Phase development and hydration kinetics of belite-calcium sulfoaluminate cements at different curing temperatures

Borštnar, Maruša; Daneu, Nina; Dolenec, Matej

doi:10.1016/j.ceramint.2020.05.029

Cited by 52 publications

(35 citation statements)

References 37 publications

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“…It can be found out that low-temperature environments have very little effect on the type of hydration products of CSA modified cement. Crystalline CH is still absent, and large amounts of ettringite can be traced in all the specimens of CSA modified cement under low-curing temperatures, which is in agreement with the previous research [14,16]. e sharp peak of ettringite in the CSA paste cured at −5 °C suggests that hydration of CSA cement still continues at lower temperature, which is beneficial for the development of both strength and densified microstructure.…”

Section: Resultssupporting

confidence: 91%

“…GFRC modified by CSA cement (CSA/GFRC) has aroused great attention among researchers, and many studies have been undertaken to investigate its mechanical properties and microstructural characteristics under different curing regimes [14][15][16]. Research by Pe ′ ra and Ambroise [17] showed that CSA/GFRC exhibited rapid development of modulus of rupture, which reaches 8 MPa at 3 h, 9.3 MPa at 24 h, and 20.5 MPa at 28 d. Song et al [15] demonstrated that CSA/GFRC still retained a large proportion of toughness after ageing for 10 years at 25 °C.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Low Temperatures on the Mechanical Performance of GFRC Modified by Low Carbon Cement

Song

Wang

2021

Advances in Civil Engineering

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Glass fibre reinforced cement (GFRC) is a composite material with great ductility but it undergoes severe strength and ductility degradation with ageing. Calcium sulfoaluminate (CSA) cement is low carbon cement, and more importantly, it exhibits great potential to produce more ductile and durable GFRC. This study focuses on mechanical performance, e.g., compressive strength, stress-strain curve, and freeze-thaw resistance of CSA/GFRC as well as its microstructural characteristics under low temperatures. XRD was applied to investigate the hydration mechanism of CSA cement under −5°C, 0°C, and 5°C. It was found out that low-temperature environments have very little effect on the type of hydration products, and the main hydration product of hydrated CSA cement cured under low temperatures is ettringite. Moreover, low-curing temperatures have an adverse effect on the compressive strength developments of CSA/GFRC but the strength difference compared with that under 20°C reduces gradually with increasing curing ages. In terms of bending performance, both ultimate tensile strength and ultimate strain value indicate considerable degradation with ageing under low temperatures after 14 d. The ultimate strain value reduces to 0.34% at −5°C, 0.39% at 0°C, and 0.44% at 5°C compared with 0.51% for that cured at 20°C for 28 d. The tensile strength of samples cured at −5°C for 28 d is only 15.2 MPa, taking up only 40% of that under 20°C. CSA/GFRC also demonstrated great capability in the antifreeze-thaw performance, and the corresponding strength remains 95.9%, 94.7%, 94.2%, and 94.3%, respectively, for that cured under 20°C, 5°C, 0°C, and −5°C after 50 freeze-thaw cycles. Microstructural studies reveal that densification of the interfilamentary space with intermixtures of C-A-S-H and ettringite is the main reason that causes the degradation of CSA/GFRC, which may result in loss on flexibility when forces are applied, therefore reducing the post-peak toughness to some extent.

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Section: Resultssupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Effect of Low Temperatures on the Mechanical Performance of GFRC Modified by Low Carbon Cement

Song

Wang

2021

Advances in Civil Engineering

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“…On the other hand, K 2 O and Na 2 O in the CMS decreased between 7 and 365 days, which was because of the cationic exchange capacity (CEC) of the mordenite during the hydraulic reaction process. The researched mordenite has high contents of Al 2 O 3 ( Figure 5 ), which inhibited the instant reaction of C 3 A and the massive formation of ettringite, as explained above [ 69 ]; at the same time, it favoured the slow and complete hydration of the belite and tobermorite, and positively influenced the increase in mechanical strength in the CMS, as Borštnar et al [ 70 ] have already noted.…”

