scholarly journals Effects of Temperature in Different Initial Duration Time for Soft Clay Stabilized by Fly Ash Based Geopolymer

2018 ◽  
Vol 4 (9) ◽  
pp. 2082 ◽  
Author(s):  
Abdalla Mohammed Shihab ◽  
Jasim M Abbas ◽  
Amer M Ibrahim
Keyword(s):  
Fly Ash ◽  
Low Cost ◽  
Soft Clay ◽  
Volumetric Strain ◽  
Curing Temperature ◽  
X Ray Diffraction ◽  
Duration Time ◽  
High Calcium ◽  
High Calcium Fly Ash ◽  
Edx Analyses

When soft clay soils are included in engineering projects, it’s stabilized usually with some kinds of admixtures named as stabilizers. The common stabilizers that highly practiced are OPC, lime, high calcium fly ash (FA), etc. Each one of these stabilizers has its shortcomings. Geopolymers are the product of alkali activated aluminosilicate sources that excelled as an alternative to ordinary binders due to its sustainability, low cost and good mechanical properties. This study investigates the effects of some key elements like liquid over fly ash ratio (Liq/FA), initial duration curing time (D) and its temperature to soil – FA based Geopolymers samples characterized by its unconfined compressive strength testing (UCS), volumetric measurements, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-Ray diffraction (XRD). The Liq/FA taken as 2.71, 3.167, 3.8 and 4.75 respectively and the duration time taken were 1, 6, 18 and 24 hrs. respectively. The tests results showed that the maximum peak strength gain when Liq/FA is 3.8 at 90 oC with 24 hrs. D. It was observed that Young’s Modulus increased with increasing curing temperature for certain D. Volumetric strain increased by increasing D and its temperature. SEM and XRD analyses confirmed the Geopolymers gels formation for a selective precursor while EDX analyses showed that silicon over aluminium ratio is 1.38 for selective spectrum within the gel to the same mixture. 

Characterization of Effloresences of Ambient and Elevated Temperature Cured Fly Ash Based Geopolymer Type Concretes

2016 ◽  
Vol 1139 ◽  
pp. 25-29 ◽  
Author(s):  
Jadambaa Temuujin ◽  
Claus Ruescher ◽  
Amgalan Minjigmaa ◽  
Burenkhangai Darkhijav ◽  
Batmunkh Davaabal ◽  
...  
Keyword(s):  
Elevated Temperature ◽  
Fly Ash ◽  
Ambient Temperature ◽  
Mineralogical Composition ◽  
Curing Temperature ◽  
Calcium Carbonates ◽  
Sodium Calcium ◽  
High Calcium ◽  
High Calcium Fly Ash

Efflorescences formed on the surface of air (ambient) and elevated (70°C) temperatures cured high calcium fly ash based geopolymer type concretes have been characterized by the XRD, SEM-EDX and FTIR techniques. The mineralogical composition of the efflorescence depends on curing temperature. At ambient temperature the main phase of efflorescence consists of atmospheric carbonation product of sodium hydroxide such as thermonatrite (Na2(CO3)·H2O, PDF 8--448), while in the 70°C cured concrete it represents sodium calcium carbonates gaylussite (Na2Ca (CO3)2·5H2O, PDF 21-343). Mineralogical composition difference between the ambient and 70°C cured concrete’s efflolorescences is related to chemical reaction of alkaline liquid with fly ash constituents.

scholarly journals Low cost and sustainable repair material made from alkali-activated high-calcium fly ash with calcium carbide residue

2020 ◽  
Vol 247 ◽  
pp. 118543 ◽  
Author(s):  
Tanakorn Phoo-ngernkham ◽  
Chattarika Phiangphimai ◽  
Darrakorn Intarabut ◽  
Sakonwan Hanjitsuwan ◽  
Nattapong Damrongwiriyanupap ◽  
...  
Keyword(s):  
Fly Ash ◽  
Low Cost ◽  
Calcium Carbide ◽  
Repair Material ◽  
High Calcium ◽  
High Calcium Fly Ash ◽  
Calcium Carbide Residue ◽  
Alkali Activated

Fly Ash in Shale Stabilization for Highway Construction

1985 ◽  
Vol 65 ◽  
Author(s):  
M. Saleh ◽  
Joakim G. Laguros
Keyword(s):  
Fly Ash ◽  
Substantial Reduction ◽  
Aluminum Silicate ◽  
X Ray Diffraction ◽  
Clay Particles ◽  
Angle Of Internal Friction ◽  
High Calcium ◽  
Field Samples ◽  
High Calcium Fly Ash ◽  
Experimental Project

ABSTRACTThe expansive shales used for roadbeds in Oklahoma are traditionally stabilized with lime. Stabilization with a Class C (high-calcium) fly ash was explored and compared to an optimum design utilizing the conjunctive use of fly ash, lime and cement, in the laboratory and in a field experimental project. Periodic visual observations indicated that the performance of test sections was excellent. Analyses of field samples showed that fly ash, either alone or mixed with lime and cement, was effective in ameliorating the texture and plasticity of the shale by reducing the amount of clay size particles and by imparting higher strength levels to the shale. Laboratory samples showed better stabilization than field samples, but the field samples performed at an acceptable level in measurements of compressive and beam strength, cohesion, angle of internal friction and resistance to deflection. The microstructure of stabilized shale was studied using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Nonbasal (hkl) reflections in stabilized oriented specimens suggest that the clay particles acquire high resistance to dispersive forces. The reduction of the areas under the peaks help explain the strength gain observed. The SEM observations indicated newly formed hydration products, possibly calcium aluminum silicate hydrate crystals, and a rather dense degree of packing as manifested by the substantial reduction of void areas as a result of stabilization.

