Use of Gypsum as a Preventive Measure for Strength Deterioration during Curing in Class F Fly Ash  Geopolymer System

Jun, Yubin; Oh, Jae Eun

doi:10.3390/ma8063053

Cited by 16 publications

(9 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…XRD patterns of the original GGBFS ( Figure 1) showed relatively strong gypsum and anhydrite peaks in comparison with existing literature [23,37,38]. Ca ions from gypsum and anhydrite can be consumed, producing a Ca-containing phase [39]. Considering that the reflection intensities of gypsum in AAS pastes were significantly decreased and the anhydrite was decreased or absent, it is believed that the formation of Ca(OH) 2 in this study may be produced from the gypsum and anhydrite.…”

Section: Samplesupporting

confidence: 73%

Alkali-Activated Slag Paste with Different Mixing Water: A Comparison Study of Early-Age Paste Using Electrical Resistivity

et al. 2020

Self Cite

View full text Add to dashboard Cite

This paper reports the electrical resistivity measurements on KOH-activated ground-granulated blast-furnace slag, which was mixed with deionized water or natural seawater at three different activator-to-binder ratios (0.4, 0.45, and 0.5). Compressive strength and X-ray diffraction analyses were performed on the samples after the measurement. The type of mixing water did not affect the setting time of samples, whereas the setting time was delayed with an increase in activator-to-binder (a/b) ratio. Regardless of the mixing water type, the increasing ratio of electrical resistivity between a/b 0.45 and 0.5 was larger than that between a/b 0.4 and 0.45. For the same a/b ratio, the pastes mixed with seawater produced higher electrical resistivity and early strength than those with deionized water. The increase in the electrical resistivity in seawater-mixed pastes could be attributed to the formation of Cl-bearing phases such as Cl-hydrocalumite, AlOCl, and aluminum chloride hydrate. It is believed that the reaction products in seawater-mixed samples were helpful in preventing water percolation, and thus, the electrical resistivity increased compared with the deionized water-mixed sample.

show abstract

Section: Samplesupporting

confidence: 73%

Alkali-Activated Slag Paste with Different Mixing Water: A Comparison Study of Early-Age Paste Using Electrical Resistivity

et al. 2020

Self Cite

View full text Add to dashboard Cite

show abstract

“…NaOH solution was prepared by dissolving NaOH pellets in seawater to 10 mol/L, and then cooling to room temperature. Na 2 SiO 3 solution was mixed with NaOH solution with a weight ratio of 3:7 [29,30]. The weight ratio of the activator (10 M NaOH in seawater + Na 2 SiO 3 solution) to the binder (fly ash or GGBFS) was fixed at 0.45.…”

Section: Sample Preparationmentioning

confidence: 99%

A Comparison Study for Chloride-Binding Capacity between Alkali-Activated Fly Ash and Slag in the Use of Seawater

Jun

Yoon

2017

Applied Sciences

Self Cite

View full text Add to dashboard Cite

Featured Application: The results of this study can be applied to the production of cementless concrete using seawater.Abstract: This study aimed to investigate the chloride-binding capacity of alkali-activated fly ash (denoted as FSW) and slag (denoted as SSW) samples and their synthesized Cl-bearing phases, which are capable of binding and immobilizing chloride when seawater is used as the mixing water. This study also examined the progressive changes in the pore structures of the FSW and SSW samples over time. The results show that the SSW sample is significantly more effective in the uptake of chloride ions compared to the FSW sample at 28 days of curing. While the FSW sample forms Cl-bearing zeolites (Cl-chabazite and Cl-sodalite) (possibly with similar types of geopolymeric gels), the SSW sample synthesizes Cl-bearing, layered double hydroxides (LDH) (Cl-hydrocalumite and Cl-hydrotalcite). Although both samples involve Cl-binding phases, the FSW sample is likely to be less efficient because it largely produces zeolites (or similar geopolymeric gels) with no Cl-binding capability (i.e., zeolites X and Y). Meanwhile, the SSW sample produces Cl-bearing LDH phases as well as C-S-H(I), which can physically adsorb chloride. The SSW sample exhibits both pore-size refinement and porosity reduction over time, while the FSW sample only exhibits pore-size refinement. Therefore, the SSW system is more advantageous in the use of seawater because it more effectively prevents Cl ingression due to greater impermeability.

show abstract

“…The sample containing 5wt% TiO2 showed the highest formation of gypsum. The presence of excess gypsum in the interior of geopolymers will reduce its mechanical strength [18]. SEM results on the composite samples made from fly ash after 3 days immersed in H 2 SO 4 solutions is shown in Figure 6.…”

Section: Resultsmentioning

confidence: 99%

The Properties of Nano TiO₂-Geopolymer Composite as a Material for Functional Surface Application

Syamsidar

2017

MATEC Web Conf.

View full text Add to dashboard Cite

Abstract. The aim of this study is to examine the properties of Nano TiO 2 -geopolymer as a material for functional surface applications such as walls, floors, bench top, arts and decoration materials. Class-C fly ash and metakaolin were used as raw materials to produce geopolymers pastes (binder). Geopolymers were synthesized through alkali activation method cured at 50°C for 2 hours using molar oxide ratios of SiO 2 /Al 2 O 3 = 3.0, Na 2 O/SiO 2 = 0.2, and H 2 O/Na 2 O = 10. Nano TiO 2 was added into geopolymers paste at different concentration namely 0 wt%, 5wt%, 10wt% and 15wt % relative the weight of fly ash or metakaolin). The measurements were commenced after the samples aged 7 days. The samples made from fly ash were immersed in 1 M H 2 SO 4 solution for 3 days for acid resistance examination. The self-cleaning properties of the composites were observed by immersing the sample into red clays solution. The X-Ray Diffraction (XRD) was performed to examine the structure and phase of the samples before and after acid resistance measurement. Scanning Electron Microscopy (SEM) was performed to examine the surface morphology of the resulting composites. The measurements results showed that Nano TiO 2 -geopolymers composite can be applied as functionally surface materials.

show abstract

Use of Gypsum as a Preventive Measure for Strength Deterioration during Curing in Class F Fly Ash Geopolymer System

Cited by 16 publications

References 25 publications

Alkali-Activated Slag Paste with Different Mixing Water: A Comparison Study of Early-Age Paste Using Electrical Resistivity

Alkali-Activated Slag Paste with Different Mixing Water: A Comparison Study of Early-Age Paste Using Electrical Resistivity

A Comparison Study for Chloride-Binding Capacity between Alkali-Activated Fly Ash and Slag in the Use of Seawater

The Properties of Nano TiO₂-Geopolymer Composite as a Material for Functional Surface Application

Contact Info

Product

Resources

About

Use of Gypsum as a Preventive Measure for Strength Deterioration during Curing in Class F Fly Ash Geopolymer System

Cited by 16 publications

References 25 publications

Alkali-Activated Slag Paste with Different Mixing Water: A Comparison Study of Early-Age Paste Using Electrical Resistivity

Alkali-Activated Slag Paste with Different Mixing Water: A Comparison Study of Early-Age Paste Using Electrical Resistivity

A Comparison Study for Chloride-Binding Capacity between Alkali-Activated Fly Ash and Slag in the Use of Seawater

The Properties of Nano TiO2-Geopolymer Composite as a Material for Functional Surface Application

Contact Info

Product

Resources

About

The Properties of Nano TiO₂-Geopolymer Composite as a Material for Functional Surface Application