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Federal Highway Administration > Publications > Research > Structures > Long-Term Performance of Epoxy-Coated Reinforcing Steel in Heavy Salt-Contaminated Concrete

Publication Number: FHWA-HRT-04-090
Date: JUNE 2004

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Appendix A. PHOTOGRAPHS OF TEST SLABS AT END OF OUTDOOR EXPOSURE AND AUTOPSIED BARS (2)

 

Figure 90. Slab #16 front, rear, and top views with specifications
Figure 90. Slab #16 front, rear, and top views with specifications. Photos. (A) Slab number 16 front view shows the 16A label on the left and 16B on the right. The green bars and the concrete look clear, with minor corrosion only on the top left and second from left bottom bars. Wires connect only between the top and bottom bars of 16B.
a) Front View		 Figure 90. Slab #16 front, rear, and top views with specifications. Photos. (B) The rear view is unlabeled, showing clear concrete with minor discoloration on the bottom bars.
b) Rear View
Figure 90. Slab #16 front, rear, and top views with specifications. Photos. (C) The top view is clear gray, with no discoloration.
c) Top View
d) Slab specifications
Specimen ID 16A 16B
Top mat Stainless Steel Stainless Steel
Bar shape (straight/bent) Bent Bent
Coating defect (%) N/A N/A
Bottom mat Black
Coating defect (%) N/A N/A
Precracked No No

Figure 91. Slab #16 extracted rebars condition. Photo. Before autopsy, the top mat bent stainless steel bars look clean.
a) Top bars

Figure 91. Slab #16 extracted rebars condition. Photo. Before autopsy, the bottom mat straight black bars show different levels of corrosion starting from no corrosion (A-B1) to moderate corrosion (B-B2).
b) Bottom bars

*A-T: Top left bar, B-T: Top right bar, A-B1&B2: Bottom left bars, B-B1&B2: Bottom right bars

Figure 91. Slab #16 extracted rebars condition

Figure 92. Slab #16 after autopsy. Photo. After autopsy, the top mat bent stainless steel bars remain unchanged.
a) Top bars

Figure 92. Slab #16 after autopsy. Photo. After autopsy, the cleaned bottom mat black bars exhibit minimal corrosion damage.
b) Bottom bars

*A-T: Top left bar, B-T: Top right bar, A-B1&B2: Bottom left bars, B-B1&B2: Bottom right bars

Figure 92. Slab #16 after autopsy

Figure 93. Slab #17 front, rear, and top views with specifications
Figure 93. Slab #17 front, rear, and top views with specifications. Photos. (A) Slab number 17 front view shows the 17A label on the left and 17B on the right. The green bars and the concrete look clear with no corrosion Wires connect the top and bottom bars of 17B; the same is true for 17A.
a) Front View		 Figure 93. Slab #17 front, rear, and top views with specifications. Photos. (B) The rear view is unlabeled, showing clear concrete with minor discoloration below the two middle bottom bars.
b) Rear View
Figure 93. Slab #17 front, rear, and top views with specifications. Photos. (C) The top view is mottled gray, with no corrosion.
c) Top View
d) Slab specifications
Specimen ID 17A 17B
Top mat Coating D Coating D
Bar shape (straight/bent) Straight Straight
Coating defect (%) 0.004 0.5
Bottom mat Coating D
Coating defect (%) 0.004 0.5
Precracked No No

Figure 94. Slab #17 extracted rebars condition. Photo. Before autopsy, all top mat and bottom mat ECRs look good without any noticeable coating deterioration other than the intentional coating defects.

Figure 94. Slab #17 extracted rebars condition

Figure 95. Slab #17 after autopsy. Photo. After autopsy, all the ECRs show the same condition, except that one top mat ECR (B-T) is partially delaminated with no noticeable corrosion underneath.

