Effect of Olive-Pine Bottom Ash on Properties of Geopolymers Based on Metakaolin (original) (raw)
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Journal of Materials Research and Technology, 2021
In this research, the use of olive pomace fly ash (OPFA) as an alkaline source for the activation of calcined clays (CC) from Bail en (Ja en, Spain) was studied. The optimal composition was obtained for 70 wt % CC and 30 wt % OPFA. The physical, mechanical and thermal properties of control geopolymers that use water as a liquid medium have been studied and compared with geopolymers that use additional activating solutions as sodium or potassium hydroxide solutions (8 M), or a mixture of alkaline hydroxide and alkaline silicate solution (NaOHeNa 2 SiO 3 or KOHeK 2 SiO 3). The results showed that OPFA can be used as an alkaline activator, showing mechanical properties slightly lower than those obtained when additional alkaline hydroxide activating solutions were used. The best compressive strength was obtained for geopolymers that use alkaline silicates as an activating solution. However, the best thermal insulation properties were obtained for control geopolymers. The microstructural characteristics of the geopolymers were evaluated by means of X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and Scanning Electron Microscopy (SEM-EDS) that corroborate the formation of geopolymeric gel in all the specimens, being the amount of gel formed greater in samples using commercial potassium activating solutions. These results demonstrate the feasibility of using this type of waste, OPFA, as activating reagents in the manufacture of geopolymers or alkaline activated materials. The manufactured geopolymers can be used as compressed earth blocks for walls and partitions, since the specimens pursue mechanical properties that comply with current regulations, presenting better thermal insulation properties.
Olive biomass ash-based geopolymer composite: development and characterisation
Advances in Applied Ceramics, 2020
Alternative fuels are being used increasingly to reduce energy costs and benefit the economics of electric power industries. Olive residues could be among those alternative fuels. This paper investigates the potential use of olive biomass ash (OBA) to develop a new sustainable binder (geopolymer composite). Refined binder chemistry was developed where the alkali and silica contents of the OBA are supplemented by calcined kaolin (CK) as alumina-rich constituents targeting balanced chemistry. The results showed that optimum formulation was achieved when 40 wt-% OBA and 60 wt-% CK were blended yielding geopolymer concrete with 28day compressive strength of 30 MPa. Further refinements were carried out by adding of CaO or NaOH. The compressive strength reached to more than 45 MPa when 5 wt-% CaO or 10 wt-% NaOH was added to the optimum blend. microstructural and mineralogical studies were performed to get insight into the microstructural changes and explain the findings.
Synthesis of Geopolymer from Blends of Tropical Biomass Ashes
IOP Conference Series: Materials Science and Engineering
Thermal conversion of biomass to produce energy inevitably generates ash as residual matter. Therefore, sustainable utilization of biomass should also consider reuse measures for the ash. This research examines the conversion of locally available biomass ashes in Indonesia into geopolymer. This is an environmentally more benign alkali-aluminosilicate alternative to the ordinary Portland cement produced by low-temperature reactions between aluminosilicates and concentrated alkali solution. Biomass ash sources in this study are corn stover, coconut shell, and sugarcane bagasse. Biomass ash blends are prepared according to a ternary simplex centroid mixture experiment design. These blends are reacted with activator solutions containing NaOH and Na-silicate and blended with sand aggregate to produce geopolymer mortar specimens. Early compressive strengths of geopolymer mortars range from 7.2 to 10.4 MPa, which surpasses the SNI 15-2049-2004 national standard for Portland cement with low heat of hydration. Statistical analysis of the experimental data indicates that the early strength as a function of biomass ash blend formulation is represented by a quadratic mixture model. Bagasse ash produces the highest strength. The quadratic terms consist of bagasse-corn and bagasse-coconut antagonistic blending terms. Morphology of the geopolymer mortar fracture surface indicates good bonding with the sand aggregate. Extensive acicular crystal growth within the amorphous geopolymer gel phase is observed in lower-strength formulations, which points to the formation of zeolite-like phase in the geopolymerization process. While the correlation of biomass ash type to the structure of the resulting geopolymer is yet to be established, this work has clearly identified the technical feasibility of producing geopolymer with satisfactory strength from tropical biomass ashes.
