Showing papers on "Geopolymer published in 2023"
TL;DR: In this article , high-strength geopolymers were prepared from red mud (RM) and Class 1, 2, and C fly ash (FA) rich in active substances (FA1, FA2, and FAC, respectively) in the presence of an AA.
31 citations
TL;DR: In this paper , seawater sea-sand Engineered Geopolymer Composites (SS-EGC) were developed and investigated for the first time, with two fly ash-to-slag ratios (8:2 and 2:8) considered in the matrices.
Abstract: In this study, seawater sea-sand Engineered Geopolymer Composites (SS-EGC) were developed and investigated for the first time. The developed EGC achieved high compressive strength (over 140 MPa) and high tensile ductility (around 8%) simultaneously. Emphasis was placed on understanding the influence of seawater and sea-sand (compared to freshwater and washed sea-sand) on the matrix properties and tensile performance of EGC, with two fly ash-to-slag ratios (8:2 and 2:8) considered in the matrices. Results showed that the use of seawater hindered the reaction of EGC matrix and led to a slight reduction of compressive strength (compared to the freshwater counterpart). It was found that the content of hydrotalcite phases in SS-EGC matrix was higher than that of freshwater EGC. In addition, using seawater was found to increase the average modulus of matrix obtained from nanoindentation, leading to a higher fiber/matrix bond strength. The tensile strain capacity of SS-EGC was slightly lower than that of freshwater EGC. The developed SS-EGC showed superior crack resistance and better sustainability than the cement-based counterpart from the literature (with similar compressive strength). The findings of this study provided useful knowledge for the design and development of high-strength high-ductility SS-EGC towards sustainable and resilient marine infrastructures.
21 citations
TL;DR: Geopolymer recycled aggregate concrete (GPRAC) is a new type of green material with broad application prospects by replacing ordinary Portland cement with geopolymer and natural aggregates with recycled aggregates as mentioned in this paper .
Abstract: Geopolymer recycled aggregate concrete (GPRAC) is a new type of green material with broad application prospects by replacing ordinary Portland cement with geopolymer and natural aggregates with recycled aggregates. This paper summarizes the research about the mechanical properties, durability, and microscopic aspects of GPRAC. The reviewed contents include compressive strength, elastic modulus, flexural strength, splitting tensile strength, freeze–thaw resistance, abrasion resistance, sulfate corrosion resistance, and chloride penetration resistance. It is found that GPRAC can be made to work better by changing the curing temperature, using different precursor materials, adding fibers and nanoparticles, and setting optimal mix ratios. Among them, using multiple precursor materials in synergy tended to show better performance compared to a single precursor material. In addition, using modified recycled aggregates, the porosity and water absorption decreased by 18.97% and 25.33%, respectively, and the apparent density was similar to that of natural aggregates. The current results show that the performance of GPRAC can meet engineering requirements. In addition, compared with traditional concrete, the use of GPRAC can effectively reduce carbon emissions, energy loss, and environmental pollution, which is in line with the concept of green and low-carbon development in modern society. In general, GPRAC has good prospects and development space. This paper reviews the effects of factors such as recycled aggregate admixture and curing temperature on the performance of GPRAC, which helps to optimize the ratio design and curing conditions, as well as provide guidance for the application of recycled aggregate in geopolymer concrete, and also supply theoretical support for the subsequent application of GPRAC in practical engineering.
18 citations
TL;DR: In this paper, a strain-hardening ultra-high-performance geopolymer concrete (SH-UHPGC) was produced using Na2CO3, Na2SiO3 and their hybridization (1:1 in mole ratio) as alkaline activators.
Abstract: In this study, strain-hardening ultra-high-performance geopolymer concrete (SH-UHPGC) was produced using Na2CO3, Na2SiO3 and their hybridization (1:1 in mole ratio) as alkaline activators. An ultra-high compressive strength was achieved for all the developed strain-hardening ultra-high-performance geopolymer concrete (i.e., over 130 MPa). Strain-hardening ultra-high-performance geopolymer concrete with hybrid Na2CO3 and Na2SiO3 activators showed the highest compressive strength (186.0 MPa), tensile strain capacity (0.44%), and tensile strength (11.9 MPa). It should be highlighted that very significant multiple cracking can be observed for all the strain-hardening ultra-high-performance geopolymer concrete even at a very low tensile strain level (e.g., 0.1%). According to the reaction heat, microstructures, and chemical composition analyses, strain-hardening ultra-high-performance geopolymer concrete with hybrid activators had the highest reaction degree, while that of Na2CO3-based strain-hardening ultra-high-performance geopolymer concrete was the lowest. It was found that the Na2CO3-based strain-hardening ultra-high-performance geopolymer concrete showed the best sustainability, and the strain-hardening ultra-high-performance geopolymer concrete with hybrid Na2SiO3 and Na2CO3 presented the best overall performance (considering the mechanical performance, energy consumption, environmental impact, and economical potential). The findings of this work provide useful knowledge for improving the sustainability and economic potential of strain-hardening ultra-high-performance geopolymer concrete materials.
