Metakaolin-Reinforced Sulfoaluminate-Cement-Solidified Wasteforms of Spent Radioactive Resins—Optimization by a Mixture Design
Round 1
Reviewer 1 Report
1. The authors should justify how the manuscript matches with the aims and scope of the journal
2. Introduction: Introduction: good description of the material as well as the topic of this paper, literature study seems to be complete.
Experimental method: Clear, comment/suggestion: A table of the cement composition, simulated radioactive resin composition should be provided as it will be easier to read.
3. Detailed explanation/clarity should be provided on how the authors formulate equation 2.
4. For Fig. 1, kindly provide the error bars for the measurement in compressive strengths.
5. How metakaolin improves the leachability of Cs from the wasteform may please be explained in more detail with respect to the microstructure.
6. Conclusion: The authors quote “The microscopic morphology was acicular and columnar crystals interspersed with amorphous gels and particles”. However, from the single SEM image provided in Figure 4, it is not clear. The authors should provide multiple SEM and XRD images and then explain the evolution of microstructure as a function of Metakaolin content.
7. The work is novel and shows promising strategy for radioactive waste disposal. However, in the discussion part the structure-property correlation has not been established properly by the authors which is one of the main themes of the journal. The authors should improve this aspect.
Author Response
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Reviewer 2 Report
It is necessary to give the characteristics of the resin: brand, type of matrix, functional groups.
How was the model resin introduced into the cement mortar, dry, wet in the form of pulp?
Was there any manipulation of the resin before its use, drying, soaking, saturation with cesium, etc.? Text have to imptove.
Line 4. Section “2.4. Solidified wasteforms durability tests. In what form was the introduction of cesium? Was cesium added directly to the cement slurry or was the model resin pre-saturated with cesium? It is necessary to supplement the experimental part with an indication of the cesium salt used.
Page 5. I am somewhat confused by the following statement "Spent resin loadings in the final wasteforms are approximately proportional to the resin volumes...", what the Authors had in mind? Is it a comparison of the amount/volume of resin added to the compound with the volume of dry/wet resin or something else? The Authors should make some additions to the text.
Figure 1. What is "Mobility" is resin floating rate or cement compound mobility? Some additions need to be made to the text. The same applies to "Initial setting time" and "Final setting time". How and what criteria were used to determine the initial setting time and the final setting time?
Page 9. How were the parameters "leaching rate R" and "cumulative leached fraction P" determined? It is necessary to supplement the text of the manuscript. The R value on the Figire 3b is measured in cm/d, perhaps a typo, as the unit should be, for example, g/cm2*d, g/m2*d, Bq/cm2*d etc.
Section “3.2. Mixture design optimization. In my opinion, the section is redundant and part of the data can be transferred without losing the quality of the article to supplimentary materials, for example, Table 2, 3, 5.
Author Response
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Reviewer 3 Report
To Authors
1. What is the physical value of Pt measured in cm?
2. The dependences in Fig. 1 show changes in different parameters of the system as a function of the metakaolin, spent resin, water reducer dosages (loadings), and the ratio between water and binder dosages (w/b ratio). Each plot shows the dependence of the four studied parameters on changes in one of the system parameters. Unfortunately, the authors do not mention for what specific values of the other system parameters those dependences were obtained. Taking into account the mutual effects of different parameters, it is necessary to show more complex graphical dependences or to mention the values of the other parameters at which those dependences were obtained. For example, when it comes to the dependences in Fig. 1a, it is necessary to mention the spent resin and water reducer loadings, as well as the w/b ratios at which those dependences were obtained. Even more so, Table 2 shows the experimental data for various combinations of the system parameters.
3. The analysis of the SEM images and XRD spectra does not mention whether the data was obtained on the materials with or without the ion-exchange resins. If the data was obtained on the materials without the resins, it is necessary to mention how the data will change with the resin loading into the cement matrix.
4. It is desirable that the authors should comment on the results of the works by O.I. Kononenko and V.V. Milyutin on spent resin solidification.
Author Response
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Round 2
Reviewer 2 Report
I dont have additional comments.
