Compressive Strength Of Geopolymers Research Articles

PENGARUH RASIO Na2SiO3 : NaOH TERHADAP KUAT TEKAN MORTAR GEOPOLIMER BATU NAPAL

This study discusses the use of marl stone as a constituent of geopolymer mortar which aims to determine the effect of the Na₂SiO3 : NaOH ratio to the compressive strength of a marl stone geopolymer mortar. In its manufacture, geopolymer mortar utilizes natural minerals with high SiO2 (silica oxide) content as precursors and uses activators as binders such as NaOH (sodium hydroxide) and Na2SiO3 (sodium silicate), silica oxides contained in these materials will react chemically and form polymer bonds. The method in this study uses an experimental method that is doing direct testing in the laboratory procedures that are carried out in accordance with the stages and planned to refer to the applicable standards. The Na₂SiOi: NaOH activator ratio used in this study is 1, 1.5, and 2. Based on the geopolymer compressive strength test results that have a maximum compressive strength at 28 days with a composition ratio of Na2SiO3: NaOH, 1: 1 for 15 , 07 Mpa. From the results of the analysis it can be concluded that the more use of Na2SiO3, the effect on compressive strength of napal geopolymer stones will decrease. So geopolymer mortar made from stone is included in a simple mortar that is mortar for non-structural parts

Comparative study: nanosilica, nanoalumina, and nanozinc oxide addition on the properties of localized geopolymer

Due to the enthusiasm of researchers to improve the performance of geopolymers by introducing nanoparticles, which has experienced a rapid increase in recent years, this study compares the effects of nanoSiO2, nanoAl2O3, and nanoZnO on the properties of the geopolymer based on local metakaolin. A detailed comparative analysis of the nano-added geopolymers was conducted using XRD, XRF, FTIR, SEM, MIP, and TG along with mechanical and physical characteristics. For a given compressive strength, the optimized values of nanoSiO2, nanoAl2O3, and nanoZnO were found to be 5%, 2%, and 0.5% respectively. The results of the aforementioned tests had clearly shown an improvement in the microstructure of the geopolymers by addition of all three types of nanoparticles; however, with regard to porosity, the nanoalumina has shown the superior behavior as compared to nanosilica and nanoZnO while with regard to water absorption, the nanosilica had shown the lowest values as compared to other nano-added geopolymers. In addition, Si/Al trends for each nanoparticle with respect to their effect on the compressive strength of the geopolymers have shown different inclinations. An analytical model to predict the compressive strength of the nano-added geopolymers in terms of the density has also been defined. Furthermore, the cost analysis has shown the highest cost reduction factor for nanoZnO geopolymer making it the most economical option as compared to other nanoparticles to achieve the same mechanical strength.

Design Mix Formulation and Optimization of Metakaolin Based Alkali Activated Geopolymer Concrete with the Taguchi Method

Concrete mix formulation is the science of deciding relative proportions of ingredients of concrete, to achieve desired properties in the most economical way. Formulation of concrete mix requires adequate knowledge of the properties of its constituents. Aluminosilicate materials have recently found applications in construction industry due to their unique and flexible properties. The metakaolin used for this study was the locally sourced kaolin calcined at 750oC. The alkali activating reagents include a fixed concentration of sodium silicate solution and sodium hydroxide solutions of three different concentrations. Strength development of metakaolin – based geopolymer concrete is quite different from that of ordinary Portland cement concrete due to differences in their constituents, hence, the need for special formulation, most especially when high strength is required. Taguchi method was adopted in this study to formulate mix proportion for high compressive strength of geopolymer concrete at ambient curing condition. Four parameters were selected that are more likely to influence the compressive strength of metakaolin – based geopolymer concrete, these include aggregate content, alkali – binder ratio, alkali reagent ratio and alkali reagent concentration. The effect of these parameters on the density, workability and compressive strength at 3, 7 and 28 days are determined. The result showed that an optimum mix obtained from a formulation formula (2.75SiO2 * Al2O3 * 0.55Na2O * 6.8H2O) produced a compressive strength of 62MPa at 28 days of open air curing. It was revealed that the molar concentration of the alkali reagent (sodium hydroxide) should be kept within 10M range for an open air curing, the alkali reagents to binder ratio should be kept at 0.7 or less with no addition of water to achieve reasonable workability. Also, it has been observed that the bulk density of metakaolin – based geopolymer concrete that yielded substantial strength fall within 2250kg/m3 and 2350 kg/m3.