17 citations
TL;DR: In this paper , the sample size effects of waste glass powder (WGP) and ground blast furnace slag (GBFS)-based geopolymer pastes cured at different conditions and ages on its physical properties and micro-characteristics were systematically investigated, including the mass loss, compressive strength, microstructures, and reaction products at different reaction stages.
17 citations
TL;DR: In this paper , a new mix design methodology was proposed by using fly ash and ground granulated blast furnace slag with 100% recycle aggregate, which is simpler and more consistent than previous procedures.
Abstract: Concrete is the most extensively used building material across the world. It can accommodate huge volumes of industrial waste by-products such as fly ash, ground granulated blast furnace slag, and construction and demolition waste which are generated in massive quantities from thermal power plants, steel plants, as a by-product, and construction waste debris respectively. Lots of fly ash, ground granulated blast furnace slag, and construction and demolition waste are discarded, creating environmental and storage issues. The manufacturing of recycled aggregate geopolymer concrete is one of the cost-effective ways to dispose vast amounts of debris. The use of recycled aggregate geopolymer concrete as structural concrete is not encouraged due to lack of appropriate mix design methodology. The current study aims to develop a new mix design methodology by using fly ash and ground granulated blast furnace slag with 100% recycle aggregate, which is simpler and more consistent than previous procedures. The suggested process has been further validated by developing a range of concretes with alkaline activate content to binder ratios ranging from 0.3 to 0.8. According to the present study, by using fly ash and ground granulated blast furnace slag along with recycled aggregate in concrete, compressive strength of an order of nearly 60 MPa can be obtained at the curing age of 28 days. SEM and XRD analysis were also carried out to evaluate the processes of polymerization. The results suggest that fly ash and ground granulated blast furnace slag have a superior synergetic influence on recycled aggregate geopolymer concrete performance. • Valorisation of recycled coarse aggregates in RAGPC. • Fresh properties characteristics of geopolymer concrete with aggregates obtained from demolition waste. • The influence of recycled aggregates on the strength of RAGPC. • The effects of RA content and AAC/B ratio on the performance of the RAGPC were investigated.
15 citations
TL;DR: In this article , an artificial geopolymer aggregate (GPA) was employed as a novel phase change materials (PCM) carrier for energy storage purposes, which can achieve an excellent mechanical strength greater than 53.2 MPa and thermal conductivity of 0.510-0.589 W/mK.
Abstract: Integrating phase change materials (PCMs) into building materials has been widely used to improve the energy efficiency of buildings, in which microencapsulation and shape stabilization of PCMs are considered as two most effective solutions. In this study, artificial geopolymer aggregate (GPA) was employed as a novel PCM carrier for energy storage purposes. Detailed investigations were conducted into the physical, mechanical, and thermal properties of GPA-PCM, which can be engineered through different raw material selections (e.g., slag content, water/binder ratio, and incineration bottom ash (IBA) content). It was demonstrated that increasing the IBA content is an efficient means to increase the porosity of GPA, an index of the capacity to accommodate PCM. Up to 16 wt.% PCM could be absorbed into the GPA through vacuum suction, resulting in a significant melting enthalpy of 24.74 J/g. Besides, GPA-PCM could achieve an excellent mechanical strength greater than 53.2 MPa and thermal conductivity of 0.510–0.589 W/mK. The time-temperature history curves of GPA revealed that up to 10.5 °C of thermal regulation was achieved due to PCM impregnation. The developed GPA-PCM composites facilitate an innovative and low-carbon solution for utilizing PCMs in construction for temperature-regulating and energy-saving purposes.
12 citations
TL;DR: In this article , the optimal percentage of slag and activators, such as potassium and calcium hydroxide ratio, were investigated in metakaolin-based geopolymer.
12 citations
11 citations
TL;DR: In this paper , the development and characterization of ambient-cured mortars with mixed CDW-based geopolymer binders and untreated fine recycled concrete aggregates (FRCA) was investigated.
