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SPR 3020 Updating Physical and Chemical Characteristics Data of Fly Ash in Concrete. Prasanth Tanikella and Jan Olek Purdue University, School of Civil Engineering, West Lafayette, Indiana. Presented to the SAC Committee October 3 rd , 2008. Presentation Outline. Research Objective

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spr 3020 updating physical and chemical characteristics data of fly ash in concrete

SPR 3020Updating Physical and Chemical Characteristics Data of Fly Ash in Concrete

PrasanthTanikella and Jan Olek

Purdue University, School of Civil Engineering,

West Lafayette, Indiana

Presented to the SAC Committee

October 3rd , 2008

presentation outline
Presentation Outline
  • Research Objective
  • Scope of the original project
  • Proposed expansion of the scope
  • Status of the project – Review of the tasks

Original Project

  • Literature Review
  • Characterization of available fly ashes

- Methods of examination

- Results and analysis

- Conclusions

Proposed Expansion

  • Evaluation of the hydration characteristics of binders
  • Binary binder systems
  • Ternary binder systems
  • Summary and conclusions of the study

Prasanth Tanikella - Purdue University

presentation outline1
Presentation Outline
  • Research Objective
  • Scope of the original project
  • Proposed expansion of the scope
  • Status of the project – Review of the tasks

Original Project

  • Literature Review
  • Characterization of available fly ashes

- Methods of examination

- Results and analysis

- Conclusions

Proposed Expansion

  • Evaluation of the hydration characteristics of binders
  • Binary binder systems
  • Ternary binder systems
  • Summary and conclusions of the study

Prasanth Tanikella - Purdue University

research objective
Research Objective
  • To revise and update the information on the basic physical and chemical characteristics of fly ashes available to INDOT and to the industry in Indiana

PrasanthTanikella - Purdue University

presentation outline2
Presentation Outline
  • Research Objective
  • Scope of the original project
  • Proposed expansion of the scope
  • Status of the project – Review of the tasks

Original Project

  • Literature Review
  • Characterization of available fly ashes

- Methods of examination

- Results and analysis

- Conclusions

Proposed Expansion

  • Evaluation of the hydration characteristics of binders
  • Binary binder systems
  • Ternary binder systems
  • Summary and conclusions of the study

Prasanth Tanikella - Purdue University

scope of the original project
Scope of the Original Project

The general scope of the project includes collecting a suite of fly ashes available for use in concrete in Indiana and characterizing them for the following properties

Chemical Properties

  • Total chemical composition (silicon, calcium, magnesium, titanium, aluminum, iron, sodium, potassium, phosphorus and sulfur)
  • Loss-on Ignition, carbon content
  • Soluble sulfates and alkalis
  • Content of magnetic particles

Physical Properties

  • Particle size distribution
  • Specific surface
  • Specific gravity
  • Mineral composition using X-Ray Diffraction
  • Morphology of particles using SEM and optical microscopy
  • Pozzolanic activity index with cement

PrasanthTanikella - Purdue University

presentation outline3
Presentation Outline
  • Research Objective
  • Scope of the original project
  • Proposed expansion of the scope
  • Status of the project – Review of the tasks

Original Project

  • Literature Review
  • Characterization of available fly ashes

- Methods of examination

- Results and analysis

- Conclusions

Proposed Expansion

  • Evaluation of the hydration characteristics of binders
  • Binary binder systems
  • Ternary binder systems
  • Summary and conclusions of the study

Prasanth Tanikella - Purdue University

proposed expansion of the scope
Proposed Expansion of the Scope

Need for the Proposed Expansion of the Scope

  • Fly ash is a very complex material, with a highly variable chemical and physical characteristics
  • Recent changes in coal combustion technologies and environmental regulations resulting in more variable quality and less predictable availability
  • Combined with the inherent chemical and physical variations, these additional changes require more comprehensive tools for quality control and performance prediction
  • Hence, there is a need to estimate the properties of cement+ fly ash binder systems as a function of the physical and chemical characteristics of the components to aid with decisions regarding the selection of fly ashes of variable quality