Geopolymer synthesized from spent fluid catalytic cracking catalyst and its heavy metal immobilization behavior

Porous geopolymers (GP) are energy saving, environment-friendly and simple in preparation, which has attracted increasing attention from both academia and industry. In this paper, geopolymer with excellent immobilization capability of heavy metals was prepared by chemical forming method. The spent fluid catalytic cracking (sFCC) catalyst, a hazardous solid waste in China, was exploited as aluminosilicate precursor. The influences of particle size of sFCC catalyst, type of activator agent solutions, mass ratios of SiO2/Na2O and (SiO2 + Na2O)/sFCC catalyst on the compressive strength of GP and the leaching toxicity of Ni were investigated in detail. Under the optimum conditions, the leaching toxicity of Ni is reduced to below 0.01 ppm, much lower than the national standard 5 ppm. The as-obtained GP was also examined by SEM, XRD and FTIR with the aim to understand the synthesis and immobilization mechanism using the sFCC catalyst as the raw material. The results show a new aluminosilicate zoisite phase with three-dimensional network structure forms. Ni element enters the grid of GP, involved in the formation of three-dimensional network structure. Besides, partial Ni element replaces the position of alkaline metal and chemical bonds AlO4.

Effects of load types and critical molar ratios on strength properties and geopolymerization mechanism

Abstract In this study, the effect of SiO2/Al2O3 (S/A), Na2O/Al2O3 (N/A) and H2O/Na2O (H/N) molar ratios on bending and compressive strength of geopolymer were investigated. The geopolymerization mechanism was also analyzed from microstructure difference by FTIR. The experimental results showed that compressive strength and bending strength of geopolymer has an opposite reaction under different critical molar ratios. The increase of S/A molar ratio and the decrease of N/A and H/N molar ratios have resulted in an increase of the compressive strength. However, it caused a noticeable decrease in bending strength. The microstructure of geopolymer indicated that the degree of polymerization and cohesion of geopolymer have systematical depending on these critical molar ratios, making the mechanical properties of geopolymer susceptible to different types of loads. This paper reveals the relationship between the microstructure of geopolymer and different mechanical properties and helps to selectively prepare corresponding geopolymer for different loading patterns.

Nanoindentation on micromechanical properties and microstructure of geopolymer with nano-SiO2 and nano-TiO2

Fly ash-based geopolymers incorporated with 2% nano-SiO2 (NS)/nano-TiO2 (NT) particles were subjected to microstructural and statistical nanoindentation analysis. With the addition of both types of nanoparticles, the compressive strength of geopolymer and the micromechanical properties of N-A-S-H gel were increased. NS exhibited higher reinforcement effect than NT on macro-strength. However, NT more significantly enhanced gel micromechanical properties. NT and especially the NS were found to have a positive effect on the early reaction rate of geopolymer. After 28 days, the gel proportion obtained by Backscattered electron (BSE) images analysis was close values of 49.16%, 55.69% and 54.02% for reference sample and NS, NT reinforced geopolymer, which were more than two times of that from the statistical nanoindentation. The effects of NS and NT on microstructure, gel proportion and gel micromechanical properties were discussed to reveal the macro-strength reinforcement mechanism. The results obtained from different techniques were also compared and discussed.

Optimization of Technological Parameters for Preparation of Geopolymers Fabricated with Pulverized Fly Ash

Geopolymer is widely considered as an important direction for the comprehensive utilization of fly ash with its production increasing sharply year by year. The effect of mixing proportion including SiO2/Al2O3 molar ratio, Na2O/SiO2 molar ratio and water-solid ratio on the performances of geopolymer fabricated with pulverized fly ash with a median particle size of 3.3 μm was investigated by an orthogonal test in this work, and the optimum preparation technics were also obtained. Results indicated that the compressive strength of geopolymer reached the maximum of 61.0 MPa when SiO2/Al2O3 molar ratio was 3.3, Na2O/SiO2 molar ratio was 0.11 and the W/S ratio was 0.30 under the optimum preparation technics of aging time of 3h, mixing time of 3min and curing at 80℃ for 24h. Overall, Na2O/SiO2 molar ratio played the most important role on the compressive strength of geopolymer, but SiO2/Al2O3 molar ratio had a minimal impact. FTIR spectrum demonstrated that the sample with the optimum proportion exhibited a more complex asymmetric stretching vibration peak, which indicated that there were more activated silicon/aluminum monomers and dimers in fly ash depolumerized and repolymerized and tetrahedral phase transitions, and then geopolymer paste with denser microstructure was formed.

