Binding Mechanism and Properties of Alkali-Activated Fly Ash/Slag Mortar

• Main Authors: Hsi-An Chen, 陳璽安
• Other Authors: Ran Huang
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/96656137703531384279

碩士 === 國立臺灣海洋大學 === 河海工程學系 === 100 === This study presents an investigation into binding mechanism and properties of alkali-activated fly ash/slag mortars. Two levels of sodium oxide (Na2O) concentrations of 4% and 6% of mineral material weight and liquid sodium silicate (SiO2) with modulus ratio of 1 ( mass ratio of SiO2 to Na2O ) were used as activators to activate various ratios of fly ash to slag. The liquid/binder ratios of 0.35, 0.5 and 0.65 were used, respectively. Compressive strength test, flexural strength test, water absorption test, drying shrinkage test, scanning electron microscopy (SEM) and X-ray diffraction analysis were performed and their performance was discussed and compared with reference mortars produced by ordinary Portland cement mortars. At the same liquid/binder ratio, higher compressive strengths have been observed in alkali-activated fly ash /slag mortars (except alkali-activated fly ash mortars) than comparable ordinary Portland cement mortars at the age of 28 days. Meanwhile, the compressive strength of alkali-activated fly ash/slag mixing ratio of 50/50 is higher than that of the other ash/slag mixing ratios, and the compressive strength of alkali-activated fly ash/slag increases with an increase dosage of Na2O. A similar trend is observed for the specimens in flexural strength test. As the level of Na2O concentrations of 6% and the fly ash/slag mixing ratio of 50/50, alkali-activated fly ash/slag mortars have the lower water absorption and least drying shrinkage. the gap between the fly ash particles are calcium aluminum silicate compounds can be seen from the microscopic analysis, and when the hydration of slag growth steady, the densification of specimens will increase substantially. Thus, the fly ash/slag mixing ratio of 50/50 alkali-activated with the level of Na2O concentrations of 6% may be considered as the optimum mix design based on the results.