Performance-Based Evaluation of Supplementary Cementitious Material Synthesized with Basic Oxygen Furnace Slag and Ground Granulated Blast Furnace Slag
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThis study investigates the properties of supplementary cementitious materials (SCMs) prepared by combining basic oxygen furnace slag (BOFS) with ground granulated blast furnace slag (GGBFS). Ten different mix proportions were designed (with a 50% OPC replacement rate, and BOFS and GGBFS accounting for 15%, 25%, and 35% respectively) to evaluate their material characteristics, fresh and hardened properties, pozzolanic activity, and durability. An overall performance ranking system was used to identify the optimal mix proportion, providing a basis for the sustainable application of steel slag in cement-based materials. The paper demonstrates strong engineering significance, clear logic, and standardized writing. However, several issues require revision:
1、All mix proportions in the paper feature a 50% OPC replacement rate, but no explanation is provided for why 50% was chosen. It is possible that different replacement rates may yield more suitable mix proportions.
2、The abstract states that "the mixture containing [15% BOFS + 35% GGBFS] achieved improved strength development and the highest overall ranking." However, the experimental groups categorized BOFS into fresh and stockpiled types. The highest ranking should correspond to one of these types. Additionally, the final conclusion mentions that the mixture with [25% BOFS + 25% GGBFS] also met the standards. The specific criteria for evaluating these three mixtures and the reasoning behind the rankings lack detailed explanation.
3、The paper notes that "[15% s-BOFS + 35% GGBFS] exhibited a decline in 91-day SAI," attributing this to "experimental error or sample averaging." However, no repeated experimental data or statistical analysis were provided. Additional clarification is needed to determine whether this was a statistical deviation, and repeated experimental results should be included to enhance credibility.
4、The introduction states that the global annual production of steel slag exceeds 1.6 billion tons. The source of this data is unclear, as it differs significantly from online search results.
Author Response
"Please see the attachment."
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsDear author(s):
By reviewing this research paper, please respond to the following amendments and notes (minor revisions).
1- The abstract needs to contain some quantitative information (including findings and novelty).
2- Please revise and update the abstract to align with the manuscript content; excessive explanation is not necessary in the abstract.
3- The keywords must contain at least five keywords from the abstract, with ";" as a separator between them.
4- For the introduction Lines 86-102 Page 2, 3: This paragraph is quite lengthy, and three references are mentioned at the end. To enhance clarity, please distribute these references throughout the paragraph. Additionally, keep the paragraph concise to ensure that it is clear where each explanation corresponds to the cited reference.
5- The lengthy paragraphs were repeated multiple times in the introduction. Please revise these sections to ensure consistency with the previous note.
6- Please the introduction is relatively long please summarized it.
7- For the introduction, Lines 166-171 Page 4: Please, you can effectively showcase the novelty of your research during a scientific presentation, while also mentioning the materials used, which will be detailed in the research itself.
8- Please it is required to be guided by the pictures of the laboratory experiments (Laboratory testing program) that were conducted on the samples of this research.
9- For Figure 5 on page 11, please note that all SEM images must include notifications to ensure clarity and understanding.
Please accept my thanks and gratitude.
Comments on the Quality of English LanguageThe authors were advised to adjust the paper's quality and English in the revised manuscript.
Author Response
"Please see the attachment."
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for Authors- The paper needs to clearly state that its novelty comes from directly comparing fresh BOFS (f-BOFS) with stockpiled BOFS (s-BOFS) in ternary blends with GGBFS. This is not currently emphasized enough in the Abstract, Introduction, and Conclusions.
- Replacing 50% of the cement is an unusually high level. The authors need to clearly explain why they chose this value, whether it aligns with previous studies, or if it represents a sustainability goal. Without this explanation, the experimental design seems arbitrary.
- Both the introduction and discussion are too long and repetitive, particularly in the background information on BOFS properties and the reiteration of results. They need to be cut by at least 20–30%, with a focus on the research gap and critical interpretation rather than a lengthy background.