Influence of modified multi-walled carbon nanotubes on the mechanical behavior and toughening mechanism of an environmentally friendly granulated blast furnace slag-based geopolymer matrix

This study aimed to investigate the mechanical behavior of an environmentally friendly granulated blast furnace slag-based geopolymer matrix reinforced with modified multi-walled carbon nanotubes (MWCNTs). The modified MWCNTs were obtained using a modification method combining nitric acid and sulfuric acid and were then dispersed using sodium dodecylsulfate (SDS) as a dispersant. Two types and three concentrations of MWCNTs were mixed directly into the aqueous solution, sonicated, and then mechanically mixed with waste granulated blast furnace slag to form the geopolymer matrix. Raman and Fourier transform infrared (FT-IR) spectroscopy were used to evaluate the ordered structure and crystallization degree of the modified MWCNTs. Then, the dispersity of the modified MWCNTs was characterized using transmission electron microscopy (TEM). The compressive and bending strengths were measured to evaluate the mechanical behavior of specimens. Moreover, the polycondensation products, polycondensation degree, pore structure, and microscopic morphology of the geopolymer matrix were analyzed using X-ray diffraction (XRD), FT-IR spectroscopy, nuclear magnetic resonance (NMR), mercury intrusion porosimetry (MIP), and field emission scanning electron microscopy with energy dispersive X-ray spectroscopy (FESEM-EDS). The experimental results showed that the incorporation of 0.1% functionalized MWCNTs had an optimal influence on the fluidity and mechanical behavior. The slump diameters of geopolymers with 0.1% functionalized MWCNTs with and without SDS were increased by 16.3% and 23.5%, respectively, compared with the reference geopolymer matrix. For geopolymer matrix samples at a curing age of 28 d, the compressive strength of geopolymers with 0.1% functionalized MWCNTs with and without SDS were increased by 16.3% and 17.6%, respectively. For the bending strength, the corresponding increases were 17.6% and 18.7%, respectively. It was found that functionalized MWCNTs could increase the degree of polycondensation, leading to a more traditional amorphous N-A-S-H phase, a finer C–S–H phase, more Q4 (2Al) and Q4 (3Al), and lower porosity. In addition, the propagation of micro-cracks in the geopolymers was inhibited by the incorporation of functionalized MWCNTs.

Investigation on Thermal Stability of Geopolymer Based Zeolite in Fire Case Study

This work aims to reveal the effects of zeolite on properties of fly ash based geopolymer under high temperature at 300 °C, 600 °C and 900 °C. The specimens were prepared by alkali activation of fly ash, which was partially replaced by two different types of zeolite at 10%, 20% and 30% by weight. The specimens were analyzed for the maximum compressive strength, weight loss percentage, XRD and SEM. The results highlighted that the percentage of weight loss increased with the ratio of zeolite replacement. The compressive strength of geopolymer with synthetic zeolite and natural zeolite at 7, 28, 60 days were similar. The high-temperature exposure resulted in the reduction in compressive strength in all proportions. At the same temperature, compressive strength of all specimens were not significantly different.

Thermal Exposure of Fly Ash-Metakaolin Blend Geopolymer with Addition of Monoaluminum Phosphate (MAP)

Recent research reveals that formulation of blended geopolymers based on the association of two aluminosilicate precursors had a better performance than one precursor geopolymers. This study presents a facile method to enhance the compressive strength of fly ash-metakaolin blend geopolymer by incorporating monoaluminum phosphate (MAP) during the geopolymerization reaction. The effect of the thermal exposure on the microstructure and compressive strength of the geopolymer are investigated. Results show that the MAP is transformed to granule structures, bonded and surrounded by geopolymer gel. The unique microstructure increases the compressive strength of the room temperature curing geopolymer from 54.7 MPa to 64.21 MPa (14.8%) with an optimum addition of 1.0 wt% MAP. This enhancement in compressive strength was ensured by the formation of an amorphous structure of aluminosilicophosphate (SiO2.Al2O3.P2O5.nH2O) phase. At higher temperatures, the formation of stable crystalline phase of berlinite and nepheline contribute to strength retention of the geopolymer. Hereby, it can be concluded that the addition of 1.0wt% MAP in the geopolymer reinforced the structure.

