Concrete deck performance relative to air entrainment.

Details

• Creators:
  Rao, Chetana ; Ardani, Ahmad
• Corporate Creators:
  Applied Research Associates
• Corporate Contributors:
  Colorado. Dept. of Transportation ; United States. Federal Highway Administration
• Subject/TRT Terms:
  • Concrete pavements
  • Bridges
  • Floors
  • Testing
  • Air entrainment
  • Pavements, Concrete--Testing
  • Bridges--Colorado--Floors
• Publication/ Report Number:
  CDOT-2009-8
• Resource Type:
  Tech Report
• Geographical Coverage:
  Illinois
• Edition:
  Final.
• Corporate Publisher:
  Colorado. Dept. of Transportation
• Abstract:
  Damage to concrete due to freeze-thaw (F-T) action is a serious concern for agencies in cold regions of the United ; States. The most effective method to protect concrete from F-T damage is through the addition of an air entraining ; agent as an admixture that creates a well distributed, closely spaced, small sized air void system in the concrete. Air ; content measurement in fresh concrete is a routine quality control and acceptance test procedure that helps to ensure ; good durability characteristics in the concrete structure. Most agencies, including the Colorado DOT (CDOT), in ; accordance with industry recommendations, perform the air content measurement at the point of placement in a ; concrete structure. Between 1993 and 2008, CDOT changed its specifications due to safety considerations of the field ; personnel. Air content measurements were performed at the point of delivery during this period. While structures built ; during this period did meet specifications, it is not clear whether the pumping and the placement operations altered the ; air void distribution. For planning future maintenance activities, CDOT was interested in evaluating the relative ; condition of bridge decks built under the point of delivery specification and verifying if they indeed possessed good FT ; durability. ; After a throrough review of 600 bridges in CDOT’s database, six bridges in the Denver metro area in districts 1and 4 ; were selected for study. NBI ratings for the selected bridges ranged from 5 to 7. Three of the bridge decks were ; constructed before 1993 (using the point of placement specification), and three were constructed between 1993 and ; 2008 (using the point of delivery specification). Three cores from each structure were extracted, and two cores were ; tested as part of the forensic evaluation plan set up for this study. The tests included petrographic analysis as per ; ASTM C 856, air void analyses and total air content determination (including specific surface and spacing factor) as ; per ASTM C 457, and chloride profile measurement at three different depths as per ASTM 1152. The test results ; indicate that the bridge decks built under both specifications have an acceptable air void system and that the bridges ; built under the point of delivery specification have better F-T resistance than the structures built under the point of ; placement specification. This implies that good materials and construction practices were used and there is no ; alarming difference in the quality of bridge decks built under the two specifications. This does not suggest, however, ; that the point of delivery specification should be adopted. The sample size selected for this study is very small, and the ; results need to be interpreted with care.
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• Format:
  PDF
• Funding:
  22.80
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/17450/dot_17450_DS1.pdf
• File Type:
  [PDF - 6.55 MB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha256:6d3f3c0a274140a6d82dd038b4f98ab196e19bf8c1d1aba6bcd24f196e4fd31d