1. I-275, two sites, varying performance. Site 2, showing deterioration at joint. Site 4, not exhibiting deterioration at joint. Site 2Site 4

2. Stereo-microscope work Site 2, poor air-void system, alkali-silica reaction with fine aggregate particles and related cracks extending into hardened paste, but only within the top inch. Site 4, adequate air-void system, alkali- silica reaction with fine aggregate particles, but without cracks extending into hardened paste.

3. Site 2, mid-panelSite 2, near jointSite 4, mid-panelSite 4, near joint Cross-section through entire pavement, pink boxes show locations of stereo- microscope images of ASR fine aggregate, tic marks every inch.

4. Site 2, near jointSite 4, near joint Polished slabs from cores taken near joint after sodium cobaltinitrite treatment to show alkali-silica reaction.

5. Site 2, stereo-microscope images of ASR susceptible fine aggregate and related cracking, both before and after sodium cobaltinitrite stain.

8. Site 4, stereo-microscope images of ASR susceptible fine aggregate, both before and after sodium cobaltinitrite stain.

11. Site 2, mid-panelSite 2, near jointSite 4, mid-panelSite 4, near joint Pink boxes show area of automated air void analyses. Air voids visibly more abundant in bottom halves of all cores.

12. Sample IDAir % Paste % Voids/ meter Paste/ Air ratio Avg. chord length (mm) Specific surface (mm -1 ) Spacing factor (mm) 2m_top half2.028.021414.30.09243.50.170 2m_bottom half4.727.22475.80.19120.90.237 2j_top half2.427.916111.50.15026.60.254 2j_bottom half4.727.22165.80.21818.40.269 4m_top half3.027.73239.20.09342.90.143 4m_bottom half6.426.73774.20.16923.60.178 4j_top half3.027.73279.20.09243.40.141 4j_bottom half7.626.44033.50.18921.20.164

13. Site 2, mid-panelSite 4, mid-panel Phenolphthalein stain to show depth of carbonation. Pink boxes show area of stereo-microscope images.

14. Site 2, (left) with carbonation depth of approx. 3 to 5 mm, and Site 4 (right) with carbonation depth of approx. 2 to 3 mm.

15. Chloride-profiling work Two billets were cut to represent cross- section of pavement at surface. The billets were cut from cores taken at mid-panel. RGB elemental maps collected where calcium assigned to red channel, chlorine assigned to green channel, and silicon assigned to blue channel. Tic marks every ¼ inch.

16. Site 2, mid-panelSite 4, mid-panel

17. Chloride-profiling work Bright green spots are from x-ray diffraction events, and not due to characteristic chlorine K-alpha radiation. These areas were avoided during collection of spot-analyses for construction of chloride profiles.

18. Chloride profile from Site 2, and best fit according Fick’s 2 nd Law, calculated as outlined in ASTM C1556.

19. Chloride profile from Site 4, and best fit according Fick’s 2 nd Law, calculated as outlined in ASTM C1556.

20. Comparison of best fit lines to Fick’s 2 nd Law – chloride penetration more pronounced at Site 2 as compared to Site 4.

21. Predicted profile for 0.45 w/c concrete after continuous NaCl brine exposure (2N conc.) for 5 years (http://ciks.cbt.nist.gov/~bentz/clpencon.html)

22. Shape of profile of NIST model better approximates shape of data set as compared to straight fit to Fick’s 2 nd law.

24. On-going work Chloride penetration more pronounced at Site 2. Underlying reasons for increased permeability have not been determined. Production of thin sections to compare microstructure of both sites is underway.