Proportion and Performance Optimization of Lightweight Foamed Phosphogypsum Material Based on an Orthogonal Experiment

Round 1

Reviewer 1 Report

The manuscript "Proportion and Performance Optimization of Lightweight Foamed Phosphogypsum Material Based on the Orthogonal Experiment" will present an important issue related to the formation of new building materials, based on an incomplete experiment plan. The research concerned the empirical and statistical analysis of the strength parameters of the studied Phosphogypsum (PG).

I believe that the manuscript may be admitted to the oil stage of the procedure provided that the following comments are taken into account:

1. Information and photographs / diagrams of test stands and test equipment used should be completed.
2. For the sake of clarity, the manuscript should include a summary table of abbreviations and markings used.
3. The legibility of descriptions in Figure 3 should be improved
4. The information on the calculation program in which the statistical analyzes were performed should be completed.
5. The information on the input quantity and the initial experiment plan, the form of the approximating function and the analysis confirming the correctness of the assumptions (research hypothesis) should be supplemented with a statistical test, e.g. Tstudent or Snedecor-Fischer
6. A Pareto analysis should be added to determine the significance level of each of the input variables and their interaction on the output value. 

Author Response

Reviewer #1:

1. Comment: Information and photographs/diagrams of test stands and test equipment used should be completed.

Response: Thanks for the reviewer’s kind suggestion. According to the reviewer’s suggestion, we list the relevant information of the test equipment in the section of 2.2 Experimental design.

（3）Main test instruments

2. Comment: For the sake of clarity, the manuscript should include a summary table of abbreviations and markings used.

Response: We have added detailed explanations of abbreviations in the revised manuscript.

3. Comment: The legibility of descriptions in Figure 3 should be improved.

Response: The legibility of descriptions in Figure 3 has been improved in our revised manuscript.

Fig. 3 Test results of (a) and (b) orthogonal samples

4. Comment: The information on the calculation program in which the statistical analyzes were performed should be completed.

Response: According to the reviewer’s suggestion, we have supplemented the information of each program in the statistical analysis, and added the corresponding contents in the revised manuscript.

The total variation values in this experiment were composed of four parts: factor A, factor B, factor C, factor D, and the corresponding error variation was calculated. Therefore, the decomposition formula of square sum and degree of freedom in variance analysis is:

SS_T = SS_A + SS_B + SS_C+ SS_D + SSe                      (3)

df_T =  df_A  +  df_B   + df_C  + df_D + df_e                (4)

n represents the number of the test; a, b, c and d represent the level of different factor (A, B, C and D); k_a, k_b, k_c and k_d represent the level under repeating of factor A, B, C and D. In this experiment, n=16, a=b=c=d=4, k_a=k_b=k_c=k_d=4. The expressions from (3) to (9) were utilized to calculate the variation and degrees of freedom caused by factor A~D.

C₀ = T²/n                              (5)

SS_T =Σx²- C₀                            (6)

SS_A=Σ/k_a - C₀                         (7)

SS_B=Σ/k_b - C₀                         (8)

SS_C=Σ/k_c - C₀                         (9)

SS_D=Σ/k_d - C₀                         (10)

df_e = df_T-df_A-df_B-df_C- df_D                   (11)

Note: C₀ is the correction number, SS_T is the total sum of squares, SS_A is the sum of squares of factor A, SS_B is the sum of squares of factor B, SS_C is the sum of squares of factor C, SS_D is the sum of squares of factor D, df_A, df_B, df_C and df_D are the degrees of freedom of factors A, B, C and D, respectively, df_T is the total degree of freedom, and df_e is the degree of freedom of error.

