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

2020 ◽  
Vol 9 (2) ◽  
pp. 90-98
Author(s):  
Baomin Wang ◽  
Chengcheng Fan ◽  
Yi Qi
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Mixing Time ◽  
Molar Ratio ◽  
Technological Parameters ◽  
Minimal Impact ◽  
Solid Ratio ◽  
Optimum Proportion ◽  
Stretching Vibration ◽  
Mixing Proportion

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.

scholarly journals Novel Analytical Method for Mix Design and Performance Prediction of High Calcium Fly Ash Geopolymer Concrete

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 900
Author(s):  
Chamila Gunasekara ◽  
Peter Atzarakis ◽  
Weena Lokuge ◽  
David W. Law ◽  
Sujeeva Setunge
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Gradient Algorithm ◽  
Geopolymer Concrete ◽  
Statistical Regression ◽  
Solid Ratio ◽  
Marquardt Algorithm ◽  
High Calcium ◽  
High Calcium Fly Ash ◽  
Matlab Programming

Despite extensive in-depth research into high calcium fly ash geopolymer concretes and a number of proposed methods to calculate the mix proportions, no universally applicable method to determine the mix proportions has been developed. This paper uses an artificial neural network (ANN) machine learning toolbox in a MATLAB programming environment together with a Bayesian regularization algorithm, the Levenberg-Marquardt algorithm and a scaled conjugate gradient algorithm to attain a specified target compressive strength at 28 days. The relationship between the four key parameters, namely water/solid ratio, alkaline activator/binder ratio, Na2SiO3/NaOH ratio and NaOH molarity, and the compressive strength of geopolymer concrete is determined. The geopolymer concrete mix proportions based on the ANN algorithm model and contour plots developed were experimentally validated. Thus, the proposed method can be used to determine mix designs for high calcium fly ash geopolymer concrete in the range 25–45 MPa at 28 days. In addition, the design equations developed using the statistical regression model provide an insight to predict tensile strength and elastic modulus for a given compressive strength.

scholarly journals One-Part Alkali-Activated Pastes and Mortars Prepared with Metakaolin and Biomass Ash

2020 ◽  
Vol 10 (16) ◽  
pp. 5610
Author(s):  
Alessandra Mobili ◽  
Francesca Tittarelli ◽  
Hubert Rahier
Keyword(s):  
Compressive Strength ◽  
Reaction Kinetics ◽  
Isothermal Calorimetry ◽  
Molar Ratio ◽  
Alkaline Solutions ◽  
Strength Increase ◽  
Biomass Ash ◽  
Solid Ratio ◽  
User Friendly ◽  
Alkali Activated

Common alkali-activated materials (AAMs) are usually manufactured with highly alkaline solutions. However, alkaline solutions are dangerous for workers who must wear gloves, masks, and glasses when handling them. This issue makes common (or two-part) AAMs not user-friendly and problematic for bulk production if no safety procedures are followed. In this paper, the possibility of manufacturing alkali-activated pastes and mortars without alkaline solution is investigated. These innovative one-part AAMs have been prepared with metakaolin as the aluminosilicate precursor, potassium-rich biomass ash as the alkaline activator, and water. AAMs have been prepared by varying the K/Al molar ratio: pastes have been studied in terms of reaction kinetics, through isothermal calorimetry, and mortars have been tested in terms of mechanical compressive strength. Results show that the K/Al molar ratio governs both the reaction kinetics and the mechanical strength of these innovative materials. The highest compressive strength is obtained when the K/Al ratio is equal to 2.5 and the water/solid ratio is equal to 0.49. If biomass ash is heated at 700 °C to decompose the calcium carbonate, its reactivity and the final compressive strength increase.

EFFECT OF MIXING PROPORTION ON COMPRESSIVE STRENGTH OF FLY-ASH BASED GEOPOLYMER PASTE AND MORTAR USING TAGUCHI’S METHOD

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Sajid Khan Afridi ◽  
Vanissorn Vimonsatit
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Elevated Temperatures ◽  
Three Dimensional ◽  
Silica Content ◽  
Polymeric Chain ◽  
Low Carbon ◽  
Solid Ratio ◽  
Mix Proportion ◽  
Alkali Activated

Alkali activated pozzolan are known low carbon cementitious binders which can be used to replace cement. The material is also known as geopolymer because of its three dimensional polymeric chain and ring like structure consisting silica and alumina. A common type of pozzolan used is fly ash because of its rich silica content; therefore the term alkali activated fly-ash based binders is adopted. Despite much research and development of this material, there is no specific standard for design mix proportion. This research used the Taguchi’s design of experiment method to determine the optimum mix proportion of alkali activated fly ash based cement paste and mortar. Four factors were considered in the tests, silica fume, sand to cementitious ratio, liquid to solid ratio, and percentage of superplasticiser. Tests were conducted on the 9 batches of alkali activated fly-ash based paste and mortar samples to determine the compressive strength under ambient condition. Tests were also conducted to determine the residual strength of the samples after exposed to elevated temperatures. ANOVA analysis of the test results revealed the main factors contribution on the tested properties and led to the determination of the optimum design proportion of the factors considered in these tests.