- Several parts of the discussion are just descriptive. The authors need to make connections:
- Microstructural evidence (XRD, SEM, PSD) leads to performance outcomes (strength, durability).
- Indices of pozzolanic activity (SAI, Chapelle, TGA/DSC) are linked to long-term durability and compressive strength.
- Right now, the manuscript has too many separate figures (like multiple graphs for flowability, compressive strength, and water absorption). The authors can combine some of these to reduce redundancy and make the trends more apparent. For example:
- Combine fresh and stockpiled BOFS results into a single comparative figure where possible.
- Present repetitive results in tables rather than using multiple plots.
- Since the manuscript draws heavily from older references, it's essential to include recent studies (2022–2024) on BOFS, GGBFS, and ternary SCM systems. This will ensure the paper stays at the forefront of current research.
- Currently, the conclusions reiterate what has already been discussed. They need to be rewritten to highlight:
- Top-performing blend(s).
- What does it mean for the real-world use of sustainable cementitious materials?
- Future research directions may include areas such as chemical activation, carbonation curing, and long-term field validation.
- Several acronyms are used throughout the paper (OPC, SCM, BOFS, GGBFS, XRD, SEM, SAI, TGA, DSC). To ensure reader clarity, authors should include a separate list of abbreviations at the end of the manuscript.
While the manuscript is mostly clear, the English needs work. Many sentences are too long and repetitive, which makes it harder to understand. To improve clarity, please rework the sentences, eliminate repetition, and use consistent terminology. It's a good idea to have a professional language editor or a fluent academic colleague review it thoroughly.
Author Response
"Please see the attachment."
Author Response File: Author Response.pdf
Reviewer 4 Report
Comments and Suggestions for AuthorsIt is well known that GGBFS (Ground Granulated Blast Furnace Slag) is a by-product of the cast iron industry, a pozzolanic material that requires an activator to develop hydraulic properties, forming a glassy, almost non-crystalline substance. Several papers in the literature can be found, as listed in the references section: https://doi.org/10.1016/j.jclepro.2021.129483. As a result, the present manuscript can be considered as another one among several found in the literature. Given your expertise in this field, I invite you to contribute to a critical discussion on why this GGBFS behaves as the average tested elsewhere, or why it shows a remarkable behavior.
Author Response
"Please see the attachment."
Author Response File: Author Response.pdf
Reviewer 5 Report
Comments and Suggestions for AuthorsThe manuscript presents a comprehensive and systematic investigation into the performance of supplementary cementitious materials synthesized from basic oxygen furnace slag and ground granulated blast furnace slag. The experimental design is rigorous, the methodology is well-documented, and the results are clearly presented. The study provides valuable insights into the synergistic effects of BOFS and GGBFS in cementitious systems. However, several issues require clarification and improvement before the manuscript can be considered for publication.
Line 61：The statement regarding "detrimental ecological and public health impacts" of steel slag is too general. Please provide specific examples or references to support this claim
Line 75–76：The text mentions aluminosilicate materials, but it is unclear where the aluminum originates in BOFS or GGBFS. Please clarify the source of Al₂O₃ in the context of the chemical composition of the slags.
Line 132–135：The reference to Altun and Yilmaz (2018) showing comparable strength with 30% BOFS replacement requires explanation. Why does this occur despite the generally low hydraulic reactivity of BOFS? A brief mechanistic explanation or reference to activation mechanisms should be provided.
Line 148–155：The difference between fresh and stockpiled BOFS is not sufficiently explained, especially in terms of chemical composition and free lime content. Please clarify:
Why f-CaO is problematic (e.g., delayed expansion, instability). How weathering affects f-CaO and mineral phases (e.g., conversion to portlandite and calcite).
While the study is well-executed, the introduction does not sufficiently highlight the research gap or novelty of this work compared to existing literature. Please clarify:
What specific limitations of previous studies this work addresses. How the combination of f-BOFS and s-BOFS with GGBFS in ternary blends provides new insights.
