Self-compacting Geopolymer Concrete Research Articles

Influence of Activator Solution and Binder Composition on the Characteristics of Self-Compacting Geopolymer Concrete

Influence of Activator Solution and Binder Composition on the Characteristics of Self-Compacting Geopolymer Concrete

Study of silicon dioxide nanoparticles on the rheological and mechanical behaviors of self-compacting geopolymer concrete

Study of silicon dioxide nanoparticles on the rheological and mechanical behaviors of self-compacting geopolymer concrete

Influential studies on microsilica as a potential replacement for fly ash-GGBFS in self-compacting geopolymer concrete: Microstructural insights and performance analysis

Influential studies on microsilica as a potential replacement for fly ash-GGBFS in self-compacting geopolymer concrete: Microstructural insights and performance analysis

Self-compacting geopolymer concrete using Class F Fly Ash

The development of self-compacting geopolymer concrete has the dual advantages of reducing environmental pollution and managing waste. The objective of the current experimental study is to create self-compacting geopolymer concrete with the best sodium silicate to sodium hydroxide ratio utilizing class F fly ash and sodium hydroxide. With varying sodium silicate to sodium hydroxide ratios (2.1, 2.3, 2.5, and 2.7), different molarities of sodium hydroxide (NaOH) (10M, 12M, and 14M) have been examined for workability and strength behavior. Self-compacting geopolymer concrete is found to be the ideal combination for a 12M sodium hydroxide solution and a 2.5 ratio of sodium silicate to sodium hydroxide solution.

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.

AI-driven critical parameter optimization of sustainable self-compacting geopolymer concrete

This study aims to optimize the critical parameters of self-compacting geopolymer concrete (SCGC) with a primary focus on enhancing compressive strength. Optimization of SCGC holds significant importance within the context of sustainable development. To implement the research, a comprehensive database was meticulously compiled by integrating data from published literature, with Fly ash and GGBFS serving as essential binders. Prior to the development of a robust machine learning model, the database underwent careful preprocessing to ensure data quality. In pursuit of optimal performance, three machine learning model's (base model) hyperparameters were diligently fine-tuned employing effective spotted hyena metaheuristic optimization technique. A hybrid model was developed using three base models and a meta-learner. The hybrid model outperformed other models owing to better accuracy and generalizability. Leveraging quasi-Monte Carlo sensitivity analysis, this study effectively identified temperature, Na2SiO3/NaOH, NaOH molarity, and percentage of superplasticizer as critical parameters with the highest impact on compressive strength. Optimization involved adjusting the temperature (25–90 °C), Na2SiO3/NaOH concentration (8–16 M), molarity (1.5–4), and superplasticizer amount (2–10%). The optimization of these crucial parameters was effectively executed using Response Surface Methodology (RSM). This study introduces a novel integrated approach within RSM, deviating from conventional quadratic or polynomial models for interaction characterization. The optimized parameters were consistent across cases involving fly ash, GGBFS, and a blend of both binders, except for temperature, which varied based on the binder type. The optimized mix parameters are used for experimental validation of results obtained through AI-driven analysis and observed to provide an expected result of compressive strength in the range of 39–43 MPa.

Influence of coatings on residual strength of geopolymer concrete columns subjected to fire exposure: An experimental investigation

Fires occurring within buildings present a grave concern, as they entail substantial risks to human lives, property, and the environment. Implementing appropriate fire safety measures becomes imperative to mitigate the occurrence of fires and ensure efficient response in the event of an incident. The primary aim of the study is to examine the performance of various coatings on the residual strengths of the reinforced normal strength self-compacting geopolymer concrete (NSGC) and high strength self-compacting geopolymer concrete (HSGC) columns subjected to standard temperature exposure in accordance with ISO 834 guidelines. The design compressive strength of the concretes was 36.12, 57.06 and 52.8 MPa. Two types of coating were employed in the present investigation namely ceramic wool wrapping and high alumina cement. A computerized electric furnace is used to heat the column specimens. Amongst the forty-two columns developed, six specimens tested without temperature exposure and protective coating as a reference specimen. Twelve specimens were heated as per ISO fire curve and tested to assess the residual axial strength performance and twenty-four specimens were coated with protective layers, then heated and tested to assess the post fire performance. It is exemplified that the composite protective coating offers effective resistance to concrete, gaining optimum axial strength performance. The findings show that these fire protecting composites have a high potential for utilizing as new strengthening techniques for reinforced concrete (RC) columns.