11 citations
TL;DR: In this article , the design development of BWP-based geopolymer brick mixes by applying full factorial design (FFD) was investigated, where molarity (4M−12M), alkaline solution ratio (1.5-2.5), and curing temperature (40-60 °C) were the experimental factors that varied to find an optimum design mix.
TL;DR: In this article , a method of developing sodium silicate from rice husk ash (RHA) and using it as an activator in the development of one-part geopolymer binders has been proposed.
TL;DR: In this paper , the potential use of red mud as a raw material in the development of high-strength geopolymers was investigated, which achieved extraordinary early compressive strength as high as 68.8 MPa.
TL;DR: In this article , the influence of waste glass powder (WGP) with fly ash in certain proportions on geopolymer concrete (GPC) was investigated by exchanging different proportions of molarity and WGP percentages in GPC.
Abstract: The influence of waste glass powder (WGP) with fly ash in certain proportions on geopolymer concrete (GPC) was investigated by exchanging different proportions of molarity and WGP percentages in GPC. For this objective, fly ash was altered with WGP having percentages of 10%, 20%, 30%, and 40%, and the effect of molarity of sodium hydroxide (NaOH) was examined. The compressive strength tests, splitting tensile tests, and flexural strength tests were conducted. The workability and setting time were also evaluated. With the addition of WGP, the workability for molarities (M) of 11, 13, and 16 NaOH reduced by an average of 17%, 10%, and 67%, respectively. The findings showed that the slump values decreased as the molarity and WGP percentages increased. Molarity significantly affected the setting time, but WGP had no effect on the setting time. Although high molarity increased the capacity, this had a noticeable negative effect on the setting time and workability. This study demonstrated that WGP had a slight negative effect on the capacity and workability. Furthermore, when the combined effects of WGP and NaOH molarity were taken into account, the use of 10% WGP with M13 NaOH was recommended to obtain the optimum sustainable GPC considering both fresh and hardening properties. Scanning electron microscopy (SEM) analysis was done on the samples, too.
TL;DR: In this paper , the authors focus on the use of nanomaterials (NMs) to improve the characteristics of fresh and hardened Geopolymer Composites (GC) and detail the benefits and drawbacks of the integration of NMs in GC.
Abstract: Nanomaterials (NMs) are being used to enhance the properties of construction materials. This review focuses on the use of NMs to improve the characteristics of fresh and hardened Geopolymer Composites (GC). Over 335 research publications are reviewed to detail the benefits and drawbacks of the integration of NMs in GC. More specifically, this review outlines the effects of numerous NMs such as Nano Silica (NS), Nano Alumina (NA), Nano Titanium dioxide (NT), Carbon Nano Tubes (CNT), Multiwall Carbon Nano Tubes (MCNT), Nano Calcium Carbonate (NCC), Nano Zinc oxide (NZ), Graphene Oxide (GO), Nano Metakaolin (NMK), Nano Fly Ash (NFA), Nano Glass Powder (NGP) and Nano-clay(NC) on Geo-polymer Paste (GPP), Geo-polymer Mortar (GPM) and Geo-polymer Concrete (GPC). The presence of NMs was found to enhance the geo-polymerization reaction and result in a denser matrix. The presence of NMs also enhances the durability of GC by preventing micro-pores interconnectivity. In hindsight, our review indicates that the addition of NMs is directly tied to producing high-performance GC, which the construction industry can effectively readily adopt. Additional insights, challenges, and future research directions are identified and discussed toward the end of this review.
TL;DR: In this paper , the authors investigated the effect of brick waste content on the fresh properties of 3D printable mixes, such as flow, setting time and rheological properties, and evaluated the hardened properties of the 3D printed brick waste geopolymer.
Abstract: This study investigates alkali-activated brick waste powder as the binder for developing 3D printable geopolymer mixes. The brick waste was used as a partial replacement to fly ash in geopolymer binders. The effect of brick waste content on the fresh properties of printable mixes, such as flow, setting time and rheological properties were investigated. Besides, the hardened properties of 3D printed brick waste geopolymer were evaluated with the varying brick waste content in the mix. The test results demonstrated that the fresh properties of 3D printable mixes were improved with the brick waste content in the mix. Compared to the control mix, the mixes containing brick waste displayed high yield strength and apparent viscosity at an early age. On the contrary, the hardened properties of compressive strength and interlayer strength of 3D printed concrete specimens were decreased with the high brick waste content; however, the incorporation of brick waste for up to 10% has enhanced the hardened properties. Finally, the sustainability assessment of brick waste geopolymer studied with embodied energy and carbon emission calculations reveals the proposed geopolymer concrete could reduce the embodied energy and carbon emission by up to 60–80%, compared to OPC concrete.