5. Comment: The information on the input quantity and the initial experiment plan, the form of the approximating function and the analysis confirming the correctness of the assumptions (research hypothesis) should be supplemented with a statistical test, e.g. Tstudent or Snedecor-Fischer

Response: Thanks for the reviewer’s kind suggestion. According to the reviewer’s suggestion, we have assumed the input information and constructed four corresponding statistical tests for inference confirmation

6. Comment: A Pareto analysis should be added to determine the significance level of each of the input variables and their interaction on the ou

   Reviewer #1:

   1. Comment: Information and photographs/diagrams of test stands and test equipment used should be completed.

   Response: Thanks for the reviewer’s kind suggestion. According to the reviewer’s suggestion, we list the relevant information of the test equipment in the section of 2.2 Experimental design.

   （3）Main test instruments

   Serial number	Apparatus	Model	Manufacturer
   1	electronic weight scale	ZCS	Rui 'an Hao Exhibition Scale Co., Ltd
   2	Microcomputer controlled pressure testing machine	CXYAW-2000S	Zhejiang Chenxin Machinery Equipment Co., Ltd
   3	Automatic cement bending and compression integrated machine	YAW-300	Zhejiang Lixian Test Instrument Manufacturing Co., Ltd
   4	electric drying oven	XMA-2000	Shanghai Qiuzuo Scientific Instruments Co., Ltd
   5	X-ray diffraction	Empyrean	PANalytical B.V.
   6	scanning electron microscope	ZEISS Gemini 300	Thermo Scientific
   7	electric agitator	OULAIDE	German Olyde Company
   8	Electric vibrating screen machine	ZBSX-92A	Zhejiang Shangyu Zhangxing Yarn Screen Factory
   9	Cement mortar test mould	40×40×160mm	Zhejiang Qishun Instrument Technology Co., Ltd
   10	Concrete test block mold	100×100×100mm	Hebei Xinfu Zhengyuan Environmental Protection Equipment Manufacturing Co., Ltd.
   11	thermal conductivity instrument	CD-DR3030	Shenyang Ziweiheng Testing Equipment Co., Ltd.
   12	Micro cement foaming machine	TH-29A	Zhejiang Tenghe Machinery Co., Ltd

    

   2. Comment: For the sake of clarity, the manuscript should include a summary table of abbreviations and markings used.

   Response: We have added detailed explanations of abbreviations in the revised manuscript.

   Abbreviations PG: phosphogypsum RPG: raw phosphogypsum HPG: hemihydrate phosphogypsum LFPM: lightweight foam phosphogypsum material SEM: scanning electron microscope XRD: X-ray diffraction R method: range analysis method ANOVA: analysis of Variance SS: sum of squares DF: degree freedom MS: mean square

    

   3. Comment: The legibility of descriptions in Figure 3 should be improved.

   Response: The legibility of descriptions in Figure 3 has been improved in our revised manuscript.

   Fig. 3 Test results of (a) and (b) orthogonal samples

    

   4. Comment: The information on the calculation program in which the statistical analyzes were performed should be completed.

   Response: According to the reviewer’s suggestion, we have supplemented the information of each program in the statistical analysis, and added the corresponding contents in the revised manuscript.

   The total variation values in this experiment were composed of four parts: factor A, factor B, factor C, factor D, and the corresponding error variation was calculated. Therefore, the decomposition formula of square sum and degree of freedom in variance analysis is:

   SS_T = SS_A + SS_B + SS_C+ SS_D + SSe                      (3)

   df_T =  df_A  +  df_B   + df_C  + df_D + df_e                (4)

   n represents the number of the test; a, b, c and d represent the level of different factor (A, B, C and D); k_a, k_b, k_c and k_d represent the level under repeating of factor A, B, C and D. In this experiment, n=16, a=b=c=d=4, k_a=k_b=k_c=k_d=4. The expressions from (3) to (9) were utilized to calculate the variation and degrees of freedom caused by factor A~D.

   C₀ = T²/n                              (5)

   SS_T =Σx²- C₀                            (6)

   SS_A=Σ/k_a - C₀                         (7)

   SS_B=Σ/k_b - C₀                         (8)

   SS_C=Σ/k_c - C₀                         (9)

   SS_D=Σ/k_d - C₀                         (10)

   df_e = df_T-df_A-df_B-df_C- df_D                   (11)

   Note: C₀ is the correction number, SS_T is the total sum of squares, SS_A is the sum of squares of factor A, SS_B is the sum of squares of factor B, SS_C is the sum of squares of factor C, SS_D is the sum of squares of factor D, df_A, df_B, df_C and df_D are the degrees of freedom of factors A, B, C and D, respectively, df_T is the total degree of freedom, and df_e is the degree of freedom of error.

