Use of Treated Non-Ferrous Metallurgical Slags as Supplementary Cementitious Materials in Cementitious Mixtures

Round 1

Reviewer 1 Report

The reviewer appreciates the authors for highlighting the absence of pozzolanic activity. The reviewer believes that these scientific studies should exist to guide researchers. The reviewer recommends the authors to expand the section that elaborates the absence of pozzolanic activity. Also add literature references to the same. This can be a handy tool for researchers.

Author Response

Thank you for your comments.

The remarks highlighting the low pozzolanic reactivity of the slags along with the underlying reasons are listed below. Some references are also added to the paper or were already in the text.

Line 402 – 406.

Line 434 – 436.

Line 603 – 606.

Line 615 – 619.

Please see references [16] and [43] of the paper reporting on the pozzolanic activity of similar slags studied in the literature. The references are cited in the paper.

Reviewer 2 Report

This paper is very well written and contains interesting and useful information on the use of alternative slags from the metals industry as an SCM.  As we look to find other sources of SCMs, this is an important inclusion in the literature.  Recommend acceptance with only very minor editorial changes. 

1. Line 135: two-third should be "two-thirds"
2. Line 136: Neither is generally for two items, since it is three items, recommend using "any"
3. Line 460:  There is a word or phrase missing after the word "equally"

Author Response

Thank you for your comments and the positive feedback. Your comments are fully addressed in the paper. Please see below.

1. Line 135: two-third should be "two-thirds"

Response: The change is made as suggested in line 135.

2. Line 136: Neither is generally for two items, since it is three items, recommend using "any"

Response: The change is made as suggested in line 136.

3. Line 460:  There is a word or phrase missing after the word "equally"

Response: The word “equally” is not followed by “reactive” in line 465.

Reviewer 3 Report

1. abstract
" Despite high amorphous contents (70% – 98%), they were found to have mediocre reactivity and contribution to strength, especially at early ages. "
This sentense is little bit wired. crystallinity is not always directly linked to the reactivity or contribute to strength.

2. Table 2 True dinsity
Please check again the repeatability and show the real significant digit

3. Table 3 
(%) should not only be for LOI

4. Table 3 
I am not sure but I am not familiar with such a cement, which contains not gypsum but anhydrite. Is there no gypsum?

5. Figure 2(b)
I cannot find the information of the colour.

6. Figure 6 (a)
use the same x-axis with the others

7. Figure (6)
If the "values in g/100 g of binder." is true, the cumulative mass should exceed 100 with the chemically bounnd water. see Figure 8(a)

Author Response

Thank you for your comments and careful examination of the paper. Please find the response to each comment below.

1. abstract
   " Despite high amorphous contents (70% – 98%), they were found to have mediocre reactivity and contribution to strength, especially at early ages. "
   This sentense is little bit wired. crystallinity is not always directly linked to the reactivity or contribute to strength.

Response: Corrected. The abstract now reads: All slags were found to have mediocre reactivity and contribution to strength, especially at early ages.

2. Table 2 True dinsity
   Please check again the repeatability and show the real significant digit

Response: Doubled checked. The density values indeed have 4 significant digits. The mass and volume measurements have a 0.0001 g and 0.0001 cm³ precision, respectively. Nevertheless, the significant digits are reduced to 3 now, so they should be fine.

3. Table 3 
   (%) should not only be for LOI

Response: Table 3 is now revised such that (%) is applied to all values and not only LOI.

4. Table 3 
   I am not sure but I am not familiar with such a cement, which contains not gypsum but anhydrite. Is there no gypsum?

Response: We double-checked our phase identification and can confirm that the peak is correctly identified as anhydrite. No peaks for gypsum existed in the XRD pattern of the cement. It is in fact quite common not to have gypsum in the milled cement. This is because the added gypsum dehydrates during the milling process into calcium sulfate hemi-hydrate or anhydrate. Also, some companies add their own calcium sulfate formulations in order to control the setting and early strength. Therefore, we believe the reported phase identification is accurate in this sense.

5. Figure 2(b)
   I cannot find the information of the colour.

Response: The following is added to the line 303 – 305:

In Figure 2b, the colours red, green, and blue indicate Si, Mg, and Ca, respectively. Regions containing both Si and Mg are shown as orange.

6. Figure 6 (a)
   use the same x-axis with the others

Response: The axis title are the same in Figure 6.

7. Figure (6)
   If the "values in g/100 g of binder." is true, the cumulative mass should exceed 100 with the chemically bound water. see Figure 8(a)

Response: The term “binder” in Figure 6 refers to the sum of the anhydrous powder (cement + admixture) and the chemically bound water. In other words, it is this sum that is considered to be 100 %. As such, the cumulative mass of the phases shall be 100 % at all ages.