industrial waste products and agricultural waste ashes to effectively use readily available and inexpensive agricultural waste materials like rice husk ash (RHA) and bagasse ash (BA). In this study, various geopolymer concrete mixtures with variable levels of precursors (fly ash, GGBS, RHA, and BA) were cast and tested for their 28-day compressive strength and X-ray diffraction (XRD) analysis. Based on the findings of the compressive strength experiments, it is found that addition of RHA and BA significantly improves the compressive strength of the geopolymer concrete. XRD traces of geopolymer concrete blended with RHA and BA revealed that both RHA and BA added geopolymer concrete has denser intermolecular bonding of materials as compared to the fly ash based and GGBS based geopolymer concrete. Additionally, the geopolymer concrete that incorporates RHA has a higher cost-effectiveness than geopolymer concrete that is combined solely with industrial by-products.

Study on Mechanical and Durability Characteristics of Sustainable Geopolymer Concrete

Abstract: The concentration of greenhouse gases in the atmosphere has increased quickly as a result of anthropogenic activities that cause global warming. To solve this issue, Portland cement-free geopolymer concrete is created by using ground granulated blast furnace slag (GGBS) as the primary binder and micronized biomass silica (MBS) in varying proportions in composition of GGBS. The outcomes of this experimental investigation demonstrate the mechanical properties and robustness of geopolymer concrete. In the creation of MBS, rice husk is utilized. Besides from compression, flexural, split tensile strength, and elastic modulus testing, further measurements of water absorption, water sorptivity and rapid chloride permeability test were also carried out. It is found that a geopolymer concrete mix with 10% MBS and 90% GGBS as a binder had the best strength and durability. Also, the compressive strengths of each geopolymer concrete mixture exceeded the required design strength. This experimental investigation shows the possibility of employing MBS as a binder raw material in the production of geopolymer concrete.

Combined effect of using steel fibers and demolition waste aggregates on the performance of fly ash/slag based geopolymer concrete

Developing sustainable construction products has been showing a rising trend recently. Geopolymer composites are remarkable binding materials fabricated based on recycling and sustainability. In this paper, an experimental investigation was conducted to study some mechanical and durability characteristics of steel fiber-reinforced fly ash/slag-based geopolymer concrete (GPC) with different proportions of recycled coarse aggregate. Steel fiber-reinforced geopolymer concrete mixtures incorporating recycled coarse aggregates of up to 40% at the interval of 10% were prepared, and the mixtures without recycled coarse aggregate were used as reference samples. The steel fiber ratio of 0.3% and 0.6% were used and the combined effect of steel fiber and recycled coarse aggregate on the geopolymer composites’ behavior regarding strength properties, sulfate resistance, elevated temperature resistance, abrasion resistance, and freezing-thawing resistance was addressed. A significant improvement in strength properties was observed in steel fiber reinforced recycled aggregate geopolymer concrete with increasing fiber content; however, the strength properties of geopolymer concrete were decreased with the increase of recycled coarse aggregate amount. Also, the properties such as abrasion resistance, resistance to elevated temperature, sulfate resistance, and freeze-thaw resistance were improved with the addition of steel fiber. It indicates that the synergetic effect of steel fiber and recycled aggregate helps to produce ecologically sound geopolymer concrete with good engineering properties and durability characteristics that will bring sustainability to the concrete sector. Generally, the results show that the recycled coarse aggregate ratio of up to 30% and 0.6% of steel fiber can be considered an ideal combination to make geopolymer concrete with better overall properties.

