Hydration of Binary Portland Cement Blends Containing Silica Fume: A Decoupling Method to Estimate Degrees of Hydration and Pozzolanic Reaction

Liao, Wenyu; Sun, Xiao; Kumar, Aditya; Sun, Hongfang

doi:10.3389/fmats.2019.00078

Cited by 51 publications

(20 citation statements)

References 61 publications

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“…in Ca(OH)2 based on the above image analysis. The analyzed Ca(OH)2 volumetric faction (26.7%) in the hydrates of the undamaged field mortar is similar to that of 27.2% reported by Liao et al [36]. This shows the reliability and feasibility of applying optical microscopy coupled with image analysis to quantitively investigate the chemical alteration caused by deicers.…”

Section: Secondary Depositssupporting

confidence: 85%

“…the volumetric (area) fraction of Ca(OH)2 normalized to the total hydrates in the paste.Compared to the undamaged field mortar, the damaged field mortar shows a significant reduction of 86.4% in Ca(OH)2 based on the above image analysis. The analyzed Ca(OH)2 volumetric faction (26.7%) in the hydrates of the undamaged field mortar is similar to that of 27.2% reported by Liao et al[36]. This shows the reliability and feasibility of applying optical microscopy coupled with image analysis to quantitively investigate the chemical alteration caused by deicers.…”

supporting

confidence: 85%

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Petrographically Quantifying the Damage to Field and Lab-cast Mortars Subject to Freeze-thaw Cycles and Deicer Applications

Qiao¹,

Nanehkaran

Suraneni

et al. 2021

Preprint

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Although calcium oxychloride (Ca-Oxy) is known to damage cementitious materials exposed to calcium chloride (CaCl2) deicers, there is little direct observation of Ca-Oxy in the field due to its instability. This paper uses optical microscopy (OM) and scanning electron microscopy coupled with energy dispersive X-ray spectrometry (SEM-EDX) to detect the formed Ca-Oxy and quantify its associated damage in a field mortar subject to freeze-thaw cycles and deicer applications. The characterized damage in the field mortar is compared to that in lab-cast portland cement paste and mortar which are submerged in a CaCl2 solution of 25 wt. % under freeze-thaw cycles (-8 to 25 °C). The field and lab-cast mortars show similar cracking patterns that are parallel to the exposure surface with a variation of 30-45° in the preferred orientation due to the constraints of sand particles. During each lab-controlled freeze-thaw cycle, the high CaCl2 concentration of 25 wt. % stabilizes the formed Ca-Oxy, which continually damages the mortar and eventually results in 3-4 times higher crack density compared to that in the field mortar. SEM-EDX analysis confirms the presence of secondary deposits including Friedel’s salt, ettringite and Ca-Oxy. Image analysis on thin section photomicrographs shows a reduction of 86.4% in calcium hydroxide (Ca(OH)2) content in the damaged field mortar compared to the undamaged field mortar, suggesting significant leaching of Ca(OH)2 to form Ca-Oxy due to the deicer application.

show abstract

Section: Secondary Depositssupporting

confidence: 85%

supporting

confidence: 85%

Petrographically Quantifying the Damage to Field and Lab-cast Mortars Subject to Freeze-thaw Cycles and Deicer Applications

Qiao¹,

Nanehkaran

Suraneni

et al. 2021

Preprint

View full text Add to dashboard Cite

show abstract

“…Compared to the undamaged field mortar, the damaged field mortar shows a significant reduction of 86.4% in Ca(OH) 2 based on the above image analysis. The analyzed Ca(OH) 2 volumetric faction (26.7%) in the hydrates of the undamaged field mortar is similar to that of 27.2% reported by Liao et al [37]. This shows the reliability and feasibility of applying optical microscopy coupled with image analysis to quantitively investigate the chemical alteration caused by deicers.…”

Section: Ca(oh) 2 Leachingsupporting

confidence: 85%

Petrographically quantifying the damage to field and lab-cast mortars subject to freeze-thaw cycles and deicer application

Qiao¹,

Hosseinzadeh

Suraneni

et al. 2021

J Infrastruct Preserv Resil

View full text Add to dashboard Cite

Although calcium oxychloride (Ca-Oxy) is known to damage cementitious materials exposed to calcium chloride (CaCl2) deicers, there is little direct observation of Ca-Oxy in the field due to its instability. This paper uses optical microscopy (OM) and scanning electron microscopy coupled with energy dispersive X-ray spectrometry (SEM-EDX) to detect the formed Ca-Oxy and quantify its associated damage in a field mortar subject to freeze-thaw cycles and deicer application. The characterized damage in the field mortar is compared to that in lab-cast portland cement paste and mortar which are submerged in a CaCl2 solution of 25 wt.% under freeze-thaw cycles (− 8 to 25 °C). The field and lab-cast mortars show similar cracking patterns that are parallel to the exposure surface with a variation of 30–45° in the preferred orientation due to the constraints of sand particles. During each lab-controlled freeze-thaw cycle, the high CaCl2 concentration of 25 wt.% stabilizes the formed Ca-Oxy, which continually damages the mortar and eventually results in 3–4 times higher crack density compared to that in the field mortar. SEM-EDX analysis confirms the presence of secondary deposits including Friedel’s salt, ettringite and Ca-Oxy. Image analysis on thin section photomicrographs shows a reduction of 86.4% in calcium hydroxide (Ca(OH)2) content in the damaged field mortar compared to the undamaged field mortar, suggesting significant leaching of Ca(OH)2 to form Ca-Oxy due to the deicer application.

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“…Kadela [19] showed the potential of a foamed concrete layer as the base of a pavement structure. As a typical pozzolanic material, fly ash can improve the hydration and compactness of a material's microstructure when it is used in cement-treated soil systems [20][21][22][23][24][25]. Most importantly, the expansive stress caused by the late hydration of high-sulphur fly ash can be buffered by the numerous pores in cement-treated materials.…”

Section: Introductionmentioning

confidence: 99%

Influences of High-Sulphur Fly Ash on the Properties of Lightweight Cement-Treated Materials Subjected to Sulphate Corrosion

et al. 2020

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In this study, the effects of high-sulphur fly ash on the properties of lightweight cement-treated materials (LCMs) immersed in sodium sulphate solutions were studied. The unconfined compressive strength of LCMs corroded by sulphate was tested. The microscopic properties were characterised by X-ray diffraction (XRD), electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM). The results show that high-sulphur fly ash has an adverse effect on the structural strength of LCMs after corrosion, but when the content of fly ash is less than 75%, the effect of fly ash on the strength is small. A small amount of high-sulphur fly ash can improve the density of the material structure; the internal pore structure of LCMs provides space for the growth of ettringite and other corrosive substances and relieves the expansion pressure. LCMs mixed with high-sulphur fly ash have a certain resistance to sodium sulphate corrosion.

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Hydration of Binary Portland Cement Blends Containing Silica Fume: A Decoupling Method to Estimate Degrees of Hydration and Pozzolanic Reaction

Cited by 51 publications

References 61 publications

Petrographically Quantifying the Damage to Field and Lab-cast Mortars Subject to Freeze-thaw Cycles and Deicer Applications

Petrographically Quantifying the Damage to Field and Lab-cast Mortars Subject to Freeze-thaw Cycles and Deicer Applications

Petrographically quantifying the damage to field and lab-cast mortars subject to freeze-thaw cycles and deicer application

Influences of High-Sulphur Fly Ash on the Properties of Lightweight Cement-Treated Materials Subjected to Sulphate Corrosion

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