Geopolymer Foams Research Articles

Effect of Precursor Blending Ratio and Rotation Speed of Mechanically Activated Fly Ash on Properties of Geopolymer Foam Concrete

This research used fly ash and slag to create geopolymer foam concrete. They were activated with an alkali, resulting in a chemical reaction that produced a gel that strengthened the concrete’s structural integrity. The experimental approach involved varying the fly ash content in the precursors at incremental percentages (10%, 30%, 50%, 70% and 90%) and subjecting the fly ash to mechanical activation through a planetary ball mill at distinct rotational speeds (380, 400, 420 and 440 rpm). The investigation discerned that the fly ash content and particle structure exert a discernible influence on macroscopic properties, including flowability, air generation height, compressive strength, dry density and microstructural characteristics such as pore distribution and hydration product arrangement in the geopolymer foam concrete. Employing analytical techniques such as X-ray diffraction (XRD) and scanning electron microscopy (SEM), it was deduced that diminishing the fly ash content correlates with an enhancement in compressive strength. Furthermore, the specific strength of the geopolymer foam concrete reached a peak of 0.041 when the activated fly ash in the planetary ball mill rotated at 420 rpm, manifesting a lightweight and high-strength outcome.

POROUS FLY ASH-BASED GEOPOLYMER USABLE AS AN UNCONVENTIONAL CONSTRUCTION MATERIAL

Geopolymer foam with thermal insulation properties was made by foaming the alumino-silicate mixture composed of fly ash and clay brick waste activated with alkaline activator (water glass and sodium hydroxide in aqueous solution). Other mixture components were expanded perlite as siliceous additive, usual fine aggregate (quartz sand), and less frequently used surfactant (olive oil). The main characteristics of the geopolymer foam were: low density, low thermal conductivity, and relatively high compressive strength. The residual materials contributed to low costs and the complete replacement of ordinary cement led to the significant reduction of CO2 emissions.

A Review of Lightweight Geopolymer Concrete Based on Slag

Abstract: The studies on Lightweight Geopolymer concrete (LGC) are leading-edge in the development of sustainable and ecofriendly concrete. Attempts were being made to develop LGC by various methods of production. This paper reviews about previously published research work on lightweight geopolymer concrete and the observations to the material binders - an alternate to the Ordinary Portland Cement (OPC) by the utilization of industrial by-products, alkaline activator solution, foaming agents, chemical expansive agents, lightweight aggregate, production methods, and their physical and mechanical properties. The main focus is to investigate pore size formation, density, compressive strength and curing conditions. From the review it is found that the stabilization of foam and the control of efflorescence are the two challenging problems faced by the industry for the mass production of lightweight geopolymer foam concrete. Furthermore, topics for future work in this field were suggested.

Physical and high temperature properties of basalt fiber-reinforced geopolymer foam with hollow microspheres

For ultra-light geopolymer foam, it is challenging to maintain excellent mechanical properties and foaming stability while continuously reducing the density. In this study, basalt fibers (BF) and hollow microspheres (HM) were used to prepare a basalt fiber-reinforced metakaolin (MK)-based geopolymer foam (FRGF) and the workability, microstructure, physical properties, high-temperature performance, and shrinkage characteristics were systematically investigated. Results indicate that incorporating 50% HM into FRGF significantly reduces the fluidity by 31.2% and reaction rate of the geopolymer paste, slows down the decomposition rate of hydrogen peroxide, and enhances the stability of the foaming process. Additionally, the incorporation of HM increases the total porosity of the FRGF from 75.4% to 86.3%, lowers the bulk density from 0.42 g/cm3 to 0.34 g/cm3, and decreases the thermal conductivity to 0.0681 W/(m⋅K). Concurrently, the introduction of BF significantly enhances the mechanical properties of FRGF, with a 28-day compressive strength reaching 2.49 MPa. After treatment at 1000 ℃, the FRGF transformed from an amorphous gel structure to a crystalline structure. The sintering between BF and the matrix notably enhances the performance of interfacial transition zone (ITZ), further increasing the energy absorption capability and decreasing the linear shrinkage of FRGF at high temperatures (1000 °C) by 55.2%. In conclusion, 50% HM and 0.6% BF demonstrated superior mechanical properties, thermal insulation, and high-temperature performance. It offers a strategy to resolve the contradiction between the density, mechanical performance, and stability of geopolymer foams and has potential applications in the field of high-temperature insulation.

