Effect of sodium sulfate on strength and microstructure of alkali-activated fly ash based geopolymer

Li, Qingfeng; Zishuai, Wang; Gu, Liuyang; Chen, Yi; Shan, Xiaokang

doi:10.1007/s11771-020-4400-4

Cited by 27 publications

(23 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…vents hydrolytic attacks on geopolymeric gels [47]. In other studies, SO4 2− facilitates zeolite crystallization in geopolymers [48], and high SO4 2− content is much more beneficial to geopolymer properties than low SO4 2− content [49]. Thus, the anions considerably influence the geopolymer properties.…”

Section: Methodsmentioning

confidence: 89%

“…Thus far, a few studies have shown that Cl-containing salts (e.g., KCl, MgCl 2 , and CaCl 2 ) induce the precipitation and crystallization of geopolymeric gels, whereas CO 3 2− -containing salt (e.g., K 2 CO 3 , MgCO 3 , and CaCO 3 ) prevents hydrolytic attacks on geopolymeric gels [ 47 ]. In other studies, SO 4 2− facilitates zeolite crystallization in geopolymers [ 48 ], and high SO 4 2− content is much more beneficial to geopolymer properties than low SO 4 2− content [ 49 ]. Thus, the anions considerably influence the geopolymer properties.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effect of Magnesium Salt (MgCl2 and MgSO4) on the Microstructures and Properties of Ground Granulated Blast Furnace Slag (GGBFS)-Based Geopolymer

et al. 2022

View full text Add to dashboard Cite

The use of seawater to prepare geopolymers has attracted significant research attention; however, the ions in seawater considerably influence the properties of the resulting geopolymers. This study investigated the effects of magnesium salts and alkaline solutions on the microstructure and properties of ground-granulated-blast-furnace-slag-based geopolymers. The magnesium salt–free Na2SiO4-activatied geopolymer exhibited a much higher 28 d compressive strength (63.5 MPa) than the salt-free NaOH-activatied geopolymer (31.4 MPa), with the former mainly containing an amorphous phase (C-(A)-S-H gel) and the latter containing numerous crystals. MgCl2·6H2O addition prolonged the setting times and induced halite and Cl-hydrotalcite formation. Moreover, mercury intrusion porosimetry and scanning electron microscopy revealed that the Na2SiO4-activated geopolymer containing 8.5 wt% MgCl2·6H2O exhibited a higher critical pore size (1624 nm) and consequently, a lower 28 d compressive strength (30.1 MPa) and a more loosely bound geopolymer matrix than the salt-free geopolymer. In contrast, MgSO4 addition had less pronounced effects on the setting time, mineral phase, and morphology. The Na2SiO4-activated geopolymer with 9.0 wt% MgSO4 exhibited a compressive strength of 42.8 MPa, also lower than that of the salt-free geopolymer. The results indicate that Cl− is more harmful to the GGBFS-based geopolymer properties and microstructure than SO42− is.

show abstract

Section: Methodsmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Effect of Magnesium Salt (MgCl2 and MgSO4) on the Microstructures and Properties of Ground Granulated Blast Furnace Slag (GGBFS)-Based Geopolymer

et al. 2022

View full text Add to dashboard Cite

show abstract

“…In the early stages, these two hydration products increase with the amount of incorporated exciter, and the AFt and C-S-H gels fill the microscopic pores of the mortar matrix species, improving the structural density and strength. However, some studies [20][21][22] showed that the Ca(OH) 2 generated after increasing the amount of the sodium sulfate admixture caused microcracking and swelling damage inside the mortar. Because AFt has certain swelling properties as a hydration product [20][21][22], it can fill into the pores inside the PAC waste-cement cementitious sand specimens and improve the mechanical properties of the material.…”

Section: Freeze-thaw Of the Pac Slag Recycled Concretementioning

confidence: 99%

The Effects of Polyaluminium Chloride (Pac) Slag on the Properties of Recycled Concrete

Xu¹

2022

Ceramics - Silikaty

View full text Add to dashboard Cite

In this paper, recycled concrete aggregates and PAC slag were used to prepare concrete. X-ray fluorescence (XRF), X-ray diffraction (XRD) and scanning electron microscope (SEM) were used to analyse the micro-properties of the PAC and the concrete. Furthermore, the effects of the activators on the water absorption, compressive strength and frost resistance of the concrete were studied. The results showed that the effects of the activators on the water absorption were not obvious, but they could improve the activity of the PAC slag, thus, the hydration products in the mortar significantly increased and the micro-structure of the mortar became denser. Furthermore, the compressive strength of the concrete at 28 days increased by 26.5 % when the activator was mixed with 3% water glass and 3 % sodium sulfate. Moreover, the activators could improve the frost resistance of the concrete. However, when the activators were added in the concrete together, negative effects were found on the frost resistance of the concrete, with a mass loss of 20 %.

show abstract

“…There is an occurrence of O=C=O stretching bands, which appear at 2400 cm −1 , except on the WFGD gypsum cured for 90 days. The disappearance of the O=C=O stretching strong bands is a result of insignificant UCS growth [55]. SEM/EDS Analysis Figures 10 and 11 show the SEM and EDS analysis of WFGD gypsum cured at different ages for a more extended period.…”

Section: Ftir Analysismentioning

confidence: 99%

Physical, Chemical and Geotechnical Characterization of Wet Flue Gas Desulfurization Gypsum and Its Potential Application as Building Materials

et al. 2021

View full text Add to dashboard Cite

In South Africa, coal represents the primary source of energy used for electricity generation. Coal power plants use the wet flue gas desulfurization (WFGD) process to remove sulfur dioxide (SO2) from their flue gas. However, this technology produces a large amount of synthetic gypsum, resulting in waste disposal and environmental pollution. This study investigated the physical, chemical and geotechnical properties of WFGD gypsum and its potential application to develop cement-free bricks. WFGD gypsum was collected from a coal power plant in South Africa. It was found that the principal oxides of WFGD gypsum were sulfur trioxide (SO3) and calcium oxide (CaO), which represented more than 90% of the total weight. Calcium sulfate (CaSO4) and calcium di aluminate (CA2) were the predominant minerals in the raw material. The density of the WFGD gypsum was 2.43 g/cm3. The maximum dry density and optimum moisture content values were 1425 kg/m3 and 18.5%, respectively. WFGD gypsum had a liquid limit of 51% but did not display any plasticity characteristics. The optimum curing temperature of gypsum bricks was 40 °C. WFGD gypsum-based bricks exhibited compressive strength of up to 2.3 MPa and a density of about 28% less than that of typical clay bricks. Additionally, there was no significant decrease in compressive strength after seven wet/dry cycles. These results show that WFGD gypsum could be used to produce lightweight building materials with low strength requirements.

show abstract

Effect of sodium sulfate on strength and microstructure of alkali-activated fly ash based geopolymer

Cited by 27 publications

References 34 publications

Effect of Magnesium Salt (MgCl2 and MgSO4) on the Microstructures and Properties of Ground Granulated Blast Furnace Slag (GGBFS)-Based Geopolymer

Effect of Magnesium Salt (MgCl2 and MgSO4) on the Microstructures and Properties of Ground Granulated Blast Furnace Slag (GGBFS)-Based Geopolymer

The Effects of Polyaluminium Chloride (Pac) Slag on the Properties of Recycled Concrete

Physical, Chemical and Geotechnical Characterization of Wet Flue Gas Desulfurization Gypsum and Its Potential Application as Building Materials

Contact Info

Product

Resources

About