Geopolymers: An option for the valorization of incinerator bottom ash derived “end of waste”
Ceramics International, 2015
In the present paper, bottom ashes from urban waste incineration were used as sole source material to develop geopolymers activated with alkali solution. This study intends to gather basic structural data on the synthesized materials at fixed curing times (3 h; 1, 4, 5, 7, 30 days; 20 months) by X-ray (XRD) and Fourier Transform Infrared (FTIR) analysis. Curing time affects both crystalline phase transformation and the geopolymeric gel structure. The XRD results showed the starting of geopolymerization, due to the alkali activation, already within the first 3 h of curing. New phases such as hydrated sodium carbonate and gismondine, confirming the progressive ash reactivity, appeared after 4 h and 1 day of curing respectively. Finally, after approximately 30 days curing at room temperature, the condensation process and, consequently, the formation of a stable 3D gel of aluminosilicate network occurred. FTIR showed a 40 cm À 1 displacement of the band at 980 cm À 1 during the first hours of the geopolymer formation confirming the formation of the geopolymeric network also from a matrix without metakaolin. Furthermore Scanning Electron Microscopy (SEM-EDS) analyses were performed to assess morphological characteristics and to evaluate the presence of unreacted aluminosilicate particles in the obtained geopolymers.
Chemical Reactions in the Geopolymerisation Process Using Fly Ash-Based Geopolymer: A Review
The development of our world, demanding the power supply which is produced by combustion of coal. Unfortunately, the million of tons of fly ash and related-products have been generated. To overcome these problems, fly ash was used in term of geopolymer to produce precast structure, non structural elements, concrete pavements, concrete products and immobilization of toxic waste that are resistant to toxic waste that are resistant to heat and aggressive environment Geopolymer is a material produced by inorganic poly-condensation, i.e., by so-called "geopolymerization." The process comprises dissolution of aluminosilicate followed by condensation of free silicate and aluminate species to form a three-dimensional structure of silico-aluminate structures. This process involving alumino-silicate materials is a complex process that has yet to be described fully. Several studies focused the dissolution reaction of fly ash, rate of reaction, thermodynamic properties of the reaction and mechanism of hardening process involved in geopolymerisation.The raw materials of geopolymer, such as kaolinitic clays, metakaolin, fly ashes, blast furnace slag, mixtures of fly ashes and slag, mixtures of fly ashes and metakaolin, mixtures of slag and metakaolin, mixtures of slag and red mud, and mixtures of fly ashes and non-calcined materials like kaolin and stilbite have significant effects on the properties of the resulting geopolymer. Recent studies have been conducted to determine the effect of SiO 2 /Al 2 O 3 ratios on the properties of the geopolymer, such as compressive strength, setting time, strength development, composition of the gel phase, and the microstructure of the alkaliactivated material. It is evident that several factors related to the chemistry of the raw materials and the production of the geopolymer affect the performance of the final geopolymer products.
Geopolymer synthetized from bottom coal ash and calcined paper sludge
Journal of Cleaner Production, 2013
This study deals with the development of geopolymers synthetized from industrial waste containing aluminosilicates. Geopolymers are inorganic polymers formed by the activation of amorphous aluminosilicates (Al 2 O 3 .SiO 2 ), which react in a strongly alkaline medium. Bottom ash (SiO 2 /Al 2 O 3 ¼ 3.3e4.5) was used as source of aluminosilicate and sodium hydroxide (NaOH ¼ 5, 10 and 15 M) and sodium silicate (Na 2 SiO 3 , SiO 2 /Na 2 O ¼ 1.58) were used as alkaline medium. Calcined paper sludge was used to increase the reactivity of the partially crystallized bottom ash. The solid waste was characterized by XRF and XRD and the geopolymer samples were characterized by XRF, XRD, SEM, FTIR and compressive strength tests. The best results were obtained with a solution of 15 M NaOH and sodium silicate and a mixture of 2:1 bottom ash and calcined paper sludge.
