Fly Ash Geopolymer Composite Research Articles

Turning waste into strength: Enhancing geopolymer composites with Oil Palm Frond Fibers (OPF)

Geopolymers are alternatives to ordinary Portland cement as construction materials. The increasing demand for sustainable construction materials has driven the utilization of industrial by-products and agricultural waste. The disposal of oil palm frond (OPF) biomass as waste in landfills poses significant environmental challenges, necessitating effective recycling strategies. This study examines the incorporation and feasibility of OPF as a reinforcing fiber in fly ash geopolymer composites, examining its impact on physical and mechanical properties. Various parameters were tested, including fiber content (10–20 wt.%), shapes (shredded and tubular), and lengths (1–3 cm). The geopolymer composites with 10 wt.% shredded oil palm frond and 1-cm tubular oil palm frond fibers enhance the compressive strength by 17% compared to the control sample without oil palm frond. The shredded oil palm frond was particularly effective, enhancing strength performance and achieving better dispersion within the geopolymer matrix. Conversely, increasing the fiber content and length generally resulted in diminished composite strength, attributed to the creation of a more porous structure and weaker fiber-matrix interactions. However, lower fiber additions were shown to decrease porosity and water absorption, highlighting the potential of optimized oil palm frond fiber content and form in improving the environmental and mechanical performance of geopolymer composites. These results support the viability of oil palm frond as a sustainable additive in geopolymers, contributing to waste reduction and material innovation in construction.

A study on fly ash, M−Sand and bottom ash incorporated ecological geo polymer blocks with banana fiber

In the modern era, global warming happens to a critical green concern. Every year, the magnitude of greenhouse gas emanation to the ambience is in increasing trend In the scenario of throw-away exploitation and making of ecological geopolymer blocks, the probability in entirety substitution of fly ash as a primary binder instead cement and incorporation of manufactured sand and bottom ash in ecological geo-polymer composite was explored This experimental study aims to investigate the properties of Incorporating M−Sand, Bottom Ash and fly ash geo polymer composites by using banana fibers.Variations in the mechanical characteristics of Ecological geopolymer composites concerning diverse concentrations of inorganic water-soluble bases solution were considered. Geo composites with natural sand with 6 m, 8 m, 10 m, 12 m and 14 m were considered. For each molarity of concentration compressive and, flexural strength were performed on fly ash geopolymer composites. On the investigation, it is concluded that the optimal molarity ratio is 12 m. The optimum molarity ratio was kept constant for the partial replacement of river sand with M−Sand. In this research, Geopolymer composites were partially replaced for river sand in the percentage proportions of 20%, 40%, 60%, 80% and 100% with manufactured sand. Investigation reveals that optimal compressive characteristics were achieved for geopolymer composite with 40% replacement of river sand with M−Sand. Furthermore with 40% replacement of M.sand for river sand as constant, partial replacement of bottom ash for river sand was done. The bottom ash was added with MS40 mix proportions with the percentages of 10, 20, 30, 40 and 50 as a partial replacement with river sand and the optimum replacement of bottom ash was identified at 40% to be optimum based on test results. Durability and microstructural studies were carried out for was also conducted Banana fibre-embedded MS40BA40 geopolymer composite compressive characteristics, with the fiber of length 30 mm and 0, 5, 7.5, 10, and 12.50 % of geopolymer composites on ecological geopolymer composite was investigated.

Effect of nano SiO2 on mechanical properties of micro-steel fibers reinforced geopolymer composites

This paper presents the mechanical properties of micro steel fiber reinforced fly ash geopolymer composites containing different amounts of nano-silica. Four different fly ash-based geopolymer composites (GPC) are prepared by using a fixed amount of micro-steel fibers (0.5% by weight) and four different amounts of nano silicon dioxide (SiO2) consisting of 0%, 1%, 2%, and 3% amounts by weight. The GPC with 0% nano SiO2 having 0.5% micro-steel fibers is taken as the control mix. Different mechanical and microstructural properties of fabricated GPC are examined by assessing their stress-strain behavior, compressive strength, flexural strength, bending load-deflection behavior, impact strength, fracture toughness, toughness modulus, elastic modulus, toughness indices, hardness, and scanning electron microscopy (SEM). The outcomes of tests depicted that the addition of nano SiO2 significantly enhanced the mechanical properties and microstructure of micro-steel fiber-reinforced GPC by producing a denser matrix and refining the interfacial zones. According to the results of this study, the recommended amount of nano SiO2 to be utilized in GPC for the optimal behavior is 2%.

Enhanced Electrical Properties of Fly Ash Geopolymer Composites with Carbon Nanotubes

Carbon nanotubes (CNTs) are used for the application in concrete especially due to their excellent physical properties. In this study, CNTs were used as a conductive admixture to prepare composites with enhanced electrical properties that might be potentially used in smart concretes or structures. We assessed the changes in selected electrical properties of fly ash geopolymer mortars (conductivity, resistance, capacitance) depending on the concentration of CNTs that ranged from 0.05 to 0.20%. The most convenient CNTs concentration was discussed considering both the electrical and mechanical properties (compressive and flexural strength). Mercury intrusion porosimetry and scanning electron microscopy were used to observe the distribution of CNTs and porosity of the mortars.