Figure 95. Slab #17 after autopsy

*A-T: Top left bar, B-T: Top right bar, A-B1&B2: Bottom left bars, B-B1&B2: Bottom right bars

Figure 96. Slab #18 front, rear, and top views with specifications
Figure 96. Slab #18 front, rear, and top views with specifications. Photos. (A) Slab number 18 front view shows the 18A label on the left and 18B on the right. The top left green bar is completely corroded and stains the concrete around it and down to the lower level bars. The remaining bars show minor corrosion discoloration with drips onto the adjacent concrete. Wires connect the top and bottom bars of 18B; the same is true for 18A.
a) Front View		 Figure 96. Slab #18 front, rear, and top views with specifications. Photos. (B) The rear view is unlabeled showing almost total rust and corrosion on the right bars and the right side of the concrete. There are also discolored stains on the bottom bars and across the bottom of the concrete.
b) Rear View
Figure 96. Slab #18 front, rear, and top views with specifications. Photos. (C) The top view is mottled gray with no corrosion, with the water dike showing on the right and bottom.
c) Top View
d) Slab specifications
Specimen ID 18A 18B
Top mat Coating F Coating F
Bar shape (straight/bent) Straight Straight
Coating defect (%) 0.5 0.004
Bottom mat Black
Coating defect (%) N/A N/A
Precracked No No

Figure 97. Slab #18 extracted rebars condition. Photo. Before autopsy, the two top mat straight ECRs (A-T and B-T) exhibit coating deterioration in the form of hairline coating cracks. The bottom mat black bars exhibit various levels of corrosion.

Figure 97. Slab #18 extracted rebars condition

Figure 98. Slab #18 after autopsy. Photo. After autopsy, a top mat ECR (A-T) is completely delaminated and corroded, while the other top mat ECR (B-T) exhibits limited delamination with some substrate corrosion. The cleaned bottom mat bars exhibit either moderate pitting corrosion (A-B2 and B-B2) or no corrosion (A-B1 and B-B1).

Figure 98. Slab #18 after autopsy

*A-T: Top left bar, B-T: Top right bar, A-B1&B2: Bottom left bars, B-B1&B2: Bottom right bars

Figure 99. Slab #19 front, rear, and top views with specifications
Figure 99. Slab #19 front, rear, and top views with specifications. Photos. (A) Slab number 19 front view shows the 19B label on the left and 19A on the right. Both top bars are completely corroded with rust running down to the lower bars and cracks between the lower bars. Wires connect the top and bottom bars of 19B; the same is true for 19A.
a) Front View		 Figure 99. Slab #19 front, rear, and top views with specifications. Photos. (B) The rear view is unlabeled showing corrosion on the right bar bleeding down to the lower level. Cracks connect the bottom bars and radiate out from the bars.
b) Rear View
Figure 99. Slab #19 front, rear, and top views with specifications. Photos. (C) The top view is mottled gray with corrosion from the precracking.
c) Top View
d) Slab specifications
Specimen ID 19A 19B
Top mat Coating F Coating F
Bar shape (straight/bent) Straight Straight
Coating defect (%) 0.004 0.5
Bottom mat Black
Coating defect (%) N/A N/A
Precracked Yes Yes

Figure 100. Slab #19 extracted rebars condition. Photo. Before autopsy, the two top mat straight ECRs (A-T and B-T) show moderate coating deterioration in form of hairline cracks with minor corrosion stain. All the bottom mat black bars are severely corroded.

Figure 100. Slab #19 extracted rebars condition

Figure 101. Slab #19 after autopsy. Photo. After autopsy, both of the top mat ECRs (A-T and B-T) are almost completely delaminated with major substrate corrosion. The cleaned bottom mat black bars exhibit severe corrosion damage.

Figure 101. Slab #19 after autopsy

*A-T: Top left bar, B-T: Top right bar, A-B1&B2: Bottom left bars, B-B1&B2: Bottom right bars

Figure 102. Slab #20 front, rear, and top views with specifications
Figure 102. Slab #20 front, rear, and top views with specifications. Photos. (A) Slab number 20 front view shows the 20B label on the left and 20A on the right. All bars show corrosion with bleeding and cracks in the concrete. Wires connect the top and bottom bars of 20B; the same is true for 20A.
a) Front View		 Figure 102. Slab #20 front, rear, and top views with specifications. Photos. (B) The rear view is unlabeled, showing minor staining and huge cracks radiating from both top bars.
b) Rear View
Figure 102. Slab #20 front, rear, and top views with specifications. Photos. (C) The top view is mottled gray, with corrosion from the precracking.
c) Top View
d) Slab specifications
Specimen ID 20A 20B
Top mat Black Black
Bar shape (straight/bent) Straight Straight
Coating defect (%) N/A N/A
Bottom mat Black
Coating defect (%) N/A N/A
Precracked Yes Yes

Figure 103. Slab #20 extracted rebars condition. Photo. Before autopsy, both of the top mat black bars exhibit severe corrosion. The bottom mat black bars also show moderate to severe corrosion except the fourth bar from the top (A-B2).