MECHANICAL PROPERTIES OF FLY ASH-BASED ALKALI-ACTIVATED CEMENT USING A STATISTICAL ANALYSIS TECHNIQUE

2014 ◽  
Vol 1 (1) ◽  
Author(s):  
Hyuk Lee ◽  
Vanissorn Vimonsatit
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Statistical Analysis ◽  
Fly Ash ◽  
Silica Fume ◽  
Dry Density ◽  
Analysis Method ◽  
Solid Ratio ◽  
Alkali Activated ◽  
Alkali Activated Cement

This paper presents the mechanical properties of fly ash-based alkali-activated cement (AAC). A statistical analysis method was used to determine the effect of mix proportion parameters on the dry density and compressive strength of fly ash-based AAC pastes and mortars. For that purpose, sample mixtures were designed according to Taguchi’s experimental design method, i.e., in a L9 orthogonal array. Four factors were selected: “silica fume content” (SF), “sand to solid ratio” (s/c), “liquid to solid ratio” (l/s), and “superplasticiser content” (SP). The experimental results were analysed by using signal to noise for quality control of each mixture, and analysis of variance (ANOVA) was used to determine the significant effect on the compressive strength of fly ash-based AAC. Furthermore, a regression-analysis method was used to predict the compressive strength according to the variation of the four factors. Results indicated that silica fume is the most influencing parameter on compressive strength, which could be decreased by superplasticiser and l/s ratio. There is no significant effect of sand-to-cementitious ratio on compressive strength of fly ash-based AAC. The dry density decreases as the sand-to-cementitious ratio is decreased. The increasing l/s ratio and superplasticiser dosage could further decrease the dry density of fly ash-based AAC.

scholarly journals Strength of Geopolymer Paste using a Ternary Blend of Fly Ash Ggbfs and Silica Fume under Ambient Conditions

2019 ◽  
Vol 8 (11) ◽  
pp. 3784-3790
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Adverse Effects ◽  
Silica Fume ◽  
Ternary Blend ◽  
Ambient Conditions ◽  
Solid Ratio ◽  
Mix Proportioning ◽  
Geopolymer Paste

In this paper, compressive strength (CS) of geopolymer paste has been studied under ambient conditions using locally available Class C fly ash, GGBFS and silica fume and a combination alkali activator, namely: NaOH and Na2SiO3 . Two approaches were used for mix proportioning and 60 mixes of the paste were proportioned. It is found that all the mixes proportioned were workable and no adverse effects were observed within 30 minutes of mixing. It is found that the ‘minimum voids’ approach along with a constant fly ash – to – activator ratio (FA/AA) is the best approach for the design of geopolymer mixes, rather than a constant water- to- solid ratio (w/s). Further, the role of GGBFS and SF on the CS of the paste has also been highlighted.

scholarly journals Synthesis and Characterization of Porous Fly Ash-Based Geopolymers Using Si as Foaming Agent

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
D. Kioupis ◽  
Ch. Kavakakis ◽  
S. Tsivilis ◽  
G. Kakali
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Apparent Density ◽  
Molar Ratio ◽  
Synthesis And Characterization ◽  
Taguchi Approach ◽  
Foaming Agent ◽  
Synthesis Parameters ◽  
Si Content

This paper concerns the synthesis of foamed geopolymers using fly ash and metallic Si as the binder and the porogent agent, respectively. The Taguchi approach was applied in order to study the effect of some significant synthesis parameters such as the Si foaming agent content (% w/w fly ash based), the alkali type (R : Na or K), and the alkalinity (R/Al molar ratio) of the activation solution on the compressive strength and apparent density of the foamed geopolymers. The final products were characterized by means of XRD, FTIR, and SEM, while optical microscopy was applied for the evaluation of the porosity. Lightweight geopolymers with a compressive strength of 2.08–14.88 ΜPa and an apparent density of 0.84–1.55 g/cm3 were prepared by introducing a Si content up to 0.2% w/w on fly ash basis.

scholarly journals Using Fly Ash Wastes for the Development of New Building Materials with Improved Compressive Strength

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 644
Author(s):  
Maria Harja ◽  
Carmen Teodosiu ◽  
Dorina Nicolina Isopescu ◽  
Osman Gencel ◽  
Doina Lutic ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Building Materials ◽  
Simple Procedure ◽  
Xrd Analysis ◽  
Partial Hydrolysis ◽  
Alkali Activation ◽  
Activation Process ◽  
Solid Ratio ◽  
Powder Xrd Analysis