Thermal and structural micro analysis of micro silica blended fly ash based geopolymer composites

The effect of micro silica addition at 0, 5 and 10% on fly ash geopolymer composites; paste, mortar and concrete prepared using the hybrid solution of sodium silicate and sodium hydroxide cured at 80 °C for 24 h, aged for 7 days studied under elevated temperature. The incorporation of micro silica at 5% level increase the composite strength at room temperature, and it is pronounced in the paste at 800 °C (50% Strength gain). Thermal stability of the composites was studied using TGA/DTA analysis till 1000 °C. The linear dimensional stability of paste and mortar maintained till 800 °C without any physical damage. 10% of micro silica addition exerts more filling effect that damage the integrity of the bulk specimen of mortar and concrete thereby decrease the compressive strength. The XRD pattern of paste 0% (M1) and 5% micro silica (M2) confirms the presence of secondary hydration product of semi-crystalline Hydroxysodalite Na4Al3Si3O12OH at room temperature. The higher intensity of Nepheline (NaAlSiO4) and Albite (NaAlSi3O8,) phases in the M2 at 800 °C represents the Si and Al-rich N-A-S-H corroborated with the observed chemical shift of Q4(4Al) in 29Si MAS-NMR and the resonance peak shift towards 60 ppm Al(IV) from 0 ppm (Al(VI)) in 27Al MAS-NMR. The symmetric and asymmetric stretch of TOSi (TSi/Al) band in ATR FT-IR spectrum of M1 and M2 compared to verify the geopolymer network.

Effects of carbon fiber on mechanical and electrical properties of fly ash geopolymer composite

High calcium fly ash geopolymer composite was prepared by incorporating short carbon fiber in the geopolymer matrix. The carbon fiber (CF) content was varied from 0 to 1%, the liquid to ash ratio was controlled at 0.5. The workability, mechanical and electrical properties of the geopolymer composites were examined. The result showed that the incorporation of 0.5%CF and above resulted in the ductile failure of specimen. The increasing CF content also resulted in decreasing workability and mechanical strength. The electrical resistivity was also reduced and was more stable to the curing age and temperature. The cyclic voltammetry (CV) curve of 60°C curing provided less peaks than that of 25°C.

Comparative Study on the Performance of Blended and Nonblended Fly Ash Geopolymer Composites as Durable Construction Materials

This article represents that the mechanical and microstructural properties and durability of fly ash-based geopolymers blended with silica fume and borax are better than those of conventional fly ash-based geopolymers. Fly ash itself contains the sources of silica and alumina which are required for geopolymerisation. But a sufficient amount of high-reactive silica is able to rapidly initiate geopolymerisation with activation. Pure potassium hydroxide pellets and sodium silicate solution were used for preparation of alkaline activator solution. Fly ash geopolymer paste exhibited better mechanical properties in the presence of silica fume with slight portion of borax. The effect of silica fume-blended geopolymer paste on temperature fluctuation (heating and cooling cycle at certain temperatures) showed better performance than nonblended fly ash-based specimens. Durability property was evaluated by immersion of geopolymer specimens in 10% magnesium sulfate solution for a period of one year. The change in weight, strength, and microstructure was studied and compared. In the magnesium sulfate solution, a significant drop of strength to around 37.26% occurred after one year for nonblended fly ash-based specimens. It is evident that specimens prepared incorporating silica fume had the best performance in terms of their properties.

Synthesis of polypropylene fiber/high-calcium fly ash geopolymer with outdoor heat exposure

Solar energy is an important source of renewable and sustainable energy. Thailand is near the equator and thus experiences hot weather throughout the year. The average maximum temperature is 35 °C and can reach 40 °C in the summer time. This outdoor heat exposure (OHE) was, therefore, used for the curing of a polypropylene (PP) fiber fiber-reinforced high-calcium fly ash geopolymer composite, in order to reduce energy consumption. Fly ash is an abundant solid waste generated from the coal-power generation process. In this research, a high-calcium fly ash was used as a source material for the geopolymer synthesis. PP fiber was also incorporated in the composites to improve tensile characteristics and control crack development. The results show that the incorporation of PP fiber in composites led to improved tensile strength, crack control, and resistance to acid solution. OHE could thus be used as an energy source for the heat curing of high-calcium fly ash PP-fiber geopolymers, resulting in a strong matrix.