Figure 103. Slab #20 extracted rebars condition

Figure 104. Slab #20 after autopsy. Photo. After autopsy, all of the clean black bars exhibit severe corrosion damage.

Figure 104. Slab #20 after autopsy

*A-T: Top left bar, B-T: Top right bar, A-B1&B2: Bottom left bars, B-B1&B2: Bottom right bars

Figure 105. Slab #21 front, rear, and top views with specifications
Figure 105. Slab #21 front, rear, and top views with specifications. Photos. (A) Slab number 21 front view shows the 21B label on the left and 21A on the right. All bars show minor corrosion with the top right being the worst but with no bleeding onto the concrete. Wires are attached between the top and bottom bars of 21B; the same is true for 21A.
a) Front View		 Figure 105. Slab #21 front, rear, and top views with specifications. Photos. (B) The rear view is unlabeled showing clear concrete with no bar corrosion.
b) Rear View
Figure 105. Slab #21 front, rear, and top views with specifications. Photos. (C) The top view is mottled gray with precracked grooves showing darker color but no corrosion.
c) Top View
d) Slab specifications
Specimen ID 21A 21B
Top mat Coating D Coating D
Bar shape (straight/bent) Straight Straight
Coating defect (%) 0.5 0.004
Bottom mat Black
Coating defect (%) N/A N/A
Precracked Yes Yes

Figure 106. Slab #21 extracted rebars condition. Photo. Before autopsy, the top mat two straight ECRs show either clean (B-T) or several coating defects circled in red. The bottom mat black bars show good condition without corrosion.

Figure 106. Slab #21 extracted rebars condition

Figure 107. Slab #21 after autopsy. Photo. After autopsy, a top mat ECR (A-T) is completely delaminated and reveals corroded substrate whereas the other top mat ECR (B-T) remains unchanged. All of the cleaned bottom mat black bars look good.

Figure 107. Slab #21 after autopsy

*A-T: Top left bar, B-T: Top right bar, A-B1&B2: Bottom left bars, B-B1&B2: Bottom right bars

Figure 108. Slab #22 front, rear, and top views with specifications
Figure 108. Slab #22 front, rear, and top views with specifications. Photos. (A) Slab number 22 front view shows the 22B label on the left and 22A on the right. The top left bar shows corrosion, and a major crack runs from the top right bar to the second lower bar with minor staining on the concrete. Wires connect the top left and bottom bars of 22B and just the lower bars for 22A.
a) Front View		 Figure 108. Slab #22 front, rear, and top views with specifications. Photos. (B) The rear view is unlabeled showing the water dike and clear concrete with corrosion and a thin drip of staining around the top right bar.
b) Rear View
Figure 108. Slab #22 front, rear, and top views with specifications. Photos. (C) The top view is mottled gray, with a few prominent cracks.
c) Top View
d) Slab specifications
Specimen ID 22A 22B
Top mat Coating A Coating A
Bar shape (straight/bent) Bent Bent
Coating defect (%) 0.004 0.5
Bottom mat Black
Coating defect (%) N/A N/A
Precracked No No

Figure 109. Slab #22 extracted rebars condition. Photo. Before autopsy, the top mat bent ECRs exhibit moderate coating deterioration and rust stains.
a) Top bars

Figure 109. Slab #22 extracted rebars condition. Photo. Before autopsy, the first bottom mat black bar (A-B1) looks clean, while the rest show moderate level of corrosion. .
b) Bottom bars

*A-T: Top left bar, B-T: Top right bar, A-B1&B2: Bottom left bars, B-B1&B2: Bottom right bars