Section: Resultsmentioning

confidence: 56%

Effects of a Natural Mordenite as Pozzolan Material in the Evolution of Mortar Settings

et al. 2021

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This paper shows the results of a study focused on the evolution and properties of mortars made with a mixture of portland cement (PC) and natural mordenite (Mor). To begin, samples of mordenite, cement and sand were studied with X-ray diffraction (XRD), X-ray fluorescence (XRF) and granulometric analysis (GA). Next, mortars with a ratio of 75% PC and 25% mordenite were prepared to determine their initial and final setting times, consistency and density. Continuing, the density, weight and compressive strength of the specimens were determined at 2, 7, 28, 90 and 365 days. Finally, the specimens were studied using SEM, XRD and XRF. The results of the study of the mordenite sample showed a complex constitution where the major mineral component is mordenite, and to a lesser degree smectite (montmorillonite), halloysite, illite, mica, quartz, plagioclase and feldspar, in addition to altered volcanic glass. Tests with fresh cement/mordenite mortar (CMM) showed an initial setting time of 320 min and a final setting time of 420 min, much longer than the 212–310 min of portland cement mortar (PCM). It was established that the consistency of the cement/mordenite mortar (CMM) was greater than that of the PCM. The results of the density study showed that the CMM has a lower density than the PCM. On the other hand, the density of cement/mordenite specimens (CMS) was lower than that of portland cement specimens (PCS). The CMS compressive strength studies showed a significant increase from 18.2 MPa, at 2 days, to 72 MPa, at 365 days, with better strength than PCS at 28 and 365 days, respectively. XRD, XRF and SEM studies conducted on CMS showed a good development of primary and secondary tobermorite, the latter formed at the expense of portlandite; also, ettringite developed normally. This work proves that the partial replacement of PC by mordenite does not have a negative effect on the increase in the mechanical strength of CMS. It indicates that the presence of mordenite inhibits the spontaneous hydration of C3A and controls the anomalous formation of ettringite (Ett). All this, together with the mechanical strength reported, indicates that mordenite has a deep and positive influence on the evolution of the mortar setting and is an efficient pozzolan, meaning it can be used in the manufacture of mortars and highly resistant pozzolanic cement, with low hydration heat, low density, stability in extremely aggressive places and a low impact on the environment.

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“…Too high or too low early curing temperatures increased the porosity of the ACP specimen, which can reduce the thermal conductivity and enhance the thermal insulation ability. However, it also exerted adverse effects on the ACP microstructure [ 29 , 30 , 31 ], accelerating the formation and expansion of microcracks during the tunnel fire, which reduced the fire resistance and heat insulation performance of ACP. With respect to the thermal conductivity and microstructure, ACP under 40 °C early curing had the best tunnel fire resistance and heat insulation performance.…”

Section: Resultsmentioning

confidence: 99%

Effect of Early Curing Temperature on the Tunnel Fire Resistance of Self-Compacting Concrete Coated with Aerogel Cement Paste

Huang

Zhu

2021

Materials

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In this paper, the effect of early curing temperature on the tunnel fire resistance of self-compacting concrete (SCC) coated with aerogel cement paste (ACP) was studied. The physical properties in terms of the compressive strength, flexural strength, and thermal conductivity of ACP were tested under different early curing temperatures. The tunnel fire resistance of ACP and SCC coated with ACP was determined, and the microstructure of ACP and SCC after a tunnel fire were characterized by scanning electron microscopy. The results show that the strength of ACP initially increased (by 10–40 °C) and then later decreased (by 40–60 °C) with the increase in early curing temperature. ACP under 40 °C early curing exhibited the minimum number of cracks and mass loss after the tunnel fire. Too high or too low early curing temperature reduced the thermal conductivity of ACP but accelerated the formation and expansion of microcracks during the tunnel fire. The residual compressive strength of SCC coated with ACP under 40 °C early curing after the tunnel fire was the highest, demonstrating the best tunnel fire resistance.

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Phase development and hydration kinetics of belite-calcium sulfoaluminate cements at different curing temperatures

Cited by 52 publications

References 37 publications

Effect of Low Temperatures on the Mechanical Performance of GFRC Modified by Low Carbon Cement

Effect of Low Temperatures on the Mechanical Performance of GFRC Modified by Low Carbon Cement

Effects of a Natural Mordenite as Pozzolan Material in the Evolution of Mortar Settings

Effect of Early Curing Temperature on the Tunnel Fire Resistance of Self-Compacting Concrete Coated with Aerogel Cement Paste

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