The characterizations of boiler ash waste from waste of palm oil industry were performed. The boiler ash was obtained from the boiler in the palm oil processing factory. The chemical and physical characterization has been analyzed using X-Ray Fluorescence (XRF), X-Ray Diffraction (XRD), particle size distribution, Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscope (SEM). From the XRF analysis, the major component of boiler ash is silica oxide (SiO 2 ), followed by calcium oxide (CaO) and ferum oxide (Fe 2 O 3 ). In order to produce geopolymer, the raw material needs to contain enough SiO 2 and aluminium oxide (Al 2 O 3 ). However, the content of Al 2 O 3 is only 3.7% but it contained high amount of SiO 2 (40.60%) and CaO which may influence the strength of the geopolymer. The median particle size of boiler ash was comparable with fly ashes, morphology of boiler ash showed irregular particle size and shape. The surface particle of boiler ash look similar with calcined kaolin but no plate like structure was observed. Hence, we believe that this material has a potential use as raw material for geopolymer production.
The Scientific World Journal, 2013
This study reports on the microstructure, compressive strength, and drying shrinkage of metakaolin (MK) based geopolymers produced by partially replacing MK by oil palm ash (OPA). The OPA was used as raw material producing different molar ratios of SiO 2 /Al 2 O 3 and CaO/SiO 2. The geopolymer samples were cured at 80 ∘ C for 1, 2, or 4 hours and kept at ambient temperature until testing. The compressive strength was measured after 2, 6, and 24 hours and 7 and 28 days. The testing results revealed that the geopolymer with 5% OPA (SiO 2 : Al 2 O 3 = 2.88 : 1) gave the highest compressive strength. Scanning electron microscopy (SEM) indicated that the 5% OPA sample had a dense-compact matrix and less unreacted raw materials which contributed to the higher compressive strength. In the X-ray diffraction (XRD) patterns, the change of the crystalline phase after heat curing for 4 hours was easily detectable compared to the samples subjected to a shorter period of heat curing.
Geopolymers are inorganic polymeric materials. Geopolymerization involves a chemical reaction between alumino-silicate oxides and alkali metal silicate solutions under highly alkaline conditions. The strength of a geopolymer depends on the nature of the source materials. Geopolymers made from calcined source materials, such as metakaolin (calcined kaolin), fly ash, and slag, for example, yield higher compressive strengths when compared to those synthesized from non-calcined materials, such as kaolin clay. This study focused on the processing of geopolymer by using fly ash in the geopolymerization process. The fly ash was replaced accordingly with 10%, 20%, 30%, 40%, and 50% of kaolin, based on weight. A solution of sodium hydroxide and sodium silicate was used as the alkali activator for the geopolymerization reaction. The samples were tested to determine their compressive strength, water absorption, and porosity. As the percentage of kaolin was increased, the strength of the geopolymer decreased. In this study, 10% kaolin replacement was the optimum replacement and produced the maximum compressive strength of geopolymer at both 7 and 28 days.
Investigating the Effects of Oil Palm Ash in Metakaolin Based Geopolymer
2013
This research reports on the microstructure, compressive strength, drying shrinkage and sulfate expansion of metakaolin (MK) based geopolymers produced by partially replacing MK by oil palm ash (OPA) in proportions of 0 %, 5 %, 10 % and 15 % by weight. The specimens were cured at a temperature of 80°C for 1, 2 and 4 hours, and compressive strength test were conducted at ambient temperature at 2, 6, 24 hours, 7 and 28 day. The testing results revealed that the geopolymer with 5 % OPA gave the highest compressive strength. Scanning electron microscopy (SEM) indicated that the 5 % OPA sample had a dense-compact matrix and less unreacted raw materials which contributed to the higher compressive strength. In the X-ray diffraction (XRD) patterns, the change of the crystalline phase for higher strength was easily detectable compared lower strength.