1. Chapter 4. Working with Silica-Fume Concrete  Conducting a Test Placement  Transporting, Placing, and Consolidating  Finishing Flatwork  Finishing Bridge Decks  Preventing Plastic-Shrinkage Cracking  Curing

2. Conducting a Test Placement Chapter Outline

3. Remember: Silica-fume concrete is more cohesive and less prone to segregation To improve workability, increase slump by about 2 in. (50 mm)

4. Cohesive silica- fume concrete -- OK to increase slump

5. Conducting a test placement

8. Transporting, Placing, and Consolidating Silica-Fume Concrete Chapter Outline

14. Silica-fume concrete requires thorough consolidation

15. Finishing Silica-Fume Concrete Flatwork Chapter Outline

16. Click on the icon above to play a video on finishing silica-fume concrete

17. Under Finish Silica- Fume Concrete Use the “One-Pass” Technique

18. One-Pass Finishing  Screed  Float  Texture  Cure Protect, Protect!

19. One-pass finishing

26. Float and brooming tool

28. Broomed surface -- all that is required for a parking structure

30. Finishing Silica-Fume Concrete Bridge Decks Chapter Outline

36. Tined surface

37. Preventing Plastic Shrinkage Cracking Chapter Outline

38. What is Plastic Shrinkage Cracking? Cracking that occurs in the surface of fresh concrete soon after it is placed and while it is still plastic. -- ACI 116R

39. Plastic shrinkage cracking

40. Silica fume concrete does not bleed and is more susceptible to plastic shrinkage cracking

42. Good fogging

44. Improper fogging

45. Evaporation retarders work well but are frequently misused

46. Curing Silica-Fume Concrete Chapter Outline

47. How Important is Curing Silica Fume Concrete?

48. “If silica-fume concrete mixtures are given 7 days of continuous moist curing, then there is no association between silica fume content and cracking.” -- Whiting and Detwiler NCHRP Report 410

49. “It is recommended that a minimum of 7 days continuous moist curing be specified.” -- Whiting and Detwiler NCHRP Report 410

50. Applying curing compound while concrete is still fresh

51. Moist curing after concrete hardens

53. Don’t forget winter protection

54. End of Chapter 4 Main Outline