GGBFS-Based Self-Compacting Geopolymer Concrete with Optimized Mix Parameters Established on Fresh, Mechanical, and Durability Characteristics

GGBFS-Based Self-Compacting Geopolymer Concrete with Optimized Mix Parameters Established on Fresh, Mechanical, and Durability Characteristics

Interfacial bond behavior between normal OPC concrete and self-compacting geopolymer concrete enhanced by nano-SiO2

This study investigated the interfacial bond performances between ordinary Portland cement concrete (OPCC) and self-compacting geopolymer concrete (SCGC). The studied factors include nano-SiO2, repair material type, curing time, casting direction, and interface pretreatment method. The interfacial bond performances were assessed by Bi-surface shear and drying shrinkage tests. The evolutions in elemental compositions, hydration products, and microstructure in the matrix and interface were verified by BSE/EDS, XRD, and FTIR tests, respectively. ANOVA analysis was conducted to quantitatively analyze the influences of each factor from a statistical approach. The results demonstrated that the bond strength of SCGC increased by 24.5% to 31.7% compared to conventional OPCC. Meanwhile, geopolymers exhibited more compact microstructures but higher drying shrinkage (εsh,u=891 µε). While nanofillers significantly amplified the cracking potential of geopolymers, which was attributed to the higher early-stage autogenous shrinkage instead of drying shrinkage. The SCGC showed a high enrichment degree of calcium at the interface, indicating that more calcium-rich products were formed. In contrast, the use of nano-SiO2 in SCGC caused the enrichment of Na, Al, and Si at the interfacial regions, which provided extra nucleation sites for the polymerization of (C, N)-A-S-H gels. The nano-SiO2 enhanced the intensity of the hydroxide ion and Si-O-T band and promoted the formation of (C, N)-A-S-H gels. The ANOVA analysis proved that the repair material, nano-SiO2, and interface treatment were significant factors to affect the interfacial bond strength. In addition, geopolymer-based repair materials were less sensitive to the casting direction, which differed from the conventional self-compacting OPCC.

Assessing the engineering properties of massive self-compacting geopolymer concretes utilising the Taguchi method

In this article, the potential of employing self-compacting geopolymer concrete in massive elements has been investigated. The main binder consisted of 85% ground granulated blast furnace slag and 15% fly ash. An alkaline solution of sodium hydroxide and sodium silicate was utilised. The effects of four parameters (binder content, water-to-binder [W/B] ratio, Na2O% and coarse-to-fine aggregate [C/F] ratio) on the fresh, mechanical and thermal properties of Massive Self-Compacting Geopolymer Concrete (MSCGC) mixes were evaluated. Taguchi’s design of experiments was used to minimise the number of trial mixes. The heat of geopolymerisation of MSCGCs was monitored using a semi-adiabatic chamber and then applied to concrete samples using a temperature match curing system. The maximum compressive and splitting tensile strengths and modulus of elasticity were 62.7 MPa, 5.04 MPa and 33.26 GPa, respectively. Binder content was identified as the most significant parameter affecting the thermal and mechanical properties of the mixtures. The impact of the C/F ratio was greater than the W/B ratio on the thermal characteristics. The results of a numerical analysis reveal that although a higher binder content enhances the mechanical properties of the MSCGCs, it leads to an increased risk of cracking owing to greater heat production.

Developing a sustainable self-compacting geopolymer concrete with 100% geopolymer-coated recycled concrete aggregate replacement