Long-term strength development and durability index quality of ambient-cured fly ash geopolymer concretes

While the geopolymer binder system is considered the foremost eco – friendly alternative to conventional Portland cement, its long – term performance has not yet been fully established. This study evaluated the long – term strength development and durability performance responses of fly ash (FA) – based geopolymer concrete mixtures activated using combined sodium silicate and sodium hydroxide solutions mixed at a varied ratio of the former to the latter, ranging from 0.72 to 4.89. The foregoing investigation was done focusing on effects of physico – chemical parameters comprising SiO2/FA, Na2O/FA and H2O/FA ratios. Concrete samples were cast then ambient – cured for one year, or oven – cured at 60 °C for 24 h followed by ambient – curing until testing. Various tests were done at 28 days or one year, including compressive strength, durability indexes, water absorption and volume of permeable pores. The durability indexes measured were water sorptivity, oxygen permeability and chloride conductivity. It was found that ambient – cured geopolymer concretes exhibited strong long – term strength gains of 60 to 90%, normal pore structure characteristics and good durability quality. However, the chloride conductivity test seemed to display erratic outputs, possibly due to ion fluxes, hence further research is needed to evaluate the method’s suitability for testing geopolymer concretes.

Durability Performance of Geopolymer Concrete of Various Strength

Geopolymers, primarily composed of fly ash, have proved an excellent substitute for ordinary portland cement (OPC) in terms of sustainability and productivity. In order to determine the geopolymer concrete's (GPC) resistance to chemical assaults and water permeability, it is necessary to obtain geopolymer concrete (GPC) of varying strengths after normal curing. The objectives of the research was to test the durability performances of the GPC of various strength under normal curing and investigating the optimum strength based on durability testing of the GPC. For this research, different type of cement-to-fly ash ratio was used for various strength data. The appropriate mixture was conducted by using the trial mix method in order to obtain better accuracy of the results data during the mixing design process. To satisfy the varied strength designs, a small proportion of OPC is added to the GPC mixture as part of the mix design. After 28 days of curing, this durability testing is undertaken after the concrete has reached its maximum strength. The compressive strength test and weights were performed and compared to the GPC mix design at 60 °C after heat curing. The 8% OPC replacement has greater resistance to sulfate attack, saltwater exposure, and water permeability compared to the 6% and 7% OPC alternatives. Consequently, the experiment reveals that the GPC's durability and strength increase as the percentage of OPC increases.

Determination of stress-strain relationship based on alkali activator ratios in geopolymer concretes and development of empirical formulations

Fly ash-based geopolymer has recently gained attention of researchers due to its potential application, as well as being an alternative binder with low emissions compared to ordinary Portland cement (OPC) in concrete production. Studies which are conducted on the design and mechanical properties of structural members produced from fly ash geopolymer concrete (GPC) are very important in terms of increasing the use of this concrete. The aim of this study is to obtain experimental data on the effect of sodium silicate/sodium hydroxide (SS/SH) and alkali activators/fly ash (AA/FA) ratios on the mechanical properties of a low calcium heat-cured fly ash geopolymer. In addition, it is to reveal the similarities and differences of OPC and GPC by comparing the mathematical formulations in existing regulations and concrete models with experimental data. Thus, geopolymer cylinder concrete samples were produced using 15 different mixtures with SS/SH ratios of 1.5, 2.5 and 3.5, while AA/FA ratios of 0.4, 0.5, 0.6, 0.7 and 0.8. At the end of the study, the optimum SS/SH ratio was obtained as 2.5. A decrease in the AA/FA ratio increases the compressive and splitting tensile strength, while an increment increases the ductility and consuming energy. In addition, the relationship between the experimental data and the splitting tensile strength and modulus of elasticity formulations depending on the compressive strength given in other studies and regulations as a part of literature was investigated, and then, two alternative empirical formulations considering the ratios of alkali activators were proposed at the end of the regression analysis. When the stress-strain relationship of OPC concrete models and GPC mixtures were compared, the closest unconfined concrete model for GPC concrete was the Hognestad model.