The literature review should be updated with recent studies to strengthen the context and demonstrate the timeliness of the research.
https://doi.org/10.1016/j.conbuildmat.2025.141167
https://doi.org/10.1016/j.conbuildmat.2025.143443
https://doi.org/10.1016/j.conbuildmat.2023.131709
https://doi.org/10.1016/j.clay.2022.106795
Line 356：Define "SG" (Specific Gravity) upon first use. In addition, the XRD analysis should explicitly mention the presence of amorphous phases and their role in reactivity, as amorphous content is critical for pozzolanic activity.
Line 396: The sentence “This indicates…and fly ash” is unclear. Please rephrase to clarify how the amorphous material in BOFS differs from the glassy phase in GGBFS or fly ash in terms of microstructure and reactivity.
Line 427: Explain why mortar with GGBFS is easier to place, compact, and finish. Refer to particle morphology, PSD, or water-reducing effects.
The manuscript does not describe how air content was measured. Please specify the test method and justify why density was not used as an alternative.
The attribution of water absorption solely to particle size is oversimplified. Consider also discussing porosity, pore structure, and chemical composition. Refer to microstructure analysis (e.g., SEM) to support the argument.
Ensure consistent color schemes across all figures (e.g., Figures 15 and 16) to avoid confusion. For example, the same mixture should be represented by the same color in all graphs.
Section 5 should be renamed “Discussion” and expanded to:
Compare findings with previous studies.
Explain the mechanisms behind the observed performance (e.g., synergy between BOFS and GGBFS).
Incorporate references to support mechanistic explanations (e.g., activation of GGBFS by BOFS alkalinity).
Author Response
"Please see the attachment."
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsAlthough the author revised the paper, I did not see the author's response to the reviewers' comments.
Author Response
The authors are grateful to the reviewers for their careful assessment of the manuscript and for offering constructive and insightful comments that have contributed to its improvement. Each point raised has been addressed in detail in the responses provided below (in italics), accompanied by the corresponding reviewer remarks. All modifications to the manuscript are highlighted in blue font. Line numbers cited in the reviewers’ comments refer to the original version of the manuscript, while the relevant locations in the revised manuscript are specified in the authors’ responses where appropriate.
Please find the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for Authors1) Emphasize that the main contribution is the direct comparison between fresh and stockpiled BOFS in ternary blends with GGBFS.
2) Justify 50% replacement: Explain why such a high OPC replacement was selected.
3) Shorten the Introduction by 20–30% to avoid repetition and focus on the research gap and key insights.
4) Strengthen connections between microstructure (XRD, SEM, PSD) and performance (strength, durability) and between pozzolanic indices (SAI, Chapelle, TGA/DSC) and long-term properties.
5) Abbreviations: Include a list of acronyms at the end for clarity.
Comments on the Quality of English LanguageThe manuscript is generally well written and technically clear. Minor grammatical polishing is recommended to improve flow, readability, and conciseness.
Author Response
The authors are grateful to the reviewers for their careful assessment of the manuscript and for offering constructive and insightful comments that have contributed to its improvement. Each point raised has been addressed in detail in the responses provided below (in italics), accompanied by the corresponding reviewer remarks.
Q1. The manuscript is generally well written and technically clear. Minor grammatical polishing is recommended to improve flow, readability, and conciseness.
Response: Thank you for this valuable comment. The authors have checked the manuscript through the university writing center to do minor grammatical polishing.
Reviewer 4 Report
Comments and Suggestions for AuthorsThe suggestions and observations have been attended .
Author Response
Thank you for this valuable comment. The authors have checked the manuscript through the university writing center to do minor grammatical polishing.
Reviewer 5 Report
Comments and Suggestions for AuthorsThis manuscript can be accepted because of the careful revison
Author Response
Thank you for this valuable comment. The authors have checked the manuscript through the university writing center to do minor grammatical polishing.
Round 3
Reviewer 1 Report
Comments and Suggestions for AuthorsThe authors have adequately addressed the reviewers' comments and revised the manuscript, so I recommend acceptance.
