Enhancement of the pozzolanic activity of natural clays by mechanochemical activation

Tole, Ilda; Delogu, Francesco; Qoku, Elsa; Habermehl-Cwirzen, Karin; Ćwirzeń, Andrzej

doi:10.1016/j.conbuildmat.2022.128739

Cited by 11 publications

(7 citation statements)

References 51 publications

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“…It is also important to evaluate research on the properties of cement matrices with pozzolanic materials of clay origin, since the improvement of properties is not always derived from factors linked only to pozzolanic reactivity. For this reason, research such as that of Yanguatin et al [ 126 ] and Tole et al [ 114 ] have used various methods for a more in-depth analysis of the materials. Figure 3 shows a graph with indicative percentages of the use of the aforementioned tests based on the research catalogued in Table 3 .…”

Section: Analysis Of the Approaches For Pozzolanic Activity Character...mentioning

confidence: 99%

Methods for Evaluating Pozzolanic Reactivity in Calcined Clays: A Review

Pinheiro¹,

Alexandre²,

Xavier³

et al. 2023

Materials

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The search for alternative materials to replace ordinary Portland cement has been the object of work that enhances the investigation of the use of pozzolanic materials and the reduction of the carbon footprint with supplementary cementitious materials. However, not all materials are available to meet the large-scale demand for cement replacement. A relevant exception is the calcined clay, a material found worldwide that, when subjected to appropriate heat treatment, presents pozzolanic reactivity and can be used as a supplementary material to cement. This review presents, through a systematic search, methods for measuring the pozzolanic reactivity of calcined clays, namely, direct, indirect, qualitative, quantitative, chemical and physical methods such as electrical conductivity (Lùxan), the force activity index, the modified Chapelle, R3, Frattini test, thermal analysis, X-ray diffraction and X-ray fluorescence spectrometry. The most usual methods to assess the pozzolanic reactivity of calcined clays were exposed and analyzed. It should be pointed out that there is greater use of the Frattini and modified Chapelle methods as well as the analysis of the mechanical strength behavior of the material in cementitious matrices. X-ray diffraction and thermal analysis were exposed as the most used correlation methods but it was also concluded that different tests are needed to generate accurate results.

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Section: Analysis Of the Approaches For Pozzolanic Activity Character...mentioning

confidence: 99%

Methods for Evaluating Pozzolanic Reactivity in Calcined Clays: A Review

Pinheiro¹,

Alexandre²,

Xavier³

et al. 2023

Materials

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“…Mechanical activation methods are effective in increasing the pozzolanic activity of 2:1 clay minerals (muscovite and montmorillonite) [2]. The pozzolanic activity of natural clay, fly ash (FA), metakaolin (MK), and quartz sand was evaluated using the strength activity index (SAI), Frattini test, and electrical conductivity test after mechano-chemical activation [3,4], and the pozzolanic activity and hydration properties of feldspar, siliceous metal tailings, and quartz improved. The activity of pozzolanic ash increases with grinding time but reaches a limit [5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Potential Utilization of Loess in Grouting Materials: Effects of Grinding Time and Calcination Temperature

Bai,

Wang,

Zhang

et al. 2024

Minerals

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There is a huge reservation of loess in the Shanxi mining area in China, which has great potential for preparing supplementary cementitious materials. Loess was modified via mechanical and thermal activation, and the pozzolanic activity was evaluated using an Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES). Moreover, the workability of grouting materials prepared using modified loess was assessed. The experimental results revealed that the number of ultrafine particles gradually increased with the grinding time, enhancing the grouting performance. The coordination number of Al decreased upon the breakage of the Al–O–Si bond post-calcination at 400 °C, 550 °C, 700 °C, and 850 °C. Moreover, the breaking of the Si–O covalent bond produced Si-phases, and the pozzolanic activity of loess increased. Furthermore, the modified loess was hydrated with different cement proportions. With increasing grinding time, the overall setting time increased until the longest time of 14.5 h and the fluidity of the slurry decreased until the lowest fluidity of 9.7 cm. However, the fluidity and setting time decreased with increasing calcination temperature. The lowest values were 12.03 cm and 10.05 h. With the increase in pozzolanic activity, more ettringite was produced via hydration, which enhanced the mechanical properties. The maximum strength of the hydrated loess after grinding for 20 min reached 16.5 MPa. The strength of the hydrated loess calcined at 850 °C reached 21 MPa. These experimental findings provide theoretical support for the practical application of loess in grouting.

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“…In a planetary mill, the accelerating force is generated by the rotation of grinding jars around their own axis, combined with the rotation of the main disk [36]. In addition to the properties of the activated material, the effectiveness of MCA in a planetary mill depends on several factors, such as the rotational speed of the main disk and grinding jars, the quantity and material of the grinding bodies, the BPR, and the duration of the MCA [37][38][39]. The increase in rotational speed and number of grinding bodies increases the frequency and intensity of collisions.…”

Section: Introductionmentioning

confidence: 99%

“…In grinding experiments, the effect of the ratio between the rotational speed of the jar and that of the main disk, namely, the transmission ratio (i), was rarely studied. According to the mathematical models describing the energy transferred to the material in a planetary mill, an increase in the value of i can lead to higher number and energy of collisions at a given rotational speed [39][40][41][42]. This raises the possibility that, to achieve the same degree of mechanochemical amorphization, it may be useful to investigate and apply reductions in the rotational speed and increases in the i factor, which may be advantageous to minimize the negative processes (e.g., agglomeration) that occur during MCA.…”

Section: Introductionmentioning

confidence: 99%

Optimization of Grinding Parameters for the Mechanochemical Activation of Kaolin with the Addition of Trass

Őze

Makó

2023

Minerals

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At present, to achieve further reductions in CO2 emissions in the cement industry, it is essential to improve the efficiency of grinding processes and reduce the energy demand. This study examined the effects of various grinding parameters (addition of trass, ball to powder mass ratio (BPR), material of grinding bodies and jars, rotational speed, and mill type) to minimize the energy consumption of the mechanochemical activation of kaolinite. X-ray diffraction, Fourier transform infrared spectroscopy, inductively coupled plasma optical emission spectroscopy, scanning electron microscopy, and specific surface area measurements were used to examine the influence of grinding parameters. It was found that the addition of as little as 25% (mass percent) trass reduced the specific energy demand for the complete amorphization of kaolinite by 56%. The application of steel grinding bodies (instead of ZrO2 ones) had a slight influence on the amorphization kinetics of kaolinite, but it could mechanochemically activate 30% more samples at the same BPR and specific energy demand. The use of the four-pot milling instead of the one-pot could considerably decrease the specific energy demand of the complete and incomplete (α = 0.9) amorphization of kaolinite. Overall, a 94% reduction was achieved in specific energy demand with steel grinding material, 14:1 BPR, four-pot milling, and the incomplete amorphization of kaolinite.

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Enhancement of the pozzolanic activity of natural clays by mechanochemical activation

Cited by 11 publications

References 51 publications

Methods for Evaluating Pozzolanic Reactivity in Calcined Clays: A Review

Methods for Evaluating Pozzolanic Reactivity in Calcined Clays: A Review

Potential Utilization of Loess in Grouting Materials: Effects of Grinding Time and Calcination Temperature

Optimization of Grinding Parameters for the Mechanochemical Activation of Kaolin with the Addition of Trass

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