An Alternative Sodium Silicate Solution From Rha Essay
An alternative sodium silicate solution from RHA was prepared, based on previous studies from literature (Bouzón et al. 2014; Mejía et al., 2016; Mellado et al., 2014; Tchakouté et al. 2016a, 2016b).
RHA was added to a NaOH solution and mixed with a magnetic stirrer with heating (90 °C ± 5 °C) for 30 min aiming to enhance the silica dissolution.
The total amount of soluble silica was determined by the gravimetric analysis as follows. Two solutions containing RHA, NaOH and water were produced: 1) untreated solution, which did not pass to the silica dissolution process; and 2) treated solution, which was kept for 30 min in heating and mixing. Portions of treated and untreated solutions were collected, filtered (11 μm), oven-dried (100 °C for 24 h), and placed in the muffle furnace (150 °C for 1 h). The residual material was weighed. The dissolved silica was the difference between treated and untreated weight. The results showed that the dissolution process is efficient and the treated solution had a soluble silica content about 50% higher than the untreated one.
The alkaline mixed solution was stored and allowed to cool at room temperature prior to use in the geopolymer binder production.
2.3 Geopolymer binder
Geopolymer binder was made by the mixture of the alkaline solution with MK+WTS. A reference mixture was made without WTS.
The materials were mixed by stirring to obtain a homogeneous slurry (1 min). The molar…