Life Cycle Assessment on Construction and Demolition Waste: A Systematic Literature Review

Life Cycle Assessment (LCA) is considered an innovative tool to analyze environmental impacts to make decisions aimed at improving the environmental performance of building materials and construction processes throughout different life cycle stages, including design, construction, use, operation, and end-of-life (EOL). Therefore, during the last two decades, interest in applying this tool in the construction field has increased, and the number of articles and studies has risen exponentially. However, there is a lack of consolidated studies that provide insights into the implementation of LCA on construction and demolition waste (C&DW). To fill this research gap, this study presents a literature review analysis to consolidate the most relevant topics and issues in the research field of C&DW materials and how LCA has been implemented during the last two decades. A systematic literature search was performed following the PRISMA method: analysis of selected works is based on bibliometric and content-based approaches. As a result, the study characterized 150 selected works in terms of the evolution of articles per year, geographical distribution, most relevant research centers, and featured sources. In addition, this study highlights research gaps in terms of methodological and design tools to improve LCA analysis, indicators, and connection to new trending concepts, such as circular economy and industry 4.0.


Introduction
The need for more buildings and infrastructure parallels the population growth and natural expansion of cities and urban projects. In this context, the construction industry has an important role in increasing greenhouse gas emissions and global warming [1]. It is estimated that approximately 40% of all raw materials obtained from the lithosphere are consumed by the construction sector, representing almost 50% of global greenhouse gas emissions [2]. In addition, construction involves high consumption of building materials, water use, and improper waste management during the EOL phase [3].
The sustainability issues previously mentioned are contrasted with new policies to promote the reduction, reuse, and recycling of construction and demolition waste (C&DW), which provide essential reductions in the consumption of virgin materials and impacts associated with primary production and transportation. Research efforts during the last two decades have been oriented to include C&DW materials as an aggregate of new concrete mixtures, for example, [4][5][6][7][8]; new design approaches include the use of building information modeling (BIM), e.g., [9,10]; and others works, for instance, [11][12][13] have evaluated environmental benefits of using C&DW as replacement of virgin materials without affecting mechanical properties significantly.
All of these research approaches have some methodological tools in common. The one most employed is the LCA, which allows consolidating, comparing, and assessing sustainability impacts through environmental, economic, and social indicators. On a additional filters to limit the type of documents (articles from only journals, English language, and matching of extracted keywords).
The PRISMA approach was used to systematically identify the most relevant works regarding the topic of LCA and C&DW ( Figure 1). First, 209 records were collected from the SCOPUS database and secondary searches after eliminating duplicates. Later, 173 articles were classified as related works after revising title, abstract, methods, and conclusions. Finally, 150 entries were classified as selected works after performing a detailed and complete revision of articles.

Bibliometric and Based-Content Analysis
The analysis of the 150 selected works was divided into two main subsections: the first dedicated to summarizing bibliometric attributes, and the second focused on the content-based study of selected works. The bibliometric analysis provides useful information about the overall attributes of articles, authors, journals, among others. For this analysis, bibliometric software was not used for analyzing data.
On the other hand, the content-based analysis aims to study in detail the objectives, methodologies, and applicability of selected works and future research directions. Table  1 summarizes the investigated aspects covered in this study and the possible categories considered for each one. In addition to the research aspects shown in Table 1, this study analyzed the use of LCA indicators, the most common C&DW materials studied in the selected works, and main research topics and trends related to LCA applications on C&DW.

Bibliometric and Based-Content Analysis
The analysis of the 150 selected works was divided into two main subsections: the first dedicated to summarizing bibliometric attributes, and the second focused on the contentbased study of selected works. The bibliometric analysis provides useful information about the overall attributes of articles, authors, journals, among others. For this analysis, bibliometric software was not used for analyzing data.
On the other hand, the content-based analysis aims to study in detail the objectives, methodologies, and applicability of selected works and future research directions. Table 1 summarizes the investigated aspects covered in this study and the possible categories considered for each one. In addition to the research aspects shown in Table 1, this study analyzed the use of LCA indicators, the most common C&DW materials studied in the selected works, and main research topics and trends related to LCA applications on C&DW. The article provides helpful information to compare and select the most suitable EOL scenario

Material selection
The article provides helpful information to select materials in the fabrication of new products