Figure 109. Slab #22 extracted rebars condition

Figure 110. Slab #22 after autopsy. Photo. After autopsy, the bent top mat ECRs are completely delaminated and corroded.
a) Top bars

Figure 110. Slab #22 after autopsy. Photo. After autopsy, the cleaned bottom mat straight black bars exhibit minor corrosion damage.
b) Bottom bars

*A-T: Top left bar, B-T: Top right bar, A-B1&B2: Bottom left bars, B-B1&B2: Bottom right bars

Figure 110. Slab #22 after autopsy

Figure 111. Slab #23 front, rear, and top views with specifications
Figure 111. Slab #23 front, rear, and top views with specifications. Photos. (A) Slab number 23 front view shows the 23B label on the left and 23A on the right. The top right bar shows severe corrosion and major cracks radiate from all the bars. Wires connect the top left and bottom bars of 23B and just the lower bars for 23A.
a) Front View		 Figure 111. Slab #23 front, rear, and top views with specifications. Photos. (B) The rear view is unlabeled showing the water dike and major corrosion on the left side and the bottom right bar with some cracks.
b) Rear View
Figure 111. Slab #23 front, rear, and top views with specifications. Photos. (C) The top view shows massive discoloration and corrosion with numerous cracks.
c) Top View
d) Slab specifications
Specimen ID 23A 23B
Top mat Black Black
Bar shape (straight/bent) Bent Bent
Coating defect (%) N/A N/A
Bottom mat Black
Coating defect (%) N/A N/A
Precracked No No

Figure 112. Slab #23 extracted rebars condition. Photo. Before autopsy, both of the top mat bent black bars and all the bottom mat straight black bars are severely corroded.
a) Top bars

Figure 112. Slab #23 extracted rebars condition. Photo. Before autopsy, both of the top mat bent black bars and all the bottom mat straight black bars are severely corroded.
b) Bottom bars

*A-T: Top left bar, B-T: Top right bar, A-B1&B2: Bottom left bars, B-B1&B2: Bottom right bars

Figure 112. Slab #23 extracted rebars condition

Figure 113. Slab #23 after autopsy. Photo. After autopsy, the cleaned top mat bent black bars and the bottom mat straight black bars exhibit severe corrosion damage.
a) Top bars

Figure 113. Slab #23 after autopsy. Photo. After autopsy, the cleaned top mat bent black bars and the bottom mat straight black bars exhibit severe corrosion damage.
b) Bottom bars

*A-T: Top left bar, B-T: Top right bar, A-B1&B2: Bottom left bars, B-B1&B2: Bottom right bars

Figure 113. Slab #23 after autopsy

Figure 114. Slab #24 front, rear, and top views with specifications
Figure 114. Slab #24 front, rear, and top views with specifications. Photos. (A) Slab number 24 front view shows the 24B label on the left and 24A on the right. All the bars show minor corrosion with little concrete staining. Wires connect the top left and bottom bars of 24B; the same is true for 24A.
a) Front View		 Figure 114. Slab #24 front, rear, and top views with specifications. Photos. (B) The rear view is unlabeled showing the water dike and minor staining and corrosion only around the bottom right bar.
b) Rear View
Figure 114. Slab #24 front, rear, and top views with specifications. Photos. (C) The top view is mottled gray, with no discoloration.
c) Top View
d) Slab specifications
Specimen ID 24A 24B
Top mat Coating A Coating A
Bar shape (straight/bent) Straight Straight
Coating defect (%) 0.5 0.004
Bottom mat Black
Coating defect (%) N/A N/A
Precracked No No

Figure 115. Slab #24 extracted rebars condition. Photo. Before autopsy, the top mat two straight ECRs (A-T and B-T) look good with intentional coating defects circled. The bottom mat four black bars exhibit corrosion-free condition.

Figure 115. Slab #24 extracted rebars condition

Figure 116. Slab #24 after autopsy. Photo. After autopsy, a top mat ECR (A-T) is completely delaminated and reveals corroded substrate. The other top mat ECR (B-T) remains unchanged. The cleaned bottom mat four black bars are shiny with minor pitting.

