Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Alkali silica reactivity of rice husk ash in cement paste
Highlights RHA particles (micro-reactive aggregates) react with alkali hydroxide to generate ASR products. Pozzolanic reaction and ASR take place successively from the exterior to interior of RHA particles. The C-S-H phases of RHA contain sodium and potassium, and its ASR products contain calcium.
Abstract The aim of this study is to investigate alkali silica reactivity of rice husk ash (RHA) in cement paste. Scanning electron microscope in combination with Energy-dispersive X-ray spectroscopy was used to analyse the mechanism of alkali silica reactivity of RHA. The results indicate that RHA has paradoxical effect on alkali silica reaction (ASR) in cement paste, especially with coarse RHA particles and at high temperatures. RHA particles indeed act as micro-reactive aggregates and react with alkali hydroxide to generate expansive ASR products even when particle size of RHA is in range of 5.7–22.6 µm. The pozzolanic reaction and ASR take place successively from the exterior to interior of RHA particles. The mechanism for the successive reactions of RHA is proposed. The C-S-H phases as pozzolanic products of RHA contain an amount of sodium and potassium, whereas the ASR products of RHA contain an amount of calcium. The Ca/Si and (Na + K)/Si ratios of pozzolanic products are much higher and lower than those of ASR products, respectively. To mitigate ASR, RHA should be ground to very fine particles, at least finer than 5 µm.
Alkali silica reactivity of rice husk ash in cement paste
Highlights RHA particles (micro-reactive aggregates) react with alkali hydroxide to generate ASR products. Pozzolanic reaction and ASR take place successively from the exterior to interior of RHA particles. The C-S-H phases of RHA contain sodium and potassium, and its ASR products contain calcium.
Abstract The aim of this study is to investigate alkali silica reactivity of rice husk ash (RHA) in cement paste. Scanning electron microscope in combination with Energy-dispersive X-ray spectroscopy was used to analyse the mechanism of alkali silica reactivity of RHA. The results indicate that RHA has paradoxical effect on alkali silica reaction (ASR) in cement paste, especially with coarse RHA particles and at high temperatures. RHA particles indeed act as micro-reactive aggregates and react with alkali hydroxide to generate expansive ASR products even when particle size of RHA is in range of 5.7–22.6 µm. The pozzolanic reaction and ASR take place successively from the exterior to interior of RHA particles. The mechanism for the successive reactions of RHA is proposed. The C-S-H phases as pozzolanic products of RHA contain an amount of sodium and potassium, whereas the ASR products of RHA contain an amount of calcium. The Ca/Si and (Na + K)/Si ratios of pozzolanic products are much higher and lower than those of ASR products, respectively. To mitigate ASR, RHA should be ground to very fine particles, at least finer than 5 µm.
Alkali silica reactivity of rice husk ash in cement paste
Le, Ha Thanh (Autor:in) / Ludwig, Horst-Michael (Autor:in)
08.01.2020
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
Effect of Silica Fume and Rice Husk Ash on Alkali-Silica Reaction
| British Library Online Contents | 2000
Effect of Silica Fume and Rice Husk Ash on Alkali-Silica Reaction
| Online Contents | 2000
| British Library Conference Proceedings | 2015
| Elsevier | 1986