1 / 64

FINAL EXAM Prasanth Tanikella Major Professor: Jan Olek

Incorporating Physical and Chemical Characteristics of Fly Ash in Statistical Modeling of Binder Properties. FINAL EXAM Prasanth Tanikella Major Professor: Jan Olek. July 23 rd , 2009. Presentation Outline. Research Objective Scope of the original project Proposed expansion of the scope

sydnee-cervantes
Télécharger la présentation

FINAL EXAM Prasanth Tanikella Major Professor: Jan Olek

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Incorporating Physical and Chemical Characteristics of Fly Ash in Statistical Modeling of Binder Properties FINAL EXAM PrasanthTanikella Major Professor: Jan Olek July 23rd, 2009

  2. 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

  3. 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

  4. 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

  5. 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

  6. 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 • 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

  7. 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

  8. 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

  9. 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

  10. 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

  11. 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

  12. 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

  13. 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

  14. 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

  15. 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

  16. 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

  17. 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

  18. ResultsChemical composition of fly ashes * INDOT list of approved fly ashes

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

  20. 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

  21. 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

  22. 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

  23. 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

  24. 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

  25. 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

  26. 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

  27. 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

  28. 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

  29. 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

  30. 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 PrasanthTanikella - Purdue University

  31. Task 4 - Physical Characteristics of fly ashes • 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

  32. 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

  33. 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

  34. 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

  35. 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

  36. 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

  37. 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

  38. 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

  39. 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

  40. 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

  41. 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

  42. 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

  43. 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

  44. 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

  45. 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

  46. 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

  47. 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

  48. 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

  49. 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

  50. 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

More Related