Measurement of sustainability impacts
The article provides helpful information about how to measure sustainability impacts in a nonconventional way

Bibliometric Analysis
This subsection includes the evolution of research articles, contributions by region, most prominent research clusters, most relevant journals, and top-cited articles during the last two decades, among others. Each one of such aspects is described in detail below. Figure 2 shows the evolution of the number of articles during the last two decades. It demonstrates that LCA and C&DW are growing topics, especially during the last five years ( Table 2). Regarding research articles, an increase from one or two works up to 37 works in less than 15 years is remarkable. This reveals an expanding research interest motivated for worldwide initiatives such as sustainable development goals, policies, and legislation related to sustainability and a more environmentally conscious society.   In terms of contributions per region, Europe and Asia have a vast advantage over the rest of the world. Just a few selected works were developed in North America, South America, and Oceania. Africa has minimum participation (one contribution) in the sample of selected works. Figure 3a summarizes the distribution of selected works by region. Figure 3b, on the other hand, shows a detailed distribution of selected works per country. Countries with a higher number of contributions based on author affiliations are China (30), Spain (23), Italy (22), Australia (12), and the USA (12). In terms of contributions per region, Europe and Asia have a vast advantage over the rest of the world. Just a few selected works were developed in North America, South America, and Oceania. Africa has minimum participation (one contribution) in the sample of selected works. Figure 3a summarizes the distribution of selected works by region. Figure 3b, on the other hand, shows a detailed distribution of selected works per country. Countries with a higher number of contributions based on author affiliations are China (30), Spain (23), Italy (22), Australia (12), and the USA (12).  In terms of contributions per region, Europe and Asia have a vast advantage over the rest of the world. Just a few selected works were developed in North America, South America, and Oceania. Africa has minimum participation (one contribution) in the sample of selected works. Figure 3a summarizes the distribution of selected works by region.        From the analysis of authors' affiliation, it was possible to identify four main research clusters among authors with several contributions in the LCA application on C&DW management and decision-making. Table 3 includes the most relevant research clusters. From the sample of 150 selected works, 11 articles were identified as key contributions based on their cumulated citations until the literature search date (21 April 2021). Table 4 comprises a brief description of the 11 articles.

Content-Based Analysis
Selected works were classified according to their objective and methodology, which were defined previously in Section 2.2. Figure 5 shows a graphical summary of the objective vs. methodology for the 150 selected works. As the main result, it is remarkable that 72% of selected works are oriented to evaluate, assess, or quantify sustainability impacts from an analytical perspective. In the second place, articles proposing methodologies, guidelines, or indicators represent 18%, where most works followed an analytical approach, and just one article is categorized as a framework. In third place, articles aiming to explore or analyze represent 10%. Finally, in this last category, most works are review-type, and just a few are based on other methodologies such as surveys or frameworks. Assessment of the performance of C&DW management systems from an environmental and economic perspective.
The practical application of selected works is summarized in Figure 6. most of the works (40%) are focused on the decision-making of the most suitable EOL strategy (recycling offsite, onsite, and landfill). EOL strategies are commonly contrasted using LCA indicators and transportation or reprocessing costs. Another relevant identified application (38%) compares the technical performance of C&DW materials versus virgin materials. Such analysis provides helpful information and methodological approaches for selecting materials and their fractions to fabricate new products. Lastly, the measurement of environmental or mechanical properties of construction materials using fractions of C&DW is also identified (6%), comprising methods, indicators, and assessment frameworks. Sixteen percent of selected works represent very particular applications or individual contributions, including analyzing waste recovery goals in specific regions, evaluating land consumption, and evaluating conventional vs. selective demolition.  Regarding the construction materials analyzed in the selected works, it was found that 49% of them (72 works) considered a very diverse group of materials that included ceramics (concrete, cement, bricks, gypsum, drywall, glass), metals (steel, iron, aluminum, copper), and polymers (insulation, rubber). Another important group of works was focused solely on aggregates from the diverse origin (19%), concrete aggregates (10%), and just nine works (6%) were oriented to a unique material (gypsum, asphalt, bricks, polymers). Fifteen percent of selected works (22) did not specify the construction material. Figure 7 shows the distribution of selected works for the categories in terms of absolute values.  Regarding the construction materials analyzed in the selected works, it was found that 49% of them (72 works) considered a very diverse group of materials that included ceramics (concrete, cement, bricks, gypsum, drywall, glass), metals (steel, iron, aluminum, copper), and polymers (insulation, rubber). Another important group of works was focused solely on aggregates from the diverse origin (19%), concrete aggregates (10%), and just nine works (6%) were oriented to a unique material (gypsum, asphalt, bricks, polymers). Fifteen percent of selected works (22) did not specify the construction material. Figure 7 shows the distribution of selected works for the categories in terms of absolute values. Regarding the construction materials analyzed in the selected works, it was found that 49% of them (72 works) considered a very diverse group of materials that included ceramics (concrete, cement, bricks, gypsum, drywall, glass), metals (steel, iron, aluminum, copper), and polymers (insulation, rubber). Another important group of works was focused solely on aggregates from the diverse origin (19%), concrete aggregates (10%), and just nine works (6%) were oriented to a unique material (gypsum, asphalt, bricks, polymers). Fifteen percent of selected works (22) did not specify the construction material. Figure 7 shows the distribution of selected works for the categories in terms of absolute values.
LCA parameters most employed are global warming potential, acidification, energy consumption, eutrophication, and photochemical ozone creation potential, which are conventional parameters included in LCA approaches. Some interesting and nonconventional parameters such as cost, person-year equivalent, land occupation, and Eco-Indicator 99 were also found less frequently in the selected works. Figure 8 summarizes and lists the LCA parameters most used in the selected works.
A detailed analysis of data shown in this section regarding bibliometric and contentbased analysis is performed in Section 4 (Discussion). Sustainability 2021, 13, x FOR PEER REVIEW 10 of 23 LCA parameters most employed are global warming potential, acidification, energy consumption, eutrophication, and photochemical ozone creation potential, which are conventional parameters included in LCA approaches. Some interesting and nonconventional parameters such as cost, person-year equivalent, land occupation, and Eco-Indicator 99 were also found less frequently in the selected works. Figure 8 summarizes and lists the LCA parameters most used in the selected works. A detailed analysis of data shown in this section regarding bibliometric and contentbased analysis is performed in Section 4 (Discussion).