Geopolymer Foam Reinforced with Iron Ore Flotation Tailing for Potassium Adsorption and Controlled Release in Water

Geopolymer Foam Reinforced with Iron Ore Flotation Tailing for Potassium Adsorption and Controlled Release in Water

Robotic 3D Printing of Geopolymer Foam for Lightweight and Insulating Building Elements.

Foam 3D printing in construction is a promising manufacturing approach that aims to reduce the amount of material, hazardous labor, and costs in producing lightweight and insulating building parts that can reduce the operational energy in buildings. Research using cement-free mineral foams derived from industrial waste showed great potential in previous studies that reduced the amount of concrete needed in composite structures. This article collates the latest developments in this line of work. It presents the material system with its principal components and the advanced robotic 3D printing setup with a climate-controlled fabrication chamber. Print path schemes and hybrid fabrication methods combining 3D printing and casting are evaluated. Furthermore, the article discusses the effect of different print path schemes on the thermal insulation and compressive strength performance of printed parts. A full-scale final prototype synthesizes these findings and demonstrates the fabrication of modular, lightweight, and insulating construction elements that can be assembled into monolithic wall structures. The advantages and challenges of this novel approach are elaborated on in the conclusions. Finally, the article presents future advancements required to leverage this research as a scalable construction method that can help address the biggest challenges in building low-carbon and energy-efficient structures.

Experimental investigation and numerical modeling on mechanical behavior of highly porous cement-based material: An overview

This paper presents an overview of recent developments in experimental investigation and numerical modeling of highly porous cement-based materials, focusing on traditional Portland cement (PC) and geopolymer foam concrete. It starts by introducing the advantages of using highly porous cement-based materials compared to their dense counterparts and then delves into the properties of PC and geopolymer foam concrete. The first part of the review is dedicated to the experimental investigation, including mixture proportions, foaming methods, mechanical properties and air-void systems. This part also summarizes and discusses various strength prediction models for foam concrete that were drawn from experimental data. The second part of the review is dedicated to the computational methods used to simulate porous materials, and attention is focused on continuum-based and discrete-based approaches. Finally, the failure mechanism of porous cement-based materials is discussed, along with comparing the failure criteria for both dense and porous cement-based materials.

Mechanical properties and energy absorption performance of foamed geopolymer under quasi-static and dynamic compression

To assess the potential for substituting foam concrete with low-carbon foamed geopolymer (FG) in the field of structural protection, a series of quasi-static and dynamic compression tests were conducted. These tests aimed to examine the mechanical performance and energy absorption of FG while considering the factors of FG density, granulated blast furnace slag (GBFS) replacement rate, and water–solid ratio. Additionally, supplementary investigations involving XRD analysis, indentation tests, X-CT scanning, and 3D reconstruction techniques were conducted to explore the influence of GBFS replacement rate on the energy absorption of FG in terms of base material properties and internal pore structure. The results of the quasi-static compressive tests showed that increasing the FG density and reducing the water–solid ratio had a positive effect on energy absorption, however, it also resulted in a notable increase in peak strength. Increasing the GBFS replacement rate not only enhanced the load-bearing capacity but also increased the extent of spalling damage, thus FG with a moderate GBFS replacement rate of 20% demonstrated superior performance in terms of energy absorption and load transfer. Under dynamic compression, all specimens predominantly experienced vertical splitting failure. However, with increasing loading velocity, crushing failure emerged at the two ends of the specimens, particularly in the case of low-density specimens. As the loading velocity increased, the specimen exhibited a significant increase in peak strength, demonstrating a notable strain rate effect, however, the energy absorption of the specimen remained relatively stable without significant alterations. In addition, a simplified DIF was proposed to predict the peak strength of FG with varying densities and two distinct GBFS replacement rates under different strain rates. It provided some valuable insights into the potential application of FG in the field of structural protection.

