The microstructural change of C-S-H at elevated temperature in Portland cement/GGBFS blended system

Jia, Zijian; Chen, Chun; Shi, Jinjie; Zhang, Yamei; Sun, ZhengMing; Zhang, Peigen

doi:10.1016/j.cemconres.2019.05.018

Cited by 83 publications

(24 citation statements)

References 30 publications

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“…When the temperature reached 600 °C, the microcracks propagated throughout the whole matrix, with the maximum width of more than 1 μm. Although our previous research showed that C-S-H was severely depolymerized at 600 °C [ 32 ], the fibrous morphology of C-S-H was still visible. At 750 °C and 950 °C, none of C-S-H morphology could be seen in the SEM images.…”

Section: Resultsmentioning

confidence: 94%

“…When the temperature was higher than 600 °C, the porosity increased almost linearly with the increase in temperature. This is mainly caused by the depolymerization of the C-S-H phases to crystal β-C 2 S [ 19 , 24 , 32 , 33 ]. However, for the carbonated cement pastes, the porosity under different high temperatures was always lower than for the corresponding uncarbonated samples.…”

Section: Resultsmentioning

confidence: 99%

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Evolution of Microstructural Characteristics of Carbonated Cement Pastes Subjected to High Temperatures Evaluated by MIP and SEM

Luo

et al. 2022

Materials

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The microstructural evolutions of both uncarbonated and carbonated cement pastes subjected to various high temperatures (30 °C, 200 °C, 400 °C, 500 °C, 600 °C, 720 °C, and 950 °C) are presented in this study by the means of mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM). It was found that the thermal stabilities of uncarbonated cement pastes were significantly changed from 400 to 500 °C due to the decomposition of portlandite at this temperature range. More large pores and microcracks were generated from 600 to 720 °C, with the depolymerization of C-S-H. After carbonation, the microstructures of carbonated cement pastes remained unchanged below 500 °C and started to degrade at 600 °C, due to the decompositions of calcium carbonates and calcium modified silica gel. At 950 °C, both uncarbonated and carbonated cement pastes showed a loosely honeycombed microstructure, composed mainly of β-C2S and lime. It can be concluded that carbonation improves the high-temperature resistance of cement pastes up to 500 °C, but this advantage is lost at temperatures over 600 °C.

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Section: Resultsmentioning

confidence: 94%

Section: Resultsmentioning

confidence: 99%

Evolution of Microstructural Characteristics of Carbonated Cement Pastes Subjected to High Temperatures Evaluated by MIP and SEM

Luo

et al. 2022

Materials

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“…148 (Cuesta et al, 2021;Jia et al, 2019;Wang et al, 2020). In addition to that SF has the finest particle size compared to the FA and GGBFS.…”

Section: Resultsmentioning

confidence: 97%

Öğütülmüş Yüksek Fırın Cürufu, Uçucu Kül ve Silika Dumanı İçeren Harçların Yüksek Sıcaklık Direnci

Öztürk

2022

Osmaniye Korkut Ata Üniversitesi Fen Bilimleri Enstitüsü Dergisi

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In the current study, elevated heat resistance of the mortars including 15% fly ash, ground granulated blast furnace slag and silica fume is investigated. Fly ash, ground granulated blast furnace slag and silica fume are replaced with cement past by weight in the prepared mortar samples. The prepared samples are kept in a furnace for 2 hours at 400 °C and 800 °C to find out effect of elevated temperature on compressive strength of the mortars. Compressive strength before and after heat exposure are measured in terms of evaluating elevated heat resistance. Control sample that does not contain any admixture, mortar including fly ash, mortar including ground granulated blast furnace slag and mortar including silica fume has 30.

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“…Since the cracking of the specimen was induced at the age of seven days, the OPC also had a large amount of unreacted binder, and the reaction of GGBFS did not occur sufficiently because of the short self-healing period of seven days, which is shorter than that observed in other studies [ 21 , 40 ]. The reaction of FA started after the generation of Ca(OH) 2 from the reaction of OPC [ 41 ]. Thus, it seems that the reaction of GGBFS did not occur because there was an insufficient amount of Ca(OH) 2 inside the cracks.…”

Section: Resultsmentioning

confidence: 99%

Self-Healing Products of Cement Pastes with Supplementary Cementitious Materials, Calcium Sulfoaluminate and Crystalline Admixtures

Park

Choi

2021

Materials

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The phase composition of self-healing products generated in cracks affects self-healing performance. This study investigated the self-healing products of cementitious materials using supplementary cementitious materials (SCMs), a calcium sulfoaluminate (CSA) expansion agent, and crystalline additives (CAs). Ground-granulated blast-furnace slag (GGBFS), fly ash (FA), and silica fume (SF) were used as SCMs, and anhydrite, Na2SO4, Na2CO3, and MgCO3 were used as crystalline additives (CAs). An artificial crack method was used to collect the self-healing products in the crack of the paste. The phase composition of the self-healing products was analyzed through X-ray diffraction (XRD)/Rietveld refinements and thermogravimetry/differential thermogravimetry (TG/DTG) analysis, and their morphology and ion concentration were examined through scanning electron microscopy with energy dispersive spectroscopy (SEM–EDS). From the results, the main compound of self-healing products was found to be calcite. GGBFS and FA decreased the content of portlandite, and the use of CAs led to the formation of alkali sulfate and alkali carbonate. The SEM–EDS analysis results showed that when GGBFS and FA were used, a large proportion of the self-healing products contained C-S-H and C-A-H, and the use of CSA led to the formation of monosulfate and ettringite.

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The microstructural change of C-S-H at elevated temperature in Portland cement/GGBFS blended system

Cited by 83 publications

References 30 publications

Evolution of Microstructural Characteristics of Carbonated Cement Pastes Subjected to High Temperatures Evaluated by MIP and SEM

Evolution of Microstructural Characteristics of Carbonated Cement Pastes Subjected to High Temperatures Evaluated by MIP and SEM

Öğütülmüş Yüksek Fırın Cürufu, Uçucu Kül ve Silika Dumanı İçeren Harçların Yüksek Sıcaklık Direnci

Self-Healing Products of Cement Pastes with Supplementary Cementitious Materials, Calcium Sulfoaluminate and Crystalline Admixtures

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