Showing papers on "Geopolymer published in 2018"
TL;DR: Future research should focus on the enhancement of geopolymer performance, testing on pollutants other than heavy metals and dyes, and verification on real wastewater in continuous operation.
275 citations
TL;DR: In this article, the material design and fresh properties of geopolymer mortar developed for 3D concrete printing application are presented, where extruded materials are deposited layer by layer to build complex architectural and structural components without the need of any formwork and human intervention.
273 citations
TL;DR: In this paper, the properties of the geopolymer mortars including fresh performance (workability, setting time, and temperature of fresh mortar), physical properties, mechanical properties (compressive strength, tensile strength, elastic properties, flexural performance, bonding behavior, and fracture behavior), durability properties (acid resistance, resistance to elevated temperature, frost resistance, water absorption, and shrinkage properties) and microstructure analysis.
Abstract: Geopolymer mortar refers to the mortar manufactured with sand and geopolymer, which is composed by the base materials containing affluent aluminium and silicon that was activated by adopting alkaline solution to serve as a binder. The investigation of the properties and application of the geopolymer mortar has attracted more and more attention of the researchers and cement based industries because of its sustainability advantages. This study reviews the properties of the geopolymer mortars including fresh performance (workability, setting time, and temperature of fresh mortar), physical properties, mechanical properties (compressive strength, tensile strength, elastic properties, flexural performance, bonding behavior, and fracture behavior), durability properties (acid resistance, resistance to elevated temperature, frost resistance, water absorption, and shrinkage properties) and microstructure analysis. This study also reviews the properties of different types of geopolymer mortars prepared using various source materials as base materials. The current study results indicate that the geopolymer mortar has exhibited significant feasibility and application prospect to be used as an environmental friendly building material, which may be an appropriate replacement to the traditional cement mortar in the future.
242 citations
TL;DR: In this paper, the influence of up to 10% ground granulated blast-furnace slag (GGBS) and silica fume (SF) inclusion within geopolymer blends cured under ambient conditions was investigated in terms of fresh and hardened properties.
Abstract: This study presents the development of fly ash-based geopolymer mixtures for 3D concrete printing. The influence of up to 10% ground granulated blast-furnace slag (GGBS) and silica fume (SF) inclusion within geopolymer blends cured under ambient conditions was investigated in terms of fresh and hardened properties. Evolution of yield stress and thixotropy of the mixtures at different resting times were evaluated. Mechanical performance of the 3D printed components was assessed via compressive strength measurements and compared with casted samples. SF demonstrated a significant influence on fresh properties (e.g. recovery of viscosity), whereas the use of GGBS led to higher early strength development within geopolymer systems. The feasibility of the 3D printing process, during which rheology was controlled, was evaluated by considering extrusion and shape retention parameters. The outcomes of this study led to the printing of a freeform 3D component, shedding light on the 3D printing of sustainable binder systems for various building components.
240 citations
TL;DR: In this article, the authors compared the mechanical performance of clayey soil stabilization using volcanic ash (VA) based geopolymer and ordinary Portland cement (OPC) and determined the effects of curing conditions and time.
190 citations
TL;DR: Granulated Blast Furnace Slag, which is traditionally considered as a waste material, is used as a replacement and partially reactive material in FA geopolymer pavement applications, and microstructural analysis indicated the coexistence of Calcium Silicate Hydrate (CSH) and Sodium Alumino Silicates Hydrate products in FA geopolitical stabilized LS/GBFS blends.
190 citations
TL;DR: In this article, fly ash-based monoliths were used as adsorbents for the removal of methylene blue from synthetic wastewaters, and the maximum uptake reported was 15.4 mg/g.
175 citations
TL;DR: In this paper, an experimental investigation was carried out to study some mechanical and microstructural characteristics of fly ash based geopolymer mortars reinforced with three different fiber types: steel, polypropylene, and polyvinyl alcohol fibers.
174 citations
TL;DR: In this paper, the micro-structure analyses of the geopolymer specimens and comparison of geopolymers with various binders are presented. But, most of the products revealed a wide hump in the XRD analysis due to the amorphous structure of aluminosilicate, and the results showed that the binders mixed with lower sodium silicate to sodium hydroxide mass ratio of 2.0-2.5 tend to react more efficiently.
168 citations
TL;DR: In this paper, the effect of alkali activator concentration and curing conditions on consistency and strength of waste clay brick powder-based geopolymer composites was investigated, and it was determined that the microstructure analysis results were consistent with the compressive strength results.