Fly ash wastes (silica, aluminum and iron-rich materials) could be smartly valorized by their incorporation in concrete formulation, partly replacing the cement. The necessary binding properties can be accomplished by a simple procedure: an alkali activation process, involving partial hydrolysis, followed by gel formation and polycondensation. The correlations between the experimental fly ash processing conditions, particle characteristics (size and morphology) and the compressive strength values of the concrete prepared using this material were investigated by performing a parametric optimization study to deduce the optimal processing set of conditions. The alkali activation procedure included the variation of the NaOH solutions concentration (8–12 M), temperature values (25–65 °C) and the liquid/solid ratio (1–3). The activation led to important modifications of the crystallography of the samples (shown by powder XRD analysis), their morphologies (seen by SEM), particle size distribution and Blaine surface values. The values of the compressive strength of concrete prepared using fly ash derivatives were between 16.8–22.6 MPa. Thus, the processed fly ash qualifies as a proper potential building material, solving disposal-associated problems, as well as saving significant amounts of cement consumed in concrete formulation.

Utilization of Phosphorus Slag and Fly Ash for the Preparation of Ready-Mixed Mortar

2013 ◽  
Vol 423-426 ◽  
pp. 987-992 ◽  
Author(s):  
Xiu Wei Liu ◽  
Lin Yang ◽  
Bin Zhang
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Raw Materials ◽  
Setting Time ◽  
Technological Parameters ◽  
Mix Proportion ◽  
Optimal Mix ◽  
Mixed Mortar ◽  
Chinese Standard ◽  
Phosphorous Slag

Phosphorous slag and fly ash were used as raw materials for the preparation of ready-mixed mortar, and a series of technological parameters, such as phosphorus slag content, fly ash content, and chemical activators were investigated based on the compressive strength and setting time of specimens in this paper and the performances of products were also tested. The results showed that the optimal mix proportion for preparing ready-mixed mortar (M10) is as follows: cement 5%, phosphorous slag 10%, fly ash 10%, sand 75%, water reducer 1% and chemical activator 1%. The consistency, water retaining, setting time, 28d compressive strength, 14d bond strength and 28d shrinkage meet the requirement of Chinese standard GB/T 25181-2010.

Study on Ultra-Strength Mortar Prepared with Mineral Admixture

2011 ◽  
Vol 675-677 ◽  
pp. 1073-1076
Author(s):  
Zu Quan Jin ◽  
Peng Zhang ◽  
Tie Jun Zhao ◽  
Bao Rong Hou
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Flexural Strength ◽  
Pore Structure ◽  
Silica Fume ◽  
Mineral Admixture ◽  
Replacement Rate ◽  
River Sand ◽  
Optimum Proportion ◽  
Curing Age

In this paper, preparation, property study of ultra-strength mortars with mineral admixture and clear river sand was carried out. The mineral admixture include fly ash, ultra-fine GGBS and silica fume. The experimental results show that the compressive strength of mortar improves with increasing amount of silica fume or ultra-fine GGBS. When the content of silica fume or ultra-fine GGBS is 30~35%, the compressive strength and flexural strength of mortar in curing age of 7 days are 100 MPa and 20MPa, respectively. But strength of mortar decreases with the increase replacement rate of fly ash. When the mortar mixes with combined of silica fume and ultra-fine GGBS, the optimum proportion of siliaca fume to ultra-fine GGBS is 2:3. And the compressive strength of mortar in curing age of 7 days is 75~100MPa when the mixed mineral admixture is 40~60%. The compressive strength of mortar is about 90MPa as it mix 60% of cement, 15% of silica fume, 15% of GGBS and 10% of fly ash. Moreover, the ultra strength mortar refines its pore structure and its capiliary pore (≥100nm) amount reduces by 78% compared to ordinary mortar.

Tentative Optimum Proportion of Supplementary Cementitious Materials in Blended Cement to Perform Better under Tannery Wastewater

2018 ◽  
Vol 937 ◽  
pp. 107-113
Author(s):  
Samina Samrose ◽  
Saifa Anzum ◽  
Samira Mahmud ◽  
Tanvir Manzur
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Blended Cement ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Effluent Treatment ◽  
Tannery Wastewater ◽  
Wastewater Sample ◽  
Supplementary Cementitious Material ◽  
Optimum Proportion

The present research studies the compressive strength of cement mortar cubes prepared from different proportions of supplementary cementitious materials (Fly Ash and Slag) in blended cement. This research aims to find the tentative optimum composition of supplementary cementitious material that shows better performance under tannery wastewater condition, such as that in effluent treatment plants. Synthetic tannery wastewater was simulated in laboratory after collecting wastewater sample from local tannery industry. Eight types of cement compositions (varying supplementary materials proportions) have been chosen. Compressive strength test has been conducted on mortar cubes over a period of three months. Test results revealed that slag addition had shown significantly stronger effects than that of fly ash addition. Also, the combined effect of fly ash and slag and their order of variation on strength were studied. The observations made from this research will be helpful for selection of blended cement proportions in future structures exposed to similar severe conditions.

Sign in / Sign up

Export Citation Format

Share Document