1. Road SchoolMarch 9 th, 2011Slide 1 of 31 Session 10 Purdue Research Updates Using Internal Curing in Concrete Bridge Decks

2. Road SchoolMarch 9 th, 2011Slide 2 of 31 Developed for Discussion with the Road School by: Carmelo Di Bella, John Schlitter, Igor De La Varga Nathan Phares and Jason Weiss March 9 th, 2011 Purdue University School of Civil Engineering Update in Research Study on Using Internal Curing in Concrete Bridge Decks

3. Road SchoolMarch 9 th, 2011Slide 3 of 31 Outline Difference between external and internal curing Importance of Internal curing Benefits of internal curing Possible improvements in terms of service life and CO 2 emission reduction Conclusion

4. Road SchoolMarch 9 th, 2011Slide 4 of 31 Outline Difference between external and internal curing Importance of Internal curingImportance of Internal curing Benefits of internal curingBenefits of internal curing Possible improvements in terms of service life and CO 2 emission reduction.Possible improvements in terms of service life and CO 2 emission reduction. ConclusionConclusion

5. Road SchoolMarch 9 th, 2011Slide 5 of 31 What Is external Curing? Supply of water to the concrete can be accomplished by ponding, spraying, or by use of saturated coverings. External curing Bloomington, 2010

6. Road SchoolMarch 9 th, 2011Slide 6 of 31 What Is Internal Curing? Internal Curing Haydite LWA SAP

7. Road SchoolMarch 9 th, 2011Slide 7 of 31 What is Internal Curing ACI “Supplying water throughout a freshly placed cementitious mixture suing reservoirs, via prewetted Lightweight aggregate, that readily release water as needed for hydration or to replace moisture lost through evaporation or self desiccation” Hiding Water In LWA to increase hydration and strength while reducing transport, shrinkage, and cracking

8. Road SchoolMarch 9 th, 2011Slide 8 of 31 What Is Internal Curing?

9. Road SchoolMarch 9 th, 2011Slide 9 of 31 Outline Difference between external and internal curing Importance of Internal curing Benefits of internal curing Possible improvements in terms of service life and CO 2 emission reduction Conclusion

10. Road SchoolMarch 9 th, 2011Slide 10 of 31 Fundamental Volume Change Le Chatelier 1850-1936 Chemical Shrinkage: The apparent volume of the cement paste may increase but there is a substantial decrease in its absolute volume. + =

11. Road SchoolMarch 9 th, 2011Slide 11 of 31 Concept – LWA Supplies Water Water stays in LWA until the time that this under pressure develops At that point water would be drawn out of bigger pores in LWA in a perfect world

12. Road SchoolMarch 9 th, 2011Slide 12 of 31 IC Mixture Proportion – How much water does the system want? LWA: water reservoirs that release water at the appropriate time (after set) Hypothesis: All Chemical Shrinkage water is replaced Bentz (1999) equation

13. Road SchoolMarch 9 th, 2011Slide 13 of 31 Outline Difference between external and internal curing Importance of Internal curing Benefits of internal curing Possible improvements in terms of service life and CO 2 emission reduction Conclusion

14. Road SchoolMarch 9 th, 2011Slide 14 of 31 Internal Curing Increases Hydration Castro 2010

15. Road SchoolMarch 9 th, 2011Slide 15 of 31 Relative Humidity Castro 2010

16. Road SchoolMarch 9 th, 2011Slide 16 of 31 Applications Texas – Pavement Construction NYDOT – 10+ Decks with IC –Reviewed and walked these decks –One crack in the negative region on a very wide bridge with a high skew –No problems reported –Additional Cost ($10 /yd3) IN-LTAP – 1 with IC, 1 conventional –No Problems reported, VADOT – Bridge Deck

17. Road SchoolMarch 9 th, 2011Slide 17 of 31 LTAP Project To Evaluate Internal Curing in Two Bridges (With Internal Curing and Without) To Document with Local Materials To Aide in Understanding What May Be Needed from Specification and What May Be Needed in A Change of Process Overall – Improve Service Life Performance for Limited Cost by Being More Efficient

18. Road SchoolMarch 9 th, 2011Slide 18 of 31 Location Two Bridges Near One Another Similar Exposure/Traffic Wanted to Monitor Long Term Performance

19. Road SchoolMarch 9 th, 2011Slide 19 of 31 Conventional Bridge

20. Road SchoolMarch 9 th, 2011Slide 20 of 31 Typical Construction

21. Road SchoolMarch 9 th, 2011Slide 21 of 31 Internally Cured Deck

22. Road SchoolMarch 9 th, 2011Slide 22 of 31 Findings of the IC Project Early on (up to 5 days) similar strength At 28 days Internal curing increases strength (Increased Hydration)

23. Road SchoolMarch 9 th, 2011Slide 23 of 31 Findings of the IC Project At 28 days similar chloride resistance At 91 Days 25% more resistance to chloride ingress (Increased Hydration)

24. Road SchoolMarch 9 th, 2011Slide 24 of 31 An Interesting Aside INDOT Class C – 5.5 k-Ohm/cm (90 d) With Internal Curing – 7.0 k-Ohm/cm (90 d) NYDOT Bridge Deck – 32 k-Ohm/cm (90 d) There is room for Indiana to reconsider the designs using to increase resistance to chlorides and increase service life

25. Road SchoolMarch 9 th, 2011Slide 25 of 31 Outline Difference between external and internal curing Importance of Internal curing Benefits of internal curing Possible improvements in terms of service life and CO 2 emission reduction Conclusion

26. Road SchoolMarch 9 th, 2011Slide 26 of 31

27. Road SchoolMarch 9 th, 2011Slide 27 of 31

28. Road SchoolMarch 9 th, 2011Slide 28 of 31 Current State FHWA/INDOT Columbus Indiana Goal is to reduce the clinker content of concrete used in transportation structures Class C concrete bridge requires 390 kg/m 3 of cementitous Current limit of 20-25% fly ash

29. Road SchoolMarch 9 th, 2011Slide 29 of 31 From FHWA/DOT Perspective w/c – 0.42 and w/c -0.3 - 40% ash have equivalent 1 day strength but have a 40% reduction in CO 2 per yd 3 of concrete w/c – 0.42 and w/c -0.3 - 60% ash have equivalent 7 day strength but have a 60% reduction in CO 2 per yd 3 of concrete

30. Road SchoolMarch 9 th, 2011Slide 30 of 31 Impact of HVFA on Microstructure De LA Varga 2011

31. Road SchoolMarch 9 th, 2011Slide 31 of 31 Conclusion Showing Benefits (reduced cracking slowed chloride ingress, similar strength) Uses cement more efficiently – increases degree of hydration Enables ‘greener’ concrete as OPC can be replaced (limestone, ash, slag) Increases ‘reserve capacity’ for temperature effects during construction Reduces fluid transport which can extend service life giving more bang for the buck