Design of Concrete Made with Recycled Brick Waste and Its Environmental Performance

Round 1

Reviewer 1 Report

This article conducted a laboratory study to explore the use of recycled brick waste (RBW) to replace some natural aggregates and to evaluate the application of RBW powder as a type II additive in concrete. Related research had focused on examining the applicability of this RBW in concrete. The following comments are suggested:

1. When applying RBW to concrete, the relevant laws and regulations that it must comply with are quite cumbersome. Which of them is the most important? The authors should explain it.
2. Is the RBW used in this study a concrete brick or a clay brick? The authors should explain it.
3. The percentage of RBW to replace natural fine aggregate or cement was only 10%. What are the considerations? The authors should explain it.
4. Based on the confidentiality obligation of the innovative technology theme, the detailed information of the concrete mixture combination is not available, which is more regrettable.
5. What is the definition of k-value? The authors should explain it.
6. In Figure 3 and Figure 4, the font of Slovakia appears. It is recommended to change it to English.
7. In Figure 5 and Figure 6, the background color of the legend box should be changed to white.

Author Response

1) The most important document is SK (or AT) Technical Assessment, which has validity at the national level equal to National Technical Stanard. Both documents, issued by TSUS in Slovakia are quoted in the article under the number 23 and 24.

2: The RBW is the mixture of industrially processed recycled recovery clay brick and concrete in the weight ratio 51: 49  % in the Hasenohrl Company, Austria.

3: The 10 % replacement of natural aggregate is also accomplished by cement substitution of an RBW powder. The powdered RBW and porous RBW  0/4 mm aggregate has slightly increased water demand. It is therefore important to prepare fresh concrete with optimal properties in the fresh state and, as ready-mixed concrete. The dosage of RBW is therefore limited.

4) The producers of the RBW (Hasenohr, Austria) and the concrete (Povazska cementaren cement plant, Ladce, Slovakia) ask for confidence, and it has to be respected from our side.  Therfore some data related to material composition were not revealed.

5)  The k-value points to the efficiency of the addition with the chosen cement during hydration with water. The k-value quantifies the effectiveness of the addition in order to express the active water component and the active amount of the binder, which are involved in setting and hardening a concrete, mortar or grout. An active amount of the binder (b) is characterized as (cement + k × addition) and an active water component as (water-to-active binder ratio). The factor k indicates the contribution of used addition to reaching the same strength as the reference concrete without the addition (the condition of equal strength). The experimental methodology is focused on comparative tests of concrete, which have the same ratio of water/binder (w/b), addition/cement (a/c), and aggregate/binder (A /b).  For k-value determination, it is necessary to produce 30 concrete mixture compositions, which differed in two doses of cement, two percentage cement replacements by a pozzolan or (as in this case)  two fineness variations by one pozzolan (an RBW powder = TERRAMENT)  and 5 different values of water to cement ratio (0.45, 0.50, 0.55, 0.60 and 0.65). The obtained data are necessary for the k - value determination. The whole tests leading to the determination of the k - value were performed on the basis of the procedures as stated in the TNI (see: citation 27 in the article). EN 206 requires for each pozzolan applied in concrete the determined k - value.

6. The Slovak text in Figures 3 and 4 is removed.

7. The background color in Figures 5 and 6 is white.

Author Response File: Author Response.docx

Reviewer 2 Report

This article is interesting, the authors should improve the following:

- In figure 3, 4, there are several words written in another language.
- In conclusions must include a general conclusion at the end of this section

Author Response

The Slovak text is removed from the figures 3 and 4.

The general conclusion is included at the end of the section Conclusions.

Author Response File: Author Response.docx

Reviewer 3 Report

It is a very interesting-modern idea and study.

The initial objectives are answered through the conclusions which are clear and well written.

I have the opinion that it can be published after some minor revisions which are listed below.

• Introduction: you could add a paragraph regarding other studies with concretes made by recycled materials when partially replacing natural aggregates such as
• Petrounias, P.; .; Giannakopoulou, P.P.; Rogkala, A.; Lampropoulou, P.; Tsikouras, B.; Rigopoulos, I.; Hatzipanagiotou, K. Petrographic and Mechanical Characteristics of Concrete Produced by Different Type of Recycled Materials. Geosciences2019, 9, 264.
• A bdallah, S.; Fan. M. Characteristics of concrete with waste glass as fine aggregate replacement. J. Eng. Technol. Res. 2014, 2, 11–17.
• Torkitrikul, P.; Chaipanich, A. Utilization of ceramic waste as fine aggregate in Portland cement and fly ash concretes. Cement Concrete Comp. 2010, 32, 440-449.
• Lines 93-110: they should be placed on the experimental procedure or methodology part or you should add a new subunit containing these lines. They definitely must be removed from the introduction part.
• Lines 130-142: they should be placed on the methodology part.
• Table 1 and table 2 must be combined to one table.
• In the discussion part you could discuss more the concrete strength.

Author Response

The Introduction is enriched by the relevant text as asked. The recommended articles are included in the list of references. 

Lines 93 - 110 are removed from Introduction and placed in the new paragraph.

Lines 130 - 142 are paced in the part of Methodology.

Tables 1 and 2 are combined into one table.

The relevant discussion text is added to the part of concrete strength.

Author Response File: Author Response.docx