PurposeConcrete, the second most used material in the world, surpassed only by water, relies on a vast amount of cement. The process of cement production emits substantial amounts of carbon dioxide (CO2). Consequently, it is crucial to search for cement alternatives. Geopolymer concrete (GC) uses industrial by-product material instead of traditional cement, which not only reduces CO2 emissions but also enhances concrete durability. On the other hand, the disposal of concrete waste in the landfills represents a significant environmental challenge, emphasising the urgent need for sustainable solutions. This study aimed to investigate waste concrete's best form and rate as the alternative aggregates in self-compacting and ambient-cured GC to preserve natural resources, reduce construction and demolition waste and decrease pertinent CO2 emissions. The binding material employed in this research encompasses fly ash, slag, micro fly ash and anhydrous sodium metasilicate as an alkali activator. It also introduces the best treatment method to improve the recycled concrete aggregate (RCA) quality.Design/methodology/approachA total of25%, 50% and 100% of coarse aggregates are replaced with RCAs to cast self-compacting geopolymer concrete (SCGC) and assess the impact of RCA on the fresh, hardened and water absorption properties of the ambient-cured GC. Geopolymer slurry was used for coating RCAs and the authors examined the effect of one-day and seven-day cured coated RCA. The mechanical properties (compressive strength, splitting tensile strength and modulus of elasticity), rheological properties (slump flow, T500 and J-ring) and total water absorption of RCA-based SCGC were studied. The microstructural and chemical compositions of the concrete mixes were studied by the methods of energy dispersive X-Ray and scanning electron microscopy.FindingsIt is evident from the test observations that 100% replacement of natural aggregate with coated RCA using geopolymer slurry containing fly ash, slag, micro fly ash and anhydrous sodium metasilicate cured for one day before mixing enhances the concrete's quality and complies with the flowability requirements. Assessment is based on the fresh and hardened properties of the SCGC with various RCA contents and coating periods. The fresh properties of the mix with a seven-day curing time for coated RCA did not meet the requirements for self-compacting concrete, while this mix demonstrated better compressive strength (31.61 MPa) and modulus of elasticity (15.39 GPa) compared to 29.36 MPa and 9.8 GPa, respectively, for the mix with one-day cured coated RCA. However, incorporating one-day-cured coated RCA in SCGC demonstrated better splitting tensile strength (2.32 MPa) and water absorption (15.16%).Research limitations/implicationsA potential limitation of this study on SCGC with coated RCAs is the focus on the short-term behaviour of this concrete. This limited time frame may not meet the long-term requirements for ensuring the sustained durability of the structures throughout their service life.Originality/valueThis paper highlights the treatment technique of coating RCA with geopolymer slurry for casting SCGC.

Production of durable high-strength self-compacting geopolymer concrete with GGBFS as a precursor

Production of durable high-strength self-compacting geopolymer concrete with GGBFS as a precursor

Mix design process for sustainable self-compacting geopolymer concrete

Faster growth of infrastructure emphasizes the utilization of eco-friendly construction materials with a low carbon footprint. The objective of this experimental study is to propose a mix design methodology for self-compacting geopolymer concrete (SCGC) considering various influencing parameters recommended for self-compacting concrete (SCC) and geopolymer concrete (GPC). The experimental test results depict that SCGC had similar flow deformability with comparatively lesser flow speed compared to SCC. The increase in a sodium hydroxide (NaOH) molarity from 8 M to 16 M negatively affected the flow deformability as well as the flow speed of SCGC. The optimum compressive strength of 37 MPa was attained for SCGC having silica sand as fine aggregate, NaOH concentration of 16 M, fly ash to sand ratio (FA/S) of 0.75, and cured for 48 H at 80 °C. A mathematical equation is proposed to calculate Young's modulus of SCGC which is around 15 GPa. Young's modulus of SCGC was lesser than OPC concrete recommended by the ACI 318, however, Poisson's ratio of SCGC was found in the recommended range of OPC concrete. A flow chart is proposed for the mix design of SCGC with consideration of experimental test results in fresh and hardened stages.

Axial compressive behaviour and physical characteristics of high strength self-compacting geopolymer concrete (HSGC) columns exposed to elevated temperature

The growing demand in the utilization of the cement has increased carbon emissions, necessitating the adoption of new technologies that are eco-friendly. Geopolymer concrete (GC) is a viable alternative to traditional cement-based concrete, with superior mechanical properties and sustainable performance. However, research on the elevated temperature exposure of geopolymer paste, mortar, and concrete is limited, particularly with respect to high-strength and self-compacting geopolymer concrete. This study aims to investigate the performance of high-strength self-compacting geopolymer concrete (HSGC) at room temperature and elevated temperatures up to 1029 ℃. The investigation is carried out consisting of two strength grades: normal strength GC and HSGC. Tests are conducted on both HSGC cube and column specimens to examine the residual compressive strength (CS) and axial compression performance of the concrete before and after exposure to elevated temperature. The fresh physical characteristics of HSGC are examined following EFNARC guidelines. Post-fire performance is analysed through physical observation, surface modification, crack pattern, weight loss (WL), and residual CS of HSGC samples. Load-Moment (P-M) interaction curves are developed to predict the ultimate load and ultimate moment capacity of the HSGC columns before and after exposure to elevated temperature. The ductility of heated and unheated HSGC columns is found to be almost same. Microstructural analysis, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS) are performed to examine the internal morphology of the HSGC samples before and after exposure to elevated temperature. Furthermore, a life-cycle assessment (LCA) is conducted to compare the cost of HSGC production with conventional cement-based concrete. The analysis indicates that HSGC emits 6.15% less CO2-e than its counterpart cement-based concrete.