Influence of the Kaolinite Calcination Conditions on the Compressive Strength of Geopolymer

Among the cementitious materials, geopolymers not only attract interest due to the low emission of CO2 in their manufacturing process, but also because of their good mechanical and chemical properties, together with their resistance to fire. They can be made from different raw materials including various wastes from industrial activities and mineral extraction. In this study, metakaolin was obtained from kaolinite calcined under different conditions. In this case kaolinite is a by-product of sand extraction. It was observed that the calcination conditions (kiln heating rate, calcination time and temperature) had a strong influence on the compressive strength of geopolymer after 28 days of cure. They also affected the composition of the geopolymer, which was prepared by mixing metakaolin, alkaline sodium silicate and sodium hydroxide solution.Compressivestrengthsintherangefrom10MPato50MPamaybeobserved, depending on the combination of these factors. A factorial design of experiments allowed the isolation of the effect of each factor and its interactions, offering new insights into the complexity of the geopolymeric reactions and highlighting the need for a rigid control of the calcination conditions of kaolinite and the composition of the geopolymer samples to obtain the desired compressive strength.
 Keywords: kaolinite, calcination, metakaolin, geopolymer, compressive strength.

Graphene Nanosheets (GNs) Addition on the Palm Oil Fuel Ash (POFA) Based Geopolymer with KOH Activator

Graphene Nanosheets (GNs) have been successfully added to the palm oil fuel ash (POFA) based geopolymer with KOH activator to improve the geopolymer compressive strength. The graphene was synthesized using turbulence assisted shear exfoliation (TASE) method and identified using Raman spectroscopy. The influence of concentrations and weight percent of graphene against the compressive strength, porosity, and morphological properties were investigated. The crystallinity phases of geopolymer and graphene were also identified using XRD. Raman spectroscopy revealed that graphene produced by TASE method had ≥ 3 layers (graphene nanosheets, GNs). Furthermore, Raman maping constructed by the intensity D band showed the graphene had different atomic arrangements at the edge (armchair and zigzag). The compressive strength and the porosity tests showed that increasing the concentration and the weight percent of graphene increased the compressive strength and reduced the porosity. The highest compressive strength and the lowest porosity (10.8 MPa and 5.92%, respectively) were exhibited by the geopolymer synthesized using 0.7 wt% graphene with concentrations of 30 mg/ml. The SEM micrographs indicated that the graphene reduced the porosity of geopolymers with a pores fulfilling mechanism due to of very small of graphene nanosheets size (∼60 - ∼80 nm).

Effects of mix design parameters on heat of geopolymerization, set time, and compressive strength of high calcium fly ash geopolymer

In this study, the effects of key design parameters, such as SiO2/Na2O mole module (Module), concentration of solute in alkaline solution (Concentration), liquid-to-fly ash mass ratio (L/F), and curing temperature on the geopolymerization process, set time, and compressive strength of high calcium fly ash geopolymer mixes were investigated. The geopolymerization process of these mixes was monitored using a semi-isothermal calorimeter at testing temperatures of 23 °C and 50 °C for 24 h. The results showed two major exothermic peaks generated during the fly ash geopolymerization processes. The first peak, the dissolution peak, appeared within the first hour after the fly ash was in contact with a liquid activator, and it did not vary very much with mix design parameters, while the second peak, the polymerization peak, varied largely in its amount and emerging time with mix design parameters of the geopolymers. As Module increased, the set time was accelerated but the total heat generated from geopolymerization and the compressive strength of the geopolymer were reduced. As Concentration increased, the set time for mixes with 1.0 and 1.5 Module prolonged but it was shortened for the mixes with 2.0 Module, while the total heat of geopolymerization and strength of these mixes were increased. Elevated curing temperature decreased the polymerization peak time, increased the total heat of geopolymerization, and improved the strength of the geopolymers. Additionally, the close relationships between the calorimetric characterization and setting time/compressive strength were obtained. To achieve optimal strength and setting behavior, it is recommended that a geopolymer mix made with high calcium fly ash shall be designed to have an activator with Modules ≤ 1.5, Concentrations of 20–25%, and L/F ≤ 0.40, and elevated curing (e.g., at 50 °C) is preferred.