Proposed Expansion

  • To estimate (quantitatively) the glass content in the fly ashes and its chemical composition as glass is the most reactive component in fly ash
  • To investigate the role of the fundamental characteristics of fly ash in binder hydration
  • To quantify the synergistic effects of adding two fly ashes to cement and to develop methods for selection of the type and the amount of fly ashes to be added to achieve the desired hydrated binder characteristics
  • Statistically model the effect of characteristics of fly ash on the hydration process of binary and ternary binders as the function of fly ash composition and glass characteristics

PrasanthTanikella - Purdue University

presentation outline4
Presentation Outline
  • Research Objective
  • Scope of the original project
  • Proposed expansion of the scope
  • Status of the project – Review of the tasks

Original Project

  • Literature Review
  • Characterization of available fly ashes

- Methods of examination

- Results and analysis

- Conclusions

Proposed Expansion

  • Evaluation of the hydration characteristics of binders
  • Binary binder systems
  • Ternary binder systems
  • Summary and conclusions of the study

Prasanth Tanikella - Purdue University

task review and status
Task Review and Status

Phase I - Original Tasks

Task 1: Literature Review Completed

Task 2: Collection of Fly Ash Specimens Completed

Task 3: Laboratory Testing Completed

Task 4: Data Analysis Completed

Task 5: Development of fly ash database In Progress

Task 6: Development of a report Completed

Phase II - Newly Added Tasks

Task 1N: Literature review of the hydration characteristics Completed

of binary and ternary binder systems

Task 2N: Selection of the experimental techniques Completed

Task 3N: Laboratory Experimentation

- Heat of Hydration (Isothermal Calorimetry) In Progress

- Setting time Completed

- Porosity at different ages (Mercury Intrusion Porosimetry) In Progress

- Rate of strength development In Progress

Prasanth Tanikella - Purdue University

task review and status1
Task Review and Status

Task 3N: Laboratory Experimentation… Continued

- Estimation of unhydrated fly ash (Selective To be Performed

dissolution and TGA)

- Estimation of the lime content (TGA) To be Performed

- Estimation of the glass content in fly ash To be Performed

- Estimation of the non-evaporable water content To be Performed

- Qualitative X-ray diffraction at different ages In Progress

of hydration of binders

Task 4N: Statistical analysis and modeling of the data In Progress

Task 5N: Development of an electronic program for the To be Performed

estimation of the amount and type of fly ash(s) to

be added to cement based on the chemical and

physical characteristics of fly ash to achieve the desired

properties of the binder

Task 6N: Report writing and editing To be Performed

Prasanth Tanikella - Purdue University

presentation outline5
Presentation Outline

Phase I - Original Project

  • Task 1 - Literature Review
  • Task 2 - Collection of Specimen
  • Task 3 - Characterization of available fly ashes

- Methods of examination

- Results

  • Task 4 - Data analysis and conclusions
  • Tasks 5 & 6 - Report Writing and Database development

Phase II - Proposed Expansion

  • Evaluation of the hydration characteristics of binders
  • Binary binder systems
  • Ternary binder systems
  • Summary and conclusions of the study

Prasanth Tanikella - Purdue University

task 1 literature review
Task 1 – Literature Review
  • A thorough literature survey was performed on the ranges of physical characteristics and chemical compositions of the fly ashes and available testing methods
  • Large variations in chemical compositions and physical characteristics of fly ashes universally reported
  • Larger volume of data available on low calcium fly ashes (Class F)
  • Current trends indicate increased availability of Class C fly ashes and decline in the availability of Class F fly ashes
  • Current INDOT’s list of approved fly ashes contains 13 class C ashes and 7 class F ashes
  • A good correlation for the physical and chemical characteristics of fly ash with the hydration properties has been reported

PrasanthTanikella - Purdue University

presentation outline6
Presentation Outline

Phase I - Original Project

  • Task 1 - Literature Review
  • Task 2 - Collection of Specimen
  • Task 3 - Characterization of available fly ashes

- Methods of examination

- Results

  • Task 4 - Data analysis and conclusions
  • Tasks 5 & 6 - Report Writing and Database development

Phase II - Proposed Expansion

  • Evaluation of the hydration characteristics of binders
  • Binary binder systems
  • Ternary binder systems
  • Summary and conclusions of the study