Figure 116. Slab #24 after autopsy

*A-T: Top left bar, B-T: Top right bar, A-B1&B2: Bottom left bars, B-B1&B2: Bottom right bars

Figure 117. Slab #25 front, rear, and top views with specifications
Figure 117. Slab #25 front, rear, and top views with specifications. Photos. (A) Slab number 25 front view shows the 25A label on the left and 25B on the right. All bars show minor corrosion but the top right bar is completely corroded and stains the concrete around it down between the lower level of bars. The concrete on the lower level has some staining. Wires connect the top and bottom bars of 25B; the same is true for 25A.
a) Front View		 Figure 117. Slab #25 front, rear, and top views with specifications. Photos. (B) The rear view is unlabeled, showing rust and corrosion on the top left bar staining down to between the lower bars. There are also concrete cracks and minor corrosion drips near the lower bars.
b) Rear View
Figure 117. Slab #25 front, rear, and top views with specifications. Photos. (C) The top view is mottled gray, with the groove line and cracks around it from the precracking.
c) Top View
d) Slab specifications
Specimen ID 25A 25B
Top mat Coating B Coating B
Bar shape (straight/bent) Straight Straight
Coating defect (%) 0.004 0.5
Bottom mat Black
Coating defect (%) N/A N/A
Precracked Yes Yes

Figure 118. Slab #25 extracted rebars condition. Photo. Before autopsy, a top mat straight ECR (A-T) exhibits moderate coating deterioration and minor rust discoloration. The second bar top mat ECR (B-T) shows severe coating deterioration. The bottom mat four black bars exhibit minor corrosion.

Figure 118. Slab #25 extracted rebars condition

Figure 119. Slab #25 after autopsy. Photo. After autopsy, a top mat ECR (A-T) is mostly delaminated with moderate substrate corrosion, while the other top mat ECR (B-T) is completely delaminated with some severe corrosion spots on the substrate. The cleaned bottom mat four black bars show minor pitting.

Figure 119. Slab #25 after autopsy

*A-T: Top left bar, B-T: Top right bar, A-B1&B2: Bottom left bars, B-B1&B2: Bottom right bars

Figure 120. Slab #26 front, rear, and top views with specifications
Figure 120. Slab #26 front, rear, and top views with specifications. Photos. (A) Slab number 26 front view shows the 26A label on the left and 26B on the right. All bars show minor corrosion, but the concrete is clean except for minor stains on the bottom right. Wires connect the top and bottom bars of 26B; the same is true for 26A.
a) Front View		 Figure 120. Slab #26 front, rear, and top views with specifications. Photos. (B) The rear view is unlabeled and shows minor corrosion on the bars with no staining on the concrete.
b) Rear View
Figure 120. Slab #26 front, rear, and top views with specifications. Photos. (C) The top view is clear gray with the groove line of the precrack showing on the right side.
c) Top View
d) Slab specifications
Specimen ID 26A 26B
Top mat Stainless Steel Stainless Steel
Bar shape (straight/bent) Straight Straight
Coating defect (%) N/A N/A
Bottom mat Black
Coating defect (%) N/A N/A
Precracked No Yes

Figure 121. Slab #26 extracted rebars condition. Photo. Before autopsy, a top mat straight stainless steel bar (A-T) show excellent condition while the other top mat stainless steel bar (B-T) exhibit some localized rust stains. The top mat bars have a diamond metal pattern instead of the usual spiral. All the bottom mat four black bars look good.

Figure 121. Slab #26 extracted rebars condition

Figure 122. Slab #26 after autopsy. Photo. After autopsy, all the cleaned bar exhibit excellent condition without any corrosion damage.

Figure 122. Slab #26 after autopsy

*A-T: Top left bar, B-T: Top right bar, A-B1&B2: Bottom left bars, B-B1&B2: Bottom right bars

Figure 123. Slab #27 front, rear, and top views with specifications
Figure 123. Slab #27 front, rear, and top views with specifications. Photos. (A) Slab number 27 front view shows the 27A label on the left and 27B on the right. All bars show minor discoloration, but the concrete is clean. Wires connect the top and bottom bars of 27B; the same is true for 27A.
a) Front View		 Figure 123. Slab #27 front, rear, and top views with specifications. Photos. (B) The rear view is unlabeled and shows the water dike with no corrosion but white staining on the concrete from the salt solution.
b) Rear View
Figure 123. Slab #27 front, rear, and top views with specifications. Photos. (C) The top view is mottled gray, with the groove line of the precrack showing on the left side.
c) Top View
d) Slab specifications
Specimen ID 27A 27B
Top mat Stainless Steel Stainless Steel
Bar shape (straight/bent) Straight Straight
Coating defect (%) N/A N/A
Bottom mat Stainless Steel
Coating defect (%) N/A N/A
Precracked Yes No

