1. Plastic Shrinkage Cracking Evaluation and Repair

2. ACI 224.1R-93 Causes, Evaluation and Repair of Cracks in Concrete Structures

3. ACI 224.1R-93 Chapter 1 – Causes & Control Chapter 2 – Evaluation Chapter 3 – Methods of Crack Repair

4. ACI 224.1R-93 Typical Plastic Shrinkage Cracking. (Price 1982)

5. ACI 224.1R-93 Chapter 1, Section 1.2 “Cracking of Plastic Concrete” Discusses Causes and Prevention ONLY!

6. ACI CP-10 -Certification for Concrete Technicians and Flatwork Finishers- Discusses Causes and Prevention ONLY!

7. NRMCA Concrete in Practice “If plastic shrinkage cracks should appear during final finishing, the finisher may be able to close them by refinishing.”

8. NRMCA Concrete in Practice Disclaimer “However, when this occurs, precautions, as described above, should be taken to avoid further cracking”

9. PCA EB001 Design & Control of concrete Mixtures “If plastic shrinkage cracks should appear during finishing, striking each side of the crack with a float and refinishing can close the crack”

11. PCA EB001 Design & Control of concrete Mixtures Disclaimer “However, the cracking may reoccur unless the causes are corrected”

12. ACI 305R Hot Weather Concreting Section 4.3.4 In relatively massive placements, revibration before floating can sometimes close this type of cracking.

13. PCA EB001 Fig. 11-11.

14. ACI 224.1R-93 Typical Plastic Shrinkage Cracking. (Price 1982)

15. Much more serious cracking!

16. Fig. 11-13. PCA EB001

17. ACI 224.1R-93 Chapter 2 Evaluation of Cracks in Hardened Concrete

18. ACI 224.1R-93 Chapter 2 1. Identify Location and Extent of Cracking

19. Typical Plastic Shrinkage Cracking

20. Much more serious cracking!

22. ACI 224 Chapter 2 2. Determine functionality - Movement - Structural -Maintenance issue -Cosmetic

23. ACI 224 Chapter 2 2.2 Map the cracks!

24. ACI 224.1R-93 Fig. 2.1-Comparator for measuring crack widths Courtesy of Edmound Scientific Co.

25. Crack Comparitor Card

26. ACI 224 Chapter 3 Methods of Crack Repair in Hardened Concrete

27. ACI 224 Chapter 3 3.2 Epoxy injection - Bonds cracks as narrow as 0.002 in. - Provides fixity - Original cause must be addressed - Typically deferred to specialist

28. ACI 503.7-07 Specification for Crack Repair by Epoxy Injection

29. ACI 224 Chapter 3 3.3 Routing and sealing - Clean cracks - Enlarge crack along exposed face - Fill and seal with suitable joint sealant - Not suitable for structural repairs

30. Groove cut wlth saw or chipping tools7 ACI 224.1R-93 Fig. 3.1-Repair of crack by muting and sealing (Johnson 1965)

31. ACI 224.1R-93 If large enough, treat as an induced crack Sawcut and fill

32. Crack ClosedNo Bond Breaker With Bond Breaker Fig. 3.2-Effect of bond breaker ACI 224.1R-93 Chapter 3 See ACI 504R Re. Aspect Ratio

33. ACI 224 Chapter 3 3.11 Polymer Impregnation Methyl Methacrylate –Flood surfaces –Heat to polymerize, or –Use a catalyst to polymerize

34. ACI 224 Chapter 3 3.12.1 Surface Treatments - Low viscosity penetrating resins - Urethanes - Epoxies - Polyesters - Acrylics

35. ACI 224 Chapter 3 3.12.2 Overlays - Polymer modified PCC - Styrene Butadiene - Bridge decks - Acrylic latex - Interior toppings - Pool decks