Autoclaved Brick from Semi-Dry Desulfuration Ash

2011 ◽  
Vol 217-218 ◽  
pp. 846-851 ◽  
Author(s):  
Hao Li ◽  
Feng Qing Zhao ◽  
Qian Li ◽  
Lin Lin Fu ◽  
Shao Jie Liu
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Natural Resources ◽  
Calcium Oxide ◽  
Calcium Sulfate ◽  
Solid Wastes ◽  
Solid Ratio ◽  
Autoclave Curing ◽  
Calcium Sulfite

The modified desulfurized ash is prepared through autoclave curing the desulfurized ash for 6 h at 175.4 oC in the presence of 2.0 wt% Fe2O3 and 0.75 wt% H2O2. In this process, 47.64 % of the calcium sulfite in the desulfurized ash is converted into calcium sulfate. The autoclaved brick is made by 36 wt% modified desulfurized ash, 24 wt% fly ash, 32 wt% sand and 8 wt% stones. The water-solid ratio is 0.10. The compressive strength of the brick is up to 15.7 MPa. For this method, the calcium oxide and calcium sulfate in the modification desulfurized ash are used to replace the lime, gypsum and other materials. The solid wastes are reused and natural resources are saved.

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.

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 Gene-Expression Programming-Based Model for Estimating the Compressive Strength of Cement-Fly Ash Stabilized Soil and Parametric Study

2021 ◽  
Vol 6 (12) ◽  
pp. 181
Author(s):  
Van-Ngoc Pham ◽  
Erwin Oh ◽  
Dominic E. L. Ong
Keyword(s):  
Gene Expression ◽  
Compressive Strength ◽  
Fly Ash ◽  
Calcium Oxide ◽  
Parametric Study ◽  
Soil Stabilization ◽  
Gene Expression Programming ◽  
Superior Performance ◽  
Stabilized Soil ◽  
Research Findings

The study aims to develop a reliable model using gene-expression programming (GEP) technique for estimating the unconfined compressive strength (UCS) of soil stabilization by cement and fly ash. The model considered the effects of several parameters, including the fly ash characteristics such as calcium oxide (CaO) content, CaO/SiO2 ratio, and loss of ignition. The research results show that the proposed model demonstrates superior performance with a high correlation coefficient (R > 0.955) and low errors. Therefore, the model could be confidently applied in practice for a variety of fly ash qualities. Besides, the parametric study was conducted to examine the effect of fly ash characteristics on the strength of soil stabilization. The study indicates that if the fly ash contains a high amount of calcium oxide, the strength of fly ash stabilized soil is significant. In addition, fly ash could be used in combination with cement to increase the strength of the mixture. A fly ash replacement ratio is suggested from 0.19 to 0.35, corresponding to the total binder used from 10% to 30%. The research findings could help engineers in optimizing the fly ash proportion and estimating the UCS of soil stabilization by cement and fly ash.

scholarly journals Compressive Strength Development of Geopolymer Mortar by Utilization Slag and Fly Ash Mixtures

2019 ◽  
Vol 9 (2) ◽  
pp. 4066-4069
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Solid Material ◽  
Solid Wastes ◽  
Strength Development ◽  
Solid Materials ◽  
Compressive Strength Development ◽  
Alkaline Activator ◽  
Materials Used ◽  
Made In

The paper displays the use of two base solid wastes materials to produce the alkaline-activated binder mortar to reduce the CO2 emission on climate change. The solid materials used in this research were slag and fly-ash to improve the compressive strength (CS) of alkaline activated mortar (AAM). The output AAM of 7 trial mixes were designed with different combinations of slag and fly ash. The mixes combinations were made in ratios of (100:0), (90:10), (80:20), (70:30), (50:50), (25:75), and (0:100), respectively. The combination of 10 M NaOH and Na2SiO3 was used as alkaline activator (AA). The wt. ratio of Na2SiO3 to NaOH = 2.5, and wt. ratio of AA to solid material = 0.52. The samples of AAM were cured at 75°C for 24 h. Among all the 7 trial mixtures, it was found that mixture with a combined ratio of slag:fly ash of 25:75 produce the maximum CS at 28 days of 88.87 MPa. Therefore, the alteration percentage of SiO2 and Al2O3 derived from fly ash in combination with CaO derived from slag contributed to significant CS improvement due to the formation of (N-A-S-H), (C-S-H) and (C-(A)-S-H) gels. The result observed of gel binder formation was confirmed by XRD and FESEM analyses.

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.

Effects of Activators on Compressive Strength of Fly Ash-Based Geopolymers

2011 ◽  
Vol 197-198 ◽  
pp. 830-836
Author(s):  
Dong Min Wang ◽  
Pei Fu Cheng ◽  
Fan Fan ◽  
Yun Fen Hou ◽  
Liang Zhang ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Calcium Oxide ◽  
Water Glass ◽  
Solution Concentration ◽  
Solid Content ◽  
Strength Development ◽  
Obvious Effect ◽  
Compressive Strength Development ◽  
Visible Effect

The effects of different activators on compressive strength of fly ash-based geopolymers have been studied. It is discovered that, alkali solution doesn’t have obvious effect, while Na2SiO3 solution has visible effect, the strength of samples rise with the increase of Na2SiO3 solution concentration. The effect of K2SiO3 solution is more obvious than Na2SiO3 solution, the strength of samples tend to first increase and then decrease with the increase of K2SiO3 solution concentration. The K2SiO3 solution with concentration of 2 M is the best activator to prepare geopolymers, which has compressive strength of 28.8 MPa at 28 d. When water glass are used as activators, the best modulus and solid content for Na-water glass (Na2O•nSiO2) are 1.2 and 32%, respectively. On this condition the sample’s compressive strength at 28 d is 38.9 MPa. However crystal calcium oxide is harmful for the compressive strength development, which is different with the conclusion accepted abroad.

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.

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