Influence of Sodium Hydroxide and Sodium Silicate Solutions on Engineering Properties of slag-based Geopolymer

• Main Authors: WENG,TZ SHIUAN, 翁子軒
• Other Authors: Ta-Peng Chang
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/6k67e4

碩士 === 國立臺灣科技大學 === 營建工程系 === 106 === In this experimental study, sodium hydroxide and sodium silicate are used separately as an activator to activate the slag. From the preliminary results, the silica modulus and the amount of alkali solutions were examined to obtain the optimum amount, then five variable of two solutions, such as the molarity, the alkali slag ratio and the silica modulus are chosen to investigate the properties of fresh and hardened paste in different ages. The research results are shown as follows: (1) In term of workability, the influence of alkali slag ratio of two solutions was greater than that of silica modulus and molarity, and according to different alkali slag ratio, the variation range of mini slump value was from 0 to 42.86% and for mini slump flow from 30 to 115.79%. It indicated that the of change of volume of two solutions is considered as the most significant variable. (2) In terms of setting time, the results showed that using sodium hydroxide and sodium silicate with modulus of 1.0, the influence of molarity was greater than that of alkali slag ratio, however when the modulus was 2.0, the influence of alkali slag ratio was greater than molarity. (3) Due to the change of Ca/Si ratio and Si/Na ratio, the highest 28 days compressive strength was obtained at 109.38 MPa using mixture with alkali slag ratio of 0.4, 3M molarity and 2.0 silica modulus. (4) Based on SEM, the microstructures of the paste are staked block-shaped when activated by sodium hydroxide, and stacked plate-shaped when activated by sodium silicate. (5) Based on XRD the major Ca, Si, O compound and C-S-H gel were observed in the paste both activated by sodium hydroxide and sodium silicate, then also found the Natrium (Na) element. (6) During the nine mix proportions paste activated by sodium hydroxide solutions, 4M had the highest compressive strength at 28 days, but when using sodium silicate solutions, 3M had the highest compressive strength at 28 days, that indicated the highest compressive strength’s optimum molarity of alkali activator would be changed in different activator. (7) The pH value of fresh paste has no relation to the alkali slag ratio, but it would slight increase due to the increase of molarity, then the value is mainly affected by using different modulus of activator, the variation range of using sodium hydroxide was from 14.178 to14.41, and for 1.0 silica modulus from 13.663 to 13.995, for 2.0 silica modulus from 12.364 to 12.937. Keywords：Sodium hydroxide, Sodium silicate, Alkali slag ratio, Slag-based geopolymer