Compressive Strength Study based on Fly Ash Geopolymer Concrete at the age of 28 days under very High Temperature

Due to creeping process at the burning material, material’s elastic modulus and yield strength will decrease.Three fire protection system are exist in handling the fire problem: active fire protection, passive fire protection, and safety management. In correlation with material problem due to fire, passive fire protection is a strategy to counter it. This paper presents the results of fire protection by using Suralaya fly ash geopolymer concrete. Three molaritas of geopolymer concrete mixture design are 2M, 4M, and 6 M. Sodium Silicate (Na2SiO3) and Sodium Hydroxide (NaOH) are used as alkaline activator. The results of the experiment were analysed by compressive strength for the optimum values. This study found that the value of compressive strength of steam curing is higher than that of water curing, the value of geopolymer concrete compressive strength of 2M is higher than that of 4M, and the value of geopolymer concrete compressive strength of 6M is higher than that of 4M.

Innovative use of micronized biomass silica-GGBS as agro-industrial by-products for the production of a sustainable high-strength geopolymer concrete

Micronized biomass silica (MBS) and ground granulated blast furnace slag (GGBS) are agro-industrial byproducts generated by incinerating of rice husk (grinding in jar mill) and blast furnaces that used produce iron, respectively. MBS accounts for 20% of the world's total paddy output of 590 million tons. These by-products (MBS and GGBS) have a high concentration of amorphous silica, which is utilized as a mineral additive in concrete. This amorphous silica interacts with hydration products, resulting in the formation of additional CSH gel. This improves concrete's strength and durability properties. Therefore, it is proven that inclusion of agro-industrial by-products in concrete helps to promote sustainable and greener development, which in turn reduces carbon footprints and waste that must be disposed of in landfills. There have been few investigations on concrete using MBS and demonstrated the great potential of employing MBS as a cement substitute or additive in normal concrete. Also, the utilization of MBS as partial replace to GGBS in geopolymer concrete (GPC) with different molarity is a novel aspect of this study. However, this study has the aim and limit to develop a high-strength eco-friendly GPC with agro-industrial byproducts (MBS and GGBS) for use in sustainable construction. The impact of incorporating MBS as a partial replacement of GGBS on compressive and split tensile strengths, sorptivity, and chloride permeability was tested up to the age of 28 days. MBS was used to replace GGBS in varying percentages in the preparation of concretes. MBS were used in concrete at 0%, 10%, 20%, and 30% replacement by weight. It was discovered that a GPC combination containing MBS 20% and the balance GGBS as the binder had the best performance in terms of its strength and durability. The compressive strengths of all GPC mixtures exceeded the intended design strength. The main findings of this study demonstrated clearly that MBS may be employed as a binder in the production of GPC.

Effective Utilization of Copper Slag for the Production of Geopolymer Concrete with Different NaOH Molarity under Ambient Curing Conditions

In spite of the considerable research on the mechanical and durability properties of geopolymer concrete, its widespread applicability is hindered due to the difficulties involved in achieving ambient curing conditions and awareness of the effective utilization of industrial by-products. This study investigates the physical and microstructure characterization of sustainable geopolymer concrete (GPC) developed with copper slag as a replacement for fine aggregate. In total, forty-four geopolymer concrete mixtures were prepared to examine their fresh and hardened properties. Four different NaOH molarities (10, 12, 14 and 16) and the replacement levels of copper slag, ranging from 0 to 100% with an increase of 10%, were considered as variables in this research. The study parameters examined includes the fresh (slump) and hardened concrete properties. Additionally, the microstructural characterization for different mixes were studied using the Fourier Transform Infrared Spectroscopy (FTIR), Electron Dispersive Spectrum (EDS) analyses and Scanning Electron Microscope (SEM). Results indicated that replacing fine aggregate with copper slag up to 100% showed no strength reduction. Increasing the molarity of the NaOH solution to 16M led to an increased strength of about 35% compared to the concrete with 10 M in all the mixes. The microstructural analysis performed using SEM/EDS and FTIR showed that a cohesive and fully compact geopolymer matrix was achieved together with the use of low-calcium fly ash and copper slag under ambient curing conditions.