Abstract: The effect of alkali activator concentration and curing conditions on consistency and strength of waste clay brick powder-based geopolymer composites was investigated. For this purpose, geopolymer mortars with twenty different activator concentrations were produced and those mixtures having optimum alkali activator concentration were subjected to different curing conditions. Test results indicated that the optimum alkali activator concentration corresponded to M s (SiO 2 /Na 2 O) ratio of 1.6 and Na 2 O content of 10% by weight of the binder. A maximum compressive strength of 36.2 MPa was achieved by curing at 90 °C, 40% RH for 5 days. In order to characterise the morphology and the structure of the resultant composites, x-ray powder diffraction analysis, thermogravimetric analysis, fourier transform infrared spectroscopy analysis, scanning electron microscopy analysis and micro computed tomography analysis were performed. It was determined that the microstructure analysis results were consistent with the compressive strength results. Denser structure was observed by microstructure analysis in the mixtures having high compressive strength.
167 citations
TL;DR: In this article, the effect of increasing slag content and activator dosage on the sulfuric acid resistance of fly ash geopolymer (GP) binders has been investigated and compared with Portland cement (PC) mix using various physical and microstructural techniques.
TL;DR: In this paper, the compressive strengths and microstructures of geopolymer pastes containing waste glass powder and high-calcium fly ash were investigated, and the results indicated that waste glass powders could be used to replace fly ash to produce geopolymers with 7-d compressive strength of 34-48MPa.
TL;DR: In this paper, the compressive strength, geopolymerization process, and microstructure of the geopolymers were characterized in this study, and it was shown that the high alkalinity of red mud contributed to geopolymization, but additional NaOH was necessary to achieve maximum compressive strengths.
TL;DR: In this article, the effect of nano silica on the short term severe durability performance of fly ash based geopolymer concrete (GPC) specimens was investigated, and four types of GPC were produced with two types of low calcium fly ashes (FAI and FAII), and ordinary Portland cement concrete (OPC) concrete was also cast for reference.
TL;DR: The results indicate the possibility of printing fibre-reinforced geopolymers which meet all the necessary properties in both the fresh and hardened states.
Abstract: This paper investigates the effect of polypropylene (PP) fibres on the fresh and hardened properties of 3D-printed fibre-reinforced geopolymer mortars. Different percentages of PP fibres ranging between 0.25% and 1.00% by volume were added to an optimised geopolymer mixture. All samples showed reasonable workability and extrudability. In addition, shape-retention ability in the fresh state was investigated as a major requirement for 3D-printing. The compressive strength of the printed specimens was tested in the hardened state in three loading directions, viz. longitudinal, perpendicular, and lateral. The flexural strength of samples was also tested in the longitudinal and lateral directions. In addition, the interlayer bond strength was investigated. Fibre addition seems to influence compressive strengths positively only when the loading is perpendicular to the interface plane. This is due to the preferential fibre alignment parallel to the direction of extrusion. The addition of fibre significantly enhanced the flexural performance of the printed samples. The use of fibre dosages of 0.75 and 1.00 vol % caused deflection-hardening behaviour of the 3D-printed geopolymers and, hence, a significantly higher fracture energy in comparison to specimens without fibre or with lower fibre content. However, an increase in the fibre volume caused some minor reduction in interlayer bond strength. With respect to properties in the fresh state, higher fibre volumes caused better shape-retention ability in the printed samples. The results indicate the possibility of printing fibre-reinforced geopolymers which meet all the necessary properties in both the fresh and hardened states.
TL;DR: In this paper, the effects of fibers on the mechanical properties of fly ash-steel slag based geopolymer were studied with the aim of recycling solid wastes, and developing a sustainable alternative to Portland cement.
TL;DR: In this article, an experimental investigation on the thermo-mechanical properties of geopolymers prepared using a class F fly ash, KOH and Na2SiO3 is presented.
TL;DR: In this article, the effects of metakaolin (MK) on the properties of a fly ash-based geopolymer concrete containing 100% recycled coarse aggregate from crushed specimens of laboratory.
TL;DR: In this paper, a comprehensive experimental program was undertaken to analyse the structural and material characteristics of synthetic fibre reinforced geopolymer concrete and the results indicated that the macro polyolefin fibres exhibited the largest fracture energy which was likely due to high mechanical bonding and low fibre aspect ratio.
TL;DR: In this paper, the properties of thermally insulating geopolymer composites that were prepared using waste expanded polystyrene as lightweight aggregate have been investigated in terms of physico-mechanical properties, thermal performance and microstructure.