Recycling vanadium-bearing shale leaching residue for the production of one-part geopolymers

Each year, the extraction of vanadium from vanadium-bearing shale generates a significant amount of mine tailing. Vanadium-bearing shale leaching residue (VSLR) not only occupies lots of land, but also poses serious threat to the surrounding environment. In this study, the VSLR was recycled as construction materials based on geopolymerization. Metakaolin was supplied as aluminum source material. The reactive activity of VSLR and metakaolin were evaluated by leaching test. The effect of factors, such as VSLR contents, water-to-solid ratios and curing temperature, on the compressive strength of geopolymer were discussed. The phase compositions of VSLR-based geopolymer was studied by x-ray diffraction (XRD) analysis, and the bond structure of geopolymer was investigated by the Fourier-transform infrared spectroscopy (FTIR) analysis, and the microstructure was investigated by scanning electron microscopy (SEM) imaging. The results show that VSLR containing part of soluble silicon component, and could be used as silicon source materials. The VSLR contents have profound effects on compressive strength, and the unreacted VSLR particles acted as aggregate. The water-to-solid ratio affects not only mechanical properties, but also the workability in application. Curing temperature mainly affects the early stages of geopolymerization, and the effects gradually weaken with the curing age prolonged.

Effect of Sodium Aluminate on Compressive Strength of Geopolymer at Elevated Temperatures

Effect of Sodium Aluminate on Compressive Strength of Geopolymer at Elevated Temperatures

Influence of calcium content on structure and strength of MSWI bottom ash-based geopolymer

This study explored the strength limitations of municipal solid waste incineration (MSWI) bottom ash-based geopolymer, which can limit its use in building materials. The calcium content in MSWI bottom ash was increased by the addition of varying amounts of granulated blast furnace slag (GBFS) and calcium-containing chemicals. The results showed that the low calcium content of MSWI bottom ash in geopolymer was the main cause of insufficient polymerisation. Both GBFS and calcium-containing chemicals improved geopolymer microstructure and enhanced the degree of polymerisation, which clearly improved the compressive strength. However, further increases in geopolymer compressive strength were not significant when the GBFS content was greater than 40%, and the compressive strength decreased sharply when hydrated Ca(OH)2 content was greater than 5%.

DEVELOPMENT OF GEOPOLYMER (GREEN) CEMENT STRENGTH WITHOUT NATURAL AND CHEMICALS ADDITIVE.

Geopolymer cement (GPC) is made from aluminum and silicon, instead of calcium and silicon(OPC). Geopolymer are a type of inorganic polymer that can be formed at room temperature byusing industrial waste (waste materials) such as ground granulated blast-furnace slag (GGBFS),Metakilon (MK) and Red mud (RD) or by products as source materials to form a solid binderthat looks like and performs a similar function to OPC. Geopolymer concrete gets advantagespecification in resistivity to highly aggressive media and the resistivity to change inmechanical and physical characterization at high temperature compared to the traditionalconcrete. this paper mainly study the preparation of Geopolymer cement to using in concreteinstead of Portland cement and discuss the effect different factors on the compressive strengthof Geopolymer paste without natural and chemicals additive (the effect ratio of (slag ,Metakilon, Red mud , sodium hydroxide and sodium silicate) Four parameters were studied.The first parameter, the effect of changing ratio between sodium hydroxide and sodium silicate.NaOH : Na2SiO3 , secondly the effect of changing ratio between slag and Metakilon GGBFS:MK, thirdly the effect of changing ratio between slag and Red mud GGBFS :RM , fourthlythe effect of changing degree curing temperature all samples curing different condition suchas air , water , steam , oven . The results show that get high compressive strength at ratiobetween sodium hydroxide and sodium silicate (NaOH : Na2SiO3), slag and Metakilon(GGBFS :MK) , slag and Red mud ( GGBFS :RM) is 1:2.5 , 0.95:0.05 , 0.90:0.10 respectivelyand the best mix have high compressive strength at various combinations between slag,Metakilon and Red mud by ratio GGBFS : MK : RM is 0.85:0.05:0.10. By inspecting the resultit can be noticed that in case geopolymer concrete the best curing method gives highcompressive strength in oven are compared air, steam, water and steam curing is better than air,water and air curing is better than water curing and the effect temperature curing type oncompressive strength, Regardless of the compressive strength of samples increases with theincrease in curing temperature.