Research Topics
This subsection describes four main topics identified in the literature analyzed. Such topics summarize the most common and relevant themes covered in LCA and C&DW during the last two decades. Each topic is described in detail as follows:  LCA parameters most employed are global warming potential, acidification, energy consumption, eutrophication, and photochemical ozone creation potential, which are conventional parameters included in LCA approaches. Some interesting and nonconventional parameters such as cost, person-year equivalent, land occupation, and Eco-Indicator 99 were also found less frequently in the selected works. Figure 8 summarizes and lists the LCA parameters most used in the selected works. A detailed analysis of data shown in this section regarding bibliometric and contentbased analysis is performed in Section 4 (Discussion).

Research Topics
This subsection describes four main topics identified in the literature analyzed. Such topics summarize the most common and relevant themes covered in LCA and C&DW during the last two decades. Each topic is described in detail as follows:

Research Topics
This subsection describes four main topics identified in the literature analyzed. Such topics summarize the most common and relevant themes covered in LCA and C&DW during the last two decades. Each topic is described in detail as follows: •

Material Selection/Definition of C&DW Fraction for Construction Applications
The most common topic related to LCA use is the decision-making on choosing construction materials and defining the range of C&DW fractions in new products or building projects. In this topic, concrete was the material most studied, commonly analyzing the carbon footprint, e.g., [128,152]; carbon footprint and embodied energy [134], greenhouse gas emissions and land-use change [7], or analyzing contamination issues such as content and leaching of sulfates in recycled aggregates [146]. Other works were focused on developing new materials or construction products, and using fractions of C&DW as aggregate or filling material. Typical applications of previous works were focused on concrete, asphalt, and bricks.
Related to concrete, [98] compared two use-cycles of natural aggregate concrete and recycled aggregate concrete to analyze the environmental impacts of recycled materials. Results demonstrated the benefits of using recycled materials, such as environmental savings, primary resource use, embodied energy, embodied emissions, and reduced pressure on landfill sites. Reference [52] evaluated the energy consumption of all processes to manufacture concrete curbs using recycled aggregates for replacing natural sand aggregates.
Other works are related to brick manufacturing with some fraction of C&DW, and acceptable results concerning mechanical and durability properties and significant environmental impact reduction. For example, [83] performed an analysis of concrete and ceramic remains used to partially substitute clay soil to produce unfired bricks. Reference [126] compared reusable blocks with recycled brick aggregate, reusable blocks with recycled concrete, reusable blocks with natural aggregate, and regular concrete wall in mechanical properties and environmental impacts. Reference [33] employed LCA to demonstrate significant environmental benefits with the use of demolished concrete blocks over conventional concrete. Similarly, [57] assessed and compared the environmental impacts and sustainability associated with natural blocks manufactured with virgin materials and three generations of ecoblocks manufactured with C&DW. Other authors, e.g., [62,76], employed LCA to quantify and compare the environmental impacts associated with the production of masonry mortar manufactured with different amounts of fine natural and recycled aggregate from C&DW.
Other less common materials were studied in the selected works analyzed; for instance, [143] performed a study to identify the stages that produce the most significant impact on the environment (materials and processes) in the use of ceramic tiles. Likewise, [137] developed a comparative LCA on the energy requirements and implications of greenhouse emissions of recycling construction and demolition rubble and container glass. Reference [55] performed an LCA approach to evaluate the performance of recovered gypsum waste to manufacture ordinary Portland cement. Lastly, [103] demonstrated the calculation of the economic potential and environmental impact of reused steel building elements.
