An alternative method for estimation of Alkali-Silica Reaction (ASR) of reactive chert aggregates is proposed. The ASR reactivity of chert aggregates (including Yoro and Seto) was studied with alkalinity under accelerated conditions at 60, 70 and 80°C and compared the results with normal sand. At different temperatures, the activation energy (Ea) value of aggregates was calculated by Arrhenius equation. The activation energy values were approximately 19.81 kJ/mol for Yoro-chert, 41.40 kJ/mol for Seto-chert and 112.52 kJ/mol for Normal-sand, respectively. The lower Ea value indicates the higher ASR reactivity of aggregates. For hydrated products, the investigation employed Coupled Plasma Atomic Emission Spectrometry (ICP-AES), X-Ray Diffraction (XRD), and 29 Si-Nuclear Magnetic Resonance (29 Si-NMR) analysis. A reduction in total dissolved silica was observed and was shown to be due to the presence of the Ca(OH)2 that was involved in the formation of ASR products, such as calcium alkali silicate hydrate (C-Na-S-H) and calcium silicate hydrate (C-S-H). After Ca(OH)2 was almost consumed, the Q 3 peaks at-92.3 ppm appeared and indicated a defect in comparison with the tobermorite structure of C-S-H that had been assigned at low Ca/Si ratio.
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