Published Online: 17 April 2008
Page Count: 13
Rupnow, Tyson D.
Post Doctoral Research Associate, Department of Civil, Construction and Environmental Engineering, Iowa State University, Ames, IA
Associate Professor, Department of Civil, Construction and Environmental Engineering, Iowa State University, Ames, IA
Schaefer, Vernon R.
Professor, Department of Civil, Construction and Environmental Engineering, Iowa State University, Ames, IA
(Received 28 August 2007; accepted 13 March 2008)
The objective of this study was to evaluate the effect of sampling location on the air void analyzer (AVA) results from a 16 state-pooled fund study. The samples were obtained at locations ahead of the paver and behind the paver on a vibrator trail and between vibrator trails. The AVA air content, specific surface, spacing factor, and percent of air voids less than 300 μm in diameter were analyzed. The total air content of concrete ahead and behind the paver was also measured according to ASTM C231 for comparison. The ASTM C231 test results showed a significant drop in total air content of the samples behind the paver compared with the samples in front of the paver. The results show that the total air content is not an indicator of the spacing factor or percent of air voids less than 300 μm in diameter. There is no significant difference in the AVA results between the samples obtained on a vibrator trail and those obtained between vibrator trails based on the data from all 16 states. When the data for each state were studied individually, the data from some states showed a significant difference in the percent of air voids less than 300 μm (D≤300 μm) as well as the specific surface between the samples obtained ahead and behind the paver. The results imply that vibration removes mainly the large air voids in concrete, and this feature can be captured by the AVA test but not by the conventional ASTM C231 pressure meter test.
Paper ID: JTE101423