Details:

Creators:
Riding, Kyle A. ; Esmaeily, Asad ; Vosahlik, Jan
Riding, Kyle A. ; Esmaeily, Asad ; Vosahlik, Jan Less -
Corporate Creators:
Kansas State University. Dept 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
Alternate URL:
http://ntl.bts.gov/lib/55000/55200/55220/KSU-13-6_Appendices.pdf
Funding:
C1942
Collection(s):
US Transportation Collection
Main Document Checksum:
[+]
urn:sha256:d89b2e7f48bc3638f57426968420ca0e4c9b677b60f62a49b0312f80a5098c75
Download URL:
https://rosap.ntl.bts.gov/view/dot/29005/dot_29005_DS1.pdf
File Type:

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