Life Cycle Assessment-Based Analysis of Environmental and Economic Benefits in Construction Solid Waste Recycling

Abstract

Under the dual pressures of global climate change and resource depletion, the recycling of construction solid waste has become a crucial link in promoting sustainable development. This study adopts the life cycle assessment (LCA) method to conduct a comparative analysis of the differences in environmental benefits between the recycling treatment of construction solid waste and the traditional simple landfill treatment. The results show that, in specific scenarios, the adoption of recycling not only significantly reduces greenhouse gas emissions but also saves a large amount of natural resources. From an economic perspective, although the initial economic investment in recycling treatment may be relatively high, its long-term environmental and economic benefits far exceed those of simple landfills. In view of the current challenges faced by the recycling treatment of construction solid waste, such as lack of data, uncertain market demand, and insufficient policy support, this study recommends strategies such as strengthening data collection, promoting market expansion, and enhancing policy support to facilitate the green transformation and sustainable development of the construction industry.

1. Introduction

Against the backdrop of the accelerated advancement in global climate governance and the sustainable development agenda, the construction industry, as a key sector in global energy consumption and greenhouse gas emissions, is facing unprecedented pressure for transformation. According to the data from the report released by the United Nations Environment Programme (UNEP) in 2022, the construction industry accounts for 36% of global final energy consumption and 37% of energy-related carbon dioxide emissions [1]. This severe situation stands in sharp contrast to the 1.5 °C temperature control target set by the Paris Agreement, highlighting the urgency of the green transformation of the construction industry. As the world’s largest developing country, during the process of advancing the “dual-carbon” goals, the low-carbon transformation of China’s construction industry is not only crucial for the effectiveness of domestic ecological civilization construction but also an important part of global climate governance.

Currently, the recycling and utilization of construction waste has become one of the core issues in the development of the global circular economy. This field has received widespread attention from numerous scholars, and many countries have also attached great importance to it and introduced a series of policies and regulations to promote its development. In its new circular economy action plan, the European Union has explicitly set the goal of achieving a 70% recycling rate of construction waste by 2030. In contrast, China’s annual output of construction waste exceeds 2 billion tons, accounting for 40% of the total urban solid waste, and the resource utilization efficiency remains at a relatively low level [2]. This situation not only causes huge waste of resources and environmental pressure, but also has a significant gap with China’s strategic goals of promoting high-quality development and building a new development pattern. Further research is urgently needed to promote its sustainable development.

This research is based on the general context of the global circular economy transformation and climate governance, focusing on the key area of the recycling and utilization of construction solid waste, aiming to solve the core problems restricting the green transformation of the construction industry. The research objective is to systematically evaluate the economic and environmental benefits of traditional treatment methods and recycling paths for building solid waste; conduct an in-depth analysis of market-based trading mechanisms; explore policy, technology, and market collaborative innovation strategies to promote the resource utilization of building solid waste; and provide scientific basis and practical paths for the green transformation of the construction industry.

At the theoretical level, the research will provide a new perspective and method for theoretical research in the field of construction waste management by quantitatively analyzing the life cycle environmental impact and carbon reduction benefits of the resource utilization of construction solid waste. It will improve the theoretical framework of the resource utilization of construction solid waste and provide a more comprehensive theoretical basis for subsequent research. At the practical level, this research will also explore the market mechanisms and policy tools for the resource utilization of construction solid waste, providing new research cases for circular economy theory and sustainable development theory, and offering specific solutions and policy recommendations for the green transformation of the construction industry. In summary, it will not only contribute to the exploration of low-carbon construction paths under China’s “dual-carbon” goals but also provide a scientific basis for green and low-carbon transformation and sustainable development, offering theoretical support and practical paths for promoting the transformation of the construction industry towards a circular economy model.

2. Recycling of Construction Solid Waste

Construction solid waste encompasses the solid materials generated during the entire life cycle of buildings and their auxiliary facilities, including construction, renovation, decoration, and demolition processes. It mainly consists of muck, waste concrete, broken bricks, waste metals, and wood [3]. Despite its complex composition, a majority of its components, such as waste concrete, metals, and wood, hold significant potential for recycling and reuse. In the early stages in China, landfilling was the predominant method for handling construction solid waste. However, with the continuous progress of ecological civilization construction and the enhancement in environmental awareness, there has been a gradual impetus for the development of a multi-level utilization system for the recycling of construction solid waste.

Currently, the recycling strategies for construction solid waste in China are categorized into four levels. At the primary level, construction solid waste is still directly landfilled. At the secondary level, upon being crushed, it is utilized for roadbeds or for simple backfilling in foundation works. At the tertiary level, through meticulous screening and processing procedures, construction solid waste is transformed into recycled aggregates. These recycled aggregates serve as substitutes for natural aggregates in the production of recycled building materials. At the quaternary level, high-quality recycled aggregates are employed to manufacture high-performance recycled building materials or other advanced building composites. The recycling and utilization of construction solid waste in China have gradually evolved from basic and simplistic treatment methods in the past to a sophisticated, multi-level, and highly efficient comprehensive utilization system. This multi-level recycling framework has effectively propelled the efficient utilization of construction solid waste.