Abstract: This research has investigated the properties of thermally insulating geopolymer composites that were prepared using waste expanded polystyrene as lightweight aggregate. The geopolymer matrix was synthetized using metakaolin and an alkaline activating solution. To improve its mechanical properties, this matrix was modified by the addition of an epoxy resin to form an organic-inorganic composite. Moreover, in order to reduce drying shrinkage marble powder was used as an inert filler. The materials obtained were characterized in terms of physico-mechanical properties, thermal performance and microstructure. The geopolymer expanded polystyrene composite have improved properties compared to Portland cement-based materials, with higher strengths and lower thermal conductivity. The research demonstrates the manufacture of sustainable lightweight thermally insulating geopolymer composites using waste expanded polystyrene.
TL;DR: In this article, a low cost, low environmental impact sodium silicate solution (waterglass) from Rice Husk Ash (RHA) and more specifically RHA from Vietnam was developed.
TL;DR: In this paper, the effects of powder activators on the properties, microstructure and environmental impact of one-part geopolymer by measuring and characterizing compressive strength, porosity, reaction heat release, and carbon dioxide equivalent (CO2-e) emission.
TL;DR: In this article, the effects of efflorescence on the microstructural and mechanical properties of fly ash-based geopolymers were investigated, and the effect of sub-florescence on the compressive strength and compressive modulus of the geopolymer was investigated.
Abstract: This paper reports the effects of efflorescence on the microstructural and mechanical properties of fly ash-based geopolymers. Geopolymer pastes manufactured by sodium hydroxide and sodium silicate activation of three Class F fly ashes exhibit varying efflorescence behaviour. The geopolymer derived from sodium silicate activation of fine fly ash, which has a compact microstructure, shows a relatively slow efflorescence rate and low efflorescence potential. The efflorescence occurring on the surface of the geopolymer specimens does not change their mineralogical characteristics. However, the compressive strength development and compressive modulus of geopolymers can be affected through processes related to the loss of alkalis, and also to subflorescence. The phenomenon of subflorescence can be regarded as an extended efflorescence taking place under the surface of the material, leading to crystallisation pressure, which may exceed the tensile strength of hardened binders and generate structural damage.
TL;DR: The use of synthetic fibers positively affected high-temperature behavior of metakaolin-based geopolymer composites in terms of strength loss, weight loss and UPV loss as mentioned in this paper.
TL;DR: In this article, a review paper summarizes the mechanical and durability characteristics as well as the microstructural properties of natural pozzolan based geopolymers and their potential as binding material.
TL;DR: In this article, methods of preparation and characterization of fly ash-based geopolymers have been presented, and the properties of geopolymer cement/mortar/concrete under different conditions have been highlighted.
Abstract: A large amount of waste coming out from industries has posed a great challenge in its disposal and effect on the environment. Particularly fly ash, coming out from thermal power plants, which contains aluminosilicate minerals and creates a lot of environmental problems. In recent years, it has been found that geopolymer may give solutions to waste problems and environmental issues. Geopolymer is an inorganic polymer first introduced by Davidovits. Geopolymer concrete can be considered as an innovative and alternative material to traditional Portland cement concrete. Use of fly ash as a raw material minimizes the waste production of thermal power plants and protects the environment. Geopolymer concretes have high early strength and resistant to an aggressive atmosphere. Methods of preparation and characterization of fly ash-based geopolymers have been presented in this paper. The properties of geopolymer cement/mortar/concrete under different conditions have been highlighted. Fire resistance properties and 3D printing technology have also been discussed.
TL;DR: In this article, the structural buildability of layered objects and the influence of the layering process were assessed in terms of flexural strength through 3-point bending tests, and the results indicated that the lay-ering process has negative impact on the mechanical strength of build-up materials.
TL;DR: In this paper, the effects of particle size distribution and fly ash source on the mechanical and microstructural properties of fly ash-based geopolymer concrete were investigated, and it was shown that the resulting compressive strength is linearly affected by the average particle size distributions.
TL;DR: In this paper, the synthesis and characterization of geopolymer foams using hydrogen peroxide (H2O2) solution as pore-forming agent and oil as stabilizing agent is described.
Abstract: Geopolymer foams, as a new type of potential eco-friendly building material, are increasingly being discussed in the literature. This study reports the synthesis and characterization of geopolymer foams using hydrogen peroxide (H2O2) solution as pore-forming agent and oil as the stabilizing agent. The geopolymer foams with low bulk densities (0.37
TL;DR: In this paper, the mechanical and thermal properties of lightweight geopolymer mortar incorporating 100% crumb rubber from recycled tires as fine aggregate are reported, which can be used for making bricks/blocks, which are environmentally friendly, lighter, and provide better thermal insulation than conventional bricks and blocks.