Effect of Silica to Alumina Ratio on the Compressive Strength of Class C Fly Ash-Based Geopolymers

2015 ◽  
Vol 659 ◽  
pp. 80-84 ◽  
Author(s):  
Patthamaporn Timakul ◽  
Kanyarat Thanaphatwetphisit ◽  
Pavadee Aungkavattana
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Curing Temperature ◽  
Infrared Study ◽  
Xrd Study ◽  
High Calcium ◽  
High Calcium Fly Ash ◽  
Solid Part ◽  
Class C ◽  
Mae Moh

This study investigated the effect of silica to alumina ratio on the compressive strength of geopolymer. The high calcium fly ash (Class C, ASTM 618) wastes from Mae Moh Thailand power plant, which is SiO2 (30.97%) and Al2O3 (17.16%)-rich materials was employed as the main solid part to prepare geopolymers, apart from kaolinite. The combination of sodium hydroxide (NaOH), sodium silicate (Na2SiO3) solution, and distilled water as 1:1:4 mass ratios were used as the liquid activator. The curing temperature in the oven was fixed at 75oC and varied curing time for 24, 48, 72 and 96 hours. Further curing was done at room temperature for 28 days before characterizations. XRD study of synthesized geopolymers showed a hump of not well-defined peaks and some major peaks of quartz, and unreacted kaolinite indicating the incomplete geopolymerization reaction. Infrared study showed the Al-O-Si and Si-O-Si bonds in all geopolymers samples. The compressive strength of geopolymer increased from 32 to 40 MPa when the ratio of SiO2 : Al2O3 was increased from 2.60 to 2.65. However, the compressive strength was decreased after increasing the SiO2 : Al2O3 ratio from 2.65 to 3.0. The highest compressive strength was found when the SiO2 : Al2O3 ratio was 2.65 with the curing condition at 75oC for 96 h which the samples also possessed high density.

Performance of a Fly Ash Stabilized Pavement

1989 ◽  
Vol 178 ◽  
Author(s):  
Joakim G. Laguros ◽  
Curt Hayes
Keyword(s):  
Fly Ash ◽  
Concrete Surface ◽  
Asphaltic Concrete ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Calcium ◽  
Field Samples ◽  
High Calcium Fly Ash ◽  
Term Basis

AbstractAn expansive shale roadbase, stabilized with a Class C (high-calcium) fly ash received an 11–inch full–depth asphaltic concrete surface layer and the highway was opened to traffic six years ago. Periodic sampling and visual observations indicate that the performance of the pavement test sections are above average.Analyses of field samples showed that fly ash was effective in ameliorating the texture and plasticity of the shale and imparting strength to it on a long term basis. Pavement deflections and the extent of cracking have not increased beyond acceptable levels during the six year period.X-ray diffraction studies show a reduction of the areas under the peaks and the SEM observations reveal a dense degree of packing and reduction of the void areas. These modifications occur during the first two years of service and any changes beyond that period appear to be minor.

Natural fiber reinforced high calcium fly ash geopolymer mortar

2020 ◽  
Vol 241 ◽  
pp. 118143 ◽  
Author(s):  
Ampol Wongsa ◽  
Ronnakrit Kunthawatwong ◽  
Sakchai Naenudon ◽  
Vanchai Sata ◽  
Prinya Chindaprasirt
Keyword(s):  
Fly Ash ◽  
Natural Fiber ◽  
Fiber Reinforced ◽  
High Calcium ◽  
High Calcium Fly Ash

Monitoring of Fluctuations in the Physical and Chemical Properties of a High-Calcium Fly Ash

1987 ◽  
Vol 113 ◽  
Author(s):  
Scott Schlorholtz ◽  
Ken Bergeson ◽  
Turgut Demirel
Keyword(s):  
Fly Ash ◽  
Chemical Properties ◽  
Operating Conditions ◽  
Physical And Chemical Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Morphological Studies ◽  
High Calcium ◽  
Physical And Chemical ◽  
And Chemical Properties

ABSTRACTThe physical and chemical properties of fly ash produced at Ottumwa Generating Station have been monitored since April, 1985. The fly ash is produced from burning a low sulfur, sub-bituminous coal obtained from the Powder River Basin near Gillette, Wyoming. One-hundred and sixty samples of fly ash were obtained during the two year period. All of the samples were subjected to physical testing as specified by ASTM C 311. About one-hundred of the samples were also subjected to a series of tests designed to monitor the self-cementing properties of the fly ash. Many of the fly ash samples were subjected to x-ray diffraction and fluorescence analysis to define the mineralogical and chemical composition of the bulk fly ash as a function of sampling date. Hydration products in selected hardened fly ash pastes, were studied by x-ray diffraction and scanning electron microscopy. The studies indicated that power plant operating conditions influenced the compressive strength of the fly ash paste specimens. Mineralogical and morphological studies of the fly ash pastes indicated that stratlingite formation occurred in the highstrength specimens, while ettringite was the major hydration product evident in the low-strength specimens.

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.

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