Cementitious Materials

1. Cementitious Materials

2. Concrete Materials Cementitious Hydraulic Cement (C150, C595, C1157) Other Supplementary Cementitious Materials (SCM’s) Pozzolans (Fly Ashes), C618 Slag Cement, C989 Silica Fume, C1240 These SCM’s are commonly referred to as Mineral Admixtures Aggregates Coarse and Fine (Rock & Sand), C33 Chemical Admixtures, C494 & C260 Water Reducers, Retarders, Accelerators, Air Entrainment, and etc. Water

3. Learning Objectives • Develop a basic understanding of: • Portland cement, C150 • Pozzolans • Fly Ash, C618 • Silica Fume, C1240 • Slag Cement, C989

4. Joseph Aspdin1824 Early Cement Works Lea’s Chemistry of Cement Aspdin’s early cement was nothing more than a hydraulic lime, but in 1824 his patent gave him the use of the term Portland cement

5. Rotary Kiln Rotary Kilns 1885England Frederick Ransome patented rotary kiln (18 inch X 15 ft) 1900 Thomas Edison takes advantage of the horizontal rotary kiln Cement manufacture changed from a batch process to a continuous process

6. Portland Cements

7. Typical Cement Plant

8. Raw Material Mining & Processing

9. Two Major Raw Materials Components in Hydraulic Cement Calcium Silica Calcium oxide Silicon oxide

10. Four Principle Oxides Major Components Minor components

11. Raw Material Proportioning Dust Collector To Preheater or Kiln Grinding Mill Iron Ore Sand • Shale Raw Meal Pump Limestone Blending and Storage Silos Raw Material Proportioning & Blending After analysis, the raw materials are proportioned, ground to fine powder, and blended. Some cement plants add water to the material during grinding, then blend and store it as a slurry.

12. Wet Process Kiln Mix is a Slurry (30% - 40% water) Advantages more uniform raw material may already contain moisture Disadvantage higher energy use Dry Process Kiln Mix is a Dry Powder Advantages preheating done outside the kiln efficiency shorter kiln length Disadvantage alkalies, sulfur, chlorides tall, sophisticated Two Types of Cement Kilns

13. Inside the Kiln

14. Heat Zone Inside the Kiln Low red -- dark red 875-1200 F bright red -- orange 1500-1650 F orange -- yellow 1650-2000 F light yellow - white 2400-2800 F

15. Voila Clinker!!

16. C2S (belite) C3A C4AF C3S (alite) Most important clinker constituent that governs strength

17. Significance of Clinker Minerals for Cement Properties • C3S Alite...Contributes to early and late strength (1-3-5 day - ...) • Increases heat of hydration • C2S Belite... Contributes to late strength (28 day + ...) • C3A Contributes to very early strength (1 - 3 day) • Increases heat of hydration • Impairs resistance to sulfate attack (durability) • C4AF Little effect (mostly color). • (Higher C3A, lower C4AF generally more reactive)

18. Dust Collector Storage Silos • Gypsum Clinker Kiln Clinker Cooler Grinding Mill Bagging Facility Cement Pump Bulk Loading Grinding Clinker & Gypsum

19. Dust Collector Storage Silos • Gypsum Clinker Kiln Clinker Cooler Grinding Mill Bagging Facility Cement Pump Bulk Loading Turning Clinker into Cement

20. Sulfate (Gypsum) for Set Control • Gypsum, or naturally occurring anhydrite • Reacts with aluminate phases • Controls chemical reactions • Proper balance needed for good performance • Slump loss • Fast set • Slow set • Slow strength Gain

21. Finish Mill

22. THE RECIPE CPU 301 October 10 -12, 2007

23. Cement Standards No AASHTO equal for C1157 AASHTO American Association of State Highway & Transportation Officials M85 / M240 AASHTO & ASTM are equal or similar specifications

24. ASTM C150 Cement Types • Type I - No restrictions regarding clinker minerals • Type II - Moderate Sulfate resistance • C3A max. 8 % • Type III - High early strength • C3A max. 15 % • Type IV - Low heat of hydration • No longer available • C3S max. 35 % (alite) • C2S min 40% (belite) • C3A max. 7 % • Type V - High Sulphate resistance • C3A max. 5.0 % • C4AF + 2 C3A max. 25 % or • C4AF + C2F max. 25 % No Type I-II

25. CPU 301 October 10 -12, 2007

26. Material Certification Report

27. Supplementary Cementitious Materials (SCMs) From left to right: • Fly ash (Class C) • Metakaolin (calcined clay) • Silica fume • Fly ash (Class F) • Slag Cement • Calcined shale

28. Slag Cement • ASTM C 989Standard Specification for Slag Cement for Use in Concrete and Mortars (classified by Strength Activity Index compared to a reference Portland Cement) • Grade 80 (SAI @ 28days = 75%) • Grade 100 (SAI @ 7days = 75% & 28days = 95%) • Grade 120 (SAI @ 7days = 95% & 28days = 115%) Slag Cement is a hydraulic cement