Regarding nonconventional materials, it was found that some authors worked on possible composite materials not directly employed in construction applications, for example, [37] who compared the use of waste materials derived from C&DW as alternative filers in the production of thermoplastic composites using recycled high-density polyethylene as a matrix material. Likewise, [94] assessed the environmental impact of wood polymer composite production using specific C&DW fractions (wood, plastic, plasterboard, and mineral wool) compared to conventional waste treatment scenarios such as landfilling and incineration. C&DW has been used as complementary material in some cases, e.g., [144], who developed a bamboo and C&DW residential building prototype and its LCA compared to a typical brick-concrete building, demonstrating benefits in embodied energy from the recycling of demolition waste.
Other studies were oriented to analyze different life cycle phases of construction materials, as in the case of [77], who assessed the environmental impacts on the production of aggregates via each scenario using life cycle assessment (virgin vs. recycled aggregates), including energy consumption and CO 2 emissions as the comparative indicator.

• EOL Decision-Making
The selection of the most suitable EOL strategy to manage C&DW is one of the most studied topics in the literature. Commonly, it is used to compare decision scenarios such as landfilling materials, recycling, and analysis of C&DW use in different fractions and incineration to obtain thermal energy. Commonly, the LCA approach is used to determine what alternative is better, according to the case study. Some relevant examples of this LCA application include [3], who evaluated environmental impacts considering landfilling, recycling, and incineration of demolition waste. Other works, such as that proposed by [139], assessed the EOL of a building to identify the demolition process variables that affect energy consumption and GHG emissions. Other authors, e.g., [119], combined LCA and LCC (life cycle cost) to analyze the environmental and economic drivers of three different waste disposal scenarios (landfilling, recycled aggregate, and recycled powder). Likewise, [115] compared the life cycle environmental implications of two C&DW management alternatives (inert landfilling and integrated wet recycling). Reference [60] presents analysis of six different scenarios for C&DW that included a combination of landfill, sorting, and recycling, and the use of material for landfill roads. Reference [41] analyzed the potential environmental impacts associated with C&DW utilization in road construction compared to landfilling, including analysis of transportation distances and the entire life cycle of construction products. In terms of industrialized treatment processes for C&DW, [29] analyzed mixes of recycled aggregates from C&DW treatment plants to evaluate the viability of their use in the construction of road layers. It was determined that these materials, when they come from C&DW with selective collection at origin, cause less environmental impact than the impact caused by the use of natural aggregates to build road layers.

• Waste Management Systems
Several studies were focused on or related to strategies around the waste management systems for C&DW. Such works commonly have a managerial approach and included broader analysis on how technical factors influence the sustainability performance of the waste management process. We can here highlight some interesting approaches. For example, [150] proposed a model to evaluate waste management systems, including environmental, economic, and social aspects of C&DW. References [56,145] quantified environmental impacts within an LCA for buildings in which life cycle stages were adjusted to several waste/material management options. Overall analysis, such as the one proposed by [141], consisted of analyzing the energy and environmental implications of the C&DW recycling chain in a particular region of Italy. It included land use, transportation, and avoiding landfills. Moreover, data related to generate life cycle inventories, such as that described in [129], were used to develop and analyze a life cycle inventory of C&DW management systems based on primary data. More recent studies, as in [15], were oriented to develop conceptual C&DW management frameworks to maximize reduction, reuse, and recycling of materials. Lastly, some interesting recent works [34,73] focused on waste prevention scenarios from early design phases. These studies aimed to predict or simulate waste generation before the construction phase and mitigate future environmental impacts derived from C&DW management.