Prasanth Tanikella - Purdue University

task 2 collection of fly ash specimens
Task 2- Collection of fly ash specimens
  • Collected 20 different fly ashes (13 Class C and 7 Class F)
  • 15 of them ( 9 class C ashes and 6 class F ashes) are currently on the INDOT list of approved pozzolanic materials
  • A database summarizing the physical and chemical characteristics of the collected fly ashes would benefit the engineers, contractors and concrete producers in choosing the fly ashes. Such database is currently in preparation

Prasanth Tanikella - Purdue University

presentation outline7
Presentation Outline

Phase I - Original Project

  • Task 1 - Literature Review
  • Task 2 - Collection of Specimen
  • Task 3 - Characterization of available fly ashes

- Methods of examination

- Results

  • Task 4 - Data analysis and conclusions
  • Tasks 5 & 6 - Report writing and Database development

Phase II - Proposed Expansion of the Scope

  • Evaluation of the hydration characteristics of binders
  • Binary binder systems
  • Ternary binder systems
  • Summary and conclusions of the study

Prasanth Tanikella - Purdue University

task 3 methods of examination
Task 3 - Methods of Examination
  • Total chemical analysis and loss-on ignition according to ASTM C 311
  • Soluble sulfates and soluble alkalis using ion chromatography and atomic absorption spectroscopy
  • Particle size distribution using laser particle size analyzer at the laboratory of Boral Material Technology Inc, Purdue’s particle size analyzer and sedimentation method
  • Content of magnetic particles using a teflon coated bar magnet
  • Crystalline components using qualitative X-ray diffraction
  • Morphologies of particles using scanning electron microscopy
  • Strength activity index with portland cement according to ASTM C 311

Prasanth Tanikella - Purdue University

results chemical composition of fly ashes
ResultsChemical composition of fly ashes

* INDOT list of approved fly ashes

results physical characteristics of fly ashes
ResultsPhysical characteristics of fly ashes

* INDOT list of approved fly ashes.

SG listed in () indicate vales from INDOT’s list of approved fly ashes.

results particle size distributions
ResultsParticle Size Distributions
  • The particle size distributions (PSDs) for 3 typical class C fly ashes and 3 typical class F fly ashes are shown here
  • Class F and Class C ashes form two different bands of PSDs
  • The band of Class C ashes is shifted towards the left of the band of Class F ashes

Class C

Class F

PrasanthTanikella - Purdue University

results xrd typical class f type i fly ash
ResultsXRD – Typical Class F (Type I) Fly Ash
  • Tyical X-ray pattern for a class F fly ash (Type I) – (5 out of 7 ashes)
  • Includes

1. Quartz – SiO2

2. Anhydrite – CaSO4

3. Mullite – Al6Si2O13

4. Hematite – Fe2O3

5. Magnetite – Fe3O4

6. Lime – CaO

  • Measured magnetic content is generally very high
  • A hump, representing a silica-type glass with a maximum at 2θ=~25° is visible
  • Glass “hump” is generally higher than that observed for Class C ashes

XRD pattern for Elmer Smith fly ash

PrasanthTanikella - Purdue University

results xrd typical class f type ii fly ash
ResultsXRD – Typical Class F (Type II) fly ash
  • X-ray pattern for a class F fly ash (Type II) – 2 out of 7 ashes (both from Miami)
  • Includes

1. Quartz – SiO2 2. Mullite – Al6Si2O13

  • The measured content of magnetic paricles was 3.68%
  • However, no crystalline iron oxide peaks were detected
  • A hump, representing a silica type of glass with a maximum at 2θ=~24° is visible (slightly lower than class F (Type I) glass

XRD pattern for Miami 7 fly ash

PrasanthTanikella - Purdue University

results xrd typical class c fly ash
ResultsXRD - Typical Class C Fly Ash
  • X-ray pattern for a typical class C fly ash
  • Includes

1. Quartz – SiO2

2. Anhydrite – CaSO4

3. Merwinite – Ca3Mg(SiO4)2

4. Periclase – MgO

5. Lime – CaO

  • Glass peak is similar for all the ashes of this type
  • Magnetite might be present in the fly ash, either in crystalline form or in the glass
  • A hump, representing a calcium-aluminate type of glass with a maximum at 2θ=~32° is visible

XRD pattern for Hennepin fly ash

PrasanthTanikella - Purdue University

results morphology of class f type i ashes
ResultsMorphology of class F (Type I) ashes
  • There is a large variation in the sizes and shapes of the particles
  • Particles with rugged surface are generally magnetic, contrary to the class C fly ashes
  • Many hollow particles present
  • Relatively smaller number of unburnt carbon particles, but bigger particles have been observed, which is consistent with the higher LOIsvalues observed in Class F ashes