Preparation of porous metakaolin-based geopolymer foam as an efficient adsorbent for dye removal from aqueous solution

Dye removal from aqueous solutions as one of the dangerous and non-degradable pollutants is one of the critical environmental issues discussed today. In this research, metakaolin-based geopolymer foam adsorbent was fabricated using a templating emulsion/chemical foaming method, characterized, and utilized to remove methylene blue dye from an aqueous solution. Dye adsorption studies were performed using batch experiments and operational parameters such as contact time, initial pH solution, temperature, initial dye concentration, adsorbent dose, and pHPZC the adsorbent investigated. The various kinetic models (pseudo-first-order, pseudo-second-order, and intraparticle diffusion) and isotherms (Langmuir, Freundlich, and Temkin) were used to analyze the experiment results. The fabricated adsorbent surface includes the bulk porous structure consisting of novel flower-like hierarchical microstructures made up of dozens of nanorods building block units. The adsorption results were fitted to the pseudo-second-order kinetic with an equilibrium time of 120 min and Freundlich isotherm models. The highest methylene blue adsorption was obtained up to 90 %. Maximum adsorption capacity was obtained at 12.5 mg/g for 10 mg/L dye solution in 40 °C and pH = 13. According to the thermodynamic investigation, the methylene blue adsorption on the geopolymer foam adsorbent was performed as spontaneous and endothermic due to the negative value of the ΔG° and positive value of ΔH°. The prepared adsorbent could remove different cationic and anionic dyes from aqueous solutions but exhibited the highest adsorption efficiency towards cationic dyes. The prepared geopolymer exhibited good adsorption performance as a promising adsorbent for dye wastewater.

Eco-Friendly Coal Gangue and/or Metakaolin-Based Lightweight Geopolymer with the Addition of Waste Glass.

Massive amounts of deposited coal gangue derived from the mining industry constitute a crucial problem that must be solved. On the other hand, common knowledge about the recycling of glass products and the reuse of waste glass is still insufficient, which in turn causes economic and environmental problems. Therefore, this work investigated lightweight geopolymer foams manufactured based on coal gangue, metakaolin, and a mix of them to evaluate the influence of such waste on the geopolymer matrix. In addition, the effect of 20% (wt.) of waste glass on the foams was determined. Mineralogical and chemical composition, thermal behaviour, thermal conductivity, compressive strength, morphology, and density of foams were investigated. Furthermore, the structure of the geopolymers was examined in detail, including pore and structure thickness, homogeneity, degree of anisotropy, porosity with division for closed and open pores, as well as distribution of additives and pores using micro-computed tomography (microCT). The results show that the incorporation of waste glass increased compressive strength by approximately 54% and 9% in the case of coal-gangue-based and metakaolin-based samples, respectively. The porosity of samples ranged from 67.3% to 58.7%, in which closed pores constituted 0.3-1.8%. Samples had homogeneous distributions of pores and additions. Furthermore, the thermal conductivity ranged from 0.080 W/(m·K) to 0.117 W/(m·K), whereas the degree of anisotropy was 0.126-0.187, indicating that the structure of foams was approximate to isotropic.

Multi-criteria optimization of geopolymer foam composition

This study presents an approach to synthesizing a mathematical model for determining the composition of geopolymer foams. The focus is on improving the accuracy of multicriteria optimization for metakaolin-based geopolymer composite composition. Experimental data on the physical and mechanical properties of geopolymers are digitized to establish the computational basis for these calculations. Optimization criteria include density, porosity, compressive strength, flexural strength, Young's modulus, volumetric heat capacity, thermal diffusivity, and thermal conductivity. In addition, parameters such as shrinkage, processability, adsorption, adhesion, and economic aspects are also considered. The proposed format aims to fine-tune the geopolymer composite formulation by using the developed model for multi-criteria analysis of technological and physical-mechanical properties of foamed geopolymer composite materials (FGCM). A synthesis of mathematical models including the main criterion, suboptimization, generalized criterion, lexicographic optimization, sorting of alternatives, interval values, and decision tree methods was used to develop methods for multi-criteria optimization of the composition of foamed geopolymers. The study additionally uses the method of criteria convolution, in which the indices of specific criteria are modified in the form of a ratio scale to clarify the limits and boundaries of changes in the composition of the geopolymer mixture. This minimizes contradictory conclusions and expert opinions and highlights the extreme values for each group of parameters. By filtering the raw information, the accuracy of estimates is improved. The exclusivity of the proposed model for determining the composition of foamed geopolymers lies in the possibility of selecting the necessary formulation by mathematical processing of digitized information of the results of measurements of physical-mechanical and operational-technological properties according to the proposed innovative algorithms and schemes. Compared to existing methods, the focus of the proposed method allows for solving problems that are inaccessible to direct observation. This is due to the discovery of hidden information about the interaction of structural and strength parameters. Combining subjective and objective elements of the choice of the optimal geopolymer formulation, the proposed methodology of information processing allows for improving the quality of determining the optimal composition of the geopolymer mixture. The results of multicriteria optimization for foamed geopolymer indicate that the optimal component composition of the geopolymer matrix, within the selected range of variation, consists of 100g metakaolin, 90g potassium activator, 5g silica fume, 100g silica sand, 7g basalt fiber, and 3g aluminum. These proportions yield the best mechanical, thermal, and technological properties.