TL;DR: In this paper , the latest research progress in the preparation of geopolymers from industrial solid waste containing heavy metals is reviewed, including the preparation techniques, application and solidification/stabilization mechanisms of heavy metals.
TL;DR: In this article , the abrasion and freezing-thawing resistance of fly ash (FA)-ground blast furnace slag (GBFS) based geopolymer mortars incorporating high content of tile ceramic wastes (TCWs) have been evaluated experimentally and mathematically using artificial neural network (ANN).
TL;DR: In this article , a novel hydrothermal technology was proposed for the solidification/stabilization of lead and cerium present in a sludge resulting from the glass polishing process.
TL;DR: In this article , the early-age reaction of metakaolin geopolymer prepared by activators with various silicate moduli was studied and a novel approach was firstly proposed to evaluate the early age reaction of geopolymers by using 1H low-field nuclear magnetic resonance (NMR) and isothermal calorimetry.
Abstract: Early-age reaction kinetics of geopolymers is one of the challenging issues associated to their mechanical performances and durability. In this work, the early-age reaction of metakaolin geopolymer prepared by activators with various silicate moduli was studied. Compared to conventional methods, a novel approach was firstly proposed to evaluate the early-age reaction of geopolymer by using 1H low-field nuclear magnetic resonance (NMR) and isothermal calorimetry. The state and relative quantity of water in geopolymer pastes were detected by NMR during reaction process. While in this timescale, the heat release of pastes was recorded by isothermal calorimetry. A good consistency to the measurement of reaction process between these two testing methods can be observed. Activator with low silicate modulus (i.e., high alkalinity) deepens the reaction degree at the same timescale and the gel pore volume is increased with the alkalinity of activator. This method is useful to monitor the early-age reaction process of geopolymer, which is expected to offer new insights into the early-age reaction kinetics of geopolymer.
TL;DR: In this paper , F-class fly ash (FFA) was refined and activated by a wet grinding process, and the activation effect of calcium carbide slag (19 %) and sodium silicate (1 %, 3 % and 5 %) was evaluated when used alone or in combination.
TL;DR: In this article , the authors utilized ground concrete waste powder including recycled paste powder and recycled concrete powder for sustainable metakaolin-based geopolymer mortar, and they found that concrete waste powders with irregular particle shape mainly contain hydration products, quartz and calcite.
Abstract: Upcycling of ground concrete waste powder as green binder is an effective and high-value approach to reducing concrete waste. This study utilized ground concrete waste powder including recycled paste powder and recycled concrete powder for sustainable metakaolin-based geopolymer mortar. Concrete waste powder with irregular particle shape mainly contains hydration products, quartz and calcite. Substituting concrete waste powder for metakaolin reduces the number of alkali-activated cementitious products in blended geopolymer paste, but the nucleation and filling effects of concrete waste powder can improve paste micro-structure. Incorporating concrete waste powder raises the drying shrinkage of geopolymer mortar; recycled paste powder blended geopolymer mortar has higher drying shrinkage than recycled concrete powder blended geopolymer mortar, and the maximum drying shrinkage of geopolymer mortar with 75% recycled paste powder is 178.7% higher than that of geopolymer mortar with 75% recycled concrete powder. The compressive strength first rises and then declines with the rise of concrete waste powder content. Recycled paste powder blended geopolymer mortar has better compressive strength than recycled concrete powder blended geopolymer mortar, and the 28-d compressive strength of geopolymer mortar with 75% recycled paste powder is 34.4% larger than that of geopolymer mortar with 75% recycled concrete powder. Substituting concrete waste powder for metakaolin up to 75% declines the water and chloride ingress in blended geopolymer mortar, and recycled paste powder blended geopolymer mortar has lower water absorption and chloride migration than recycled concrete powder blended geopolymer mortar. Optimizing concrete waste powder type and content can prepare sustainable metakaolin-based geopolymer mortar having superior strength and low transport property.
TL;DR: In this article , a high-ductile engineered geopolymer composites (EGC) using calcined natural clay was developed, and the effect of the slag and fiber contents on the tensile behavior of EGC was analyzed.