Mechanical and microstructural properties of MK-FA-GGBFS-based self-compacting geopolymer concrete composites

Self-compacting geopolymer concrete (SCGC) is an eco-efficient and sustainable concrete with a lower carbon footprint than conventional concrete. The combination and doping of composites present a challenge in investigating the mechanical and microstructural properties of SCGC. This experimental work investigated the effect of different dosing levels of metakaolin (MK), fly ash (FA), and ground granulated blast furnace slag (GGBFS) on the properties of SCGC composites from both macroscopic and microscopic aspects. The main objectives of this study are to determine the fresh properties of SCGC in the fresh state and its mechanical properties in the hardened state and to explain the reasons for the differentiation of macroscopic properties through mesoscopic and microscopic analyses. Results showed that both MK and GGBFS reduce the flowability of fresh geopolymer concrete, with MK having a greater negative effect than GGBFS, with maximum and minimum slump flows of 645 mm and 505 mm, respectively. With the increase of MK and GGBFS admixture, the compressive strength of SCGC continuously increased until reaching the maximum value of 51.76 MPa, which corresponded to maximum admixtures of 50% and 40% for MK and GGBFS, respectively. GGBFS had the greatest positive effect on the rapid development of the early mechanical properties of SCGC, with calcium oxide (CaO) playing a crucial role. The 3d/7d compressive strength of SCGC was 0.83/0.85 of 28d when the slag admixture reached 40%, respectively. Strength prediction models with excellent fit coefficients were developed, and the correlation coefficients for the three equations were 0.83, 0.98, and 0.99. A higher stress level of SCGC corresponds to a higher intensity and density of the acoustic emission signal. Thermal analysis results showed that the higher the CaO content in the SCGC specimen, the smaller the residual mass of the sample, i.e., the higher the number of gels and compressive strength. Scanning electron microscope images showed that a higher CaO content of SCGC corresponded to a denser matrix structure and better mechanical properties.

Behavioural studies on binary blended high strength self compacting geopolymer concrete exposed to standard fire temperature

The production of Ordinary Portland Cement Concrete (OPCC) results in high carbon emissions and energy demand, necessitating the search for eco-friendly alternatives. Geopolymers, which utilize waste materials, are identified as a suitable alternative. Industrial by-products such as Fly Ash (FA), Ground Granulated Blast Furnace Slag (GGBS), and Metakaolin (MK) are used as precursor materials for binary blended High Self-Compacting Geopolymer Concrete (HSGC) production. Two HSGC mixes and one normal strength self-compacting mix are developed for comparison. This study aims to look at the residual strength characteristics of NSGC and HSGC specimens. Binary blended NSGC, HSGC, and temperature exposure are the key factor examined in the present study. The current study aimed to evaluate the residual strength of NSGC and HSGC exposed to temperature exposure using the ISO 834 guidelines. HSGC specimens are divided into four groups based on curing and cooling type: ambient curing, oven curing, air cooling, and water cooling. Mechanical properties such as Compression Strength, Tensile Strength, and Flexural Strength before and after exposure to elevated temperature are evaluated. Microstructural investigations are conducted to examine the internal structure of the binary blended HSGC mixes. The experimental results are validated using Indian code (IS 456), American code (ACI 318), European code (EC2), and Australian code (AS 3600). Compressive strength of the HSGC specimens was severely reduced when subjected to 1029 ℃, resulting in the formation of wider cracks attributed to the degradation of the gel structure. The oven-cured specimens possess 72 to 80% loss in strength, whereas ambient-cured specimens possess 77 to 86% loss in strength. The findings reveal that the binary blended mix FA/MK = 1 exhibits higher strength loss (%) compared to FA/GGBS and FA. Ambient-cured HSGC specimens exhibit higher mass loss than oven-cured HSGC mixes, and water-cooled samples show higher strength loss and wider cracks compared to air-cooled specimens. The scientific value of this study lies in the the fire performance and residual mechanical properties of binary blended HSGC mixes developed under various curing and cooling methods. Also, the experimental results are validated with multiple international codes (American, Australian and Indian Standards). These findings contribute to the understanding on the behaviour of HSGC under elevated temperature conditions by providing valuable insights for the development of eco-friendly concrete alternatives with improved fire performance.