   5. Comment: The information on the input quantity and the initial experiment plan, the form of the approximating function and the analysis confirming the correctness of the assumptions (research hypothesis) should be supplemented with a statistical test, e.g. Tstudent or Snedecor-Fischer

   Response: Thanks for the reviewer’s kind suggestion. According to the reviewer’s suggestion, we have assumed the input information and constructed four corresponding statistical tests for inference confirmation

   6. Comment: A Pareto analysis should be added to determine the significance level of each of the input variables and their interaction on the output value.

   Response: Thanks for the reviewer’s kind suggestion. In the manuscript, we did not consider the interaction between two factors, therefore the interactive experiments were not conducted on this material. In our future work, a Pareto analysis can be applied to determine the significance level of each of the input variables and their interaction on the output value.

   tput value.

Response: Thanks for the reviewer’s kind suggestion. In the manuscript, we did not consider the interaction between two factors, therefore the interactive experiments were not conducted on this material. In our future work, a Pareto analysis can be applied to determine the significance level of each of the input variables and their interaction on the output value.

Author Response File: Author Response.pdf

Reviewer 2 Report

The article presents the results of a topical and well-executed investigation, which has scientific and practical value. To make this article eligible for publication in journal „Buildings “, I suggest that authors make the following improvements:

1. The article presents the LFPM composition optimization experiments conducted by the authors and the results obtained. At the beginning (in Section 2) of the article, optimization criteria for optimal mix proportions should be described. (The certain criteria are presented in the text next to the assessment of individual impacts, but it is complicated to understand main optimization essence when reading the text).
2. Section 2.2 Experimental design. (2) optimization experiment. Reading the article before this section, it seemed that main purpose of research was to optimize the percentage composition of the material components, from this point - the amount of additives. It should be made clearer what has been optimized, by what tests and by what criteria. I suggest to do this in the section (2) Experimental design.
3. Lines 150-154. the information on testing standards is unclear. Maybe it is possible to find links and put them on the references list? Or specify relevant more or less similar international standards?
4. 2.1. In section 3.2.1. the results of the study are presented only in column charts, from which it is difficult to determine specific values of indicators that could be used by readers of the article. I suggest that you also include tables with numeric values.
5. The authors should show in their conclusions that the new material having optimal characteristics is better, or at least different from the similar-purpose materials from phosphogypsum identified in the literature review.
6. From a point of view of material engineering, the presentation of the results in the article is appropriate. However, journal „Buildings“ publish articles in the field of civil engineering, so the intended use of new material with optimized properties should be indicated at least briefly.
7. The article contains significant inaccuracies in style and expression that should be corrected:

Line 28-29. „...and 5 tons of phosphogypsum can be produced from one ton of phosphoric acid. “

Line 57. Cement can improve thermal conductivity – increase or reduce?

Line 141. The dosages...... 0,1 % from ........mass of LFPM, volume or....?

Table 2 has nude figures. It must be indicated that these are proportions of the composition.

Table 3: Some letters are missing.

Author Response

Reviewer #2:

1. Comment: The article presents the LFPM composition optimization experiments conducted by the authors and the results obtained. At the beginning (in Section 2) of the article, optimization criteria for optimal mix proportions should be described. (The certain criteria are presented in the text next to the assessment of individual impacts, but it is complicated to understand main optimization essence when reading the text)

Response: We have explained the role of foam stabilizer and waterproof agent in the optimization test. By adding foam stabilizer to improve the stability and uniformity of the foam, the dry density fluctuated slightly when the strength of the composite is improved. Adding waterproofing agent was mainly to improve water resistance and strength. The corresponding contents have been added in the Section 2.2.

