Air void clustering.

Details

• Creators:
  Riding, Kyle A ; Esmaeily, Asad ; Vosahlik, Jan
• Corporate Creators:
  Kansas State University. Department of Civil Engineering
• Subject/TRT Terms:
  Admixtures Air Entraining Agents Air Voids Coarse Aggregates Compressive Strength Concrete Mixing 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.
  
  
• Format:
  PDF
• Funding:
  C1942
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:c4d8cc6a2023ac647aaa972c25f01e06382b79e23a16d75426cf68ce2d11d5370fd8fdc773b6f20f4146dc32a91b8abd5c578a86984fee262cb88017c0ccea7f
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/29005/dot_29005_DS1.pdf
• File Type:
  [PDF - 3.53 MB ]