•
Other Trends Some interesting and novelty approaches were identified in the research articles selected. In the case of sustainability indicators dedicated to C&DW, [15] proposed a cycle-based C&DW sustainability index to assist designers during the selection of material, sorting, recycle/reuse, and treatment or disposal options for C&DW. In the field of methodological approaches, LCA has been combined with different tools to improve results and robustness of the life cycle analysis. Several variations of LCA and combinations can be noted. For instance, [4] proposed LCSA (life cycle sustainability analysis) applied to concrete recycling. Approaches based on building information modeling (BIM) were also identified, e.g., [9,10,39], which analyzed the environmental impact of materials converted into waste by evaluating with a BIM tool.

Common Findings
This subsection summarizes the most representative results from selected works in terms of sustainability after applying LCA on C&DW analysis or management: • LCA demonstrates the reduction of this new material on the global warming potential of concrete. Reductions from 66 to 70% are possible for high strength concrete with low clinker content and 7-35% with a higher clinker content [135]. Similarly, [132] developed a comparative analysis of recycled and conventional concrete. Results demonstrated a reduction of (−30%) environmental impacts for Eco-Indicator 99 and ecological scarcity. • Transportation stage plays a critical role in the recycling process of C&DW [69,78,129,137]. Depending on the distance to the destination (in the case of production exportation), it can be one of the most predominant stages from the environmental perspective [143].

•
It is necessary to analyze the environmental performance of a system from different perspectives before decision-making. Recycling waste is not always the best alternative for C&DW; it depends on regional differences in operations and waste composition [43]. • Benefits from substituting primary raw materials can be overset by the increased impacts due to additional energy requirements of the selective demolition compared to the traditional one. Consequently, the environmental sustainability of selective demolition should be addressed on a case-by-case basis [124]. • Preventative models can support the preparation of national waste programs and could serve as an instrumental tool to simulate the environmental impacts of construction waste management scenarios that include waste prevention [34].

•
LCA and GIS (geographical information systems) provide beneficial results to analyze EOL scenarios by considering the number, size, type, and location of recycling plants [141].

