In-situ Monitoring the Setting Behavior of Foamed Concrete Using Ultrasonic Pulse Velocity Method
来源期刊：Journal Of Wuhan University Of Technology Materials Science Edition2013年第6期
论文作者：SHE Wei ZHANG Yunsheng JONES MR GUO Panpan
文章页码：1146 - 1154
摘 要：The applicability of ultrasonic pulse velocity（UPV） method to in-situ monitor setting and hardening process of foamed concrete（FC） was systematically investigated. The UPVs of various FC pastes were automatically and continuously measured by a specially designed ultrasonic monitoring apparatus（UMA）. Ultrasonic tests were performed on FC mixtures with different density（300, 500, 800 and 1 000 kg/m3）, and different fly ash contents（0%, 20%, 40% and 60%）. The influence of curing temperatures（20, 40, 60 and 80°C） was also studied. The experimental results show that three characteristic stages can be clearly identified during the setting process of an arbitrary FC paste: dormant stage, acceleration stage, and deceleration stage. Wet density, fly ash content, and curing temperature have great impact on setting behavior. A stepwise increase of the wet density results in shorter dormant stage and larger final UPV. Hydration reaction rate is obviously promoted with an increase in curing temperature. However, the addition fly ash retards the microstructure formation. To aid in comparing with the ultrasonic results, the consistence spread test and Vicat needle test（VNT） were also conducted. A correlation between ultrasonic and VNT results was also established to evaluate the initial and final setting time of the FC mixtures. Finally, certain ranges of UPV with reasonable widths were suggested for the initial and final setting time, respectively.
SHE Wei1,2，ZHANG Yunsheng1，JONES MR2，GUO Panpan1
1. Jiangsu Key laboratory for Construction Materials,Southeast University2. Concrete Technology Unit,Division of Civil Engineering,University of Dundee
摘 要：The applicability of ultrasonic pulse velocity（UPV） method to in-situ monitor setting and hardening process of foamed concrete（FC） was systematically investigated. The UPVs of various FC pastes were automatically and continuously measured by a specially designed ultrasonic monitoring apparatus（UMA）. Ultrasonic tests were performed on FC mixtures with different density（300, 500, 800 and 1 000 kg/m3）, and different fly ash contents（0%, 20%, 40% and 60%）. The influence of curing temperatures（20, 40, 60 and 80°C） was also studied. The experimental results show that three characteristic stages can be clearly identified during the setting process of an arbitrary FC paste: dormant stage, acceleration stage, and deceleration stage. Wet density, fly ash content, and curing temperature have great impact on setting behavior. A stepwise increase of the wet density results in shorter dormant stage and larger final UPV. Hydration reaction rate is obviously promoted with an increase in curing temperature. However, the addition fly ash retards the microstructure formation. To aid in comparing with the ultrasonic results, the consistence spread test and Vicat needle test（VNT） were also conducted. A correlation between ultrasonic and VNT results was also established to evaluate the initial and final setting time of the FC mixtures. Finally, certain ranges of UPV with reasonable widths were suggested for the initial and final setting time, respectively.
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