【摘 要】
：
In this paper, the accelerated method was conducted to investigate the ASR reactivity of two cherts (Yoro and Seto) which were used as aggregate materials for concrete mixing.The reaction was stopped
【机 构】
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Division of sustainable resources, Hokkaido University, 060-8628, Japan
【出 处】
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The 14th International Congress on the Chemistry of Cement (
论文部分内容阅读
In this paper, the accelerated method was conducted to investigate the ASR reactivity of two cherts (Yoro and Seto) which were used as aggregate materials for concrete mixing.The reaction was stopped at 1, 3, 5,7, 10, 14, 20 and 24 days by filtration the fluid through 0.45-μm filter and washing the solids with acetone to stop reactions.Solids were placed in an oven at temperature 40℃ until them were dehydrated.Two phases of samples (solid and liquid) were prepared for measurements including X-Ray Diffraction (XRD),29Si Nuclear Magnetic Resonance (29Si-NMR), and Inductive Coupled Plasma Atomic Emission Spectrometer (ICP-AES).Apparently ASR product can be formed due to the effect of Ca(OH)2 solids presenting in 0.1M-NaOH solution under high temperature at 80℃.ASR product was observed by using XRD in both qualitative (peaks pattern detected at 29℃ 2 θ) and quantitative (ASR content) analysis.No appreciable peak patterns of ASR was generated in the samples without Ca(OH)2.In 29Si-NMR, relative intensity of the solids mixed with Ca(OH)2 was detected that the peak was dominated by-85 ppm (Q2-sites).This was attributed to ASR formation, like tobermorite type C-S-H.Moreover, ICP-AES was used to determine the dissolution of Si and other ions remained in the solutions.Higher content of dissolved Si was examined in the liquid of Yoro-chert than that of the Seto-chert with increasing reaction time but low content of Ca ions remained in low for both samples.In conclusion, all results revealed much evidence to explain the reason why incorporation of Yoro-chert increased expansion of concretes due to ASR when compared to Seto-chert, especially for a long-term investigation.
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