Green Building Materials for Circular Economy - Geopolymer Foams

This study aims to design and investigate foamed geopolymers as a green material dedicated to the circular economy. For synthesis as raw material, the main waste materials of two Polish coal mines, Wieczorek and Staszic, are applied. Additionally, various foaming methods are employed to utilize the by-product of energy production, especially the fly ash generated by the Skawina power plant. In this study, the main issues addressed are related to the selection of the most appropriate foaming agent and the optimization of the process parameters, including temperature, time, and mixture components. Hydrogen peroxide, aluminum powder, and a commercial foaming agent are selected as foaming agents in this research. During the process of sample preparation, stabilizers are applied in the form of polyglycol and cellulose. Through the conducted test, the results show that hydrogen peroxide and aluminum powder emerged as the two most optimal foaming agents.

Batch and fixed bed adsorption of methylene blue onto foamed metakaolin-based geopolymer: A preliminary investigation

Synthetic dyes, represent a serious hazard for the aquatic environments and groundwater system. The removal of dyes by the adsorption process avoids the production of sludge and secondary toxic compounds and offers high efficiency and very short operational times. In the present work, cationic Methylene Blue (MB) dye was used as a model pollutant to investigate the adsorption properties of a foamed geopolymer. The adsorbent has an apparent density of 0,75 g/cm3. It is characterized by a complex system of spherical and interconnected macro-pores with a mesopore volume of 0.143 cm³ /g that favors the mass transport and a pHpzc equal to 8.2. Batch and fixed granular bed column tests were carried out. The maximum MB uptake, in batch experiments, was 40.0 mg/g. Removal efficiency was around 95% up to a MB concentration of 25 mg/L. The pseudo second order kinetic model and Langmuir isotherm model better describe MB adsorption onto geopolymer. Fixed granular bed column tests were carried out by varying the initial dye concentration at a constant flow rate and bed height. Results are better fitted by Yoon and Nelson model. The obtained results demonstrate that foamed geopolymers are good candidates for the removing MB from aqueous solutions.

A state-of-the-art review on geopolymer foam concrete with solid waste materials: components, characteristics, and microstructure

A state-of-the-art review on geopolymer foam concrete with solid waste materials: components, characteristics, and microstructure

Physico-mechanical properties and micromorphological characteristics of graphene oxide reinforced geopolymer foam concrete

Physico-mechanical properties and micromorphological characteristics of graphene oxide reinforced geopolymer foam concrete

Physical, hydrolytic, and mechanical stability of alkali-activated fly ash-slag foam concrete

Foam concrete is prone to instability during mixing, casting, and curing. Besides preformed foam stability characteristics and volume, several geopolymer mix parameters, viz., precursor composition, silica modulus, alkali content, and water content, influence the overall foamed concrete stability, the understanding of which is still limited. This study evaluates the effect of the above parameters on the physical, hydrolytic, and mechanical stability of fly ash and slag-based foamed geopolymer. Physical stability was assessed by the design of experiments using a central composite design (inscribed), while systematic laboratory experiments assessed hydrolytic and mechanical stability characteristics. The foamed geopolymer behavior is sensitive to silica modulus and solid alkali-to-binder ratio, showing maximum interaction effects for producing stable foamed geopolymer for i) target to actual fresh density difference and ii) settlement along the height. The water-to-binder ratio was the most significant factor affecting the homogeneity across the cross-section along the height.Further, the alkali and slag content significantly affected the hydrolytic and mechanical stability characteristics. An optimum proportion of slag content, silica modulus, solid alkali-to-binder ratio, and water-to-binder ratio is suggested for the maximum benefit of fly ash and slag-based foamed geopolymer. This study provides a framework for comprehensive stability assessment of foamed geopolymers and can aid in developing sustainable lightweight materials for industrial applications.