29. Iron ore, coke and limestone added to the top Blast furnace Molten slag and iron flow from the bottom Blast Furnace Slag (BFS) 3000 oF +/-

30. Molten Blast Furnace Iron & Slag

31. Granulated Blast-Furnace Slag (GBFS) Molten slag is quenched with a large quantity of water, about a 10:1 ratio “Shock” of the water vitrifies the slag into a glassy sand like material Slag Water

32. Ground Granulated Blast-Furnace Slag Ball Mill Slag Cement

33. Slag - Features and Benefits • Benefits for Hardened Concrete • Later age strength • Increased flexural strength • Lighter, brighter color (substitute for white cement) • Increased ability to reflect solar heat • Reduced permeability and increased durability • Increased resistance to alkali silica reaction • 25% to 70% • Increased sulfate resistance (low alumina slag) • 40% to 70%

34. Slag - Cautions • As cement replacement rates increase, freeze/thaw durability can be reduced (on flat work) • Sensitive to cold weather, below 40 deg F(set time and early strength) • As levels of unoxidized sulfide sulfur increase, a temporary greening of the hardened concrete may occur

35. Pozzolans • ASTM C618 Standard Definition • “pozzolan, n. • a siliceous or siliceous and aluminous material which in itself possesses little or no cementitious value but which will, in finely divided form and in the presence of moisture, chemically react with calcium hydroxide to form compounds possessing cementitious properties”

36. Fly ash • A by-product produced at coal-fired electric generating power plants • Residue (or ash) from the combustion of ground or powdered coal…in other words coal ash

37. Fly Ash Flow Process Coal Pulverizer Boiler Electrostatic Precipitation Fly Ash Silo Customers Coal/Source

38. Fly Ash • Fly Ash: A finely divided residue that results as a product from the combustion of pulverized coal in electric generating power plants. • Class C Fly Ash: Most often comes from the burning of sub-bituminous coal and generally has a calcium oxide content above 20%. • Class F Fly Ash: Most often comes from the burning of bituminous coal and generally has a calcium oxide content of less than 10%. • Bituminous coal (F) • Subbituminous coal (C ) Older coals - eastern - North America and on the west coast Younger coals - western - North America

39. ASTM C 618/AASHTO 295 Specification Classes • Class F—Fly Ash with pozzolanic properties • Class C—Fly Ash with pozzolanic and cementitious properties Fly Ash

40. Fly Ash • Class C • “C” ash is cementitious and pozzolanic • Class C ash contains higher CaO contents • (8% - 40%) • High lime content, light color • Due to lower carbon and iron contents • ASTM C 618 • Medium – High CaO ( 18 - 40+% )

41. Fly Ash • Class F • “F” ash is pozzolanic • Class F ash contains low CaO content • ( 1-15% ) • Low lime content, dark color • Due to presence of unburned carbon • ASTM C 618 • Low CaO ( 2-15% ) Type F ash is usually preferred for durability, (ASR)

42. Fly Ash - How Does it Work? • Fly ash reacts with the cementitious free lime during the cement hydration process to enhance the density of crystal growth and realize concrete strength gain.

43. Reactions Primary cement reaction (fast): C3S (and C2S) + water = C-S-Hgel Byproduct from hydration = Calcium Hydroxide Pozzolanic reaction (slow): Fly Ash + Calcium Hydroxide=C-S-Hgel

44. Fly Ash - Features and Benefits • Improved concrete mix workability • Reduced permeability • Increased resistance to alkali-silica reactivity & sulfate conditions with Class F • Reduced heat of hydration • Primarily Class F more so than Class C

45. Fly Ash - Cautions • Fly ash can affect air entrainment dosages • Increase initial set time • Lower early age strengths • Especially w/ Class F

46. Other Considerations • Must accommodate specific gravity difference when batching with fly ash and slag cement • specific gravity of fly ash = 2.2 - 2.8 • specific gravity of slag cement = 2.6 - 2.9 • specific gravity of Portland cement = 3.15 • Must adequately cure concrete when slow hydration occurs

47. Fly Ash - Potential Uses • Primary Applications • Concrete • Concrete Products

48. Silica Fume (microsilica): pure, amorphous silica with particle size of 0.1-0.2 m, collected during the manufacture of silicon and ferrosilicon alloys

49. Specification for Silica Fume ASTM C1240 • finely divided residue resulting from the production of silicon, ferro-silicon, or other silicon-containing alloys that is carried from the burning surface area of an electric-arc furnace by exhaust gases.

50. Silica Fume Basics • Typical amounts used in concrete 5% to 10% • Adds to strength gain • Reduces permeability • Reduces Alkali Silica Reactivity