The mechanism of hydration of MgO-hydromagnesite blends

Kuenzel, Carsten; Zhang, F.; Ferrándiz-Mas, Verónica; Cheeseman, Christopher; Gartner, E.M.

doi:10.1016/j.cemconres.2017.10.003

Cited by 118 publications

(105 citation statements)

References 26 publications

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“…After 95 days of hydration, there were two major differences between cement and CWA in the hydrated samples ( Figure 9 b); the broad band at about 3400 cm −1 corresponding to the O−H stretching vibrations (v1 and v3) in the water molecules was much more pronounced in CWA than in cement, confirming that CWA retains water [ 46 ]. The band in the range 1420–1480 cm −1 is attributed to CO 3 2− /HCO 3 − [ 45 ], confirming the formation of more carbonates in CWA. These carbonates could fill the cracks or voids and consequently contribute to a denser structure and less water penetration.…”

Section: Resultsmentioning

confidence: 95%

“…ATR-FTIR analyses were also performed on powdered material (cement and CWA) and on the hydrated samples at 95 days of age ( Figure 9 ). All bands identified by FTIR ( Figure 9 a) are those commonly found in cements, and the only significant difference between CEM and CWA is a band at 3700 cm −1 attributed to Mg(OH) 2 [ 45 ]. Some carbonates could also be present, e.g., a single asymmetric stretching band observed between 1450 and 1400 cm −1 could be attributed to MgCO 3 .…”

Section: Resultsmentioning

confidence: 99%

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The Effect of Crystalline Waterproofing Admixtures on the Self-Healing and Permeability of Concrete

et al. 2021

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This paper investigates the effectiveness of a specific crystalline waterproofing admixture (CWA) in concrete as a function of a water–binder ratio. Four concrete mixes with and without CWA were prepared; two of them with a water–binder ratio of 0.45 and two of them with a water–binder ratio of 0.55. Water permeability and compressive strength were tested on hardened concrete specimens and self-healing of cracks over time was observed. Cement paste and CWA paste were prepared to clarify the results obtained on the concrete specimens. SEM and EDS and XRD and FTIR were performed on the hardened pastes to explain the mechanism of CWA working. The results show that the addition of CWA had no significant effect on the compressive strength of the concrete, but reduced the water penetration depth in the concrete, and the reduction was more effective for mixes with lower water–binder ratio. Regarding the self-healing effect, it can be concluded that the addition of CWA improves the crack healing in concrete, but the efficiency of self-healing is highly dependent on the initial crack width. The mechanisms involved in the reduction of water penetration depth and crack healing in concrete can be explained by different mechanisms; one is creation of the CSH gel from unreacted clinker grains, then formation carbonate, and additional mechanism is gel formation (highly expansive Mg-rich hydro-carbonate) from magnesium based additives. The presence of sodium silicate, which would transform into carbonate/bicarbonate, also cannot be excluded.

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Section: Resultsmentioning

confidence: 95%

Section: Resultsmentioning

confidence: 99%

The Effect of Crystalline Waterproofing Admixtures on the Self-Healing and Permeability of Concrete

et al. 2021

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“…A wide range of bands were observed in the MgO power, which were also apparent in the prepared samples, along with additional bands. The band at ~3700 cm -1 was associated with the anti-symmetrical stretching of O-H bonds, referring to the formation of brucite [47][48][49]. Similarly, the presence of brucite was also linked with the small band at ~3650 cm -1 , which was attributed to the free O-H vibration [47][48][49][50].…”

Section: Ftir Analysismentioning

confidence: 99%

“…A few small bands were observed in the region from 1380 to 1450 cm -1 , which could be ascribed to the formation of different carbonate phases. The peak profile and band width between this region could show variations, depending on the type of carbonates [47][48][49][50]. The band at ~1120 cm -1 was due to the symmetrical stretching of the CO3 2ion [47,53,54], whereas the band at ~1015 cm -1 occurred due to the symmetrical stretching of CO3 2in the form of magnesium carbonate [47].…”

Section: Ftir Analysismentioning

confidence: 99%

Performance of MgO and MgO–SiO2 systems containing seeds under different curing conditions

Singh

Sonat

Yang

et al. 2020

Cement and Concrete Composites

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This study investigated the strength and microstructural development of MgO and MgO-microsilica (MS) systems under sealed and carbonated conditions. The influence of hydromagnesite seeds on the performance of each system was also evaluated. The hydration mechanisms were studied via isothermal calorimetry. A correlation between the strength development and formation of different phases was established. XRD, TG/DTG, FTIR and SEM were used for the identification and quantification of different hydrate and carbonate phases. MgO systems relied on the conversion of brucite into carbonate phases for their strength development, whereas M-S-H was the main source of strength in MgO-MS systems. The effect of seeding was evident in MgO-MS systems, where the extra space provided by the seeds increased the rate and degree of hydration. The formation of M-S-H was responsible for strength development and denser microstructures, which could be further improved via the increased utilization of unreacted MgO and MS.

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“…Kuenzel et al [27] studied the influence of hydromagnesite on MgO hydration and found that hydromagnesite reacted with MgO to form artinite, with a strength of 24.6 MPa. The reaction is as follows:…”

Section: Introductionmentioning

confidence: 99%

Effect of Carbonation on the Water Resistance of Steel Slag—Magnesium Oxysulfate (MOS) Cement Blends

Guan

Chang

et al. 2020

Materials

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Magnesium oxysulfate (MOS) cement has the advantages of lightweightedness, high strength, and low thermal conductivity, but the utilization of MOS cement is limited due to low water resistance. This paper studied the influence of steel slag and CO2 treatment on the compressive strength and water resistance of MOS cement. The hydration products and microstructures were characterized by X-ray diffraction (XRD), thermogravimetric analysis–differential scanning calorimetry (TG–DSC), scanning electron spectroscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). The results showed that the strength of MOS cement reached 89.7 MPa with steel slag and CO2 treatment; the water-resistance coefficients of the control and samples containing 10%, 20%, and 30% reached 0.91, 0.81, 1.01, and 1.08 MPa, respectively. The improvement in the strength and water resistance coefficients was because of carbonation that accelerated the hydration of C2S in the steel slag and formed a Ca–Mg–C amorphous substance. The carbonation products contributed to better water stability and denser matrix denser while inhibiting the hydration of MgO, which led to improving the water resistance of the sample.

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The mechanism of hydration of MgO-hydromagnesite blends

Cited by 118 publications

References 26 publications

The Effect of Crystalline Waterproofing Admixtures on the Self-Healing and Permeability of Concrete

The Effect of Crystalline Waterproofing Admixtures on the Self-Healing and Permeability of Concrete

Performance of MgO and MgO–SiO2 systems containing seeds under different curing conditions

Effect of Carbonation on the Water Resistance of Steel Slag—Magnesium Oxysulfate (MOS) Cement Blends

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