Abstract: An economical and widely available raw material is essential for the application and popularization of geopolymer. Due to the vast reserves of natural clay, calcined natural clay is considered a cost-effective geopolymer raw material. The present study aims at developing a high-ductile engineered geopolymer composites (EGC) using calcined natural clay. Firstly, natural clay as a construction waste was ground and calcined, and the calcined natural clay was mixed with ground granulated blast furnaces slag (GGBFS) and polyvinyl alcohol (PVA) fiber to prepare geopolymer composite samples. Then, the mini slump and uniaxial tensile test were conducted on the geopolymer composite samples, and the digital image correlation technology (DIC) was used to further analyze the effect of the slag and fiber contents on the tensile behavior of EGC. Finally, the optimal slag and fiber contents for EGC with highest ductility were proposed. The results showed that the natural clay exhibited a certain reactivity after a thermal activation process due to the presence of a small amount of kaolinite. The tensile properties of geopolymer composites prepared by calcined natural clay were significantly enhanced with increasing fiber content. Meanwhile, the incorporation of slag could enhance the tensile properties, while excessive slag content decreased the tensile properties. The EGC with 10.0% slag content and 2.5% fiber content exhibited the highest ductility, with an ultimate tensile strength of 3.61 MPa and a tensile strain capacity of 6.59%. • The engineered geopolymer composites were prepared by calcined natural clay. • The effect of slag and fiber content on the tensile behavior was analyzed. • The crack characteristics were analyzed by digital image correlation technology. • The slag and fiber content for the highest ductile geopolymer was proposed.
TL;DR: A comprehensive review of the state-of-the-art of EGC in terms of design theory, mix design, fabrication process, engineering properties, durability and environmental benefit is presented in this article .
Abstract: Engineered cementitious composite (ECC) featuring extraordinary tensile ductility is a promising option for many structural applications but its large-scale manufacture is not eco-friendly due to its binding ingredient, Portland cement. One of the potential alternatives to ECC is engineered geopolymer composites (EGC) that have been increasingly studied in recent years. This paper presents a comprehensive review of the state-of-the-art of EGC in terms of design theory, mix design, fabrication process, engineering properties, durability and environmental benefit, with special focus on the effects of different material composition factors including precursor, activator, aggregate, additive and fibre on the critical material properties of EGC especially uniaxial tensile properties. The correlations between essential mechanical properties are discussed in depth. The unique tensile behaviour of EGC can be tailored by modifying the material composition that would change its internal microstructure and in turn alter the matrix properties and fibre-matrix interfacial behaviour. Compared to typical ECC, around 64% of EGC mixtures have higher tensile strain capacity (over 2.49%) and about 27% of mixtures exhibit larger tensile strength (over 4.86 MPa). Through adjusting the mix design of EGC, it holds promises as a cost-effective and sustainable material for applications against dynamic loadings, fire and chemical attacks, as well as 3D concrete printing. This review summarises the recent advances in EGC and identifies the remaining challenges in development of EGC with desired properties for practical applications.
TL;DR: In this paper , a novel eco-friendly geopolymer was synthesized from 100% solid wastes comprising red mud (RM), calcium carbide slag (CS), ground granulated blast furnace slag and fly ash (FA) in order to lower the carbon footprint of geopolymers by avoiding the utilization of energy-intensive commercial alkali activators.
Abstract: The commercial alkali activators could account for more than 50% of the cost for producing geopolymers. Thus, to lower the carbon footprint of geopolymer by avoiding the utilization of energy-intensive commercial alkali activators, a novel eco-friendly geopolymer was synthesized from 100% solid wastes comprising red mud (RM), calcium carbide slag (CS), ground granulated blast furnace slag (GGBS) and fly ash (FA) in this study. Effects of GGBS contents and curing conditions on the compressive strength, fluidity and water requirement for normal consistency were investigated. The hydration products in the binders cured at different conditions were characterized by X-ray diffraction (XRD), thermogravimetric (TG), Fourier transformation infrared spectroscopy (FTIR) and scanning electronic microscopy (SEM). The results showed that GGBS improves the compressive strength as well as the mortar fluidity and reduces the water requirement for normal consistency of the geopolymer. Raising the curing temperature up to 60 °C and prolonging the heat curing duration to 12 h facilitate the dissolution and polymerisation of the FA-GGBS and therefore increase the amount of gel and crystalline products, whereas excessive heat-curing at temperatures higher than 60 °C and durations longer than 12 h causes shrinkage cracks at later age, which was detrimental to the compressive strength. The mineralogical characterization revealed that the amount of gel governs the strength development and heat curing favors the formation of secondary crystalline phase hydrotalcite. The developed binder can be used to produce low-carbon clinker-free concrete blocks to improve the sustainability of concrete industry.