Mix design and flexural toughness of PVA fiber reinforced fly ash-geopolymer composites

The orthogonal experiment design method was employed to study the mix design of poly(vinyl alcohol)(PVA) fiber reinforced fly ash-geopolymer composites (FRGC) in this paper. The influence of major mix design parameters on the working performance, setting time and mechanical properties of fly ash-geopolymer was researched. Furthermore the effect of two different kinds of PVA fibers on the tensile properties and flexural toughness of FRGC was also investigated in this paper. The composition, morphology and structure of FRGC were analyzed by X-ray diffraction and scanning electron microscopy. Based on the orthogonal experiment results, it can be concluded that the optimal values of the water/binder ratio, the modulus of sodium silicate, dosage of alkali excitation agent and the GBFS/binder ratio are 0.28, 1.2, 14% and 40%, respectively. The toughening effect of samples with 12mm PVA fiber is more obvious than that of samples with 8mm PVA fiber. The flexural toughness index of samples with 12mm PVA fiber is higher than that of the control sample by over 1300%. The results of microscopic tests uncovered that continuous geopolymer gel network structure formation presented in matrix contributes to the improvement of toughness and compact degree of interface transition zone (ITZ). Furthermore, the geopolymer gel covered on PVA fiber improves the interfacial bonding strength between the composite matrix and PVA fiber.

Ductile behavior of polyethylene fibre reinforced geopolymer composite

This paper presents the effects of various volume fractions of polyethylene (PE) fibres of 0.5%, 1%, 1.5% and 2% on tensile, flexure and compressive behavior of PE fibres reinforced geopolymer composites (PE-FRGC). Results show that the 1% PE fibre by volume is the optimum fibre volume fraction for fly ash geopolymer composite, which exhibit superior strain and deflection hardening behavior in uni-axial tension and three-point bending, respectively. Results also show that the compressive strength of the composites decreases with increase in volume fractions of PE fibre. The fibre surface examination of PE fibre in the gopolymer matrix using scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) revealed no significant damage of PE fibre in the alkaline geopolymer matrix.

Fabrication of hollow microspheres filled fly ash geopolymer composites with excellent strength and low density

Novel high-strength lightweight inorganic nonmetal material (INM) was initially fabricated by the filling of hollow microspheres in fly ash geopolymers in this study. The optimal properties in relation to compressive strength versus density of prepared samples were noted to be (14MPa versus 580Kg/m3), (17.9MPa versus 641Kg/m3), and (22.1MPa versus 782Kg/m3). Such excellent properties were similar to that of high-performance foam ceramics, but with no calcination process in the present work. The excellent performance was demonstrated to result from the high degree of geopolymerization and excellent filling properties of employed hollow microspheres in geopolymer matrix.

Geopolymer Extruded Composites with Incorporated Fly Ash and Polyvinyl Alcohol Short Fiber

In this study, extrusion technique was used to develop a polyvinyl alcohol (PVA) short-fiber-reinforced fly ash geopolymer composite (SFRFGC). There was systematic investigation of fiber volume fraction and fly ash content effects on SFRFGC's flexural and rheological behaviors. That PVA fiber addition greatly increases normally-cured SFRFGC ductility, especially in the case of high-volume fiber fractions, is shown in the experimental results. This results in an SFRFGC failure mode change from brittle to ductile patterns. Fly ash addition, in contrast, exhibits an important rheological and flexural behavior influence. Fresh SFRFGC paste extrudability can be obviously improved by fly ash's spherical shape. Low deflection and very high flexural strength are seen in SFRFGC with a low percentage of and without fly ash. Conversely, large deflection and low flexural strength are seen in SFRFGC with a high fly ash percentage. A scanning electron microscope was also used to investigate failure mechanism.

Impact properties of geopolymer based extrudates incorporated with fly ash and PVA short fiber

A PVA short fiber reinforced fly ash-geopolymer composites manufactured by extrusion technique (SFRGC) is developed in this study. The effects of fly ash content and fiber volume fraction on the rheological and impact behaviors of SFRGC are systemically investigated. Freeze–thaw cycles and sulfuric acid attack tests are also employed to study the durability of SFRGC. The experimental results show that for normally curing SFRGC, the addition of PVA fiber increases greatly the ductility of SFRGC, especially in the case of high volume fraction of fiber, resulting in the change of impact failure mode from brittle pattern to ductile one. As a result, a great increase in the impact toughness is seen in SFRGC with high fiber content. Comparatively the addition of fly ash exhibits obvious influence on the rhelogical and impact behaviors. The spherical shape of fly ash can greatly improve the extrudability of fresh SFRGC pastes. SFRGC without or with low percentage of fly ash possesses very high impact strength and stiffness. However, when too much fly ash is incorporated, the impact resistance of SFRGC is reduced rapidly. For SFRGC undergone freeze–thaw cycles and 1 month of sulfuric acid solution attack, only 5% or less of loss in impact strength is observed. The corresponding microstructure and failure mechanism are also explored by Laser particle size analysis (LSA), X-ray diffraction analysis (XRD), Scanning Electron Microscope (SEM), and Mercury intrusion porosimetry (MIP) techniques.