The Effects of Replacement Metakaolin with Diatomite in Geopolymer Materials

Geopolymers are aluminosilicate inorganic polymers. In this study, the effects of replacement metakaolin with diatomite in geopolymer materials were investigated. The geopolymer materials were prepared by leaching diatomite (from Lampang province) and metakaolin (from Ranong province) with alkaline activator solutions. The fresh slurry was cast into plastic molds with a cubic shape and then cured at room temperatures. Effects of ratios between diatomite and metakaolin were investigated. Furthermore, influences of curing time on the properties of the studied samples were also determined. Many techniques for material characterization such as XRF, XRD, and SEM were employed in this work. The mechanical property of geopolymer compressive strength was tested after curing. It was found that compressive strength of the samples increased with increased amounts of diatomite.

Investigating geopolymer cement performance in presence of water based drilling fluid

Oil well cementing is one of the most important steps in drilling and completion processes and providing a full zonal isolation which is the most important features in the oil cementing. Traditionally, Portland cement is used for oil cementing operations, however, a few years ago, a new cost-effective material came to light called geopolymer. In this research, a fly ash class C based geopolymer was used. This research investigates the effect of drilling fluid contamination with geopolymer cement to understand its impact on geopolymer rheological and mechanical performance. Initially, the optimized geopolymer was prepared and mixed with different drilling fluid ratios, including 0%, 5%, and 10% by weight of cement at atmospheric pressure and ambient temperature (24 °C). Same percentages were added to Portland cement to compare it with the geopolymer. Four tests were conducted to determine the effects of drilling fluids including: rheology, density, fluid-loss, and compressive strength for different curing time (1 day, 3 days, and 7 days). Results showed that drilling fluids enhanced the geopolymer rheological behavior by improving geopolymer viscosity and reducing the fluid loss. Drilling fluids reduced the geopolymer viscosity which facilitates the pumping operation during the cementing. In contrast, mixing the drilling fluid with Portland cement had a negative effect on rheological behavior as well as fluid loss. Mixing the drilling fluid with Portland cement increased the fluid loss significantly. In term of compressive strength, as the amount of drilling fluids increased, the compressive strength of geopolymer was not significantly affected. After 3 days curing time, geopolymer lost about 8.5% of its strength when 5% of drilling fluids weight percent was added. Whereas, Portland cement has lost 38.4% of its strength when 5% of drilling fluids weight percent was added. After 7 days curing time, geopolymer lost about 23% of its strength when 5% of drilling fluid by weight of cement was added. However, Portland cement lost 49% of compressive strength in the same conditions. These obtained results indicates that geopolymer has the ability to withstand the drilling fluids contamination.

Kajian Karakteristik Kimia dan Fisika Abu Layang yang Menjadi Penentu Kekuatan Mekanik Perekat Geopolimer Berbahan Dasar Abu Layang

Conversion of fly ash into geopolymers is one of the right ways to reduce the problem of coal ash waste which is hazardous and poisonous waste while its production continues to increase every year. In this study, fly ash from Pacitan power plant, Semen Gresik, Petrokimia Gresik, and Australia were used as the raw materials for making geopolymers. The geopolymers were made based on previous research. Geopolymer compressive strength that was measured at 7 days after curing was 46.71; 42.6; 42.6; 9.55 MPa, respectively. Analyses of phase composition and crystallinity, morphology and particle size and composition of fly ash constituents showed that the factor that had the strongest influence in this study was the size of fly ash particles. Fly ash with the largest particle size produces geopolymers with the lowest compressive strength. High calcium content produces a short setting time and all geopolymers that have high compressive strength are made from fly ash with a high content of Fe 2 O 3