Evaluation and Optimization of the Life Cycle in Maritime Works

Round 1

Reviewer 1 Report

Dear Authors,

the paper presented is very interesting in its scope. There are, however several points that need to be addressed before publication.

The paper lacks in terms of demonstrating the current state of research in the issue. Chapters 1 and 2 need a more thorough bibliographical approach on other similar research findings - or the lack of them.

On the methodology side, a more concise approach on the system boundaries and the selection of the working unit of the LCA has to be made in order to compare the findings for each case and in order for them to be comparable to other studies.

Figure 2 shows very small variations between the cases. Taking into account the simplicity of the approach (no maintenance, no provisional materials, no construction methods taken into account) that offers little basis for concrete conclusions.

On Table 3 energy use is not considered for the calculations, is that on purpose or the used energy for the construction is considered minimal?

Figure 3 needs to be made more readable.

 

Line 56 - Please explain the acronym GRP 

Line 299 - Correct first capital letter

Line 396 - Please explain 'In the charts and tables'

Author Response

Clarifications included in paper according to Peer Review 1 suggestions

 

 

Dear Authors, the paper presented is very interesting in its scope. There are, however several points that need to be addressed before publication.

 

• The paper lacks in terms of demonstrating the current state of research in the issue. Chapters 1 and 2 need a more thorough bibliographical approach on other similar research findings – or the lack of them.

Some references related to Life Cycle Assessment in other subjects related to infrastructures have been introduced. That is the case of roads, where some studies about impact of the use of different materials have already been done. Furthermore, references in marine environment have been introduced as well, as Life Cycle Assessment in ocean energy solutions. No cases have been found related to breakwaters or caissons.

However, Life Cycle Assessment on roads has a longer path and some examples are shown. In maritime engineering, no examples have been found on caissons or breakwater, and the ones referred to structures with glass fiber in marine atmosphere are already introduced in the paper. Two examples of Life Cycle Assessment in ocean energy structures have been introduced as well.

 

53: “Even though in some infrastructures, as buildings, LCA is becoming more common, in transports infrastructures is not yet widespread. However, there are fields, as roads construction, where some examples can be found, showing improvements on sustainability depending on materials used for pavement [3-7]. In coastal engineering sector, not many cases have been analysed yet, and no experiences in breakwaters or caissons have been found. There are not many references on the subject , and not many maritime infrastructures have been reinforced with fiber glass ; furthermore, no public Environmental Product Declarations (EPD) from fiber glass rebars are available yet. However, in ocean energies some LCA cases have been studied in wave energy production systems [8, 9]”

 

• On the methodology side, a more concise approach on the system boundaries and the selection of the working unit of the LCA has to be made in order to compare the findings for each case and in order for them to be comparable to other studies.

Completar System boundaries.

For Escombreras Breakwater, the declared unit is the whole breakwater crown, which is 400 meters long and cross section is shown in Figure 1 ; the bill of quantities of the Declared Unit is shown in Table 2.

165: “Declared Unit is the whole breakwater crown, considering that is 400 meters long and a cross section as shown in Figure 1. The Bill of Quantities of the Declared Unit is shown In Table 2.”

In the case of Valencia caisson type 1:

173: “ the Declared Unit is the whole caisson, and quantities are shown in Table 5.”

According to the units of measurement, other than Declared Units, Key indicators’ units have been included in table 1 for an easier interpretation.

SYSTEM BOUNDARIES:

Auxiliary equipment and materials have not been considered; namely, Formworks (there will be the same in both cases) , cranes (however , in GFRP case smaller cranes would be needed), site installations (same in both cases).

This first approach is not going deeper into detail as authors were seeking for arguments to invest further in this research.

 

• Figure 2 shows very small variations between the cases. Taking into account the simplicity of the approach (no maintenance, no provisional materials, no construction methods taken into account) that offers little basis for concrete conclusions.

Even though the differences are not enormous, in table 3 we can find in % that the improvement is not negligible. Considering that is the most conservative case (as reviewer underlined, no maintenance is included- that is estimated in discussion- , no provisional materials or auxiliary elements - that will be smaller in fiber case, like cranes- , and no construction methods - floating dock or formworks on dry dock - ) it is worth analysing further, including variations on materials and maintenance (as done in additional improvements and Discussion). Then the indicators reduction would be higher, and could be even more considering that auxiliary equipment, as cranes, will be smaller.

What is shown in Figure 2, is what the authors are considering as the most conservative case, and that there´s place for improvement.

Further elements shown along the investigation reinforce the interest of fiber glass rebars.

Worse case is treated first, and as improvements are found, the research goes on and seeks for elements improving further.

• On Table 3 energy use is not considered for the calculations, is that on purpose or the used energy for the construction is considered minimal?