A Review on Durability of Foam Concrete

Foam concrete is a promising material in building and construction applications, providing such outstanding properties as high specific strength, excellent thermal insulation, and effective acoustic absorption in human-inhabited buildings. However, because the porosity and permeable water absorption properties of foam concrete are significantly higher, its durability is often not comparable to that of ordinary concrete, and so the durability of foam concrete requires significant attention during the life cycle of building applications. Durable materials can greatly reduce the environmental impact of waste from maintenance and replacement and the consumption of natural resources resulting from the production of repair and replacement materials. After hardening, the durability of foam concrete includes freeze-thaw cycle resistance, elevated temperature resistance, carbonation resistance, efflorescence resistance, sulfate resistance, chloride resistance, alkali-silica reaction, and so on. This paper reviews articles on the durability of ordinary Portland cement (OPC) foam concrete, geopolymer foam concrete (GFC), magnesium phosphate cement (MPC) foam concrete, sulphoaluminate cement (SAC) foam concrete, and limestone calcined clay cement (LC3) foam concrete and compares their durability to provide a reference for the life cycle design and service life estimation of foam concrete members.

Insulating phosphoric acid-based geopolymer foams with water and high temperature resistance

This paper aims to determine the feasibility of phosphoric acid-based geopolymer highly porous foams elaborated by a surfactant induced mechanical foaming. The processing and consolidation parameters of the basalt fibers reinforced foams were determined. The influence of the aluminosilicate source on the synthesis of usable samples is reported, showing that the Si/Al ratio as well as the reactivity of the source is crucial to ensure a good consolidation. The effect of the Al/P composition of the geopolymer foam on its properties is also discussed. Two optimal formulations with very good properties (water and temperature resistance, mechanical strength, low thermal conductivity) could be established. Their working properties as well as their main physico-chemical characteristics, allowing to understand their formation mechanism were studied. Both withstood immersion in water and exposition to high temperatures. Their size may also be increased without any difference. Their insulating (61 to 75 mW.m−1K−1) and mechanical performances (80 to 190 kPa) are reported, as well as the study of their networks and microstructures.

Geopolymer based foams from steel slag – A green technology

The Induction Furnace slag is an industrial byproduct obtained during the manufacture of the steel. Due to its hardness and incompatible chemical composition it’s not used in cement industries and hence is wasted in landfills. A vast quantity of steel slag from the numerous steel industries situated in India. The proper utilization of the steel slag shall be needed to prevent the pollution caused by its disposal as landfill. Since it is a by-product from steel industry, it is available free of cost. The geopolymer is a green technology of making concrete like material without the use of cement and has minimal carbon foot print. The geopolymer is prepared through alkali treatment of industrial wastes like steel slag and fly ash, leading to formation of alumina-silicate based composite. The geopolymer has good potential in the application in Non-load bearing structures. In this paper the fabrication of geopolymer foams and their application is discussed. The geopolymer foams could be engineered to form foams and their application is discussed. The geopolymer foams could be engineered to form foam having isolated cells or interconnected cells to cater to various applications. The geopolymer foams are a green technological option to utilize industrial waste and produce products useful to the society at a cheaper cost.

Sustainable cementitious composites with 30% porosity and a compressive strength of 30 MPa

Many researchers have tried to increase the porosity of cement-based materials for different applications, but a limitation of the existing technology is that it is difficult to achieve more than 30 MPa compressive strength for materials that have a porosity of more than 30%. To overcome the decrease in compressive strength, some studies have developed fly ash-based foam geopolymers with silica fume as the foaming agent. However, this material requires heat curing and has a rapid setting problem. Therefore, the present study aimed to develop a material that can maintain compressive strength above 30 MPa while increasing the porosity to 30%, solving the curing problem, and extending the setting time. This study proposes a sustainable material design based on the concept of limestone calcined clay cement (LC3) and a fly ash–based foamed geopolymer. The results show that the proposed material can generate porosity of more than 30% and maintain a compressive strength above 30 MPa while the rapid setting and curing limitation problems are solved. Moreover, the developed cementitious composite was proven to reduce CO2 emissions by 31.91% compared to conventional construction materials, which highlights that the newly developed material can be classified as a low carbon construction material.