Air void clustering.

Details

• Creators:
  Riding, Kyle A ; Esmaeily, Asad ; Vosahlik, Jan
• Corporate Creators:
  Kansas State University. Department of Civil Engineering
• Subject/TRT Terms:
  • Air voids
  • Coarse aggregates
  • Concrete mixing
  • Compressive strength
  • Admixtures
  • Air entraining agents
  • Laboratory studies
• Publication/ Report Number:
  K-TRAN: KSU-13-6
• Resource Type:
  Tech Report
• Geographical Coverage:
  Kansas
• Corporate Publisher:
  Kansas. Dept. of Transportation
• Abstract:
  Air void clustering around coarse aggregate in concrete has been identified as a potential source of ; low strengths in concrete mixes by several Departments of Transportation around the country. Research was ; carried out to (1) develop a quantitative measure of air void clustering around aggregates; (2) investigate ; whether air void clustering can be reproduced in a laboratory environment; (3) determine if air void ; clustering contributes to lower compressive strengths in concrete mixes; and (4) identify potential factors ; that may cause clustering. Five types of coarse aggregate and five different air entraining agents were ; included in the laboratory study to determine if aggregate type or chemical composition of the air entraining ; agent directly relates to air void clustering. A total of 65 mixes were made, implementing the frequently used ; technique of retempering that has been previously associated with air void clustering around aggregates. ; Cylinders for compressive strength testing as well as samples for total air void analysis in the hardened ; concrete were made. Compressive strength at 7 and 28 days was determined, and automated testing for total ; air void analysis (including a new method of clustering evaluation) was performed on all mixes. This study ; found that it is possible to reproduce air void clustering in laboratory conditions. However, the results have ; shown that retempering does not always cause air void clustering. It was also observed that air void ; clustering is not responsible for a decrease in compressive strength of retempered concrete, as neither ; aggregate type nor chemical composition of the air entraining agent had a significant impact on severity of ; void clustering around coarse aggregate particles. It was found that the total air content and an ; inhomogeneous microstructure of the cement paste, not air void clustering, were responsible for lower ; strengths.
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• Format:
  PDF
• Funding:
  C1942
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/29005/dot_29005_DS1.pdf
• File Type:
  [PDF - 3.53 MB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:c4d8cc6a2023ac647aaa972c25f01e06382b79e23a16d75426cf68ce2d11d5370fd8fdc773b6f20f4146dc32a91b8abd5c578a86984fee262cb88017c0ccea7f