Discussion
After performing the literature search, identifying the selected works, and developing the bibliometric and content-based analysis, several issues can be highlighted concerning the concept of LCA and C&DW.
Firstly, LCA approaches and C&DW are a growing and trending topic that will be gaining more relevance in waste management and the design and planning of new industrial and residential projects worldwide. Furthermore, there is a generalized pressure for finding more environmentally friendly solutions and the almost mandatory requirement of measuring and reducing impacts during the whole life cycle of buildings. Therefore, more research efforts are required worldwide to contribute more specialized knowledge to aid designers, architects, and engineers during the conception of new building projects and the EOL management of existing ones. LCA is still challenging due to the data required, the availability of indicators, and characterization factors related to each case study. However, it is a helpful tool to analyze and make decisions related to environmental issues for using and managing C&DW.
Following the previous idea, it is notable that only a few countries have an important research advance in evaluating C&DW materials from a holistic life cycle perspective. For example, countries such as China, Spain, and Italy have a well-established research agenda in the field, proposing strategies and engineering approaches to manage and recover material from existing buildings and comparing technical performances between C&DW and virgin materials. Although most research is limited to a particular region, province, or city, methodological approaches based on geographic information systems, optimization techniques to analyze logistic burdens and costs, detailed environmental analysis, and statistical approaches can be extrapolated to other countries and regions. Furthermore, it is necessary to include in such an analysis the source of virgin materials and construction products from a worldwide point of view since several materials are imported depending on the demanding country or region.
In terms of objectives or purpose of selected works, most are dedicated to evaluate, assess, and quantify technical attributes (environmental, economic, and related to mechanical properties) of C&DW. Such works focus on providing helpful information to make decisions related to select materials, determine the most suitable waste management strategy (recycling onsite, offsite, and landfill) existing C&DW. Nevertheless, the practical application of such works is limited by local conditions and other factors, such as current legislation, transportation infrastructure, and technology availability. In terms of mate-rials, management alternatives for C&DW need to be addressed individually due to the vast amount and variety of construction materials currently available. It is necessary to consolidate comprehensive databases, preferably including the origin and destination of raw materials.
Some works propose new methodologies, guidelines, or indicators to study C&DW materials compared to conventional virgin materials. However, these studies are fewer compared to those dedicated to evaluating, assessing, and quantifying, which demonstrates a lack of methodological approaches, not only for the management of C&DW, but also for the whole life cycle, starting from early design phases. Nevertheless, unfortunately, most existing buildings closer to their EOL stage were constructed without considering life cycle implications, especially those built before 2000. Lastly, in a minor proportion, several works aimed to explore or analyze previous research results. Such articles are review-type and consolidate information and data from LCA application cases on buildings, and highlight research gaps in a general perspective. As an important opportunity, it is remarkable that LCA shows improved results when it is combined with other methodological tools such as material flow analysis, life cycle cost, environmental life cycle costing, multicriteria analysis, among others. Selected works consider a wide variety of C&DW materials that include concrete, steel, brick, plaster, insulation, glass, aluminum, gypsum, board, ash, timber, wood, and rubber.
Moreover, most analytical works consider five to twelve materials, including all possible materials obtained from demolition tasks. This provides a robust characterization in terms of LCA. However, to fully assess many materials through LCA (primary production, secondary production, transportation, use, and EOL) requires a vast amount of information that can be difficult to find in the literature, especially when a local context analysis is necessary and when the chemical composition of materials can vary according to their geographical source. The complexity of this issue is increased when eight or more LCA parameters or indicators are required.
Indicators employed in LCA include various chemical, physical, and technical parameters that provide full detail of sustainability burdens in different life cycle stages (manufacturing, use, and EOL). However, there is no homogeneity in the use of LCA indicators, which does not allow a technical comparison of research works. Therefore, to avoid confusion and misunderstanding of results from the case study analysis, it is necessary to dedicate research efforts to the definition of worldwide accepted indicators or measurement parameters.

Barriers and Future Challenges
From the analysis of selected works, several common barriers were identified. The most relevant are described in detail below: • LCA is a method based on data inventory; therefore, the robustness of each analysis depends on the availability of data to measure and compare environmental indicators. A significant proportion of selected works (30% approximately) employed a complete set of environmental indicators. Meanwhile, most of the works (50% approximately) employ one to four indicators. This demonstrates a bias in the implementation of the method in the group of selected works. This situation makes it difficult to make a detailed comparison among the research works with traceability and reliability.

•
There are no widely extended policies related to the disposal of debris in construction sites and the threshold of recycled-content building materials [17,144]. This is evidenced in the type of approach proposed by most research works based on local analysis (municipalities, cities, or regions). Therefore, there is no formal approach to evaluate C&DW through LCA in a world unified methodology. The consequences of this situation can be seen on a larger scale in the European Union (Figure 9), where although the recovery average of C&DW is around 30%, the situation varies from country to country. For example, southern countries such as Spain, Portugal, and Greece only recover approximately 5% of the generated C&DW, while northern countries such as Holland, Belgium, and Denmark recover more than 80% of the CD&DW.
sites and the threshold of recycled-content building materials [17,144]. This is evidenced in the type of approach proposed by most research works based on local analysis (municipalities, cities, or regions). Therefore, there is no formal approach to evaluate C&DW through LCA in a world unified methodology. The consequences of this situation can be seen on a larger scale in the European Union (Figure 9), where although the recovery average of C&DW is around 30%, the situation varies from country to country. For example, southern countries such as Spain, Portugal, and Greece only recover approximately 5% of the generated C&DW, while northern countries such as Holland, Belgium, and Denmark recover more than 80% of the CD&DW. Figure 9. C&DW recovery in European Union countries. Adapted from ref. [153].
• The economic viability of C&DW management is insufficient to guarantee its implementation. Other factors must be included in the analysis, such as logistic deadlines, availability of resources, transportation issues, derived environmental impacts, among others [150]. It is necessary to have an entire database of environmental and technical data from all raw materials (including geographical origin) to develop robust analysis based on a sustainability perspective that includes environmental and social aspects.

