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Effect of NaOH content on hydration, mineralogy, porosity and strength in alkali/sulfate-activated binders from ground granulated blast furnace slag and phosphogypsum
Abstract This study investigates the effect of NaOH content on alkali/sulfate-activated binders from 90 wt% ground granulated blast furnace slag (GGBFS) and 10 wt% phosphogypsum (PG). Alkali activators were prepared with a NaOH molarity ranging from 0 M to 4 M. The hydration was monitored using in-situ X-ray diffraction (XRD) and isothermal calorimetry. The hydration product assemblage was investigated using XRD, thermogravimetric analysis (TGA), Fourier-transformed infrared (FTIR) spectroscopy, nitrogen adsorption/desorption and compressive strength tests. A molarity of 0 M NaOH gave rise to the highest porosity and highest strength, although setting occurred only after 7 days. From a molarity of 2 M NaOH and higher, ettringite disappeared and got replaced by a monosulfate phase (i.e., NaCa4Al2O6(SO4)1.5.15H2O) and amorphous aluminum-hydroxide. This study shows the potential of using GGBFS and PG for the development of novel by-product based cementitious binders.
Highlights The binder was a mixture of 90 wt% GGBFS and 10 wt% phosphogypsum. The NaOH molarity of the alkali activator ranged from 0 M to 4 M. A molarity of 0 M NaOH yielded highest porosity and strength, and slowest setting. Portlandite acted as a catalyst promoting further slag dissolution. From 2 M NaOH and higher, ettringite disappeared and carbonation was enhanced.
Effect of NaOH content on hydration, mineralogy, porosity and strength in alkali/sulfate-activated binders from ground granulated blast furnace slag and phosphogypsum
Abstract This study investigates the effect of NaOH content on alkali/sulfate-activated binders from 90 wt% ground granulated blast furnace slag (GGBFS) and 10 wt% phosphogypsum (PG). Alkali activators were prepared with a NaOH molarity ranging from 0 M to 4 M. The hydration was monitored using in-situ X-ray diffraction (XRD) and isothermal calorimetry. The hydration product assemblage was investigated using XRD, thermogravimetric analysis (TGA), Fourier-transformed infrared (FTIR) spectroscopy, nitrogen adsorption/desorption and compressive strength tests. A molarity of 0 M NaOH gave rise to the highest porosity and highest strength, although setting occurred only after 7 days. From a molarity of 2 M NaOH and higher, ettringite disappeared and got replaced by a monosulfate phase (i.e., NaCa4Al2O6(SO4)1.5.15H2O) and amorphous aluminum-hydroxide. This study shows the potential of using GGBFS and PG for the development of novel by-product based cementitious binders.
Highlights The binder was a mixture of 90 wt% GGBFS and 10 wt% phosphogypsum. The NaOH molarity of the alkali activator ranged from 0 M to 4 M. A molarity of 0 M NaOH yielded highest porosity and strength, and slowest setting. Portlandite acted as a catalyst promoting further slag dissolution. From 2 M NaOH and higher, ettringite disappeared and carbonation was enhanced.
Effect of NaOH content on hydration, mineralogy, porosity and strength in alkali/sulfate-activated binders from ground granulated blast furnace slag and phosphogypsum
Gijbels, Katrijn (author) / Pontikes, Yiannis (author) / Samyn, Pieter (author) / Schreurs, Sonja (author) / Schroeyers, Wouter (author)
2020-03-24
Article (Journal)
Electronic Resource
English
Hydration of alkali-activated ground granulated blast furnace slag
| Tema Archive | 2000
Hydration of alkali-activated ground granulated blast furnace slag
| British Library Online Contents | 2000
| British Library Online Contents | 2018