Figure 124. Slab #27 extracted rebars condition. Photo. Before autopsy, all the top and bottom mat straight stainless steel bars show excellent condition. All bars have a diamond metal pattern instead of the usual spiral.

Figure 124. Slab #27 extracted rebars condition

Figure 125. Slab #27 after autopsy. Photo. After autopsy, all the cleaned stainless steel bars exhibit excellent condition.

Figure 125. Slab #27 after autopsy

*A-T: Top left bar, B-T: Top right bar, A-B1&B2: Bottom left bars, B-B1&B2: Bottom right bars

Figure 126. Slab #28 front, rear, and top views with specifications
Figure 126. Slab #28 front, rear, and top views with specifications. Photos. (A) Slab number 28 front view shows the 28A label on the left and 28B on the right. All bars show corrosion discoloration but the top right bar stained and cracked the concrete. Wires connect the top and bottom bars of 28B; the same is true for 28A. The water dike is visible.
a) Front View		 Figure 126. Slab #28 front, rear, and top views with specifications. Photos. (B) The rear view is unlabeled and shows the water dike with corrosion and cracks around the top left and some staining along the bottom.
b) Rear View
Figure 126. Slab #28 front, rear, and top views with specifications. Photos. (C) The top view is mottled gray, with minor cracks on the right side.
c) Top View
d) Slab specifications
Specimen ID 28A 28B
Top mat Coating E Coating E
Bar shape (straight/bent) Straight Straight
Coating defect (%) 0.004 0.5
Bottom mat Black
Coating defect (%) N/A N/A
Precracked No No

Figure 127. Slab #28 extracted rebars condition. Photo. Before autopsy, the two top straight ECRs (A-T and B-T) exhibit moderate coating degradation with minor corrosion. Two of the bottom mat straight black bars (B-B1 and B-B2) show moderate corrosion while the other bottom mat black bars (A-B1 and A-B2) are corrosion free.

Figure 127. Slab #28 extracted rebars condition

Figure 128. Slab #28 after autopsy. Photo. After autopsy, the top mat straight ECRs (A-T and B-T) show significant coating delamination and severe substrate corrosion. The cleaned bottom mat black bars exhibit either moderate corrosion damage (B-B1 and B-B2) or good condition (A-B1 and A-B2).

Figure 128. Slab #28 after autopsy

*A-T: Top left bar, B-T: Top right bar, A-B1&B2: Bottom left bars, B-B1&B2: Bottom right bars

Figure 129. Slab #29 front, rear, and top views with specifications
Figure 129. Slab #29 front, rear, and top views with specifications. Photos. (A) Slab number 29 front view shows the 29A label on the left and 29B on the right. All bars show minor discoloration and minor concrete staining. Wires connect the top and bottom bars of 29B; the same is true for 29A. The water dike is visible.
a) Front View		 Figure 129. Slab #29 front, rear, and top views with specifications. Photos. (B) The rear view is unlabeled and shows the water dike with minor staining near the bottom bars.
b) Rear View
Figure 129. Slab #29 front, rear, and top views with specifications. Photos. (C) The top view is mottled gray with cracks.
c) Top View
d) Slab specifications
Specimen ID 29A 29B
Top mat Coating E Coating E
Bar shape (straight/bent) Straight Straight
Coating defect (%) 0.004 0.5
Bottom mat Coating E
Coating defect (%) 0.004 0.5
Precracked No No

Figure 130. Slab #29 extracted rebars condition. Photo. Before autopsy, a top mat straight ECR (B-T) shows moderate coating degradation and all the other straight ECRs show good condition except for intentional coating defects.

Figure 130. Slab #29 extracted rebars condition

Figure 131. Slab #29 after autopsy. Photo. After autopsy, the second ECR from the top (B-T) shows extensive coating delamination and substrate corrosion.