It's not considered as minimal, but, as the authors are not considering construction methods (floating dock or dry dock) or site installation, additional energy is 0. The value of Energy Use (B6) I the software, is related to “Energy consumption – annual “and “Energy use on the site”.

Energy “embedded” in materials is already included in indicators.

To prevent confusions on tables, B1 to B7 , and C and D rows have been deleted, has they are not contributing to clarify concepts at this point.

The authors would like to underline the differences (mainly in construction materials used) and omit, at this stage , common elements, in order to simplify calculations.

A slighter reduction of “Energy use on site”  would be registered for glass fiber construction as elements to be installed are lighter (76,000 kg steel vs 44,352 GFRP kg).

Figure 3 needs to be made more readable.

Quality of figure has been improved to make it more readable.

 

Line 56 - Please explain the acronym GRP

Glass Fiber Reinforced Polymer (GFRP) , GRP was an incorrect acronym. Explanation has been introduced at the beginning of the paper.

Line 299 - Correct first capital letter

It has been corrected in the paper

 

Line 396 - Please explain 'In the charts and tables'

It’s related to Figure 12, Figures 9-10 for cement improvements, Figure 11 for concrete improvements and Figure 13 radar chart .

Table is only Table 8, so it must be in singular.

 

Author Response File: Author Response.pdf

Reviewer 2 Report

This paper analyzes the use of GFRP materials as a replacement for the steel in reinforced concrete in building maritime infrastructure. The aim is to quantitatively verify that the composite materials are the environmental and resistant alternative in the marine building sector. Such an approach is one of the possible answers to the sustainability questions in the maritime civil engineering sector.

 

The analysis uses Life Cycle calculations for two different construction cases. They use a commercial type of software solutions to calculate the Life Cycle indicators like GWP, OPD, AP, EP, POCP and ADPE. Not all data are present since the cases are in Spain, and the manufacturers do not provide complete EPD for their products. For the missing data, the authors justify the alternatives.

 

This methodology proposes a new aspect of maritime civil engineering in the sustainability direction. They show that the use of different reinforcements, a different type of concrete, the use of saltwater and other possible alternatives can reduce the environmental footprint from 6% to 30%. The use of non-steel materials reduces the lifetime maintenance and introduce the possibility of saltwater. The economic costs still need estimates for such structures. Still, the answer is probably very complicated and is not only a matter of a calculation for the cost of inbuild material.

 

To be corrected:

All Figures have a small resolution. Figure 1, 3, 5, 6, 7, 9, 10, 11, 12, 15, 16 must be replaced with Figures of higher resolution.

Author Response

Clarifications included in paper according to Peer Review 2 suggestions

 

This paper analyzes the use of GFRP materials as a replacement for the steel in reinforced concrete in building maritime infrastructure. The aim is to quantitatively verify that the composite materials are the environmental and resistant alternative in the marine building sector. Such an approach is one of the possible answers to the sustainability questions in the maritime civil engineering sector.

The analysis uses Life Cycle calculations for two different construction cases. They use a commercial type of software solutions to calculate the Life Cycle indicators like GWP, OPD, AP, EP, POCP and ADPE. Not all data are present since the cases are in Spain, and the manufacturers do not provide complete EPD for their products. For the missing data, the authors justify the alternatives.

This methodology proposes a new aspect of maritime civil engineering in the sustainability direction. They show that the use of different reinforcements, a different type of concrete, the use of saltwater and other possible alternatives can reduce the environmental footprint from 6% to 30%. The use of non-steel materials reduces the lifetime maintenance and introduce the possibility of saltwater. The economic costs still need estimates for such structures. Still, the answer is probably very complicated and is not only a matter of a calculation for the cost of inbuild material.

To be corrected:

All Figures have a small resolution. Figure 1, 3, 5, 6, 7, 9, 10, 11, 12, 15, 16 must be replaced with Figures of higher resolution.

 

 

Figures have been saved again, changed from jpg to png, seeking for higher resolution. There are slight improvements, however, not in every case the improvements are noticeable.

Author Response File: Author Response.pdf

Reviewer 3 Report

For authors

- abstract should be written in one paragraph

- it is not advisable to use abbreviations in the keywords (especially because they have not been previously explained)

- Lines 56 GRP – the abbreviation is not explained?

- Lines 37 – 39 does the definition “The life cycle is the tool… ” mean the same as the definition in lines 53 – 54?

- the capitalization should be the same throughout the text (“The life cycle” or “The life Cycle”)

- Lines 80 Table 1: Life Cycle indicator table according to EN 15978. The title of the table should be located above and not below the table.

-Lines 117 – 126 Have the described parameters been analyzed? It is not clear how and why the analysis is used, what is its purpose?

- Lines 158 explain the meaning of the abbreviation: LCA, ATP?

- Lines 161 – 166 “It can be seen…“ It is not clear on what grounds this can be seen?