Zimmer

Elmer Smith

Petersburg

Mill Creek

PrasanthTanikella - Purdue University

results morphology of class f type ii ashes
ResultsMorphology of class F (Type II) ashes
  • Miami 7, a class F fly ash was found to have numerous irregular particles
  • The broken curved fragments contain silica and alumina
  • It could have been a hollow particle before it broke
  • Miami 8 - similar chemical composition to Miami 7 fly ash
  • Contains more spherical particles compared to Miami 7 ash

Miami 7 Fly ash

Miami 8 Fly ash

PrasanthTanikella - Purdue University

results morphology of class c ashes
ResultsMorphology of class C ashes
  • Wide range of sizes of spherical particles
  • Many hollow particles with shell generally composed of silica and alumina
  • Frequent irregularly-shaped particles (often with rugged surfaces) predominantly composed of sulfates or magnesium, or rarely sodium

Labadie

Kenosha

Will County

Rush Island

PrasanthTanikella - Purdue University

presentation outline8
Presentation Outline

Phase I - Original Project

  • Task 1 - Literature Review
  • Task 2 - Collection of Specimen
  • Task 3 - Characterization of available fly ashes

- Methods of examination

- Results

  • Task 4 - Data analysis and conclusions
  • Tasks 5 & 6 - Report writing and Database development

Phase II - Proposed Expansion

  • Evaluation of the hydration characteristics of binders
  • Binary binder systems
  • Ternary binder systems
  • Summary and conclusions of the study

Prasanth Tanikella - Purdue University

task 4 data analysis chemical analysis of fly ashes
Task 4 – Data AnalysisChemical analysis of fly ashes
  • The number of available Class C fly ashes is much higher than the number of the available Class F fly ashes
  • With respect to chemical composition two classes of fly ashes are consistent in their own class, with a few exceptions (as indicated below)
  • Class F ashes
    • Class F ashes can be divided into two Types (I and II) as they are different in most respects including chemical composition and physical characteristics
    • Both Type II ashes are products of the same coal plant (Miami)
    • For both types, the combined silicon, aluminum and iron content varies from 81% to 91%
    • Iron oxide content varies from 18% to 25%, except for two fly ashes (Miami 7 and Miami 8) which have much lower iron content (close to 5%)
    • Typical CaO contents below 5% (except for Elmer Smith)
    • Moderate alkali contents of around 2.3% for most
    • Sulfate contents of fly ashes less than 3.1%
    • LOI (more than 1%) is much higher compared to class C ashes

PrasanthTanikella - Purdue University

chemical analysis of fly ashes
Chemical analysis of fly ashes
  • Class C Ashes
    • Typical combined silicon, aluminum and iron content of 56% to 65% (except Rockport =72%) which has a high SiO2 content (43%)
    • Iron oxide content does not vary a lot from 6%, except for one fly ash (Edwards=10%)
    • Typical CaO contents of 22% to 26% (except Rockport = 17%)
    • Moderate alkali contents of around 2% for most, with almost none of the alkalis soluble
    • Sulfate contents less than 1.3%
    • Loss on Ignition (LOI) less than 1%

Prasanth Tanikella - Purdue University

task 4 data analysis physical characteristics of fly ashes
Task 4 – Data AnalysisPhysical Characteristics of fly ashes
  • The particle size distribution is consistent within each of the Class C ash and Class F ash groups. However, discrepancies have been observed in PSD obtained form laser particle size analyzer (LPSA) performed at two different laboratories (will be addressed later)
  • The percentage of particles less than 1 micron in size is found to be less than 1%, consistent with the literature
  • Large difference between the mean sizes of the two classes of ashes, with the particle size of class F fly ash being higher
  • The average pozzolanic activity index of class C ashes (128.5%) is higher than class F ashes (110%). This can be explained by the lower mean particle size and the presence of silica and lime in the glass phase
  • The average strength activity index of class F (Type II) ash (115.25%)is higher than class F (Type I) ashes ( 109%)