Figure 131. Slab #29 after autopsy

*A-T: Top left bar, B-T: Top right bar, A-B1&B2: Bottom left bars, B-B1&B2: Bottom right bars

Figure 132. Slab #30 front, rear, and top views with specifications
Figure 132. Slab #30 front, rear, and top views with specifications. Photos. (A) Slab number 30 front view shows the 30A label on the left and 30B on the right. The top bars show major cracks and corrosion that stains the concrete down to the lower bars. Wires connect the top and bottom bars of 30B; the same is true for 30A.
a) Front View		 Figure 132. Slab #30 front, rear, and top views with specifications. Photos. (B) The rear view is unlabeled and shows extensive corrosion staining on the top bars and bleeding to the bottom bars.
b) Rear View
Figure 132. Slab #30 front, rear, and top views with specifications. Photos. (C) The top view is mottled gray and shows the precracks with minor cracks radiating from them.
c) Top View
d) Slab specifications
Specimen ID 30A 30B
Top mat Coating C Coating C
Bar shape (straight/bent) Straight Straight
Coating defect (%) 0.004 0.5
Bottom mat Black
Coating defect (%) N/A N/A
Precracked Yes Yes

Figure 133. Slab #30 extracted rebars condition. Photo. Before autopsy, the top mat two straight ECRs (A-T and B-T) exhibit severe coating deterioration with hairline cracks, coating blisters and major rust discoloration. The bottom mat four black bars exhibit different levels of corrosion, i.e., severe (B-B2 and A-B2), moderate (B-B1) and corrosion-free (A-B1).

Figure 133. Slab #30 extracted rebars condition

Figure 134. Slab #30 after autopsy. Photo. After autopsy, the top mat straight ECRs (A-T and B-T) experience complete coating delamination and reveal intensive substrate corrosion. The cleaned bottom mat two black bars (B-B1 and B-B2) exhibit moderate pitting damage and the other two bars (A-B1 and A-B2) exhibit intact condition.

Figure 134. Slab #30 after autopsy

*A-T: Top left bar, B-T: Top right bar, A-B1&B2: Bottom left bars, B-B1&B2: Bottom right bars

Figure 135. Slab #31 front, rear, and top views with specifications
Figure 135. Slab #31 front, rear, and top views with specifications. Photos. (A) Slab number 31 front view shows the 31A label on the left and 31B on the right. The concrete surface shows minor cracks and corrosion drips. Wires connect the top and bottom bars of 31B and only the bottom bars for 31A.
a) Front View		 Figure 135. Slab #31 front, rear, and top views with specifications. Photos. (B) The rear view is unlabeled and shows minor discoloration drips on the lower half of the slab.
b) Rear View
Figure 135. Slab #31 front, rear, and top views with specifications. Photos. (C) The top view is mottled gray with no discoloration.
c) Top View
d) Slab specifications
Specimen ID 31A 31B
Top mat Coating E Coating E
Bar shape (straight/bent) Bent Bent
Coating defect (%) 0.5 0.004
Bottom mat Black
Coating defect (%) N/A N/A
Precracked No No

Figure 136. Slab #31 extracted rebars condition. Photo. Before autopsy, the top mat two bent ECRs show minor coating deterioration.
a) Top bars

Figure 136. Slab #31 extracted rebars condition. Photo. Before autopsy, the bottom mat four black bars show good condition except for rust on the ends.
b) Bottom bars

*A-T: Top left bar, B-T: Top right bar, A-B1&B2: Bottom left bars, B-B1&B2: Bottom right bars

Figure 136. Slab #31 extracted rebars condition

Figure 137. Slab #31 after autopsy. Photo. After autopsy, the top mat bent ECRs show minor coating delamination and mild substrate corrosion.
a) Top bars

Figure 137. Slab #31 after autopsy. Photo. After autopsy, the cleaned bottom mat straight black bars exhibit good condition.
b) Bottom bars

*A-T: Top left bar, B-T: Top right bar, A-B1&B2: Bottom left bars, B-B1&B2: Bottom right bars

Figure 137. Slab #31 after autopsy

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