- Lines 205 Table 2: Summary of alternative measurements of the Escombreras Breakwater crown [13]. The title of the table should be located above and not below the table.

- Lines 226 Table 3: Quantitative comparison of solutions 3A and 3B. The title of the table should be located above and not below the table.

- Lines 243 Table 4: Escombreras Breakwater crown comparative table of solutions Key indicators. The title of the table should be located above and not below the table.

- Lines 266 Table 5: Most important measurements of Caisson type I in the Valencia dock. The title of the table should be located above and not below the table.

Lines 274 Table 6: Comparative table of impact indicators for Steel vs GFRP. The title of the table should be located above and not below the table.

- GFRP - what does this abbreviation mean?

- Lines 287 Table 7: Values of results in the Life Cycle for caisson solutions. The title of the table should be located above and not below the table.

Author Response

Clarifications included in paper according to Peer Review 3 suggestions

 

 

For authors

• abstract should be written in one paragraph

It has been changed.

• it is not advisable to use abbreviations in the keywords (especially because they have not been previously explained)

Thank you, it has been corrected

• Lines 56 GRP – the abbreviation is not explained?

It was a mistake, and explanation of Acronym has been included: Glass Fiber Reinforced Polymer (GFRP)

• Lines 37 – 39 does the definition “The life cycle is the tool… ” mean the same as the definition in lines 53 – 54?

37-39: "The Life Cycle is the tool that makes this analysis possible, considering the entire service life of the infrastructure and not just the construction phase, but also its maintenance, conservation, and, therefore, durability."

53-54: "The life cycle is the tool that will make it possible to define what is important and where to start, as well as the short-term plans to guarantee Sustainable”

First paragraph is closer to a definition, second one is showing how it can be used to improve sustainability of infrastructures. In fact, they could be considered as complementary.

 

• the capitalization should be the same throughout the text (“The life cycle” or “The life Cycle”)

It has been reviewed across the whole text and introduced as : “Life Cycle”

• Lines 80 Table 1: Life Cycle indicator table according to EN 15978. The title of the table should be located above and not below the table.

It has been changed

• Lines 117 – 126 Have the described parameters been analyzed? It is not clear how and why the analysis is used, what is its purpose?

Those parameters are the ones that appear in all the results (tables and charts). Exposition has been improved to make it more understandable.

All those indicators are the ones that are used across the whole study, to check different aspects of Environmental impact. Those ones are some of the most important ones that may help assess the Life Cycle, considering not only Global Warming for decision making.

• Lines 158 explain the meaning of the abbreviation: LCA, ATP?

ATP is the name of the company that supported the authors with their calculations and data : http://www.atp-frp.com/html/gfrp_rebar.html

LCA : Life Cycle Assessment , the Acronym explanation has been introduced in the text.

• Lines 161 – 166 “It can be seen…“ It is not clear on what grounds this can be seen?

According to the results of comparisons in different cases, steel reinforcement vs GFRP reinforcement.

One clarification has been introduced trying to expose the idea more clearly.

• Lines 205 Table 2: Summary of alternative measurements of the Escombreras Breakwater crown [13]. The title of the table should be located above and not below the table.

It has been changed

- Lines 226 Table 3: Quantitative comparison of solutions 3A and 3B. The title of the table should be located above and not below the table.

It has been changed

• Lines 243 Table 4: Escombreras Breakwater crown comparative table of solutions Key indicators. The title of the table should be located above and not below the table.

It has been changed

• Lines 266 Table 5: Most important measurements of Caisson type I in the Valencia dock. The title of the table should be located above and not below the table.

It has been changed

• Lines 274 Table 6: Comparative table of impact indicators for Steel vs GFRP. The title of the table should be located above and not below the table.

It has been changed

• GFRP - what does this abbreviation mean?

An explanation of Acronym has been included at the beginning of the paper: Glass Fiber Reinforced Polymer (GFRP)

 

• Lines 287 Table 7: Values of results in the Life Cycle for caisson solutions. The title of the table should be located above and not below the table.

It has been changed

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The paper represents a novel area for LCA implementation. The methodology is clear - although it lacks depth due to the nature of the works.

The working unit that is chosen is a shorthcoming to make the results comparable to future studies. 

Figures and overall presentation is fiarly acceptable.

Author Response

Peer review 1 – round 2:

 

• The paper represents a novel area for LCA implementation. The methodology is clear - although it lacks depth due to the nature of the works.

This works aims to be a first step and aims to deepen into detail with some contractor’s collaboration ; the authors hope that , they would be supportive considering these encouraging results , and that more sustainable solutions in caissons construction will be implemented.

 

 

• The working unit that is chosen is a shorthcoming to make the results comparable to future studies.

Thank you, that’s the aim of our research, be able to compare easily different configurations and the materials.

 

• Figures and overall presentation is fairly acceptable.