PrasanthTanikella - Purdue University

task 4 physical characteristics of fly ashes
Task 4 - Physical Characteristics of fly ashes
  • The results of the pozzolanic activity index (PAI) indicate that the “Zimmer” fly ash (with PAI =96) does not meet the requirements of ASTM C 618 (PAI=100) and is thus not recommended for use in concrete
  • The median density of class C ashes (around 2.72) is higher than the median density of class F, Type I ashes (around 2.64). Class F (Type II) ashes have the lowest density (around 2.23)
  • The values of specific surface area of all class F ashes were lower than that of class C ashes, which is consistent with the higher mean particle sizes of class F ashes
  • Also, the magnetic particle content in all the class F ashes (Type I) is much higher compared to all of those in class F (Type II) and class C ashes
  • The magnetic particle content of class F (Type II) ashes was found to be the least of all the ashes

PrasanthTanikella - Purdue University

task 4 analysis discrepancies in psd data
Task 4 - AnalysisDiscrepancies in PSD Data

Particle size distribution (PSD)

  • PSD analyzed in two laboratories using laser particle size analyzer (LPSA)
  • Significant differences were observed in the PSD obtained for most of the fly ashes, while a few agree up till a specific particle size

PrasanthTanikella - Purdue University

task 4 analysis andreasen pipette analysis
Task 4 - AnalysisAndreasen Pipette Analysis
  • An attempt was made to resolve the differences in the observed PSD using the Andreasen Pipette
  • Particles suspended in dispersing solution
  • Particles settle at different rates. The rates depend on the radius and density of the particles
  • Stokes law used to calculate the particle size

PrasanthTanikella - Purdue University

task 4 analysis discrepancies resolved
Task 4 - AnalysisDiscrepancies resolved
  • The pipette analysis seems to work well for particles larger than 5 micron particle size and is coincident with Lab 1’s results. The results below 5 microns seem to diverge from either of the curves
  • Even though the sedimentation technique does not work well for particles smaller than 5 microns, based on the literature data it is reasonable to assume that the PSD based on Lab 1 data is accurate

PrasanthTanikella - Purdue University

task 4 analysis x ray diffraction
Task 4 - AnalysisX-ray Diffraction
  • In general, the fly ashes have been consistent in their own groups
  • Class F ashes can be divided into two groups based on the chemical composition found using X-ray diffraction
  • Class F (Type I) ashes had relatively lower and narrower glass humps compared to the Class F (Type II) ashes
  • The glass humps of Class C fly ashes were smaller and narrower than those for Class F (Type II) ashes but taller and narrower than those for Class F (Type I) ashes
  • The percentages of magnetic particles in Class F(Type I) ashes were very high (over 25%) and the strength activity indexes of these ashes were the lowest
  • The amounts of magnetic particles in Class F(Type II) ashes were the lowest (about 4%) but the PAIs of these ashes were higher than those of Class F (Type I) and much lower than those of Class C ashes
  • There content of magnetic particles in Class C ashes was negligible, which is also evident from the XRD analysis as no hematite and magnetite was found in most of these ashes

PrasanthTanikella - Purdue University

task 4 analysis morphology
Task 4 - AnalysisMorphology

General Inferences

  • Very few particles above 200 microns in size
  • Quite a few large particle of almost 100 micron size
  • Also seen, large number of particles smaller than 5 microns
  • Most particles spherical
  • A few pieces of carbon 20-25 micron in size can be seen with a “Swiss Cheese” structure
  • Fly ash particles are found inside some of the hollow particles

PrasanthTanikella - Purdue University

task 4 analysis morphology1
Task 4 - AnalysisMorphology

General Inferences

  • Conglomerates of large and very small particles of fly ash is visible
  • An irregular piece of fly ash is seen
  • Extremely large fragments of carbon particles are also seen
  • Very few rod like particles are found

PrasanthTanikella - Purdue University

conclusions phase i characterization of fly ashes
Conclusions – Phase ICharacterization of fly ashes
  • Significant variations in the chemical and physical characteristics of fly ashes observed
  • Class C fly ashes more abundant than class F ashes
  • Class F ashes can be divided into two (Type I and Type II as defined) based on the crystalline chemical composition seen using X-ray diffraction techniques
  • The reactivity (pozzolanic activity index) of class F Type I ashes was found to be lower than class F Type II ashes
  • The reactivity of class C ashes was found to be the highest of the three classes
  • However, the glass hump of class C ashes was found to be lower than class F Type II ashes, thus indicating that although Class C fly ashes have less glass, this glass is more reactive
  • The morphology of the ashes was similar irrespective of the class, with a few exceptions
  • The particle size distributions of class C and class F ashes were significantly different.
  • All mean particle sizes in class F were larger than mean particle sizes in class C ashes, resulting in a lower surface area of class F ashes
  • The larger particle size also could lead to a lower reactivity in these ashes
  • The LOI values of all class F ashes were higher than that of the C ashes. This will have direct impact on the air entraining operations