“The foam stabilizer can improve the stability and uniformity, and the waterproof agent can reduce the water absorption of the material. Therefore, the influence of the foam stabilizer and waterproof agent on the strength, dry density and softening coefficient of the composites was analyzed. Specifically, based on the recommended optimal mix proportion from orthogonal experiments, foam stabilizer and waterproofing agent were added. According to the relevant references, the foam stabilizer content was 0.1 %, 0.2 %, 0.3 %, 0.4 %, 0.5 % and waterproofing agent content was 1.5 %, 3.0 %, 4.5 %, 6 %, 7.5 %, respectively. The effect of the dosage on the performance of LFPM was discussed.”

2. Comment: Section 2.2 Experimental design. (2) optimization experiment. Reading the article before this section, it seemed that main purpose of research was to optimize the percentage composition of the material components, from this point-the amount of additives. It should be made clearer what has been optimized, by what tests and by what criteria. I suggest to do this in the section (2) Experimental design.

Response: Thanks for the reviewer’s kind suggestion. According to the reviewer’s suggestion, we have made further revisions to the optimized test section according to your suggestion and explained the instrument and reference standard of the test. The reference standard (Table 3) is introduced in the 2.3 test method.

3. Comment: Lines 150-154. the information on testing standards is unclear. Maybe it is possible to find links and put them on the references list? Or specify relevant more or less similar international standards?

Response: The testing standards have been added as references.

[40] JG/T 266-2011, Foamed Concrete[S].

[41] GB/T 9776-2008, building gypsum [S].

[42] JC/T 698-2010, Gypsum block[S].

4. Comment: In section 3.2.1. the results of the study are presented only in column charts, from which it is difficult to determine specific values of indicators that could be used by readers of the article. I suggest that you also include tables with numeric values.

Response: Thanks for the reviewer’s kind suggestion. We have added test results in Table 8 and 9 to determine the specific index values.

5. Comment: The authors should show in their conclusions that the new material having optimal characteristics is better, or at least different from the similar-purpose materials from phosphogypsum identified in the literature review.

Response: The LFPM prepared in this paper exhibited good characteristics in new building materials. The use of RPG was economical and practical, and improves the utilization rate of phosphogypsum. These experimental results were rare in the existing research results.

6. Comment: From a point of view of material engineering, the presentation of the results in the article is appropriate. However, journal „Buildings“ publish articles in the field of civil engineering, so the intended use of new material with optimized properties should be indicated at least briefly.

Response: The LFPM studied in this paper is mainly used in the partition wall and filling wall engineering of building materials.

7. Comment: The article contains significant inaccuracies in style and expression that should be corrected:

Line 28-29. „...and 5 tons of phosphogypsum can be produced from one ton of phosphoric acid. ”

Line 57. Cement can improve thermal conductivity – increase or reduce?

Line 141. The dosages...... 0,1 % from ........mass of LFPM, volume or....?

Table 2 has nude figures. It must be indicated that these are proportions of the composition.

Table 3: Some letters are missing.

Response:

Line 28-29. „...and 5 tons of phosphogypsum can be produced from one ton of phosphoric acid. ”

Phosphogypsum (PG) was a by-product of solid waste produced from the production of wet-process phosphoric acid, for instant, one ton of phosphoric acid produced 5 tons of phosphogypsum [1, 2].

Line 57. Cement can improve thermal conductivity – increase or reduce?

Cement can increase thermal conductivity, water resistance and mechanical strength.

Line 141. The dosages...... 0,1 % from ........mass of LFPM, volume or....?

In the manuscript, the dosage denotes a proportion fraction of total dry material mass.

Table 2 has nude figures. It must be indicated that these are proportions of the composition.

The figures denote the proportion fractions of different factors of total dry material mass. The corresponding unit (%) has been added. 

Table 3: Some letters are missing.

The word spelling in Table 3 has been corrected.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The authors revised the manuscript in line with my comments. I believe that the manuscript may be admitted to the next stages of the procedure.