•
Commonly, it is concluded that recycling is more sustainable, but from an absolute perspective, it can cause an unacceptable impact on the environment [150]. The impact of recycling must be considered in any LCA analysis using a case-by-case basis.

•
According to the results previously explained and discussed, five main research challenges need to be addressed to improve the applicability and effectiveness of LCA approaches to study C&DW. • LCA implementations found in the existing literature focus on specific locations or cities; there is no traceability of the primary source of materials that can even be • The economic viability of C&DW management is insufficient to guarantee its implementation. Other factors must be included in the analysis, such as logistic deadlines, availability of resources, transportation issues, derived environmental impacts, among others [150]. It is necessary to have an entire database of environmental and technical data from all raw materials (including geographical origin) to develop robust analysis based on a sustainability perspective that includes environmental and social aspects. • Commonly, it is concluded that recycling is more sustainable, but from an absolute perspective, it can cause an unacceptable impact on the environment [150]. The impact of recycling must be considered in any LCA analysis using a case-by-case basis. • According to the results previously explained and discussed, five main research challenges need to be addressed to improve the applicability and effectiveness of LCA approaches to study C&DW. • LCA implementations found in the existing literature focus on specific locations or cities; there is no traceability of the primary source of materials that can even be imported from distant regions. A robust LCA approach should consider the entire life cycle, considering socioeconomic conditions of locations or countries where raw material is obtained and processed until it is delivered as a construction material or product. The same consideration should be included to select the most suitable EOL alternative of C&DW, involving long travel distances.

•
Most research works are focused on recycling concrete or aggregates of different nature. However, it is necessary to propose new approaches that provide different circular economy strategies such as repair or repurpose to avoid reprocessing of C&DW material that can be more expensive in terms of cost and environment. Recycling is considered one of the less desirable among the circular economy strategies [154,155], since it involves using resources (energy, water, additional supplies) that can be significant compared to the extraction of virgin material. Nevertheless, due to the nature of construction materials, it is difficult to apply many strategies compared to electronics, industrial machines, and domestic appliances.
• Dedicated design methodologies that include prediction of environmental impact, maintenance tasks, and demolition processes must integrate LCA data from early design phases. Building information modeling presents vast potential as a tool for including LCA aspects and facilitating the waste management of buildings during their EOL stage. • Industry 4.0 technology and advanced techniques such as artificial intelligence, machine learning, and digital twin are required to boost new research efforts for building project design and waste management. In addition, simulation tools and modeling software need to include material property databases to assess and select materials from early design phases. Thus, it facilitates calculations and the decision-making of construction materials and their fractions when C&DW sources are considered for replacing virgin material. • More research is required to evaluate the role of legislation and policies in different countries related to the waste management of C&DW and their evolution during the last decade. For example, stimulating and controlling approaches should be considered to move construction to a circular economy model. In addition, some new business models associated with the servitization of buildings (co-living, working spaces, rent-based offices) must be assessed in the use stage to compensate for possible costs during the EOL phase.

Conclusions
This article aimed to consolidate and summarize relevant trends and insights from a systematic literature review of works related to LCA and C&DW during the last two decades. The works identified and selected were analyzed following a bibliometric and content-based analysis. Global bibliometric parameters included the evolution of works in time, geographical distribution of works, most relevant research centers, featured journals, and research clusters. The content-based analysis covered objectives and methodology, practical application, C&DW materials studied, and LCA parameters. Research gaps lie in the need for more research dedicated to design methodologies that provide helpful guidelines to consider the whole life cycle of buildings from early design stages, to include a more circular economy perspective to generate additional alternatives to recycling and recovery of C&DW, and to more broadly analyze globalized supply chains to consider the entire life cycle impact of raw materials. Additionally, there is a need to integrate Industry 4.0 and new data-driven methods to optimize design and decision-making around the management of construction materials. Furthermore, research is necessary to analyze the impact of uneven evolution of legislation and policies worldwide and evaluate their impact on long-term sustainability performance in the world construction sector.  Acknowledgments: The authors would like to thank the Engineering Faculties of Pontificia Universidad Javeriana and Universidad El Bosque University for their support during the development of this study.

Conflicts of Interest:
The authors declare no conflict of interest.