PrasanthTanikella - Purdue University

task 5 development of a database
Task 5 – Development of a database
  • An electronic database would be developed as shown here
  • Draw down menu for all the fly ashes to extract the data will be provided
  • The database would contain the chemical and physical characteristics of fly ashes along with the SEM pictures and XRD patterns

PrasanthTanikella - Purdue University

task 6 report writing
Task 6 – Report Writing
  • A draft final report has been prepared and can be provided to the SAC for review
  • The report contains all the details of the original project, methods of examination, the results, a comprehensive discussion and a conclusion section. However, the data base section has not yet been completed

PrasanthTanikella - Purdue University

presentation outline9
Presentation Outline

Phase I - Original Project

  • Task 1 - Literature Review
  • Task 2 - Collection of Specimen
  • Task 3 - Characterization of available fly ashes

- Methods of examination

- Results

  • Task 4 - Data analysis and conclusions
  • Tasks 5 & 6 - Report writing and Database development

Phase II - Proposed Expansion

  • Evaluation of the hydration characteristics of binders
  • Binary binder systems
  • Ternary binder systems
  • Summary and conclusions of the study

Prasanth Tanikella - Purdue University

phase ii evaluation of the hydration characteristics of cement fly ash binder systems
Phase II - Evaluation of the hydration characteristics of cement-fly ash binder systems
  • When used as a substitute for part of the cement, fly ash offers a lot of benefits, both in terms of early and later hydration characteristics and in terms of the economy
  • As seen earlier, no two fly ashes are entirely similar with respect to their chemical and physical properties
  • As a consequence, their incorporation into cementitious binder systems can result in highly variable hydration characteristics
  • It is important to understand and estimate the properties of cement-fly ash binder systems for its field application
  • In addition, we can also estimate the amount and type of fly ash(s) to be added to the binder system to achieve some required properties using models that account for variable characteristics of the fly ashes

PrasanthTanikella - Purdue University

phase ii evaluation of the hydration characteristics of binders
Phase II - Evaluation of the hydration characteristics of binders
  • A rational basis for the modeling approach is that the model is based entirely on the fundamental physical and chemical characteristics of the components
  • The early hydration characteristics of binder systems, which can be statistically modeled, would be helpful in choosing the right type and the right amount of fly ashes for field applications. These include:

- Setting time

- Pozzolanic activity index

- Amount of heat generated

- Peak heat of hydration

- Time after mixing when the peak occurs

- Degree of hydration

PrasanthTanikella - Purdue University

phase ii materials and proportions
Phase II - Materials and Proportions
  • Type I portland cement manufactured by Buzzi Cement in Greencastle, Indiana
  • Binary binder systems with a fly ash replacement of 20% by weight
  • Ternary binder systems with a combined fly ash replacement (two fly ashes) of total 20% by weight
  • Water to binder ratio of 0.41, kept constant throughout

PrasanthTanikella - Purdue University

phase ii tests methods and techniques
Phase II - Tests methods and Techniques
  • Setting time – Performed according to ASTM C 191
  • Heat of hydration – Isothermal calorimetry
  • Strength activity index – Performed according to ASTM C 311
  • Pore structure – Mercury intrusion porosimetry
  • Non-evaporable water content – Using the LOI technique
  • Degree of hydration
  • Glass content in fly ashes – Two techniques are being looked into
  • A thorough statistical analysis of the data will be performed and a statistical model for the above properties will be developed based on the significantly affecting physical and chemical properties of the fly ash and cement