Workability and Compressive Strength of Self-Compacting Geopolymer Concrete Blended with Industrial and Agricultural Waste

Workability and Compressive Strength of Self-Compacting Geopolymer Concrete Blended with Industrial and Agricultural Waste

Structural assessment of Basalt FRP reinforced self-compacting geopolymer concrete using artificial neural network (ANN) modelling

Basalt FRP geopolymer composites are considered a sustainable solution to address the conventional OPC-Steel composite structures' structural and environmental concerns, especially the increased carbon emissions and structural deterioration due to corrosion attacks. Recent research on novel composites reports the superior performance of these FRP-geopolymer concrete structural applications reporting high strength and durability. However, the existing design guidelines do not accurately predict the flexural capacity and strength characteristics, which hinders the broader use of FRP-based geopolymer composites. This study aims to develop a prediction tool to help the researchers model the structural performance of the novel FRP-geopolymer composite based on modern machine learning algorithms. It shall address the lack of data on novel composites' structural and long-term performance in various exposure conditions. This paper thus reports the suitability of Artificial Neural Network (ANN) based models to accurately predict the flexural strength of Basalt FRP reinforced self-compacting geopolymer concrete beams under various exposure conditions. The ANN model is trained and validated against the experimental data from the long-term study conducted on the beam specimens subjected to one-year ambient and marine exposures. The ANN prediction model developed in this study reported close agreement with the experimental data showing better prediction accuracy than the existing empirical and numerical models.

Long-term performance of basalt fibre-reinforced marine geopolymer concrete in harsh environment

The current study reports on the long-term structural performance of novel reinforced marine geopolymer concrete beams under accelerated weathering conditions. The study covers the flexural performance of 40 geopolymer concrete beams reinforced with basalt fibre-reinforced polymer (BFRP) bars, including 12 beams under sustained loading when exposed to 3, 6 and 12 months of accelerated marine environment consisting of tidal cycles of seawater at a temperature of 50°C. The experimental results revealed that the novel marine geopolymer concrete reinforced with BFRP bars reported minimal micro- and macro-mechanical degradation compared to geopolymer concrete or ordinary concrete beams under the same exposure environment, with and without sustained loading. The BFRP-reinforced self-compacting geopolymer concrete (SCGC) beams reported 87% residual ultimate load after 12 months of exposure to marine environments, while the sustained loaded BFRP-SCGC beams reported a residual strength of 79%. In addition, microstructural assessment using scanning electron microscopy and energy dispersive X-ray spectroscopy analysis revealed that after 12 months of exposure there was a trace of chloride salts, indicating the chemical ingress over time; however, the impact on structural properties is not distinct.

Influence of GGBFS-based blended precursor on fresh properties of self-compacting geopolymer concrete under ambient temperature

Geopolymer concrete having self-compacting nature is known as self-compacting geopolymer concrete (SCGC) which does not need mechanical compaction to improve the concrete density. The geo-polymerization process primarily depends on aluminosilicate materials and alkaline activator solution (AAS). The type of precursor material greatly affects the hardened concrete properties i.e. both the short-term and long-term concrete characteristics. The present study aims to achieve an optimal blended precursor-based SCGC possing acceptable fresh property characteristics where ground granulated blast furnace slag (GGBFS), the precursor in the control GGBFS-based SCGC is partially replaced by silica fume (SF), and rice husk ash (RHA) with various proportions. Mix proportions with the replacement of GGBFS by SF (10%, 20%, 30%, 40%) and RHA (5%, 10%, 15%, 20%) are prepared along with one control GGBFS-based SCGC. The fresh property of the nine SCGC mixes are interpreted through the filling ability (slump flow, T50cm slump, V-funnel); passing ability (L-box, J-ring), and resistance to segregation (V-funnel at T5minutes) test. All the ambient temperature-cured SCGCs are made with the following mix parameters: 12 M sodium hydroxide molarity, AAS ratio of 2.5, superplasticizer dose of 7%, and extra water of 24%.