| Summary: | 碩士 === 國立臺灣海洋大學 === 河海工程學系 === 106 === Since the liquid sodium silicate (water glass) has the ability to reach earlier setting which is the admixture likely to be used in construction for the cementitious materials. However, construction may affect by the rapid setting coagulation. Thus, the possible alternative solution is using the solid sodium silicate.The solid sodium silicate can not be obtained easily; therefore, there are few related researches and reference data in this area.
The purpose of this research is to investigate the effect of sodium silicate on the performance of cementitious materials , and is verified by various tests .Testing variables include the mixing ratio of solid (liquid) sodium silicate, granulated blast-furnace slag and cement mixing ratio. The fixed control variable is mixing ratio of fine aggregate and mixing water. The overall test is divided into three groups.
As the testing result, the groups with solid sodium silicate had ability to reach earlier setting, but the setting time was longer than the group with the addition of liquid sodium silicate. The lower the molar ratio is, the shorter the setting time is, which is caused by the higher content of Na2O could initiate intense alkali-activate reaction.
Compressive strength test results showed that the strength of the addition of liquid sodium silicate and granulated blast-furnace slag was well below than the control groups. As for the samples with the addition of solid sodium silicate, when the higher molar ratio was used (M=3), the compressive strength was better than the control groups in long term and short term due to the higher content of SiO2. However, when the lower molar ratio was used (M=1), the compressive strength in long term was lower than the control groups. Moreover, it was observed that when the proportion of granulated blast-furnace slag was higher, the effect of reducing the compressive strength was more obvious.
As the use of different molar ratio corresponding to the different setting time and the performance of compressive strength is different; therefore, to ensure quality and safety, the appropriate mixing design is necessary.
Through the water absorption test results showed that higher molar ratio of solid sodium silicate had lower water absorption and denser, which could verify the phenomenon of the higher compressive strength.
After the discussion of a comprehensive analysis,【when only considering the setting time without special strength requirements】, the addition of solid sodium silicate can be used. And, solid sodium silicate could add into cementitious material with the appropriate mixing design. However, 【in considering setting time and taking the material strength requirements into account】, the higher molar ratio of solid sodium silicate may be suggested as the admixture of cementitious materials under the conditions. Besides, the solid sodium silicate with lower molar ratio and mixed with granulated blast-furnace slag or liquid sodium silicate are not suggested for this condition.
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