PrasanthTanikella - Purdue University

estimation of the glass content
Estimation of the Glass Content
  • Glass is the amorphous content in fly ash
  • The reactivity of the fly ash depends on the amount of glass present and its composition
  • Two techniques are being investigated for the quantitative estimation of the glass content in fly ash
  • Quantitative estimation of glass in fly ash using infrared spectroscopy
    • Method was applied to slag and the results were satisfactory
    • Ref: A. R. N. Ebrendu, K. E. Daugherty, The quantitative estimation of glass in slag by infrared spectroscopy, Cem. and Concr. Res, Vol. 14 (1984), pp 873-883
  • Quantitative estimation of glass in fly ash using QXRD analysis
  • The amorphous portion of the fly ash can be estimated using the Rietveld-based SIROQUANT technique
  • Two techniques were investigated,

- XRD analysis of samples spike with known masses of synthetic corrundum or zinc oxide

- Analysing the raw or unspiked fly ash directly using SIROQUANT technique

  • Ref: Colin R. Ward, David French, Determination of glass content and estimation of glass composition in fly ash using quantitative X-ray diffractometry, Fuel 85 (2006) 2268-2277

PrasanthTanikella - Purdue University

presentation outline10
Presentation Outline

Original Project

  • Task 1 - Literature Review
  • Task 2 - Collection of Specimen
  • Task 3 - Characterization of available fly ashes

- Methods of examination

- Results

  • Task 4 - Data analysis and conclusions
  • Tasks 5 & 6 - Report writing and Database development

Proposed Expansion

  • Evaluation of the hydration characteristics of binders
  • Binary binder systems
  • Ternary binder systems
  • Summary and conclusions of the study

Prasanth Tanikella - Purdue University

binary binder systems
Binary Binder Systems
  • Binary binder systems include Type I portland cement replaced by a fly ash at 20%
  • Water to binder ratio kept constant at 0.42

Prasanth Tanikella - Purdue University

experimental design binary binder systems
Experimental Design - Binary binder systems
  • All the available 20 fly ashes will be tested for all the aforementioned properties
  • Data is collected, processed and is used for statistical modeling
  • Statistically significant variables (chemical and physical properties of the binder system) affecting a specific property are found and their relevance to the property is established
  • Statistical models will be developed using these statistically significant variables for all the properties

Prasanth Tanikella - Purdue University

results setting time
Results – Setting time
  • The initial setting time for all the binary binder systems was found out according to ASTM C 191. Normal consistency of each paste was measured and is used for measuring the setting time of the pastes
  • The setting time for the cement paste was found to be 2.73 hours at a consistency of 0.265 water/binder ratio

Prasanth Tanikella - Purdue University

statistical analysis setting time
Statistical Analysis – Setting time
  • There is a significant variation found in the setting times, in both the classes of fly ashes
  • The correlation coefficients for set time with other variables for all the fly ashes are shown below (significant ones are highlighted in green)
  • No significant correlation of set time with any of other variables

Prasanth Tanikella - Purdue University

statistical analysis setting time1
Statistical Analysis – Setting time
  • The correlation coefficients for set time with other variables for class C fly ashes is shown below
  • There are significant correlations of set time with other variables, shown in yellow
  • Strength activity index (SAI) is also correlated with a few variables

Prasanth Tanikella - Purdue University

statistical analysis setting time2
Statistical Analysis – Setting time
  • The correlation coefficients for set time with other variables for class F fly ashes is shown below
  • Not many significant correlations of set time with other variables
  • Model built with correlated variables which might not be significant
  • Notice that the pozzolanic activity index (PAI) is correlated with set time

Prasanth Tanikella - Purdue University

modeling setting time
Modeling – Setting time
  • A preliminary model for set time with other variables for class C fly ashes is shown
  • Variables – Sulfate and (Sulfate)3x(Alumina) = S3A
  • Highly significant model (p-value < 0.01)
  • Not so good R2 Value – 0.6456
  • Not significant variables (p-values > 1)
  • Significant error
  • Scope to improve the model using various functions and standardizing variables

Prasanth Tanikella - Purdue University

modeling setting time1
Modeling – Setting time
  • A preliminary model for set time with other variables for class F fly ashes is shown
  • Variables – Sulfate and (sulfate)x(Alumina)3= SA3
  • Not significant model (p-value > 0.01)
  • Not so good R2 Value – 0.6725
  • Not significant variables (p-value >0.01)
  • Significant error
  • Scope to improve the model using various functions and standardizing variables

Prasanth Tanikella - Purdue University

modeling inferences
Modeling – Inferences

General scope for improving the set time model

  • Consider the chemical composition of the entire binder system
  • Explore the possibilities of including more variables, which theoretically affect the dependent variable (set time)
  • Include the glass content and composition of the fly ash

Models for other measurable variables

  • Setting time measurement is more arbitrary compared to any other measurable property
  • Accurate definition and measurement for all the other properties including heat of hydration, porosity, unhydrated fly ash

Prasanth Tanikella - Purdue University

presentation outline11
Presentation Outline

Phase I - Original Project

  • Task 1 - Literature Review
  • Task 2 - Collection of Specimen
  • Task 3 - Characterization of available fly ashes

- Methods of examination

- Results

  • Task 4 - Data analysis and conclusions
  • Tasks 5 & 6 - Report writing and Database development

Phase II - Proposed Expansion

  • Evaluation of the hydration characteristics of binders
  • Binary binder systems
  • Ternary binder systems
  • Summary and conclusions of the study

Prasanth Tanikella - Purdue University

ternary binders
Ternary Binders
  • Binders with cement and two different fly ashes, including both Class F and Class C ashes

Advantages over a binary system

  • Can choose two different fly ashes in the available suite, with different chemical and physical compositions and mix in various proportions to obtain a binder with required characteristics

Disadvantages

  • More intensive and cumbersome modeling process
  • We can expect more errors in the prediction
  • Other factors, including the mixing procedure of the fly ashes might affect the properties

Prasanth Tanikella - Purdue University

available statistical techniques
Available Statistical Techniques
  • Full factorial design

- Very cumbersome to apply for a large amount of data

- 20 fly ashes lead to a number of combinations of 190 at a specific proportion

- More effective model with reduce error in prediction

  • Fractional factorial design (Taguchi method)

- Reduces the number of experiments to be performed drastically

- Requires about 18 runs for each of the property, depending on the number of significant variables

- Model can be as accurate, prediction might have a slight additional error

PrasanthTanikella - Purdue University

orthogonal arrays taguchi method
Orthogonal Arrays – Taguchi Method
  • Standard tables, known as orthogonal arrays are used for the design of experiments
  • The chosen performance characteristic is analogous to the “signal to noise ratio” instead of the average value to interpret the trial result data
  • This ratio represents the scatter around the target

PrasanthTanikella - Purdue University

evaluating setting time using orthogonal array
Evaluating setting time using orthogonal array
  • Factors affecting the property are identified, using both statistical and analytical methods
  • The factors are chosen at three different levels, depending on their mean value and the range of values
  • The experimental design is based on the number of factors and the number of levels
  • Typical test matrix for a four factor and three level experimental design is shown
  • Full factorial technique gives a set of 81 experiments for the same
  • ANOVA is used to build a model

Significantly affecting variables for setting time

A sample test matrix for the above factors and levels

PrasanthTanikella - Purdue University

presentation outline12
Presentation Outline

Phase I - Original Project

  • Task 1 - Literature Review
  • Task 2 - Collection of Specimen
  • Task 3 - Characterization of available fly ashes

- Methods of examination

- Results

  • Task 4 - Data analysis and conclusions
  • Tasks 5 & 6 - Report writing and Database development

Phase II - Proposed Expansion

  • Evaluation of the hydration characteristics of binders
  • Binary binder systems
  • Ternary binder systems
  • Summary and conclusions of the study

Prasanth Tanikella - Purdue University

conclusions phase 2
Conclusions – Phase 2
  • The current study is aimed at statistically modeling the hydration properties of binary and ternary binders systems
  • A comparison of the two models will be made, including a statistical testing of the ability to use the binary model to ternary mixes
  • A binary binder model for setting time is developed and its refining would be done after consulting the Statistics Department, Purdue University
  • The experimental technique to model the ternary binder system has been established and will be confirmed after consulting with the Statistics Department, Purdue University
  • The outcome of the project would be a program which predicts the early age properties of binary and ternary binder systems
  • The program would also be able to estimate the type and amounts of fly ash to be added to cement to achieve certain desired early age properties

Prasanth Tanikella - Purdue University

project timeline
Project Timeline
  • Brown – Original proposed tasks
  • Green – Tasks completed
  • Yellow – Future tasks

PrasanthTanikella - Purdue University