Both domestic and international scholars have carried out extensive research on the recycling of construction solid waste and its associated environmental benefits. In the domestic literature, Li et al. (2020) conducted an in-depth analysis of the environmental impacts of four mobile resource utilization projects for construction waste using life cycle assessment methods, and compared the impacts and energy consumption limits of each project at different stages [4]. Jiang et al. (2024) established a Carbon Emission Accounting Model (CEAM) to assess the carbon emission benefits of various stages of construction and demolition waste (CDW) recycling, finding that the carbon emissions from recycling metal materials are significantly lower than those from ordinary building materials [5]. Internationally, Niekurzak et al. (2025) analyzed the regulatory mechanisms, ecological costs, and benefits of using urban and industrial waste as alternative fuels in the European cement industry based on research results from Polish cement plants [6]. Marinković et al. (2010) and Hossain et al. (2016) compared the environmental impact of natural aggregates and recycled aggregates made from construction waste through experiments and case evaluations and found that recycled aggregates have significant advantages in reducing ecological damage [7,8]. Dias et al. (2021) pointed out that although the production cost of recycled aggregates is relatively high, their environmental footprint is substantially lower than that of natural aggregates [9]. Ortiz et al. (2010) compared the environmental effects of different construction waste treatment methods through case studies and found that compared to incineration and landfills, recycling treatment methods are more effective in reducing carbon emissions and energy conservation [10]. In many developed countries, the development of construction waste recycling initiated at an early stage and has now reached a relatively mature stage, successfully achieving the industrialization of construction waste recycling treatment. Some scholars, from the perspective of the recycling industry, have conducted in-depth research on various aspects, including its economic viability, industry-driving forces, industrial chain structure, and supply chain management. Based on the industrial chain information system of recycled aggregates replacing virgin aggregates, Yu (2021) proposed a dynamic supply–demand model for construction waste recycling, which offers valuable decision-making support for both industrial chain participants and the government [11]. Jain et al. (2020) analyzed the attitudes and behavioral intentions of builders toward recycling construction waste, which can be utilized by relevant parties such as policy-makers and regulatory agencies for research and management purposes [12]. Brandao et al. (2021) developed a conceptual model of the reverse supply chain related to construction demolition waste, using it to analyze key participants, government strategies, and process paths in the management of construction waste [13]. Badraddin et al. (2022) analyzed the key success factors in the recycling process of waste concrete and the obstructive factors in the application of recycled products, aiming to identify crucial strategic measures [14].

In conclusion, the recycling of construction solid waste not only effectively conserves resources but also substantially reduces carbon emissions and minimizes negative environmental impacts. This is of great significance for promoting the sustainable development of the construction industry and environmental protection. An in-depth exploration of the carbon reduction potential of construction solid waste provides essential theoretical support for formulating scientific and rational recycling policies and technical solutions.

3. Life Cycle Assessment

Life cycle assessment (LCA) is a comprehensive methodology for evaluating the environmental impacts of a product or service throughout its entire life cycle, from the extraction of raw materials to the disposal of waste. It covers the entire process from “cradle to grave”, including stages such as raw material acquisition, processing, manufacturing, packaging, transportation, use, sales, disposal, and recycling. Initially applied in the industrial sector, since the 1990s, LCA has gradually expanded to the construction industry, especially for assessing the environmental impacts of building materials, such as energy consumption, carbon footprint, and their effects on the ecosystem [15]. By analyzing the full life cycle of building materials, LCA helps researchers explore strategies to reduce environmental burdens, playing a crucial role particularly in waste disposal and resource recycling. In 1997, the International Organization for Standardization (ISO) standardized the definition of LCA in the ISO 14044 standard, clearly defining it as a process for evaluating the inputs, outputs, and potential environmental impacts throughout the entire life cycle of a product system [16]. In the “Environmental Management Life Cycle Assessment Principles and Framework”, the International Organization for Standardization (ISO) elaborated on the process of life cycle assessment (LCA), which includes four core steps: goal and scope definition, life cycle inventory analysis (LCI), life cycle impact assessment (LCIA), and life cycle interpretation. These four steps are not only interconnected but also form a cyclical and integral evaluation process.

Regarding the recycling of construction solid waste, LCA can effectively evaluate the recycling process of construction solid waste and its environmental benefits. LCA can assist in identifying carbon emissions and energy consumption during the treatment, reuse, and recycling of construction solid waste, and optimize the resource recovery pathway, thus providing a scientific basis for the recycling of construction solid waste and promoting more environmentally beneficial management strategies. Scholars from various countries have conducted in-depth research. In China, Liu et al. (2024) conducted a study on the application of construction waste glass (WG) in concrete in China by using a comprehensive life cycle assessment and multi-criteria decision analysis (LCA-CDA) within the cradle range, providing a basis for sustainable building material selection [17]. Zhang et al. (2023) demonstrated through LCA and LCC results that the production of recycled aggregates (RAs) using construction and demolition waste (CDW) is environmentally and economically feasible, and RA can generate significant environmental and economic benefits [18]. Liu et al. (2024) analyzed the impact of co-treatment of industrial solid waste with different proportions in urban solid waste incineration plants on the environment and economy through life cycle assessment (LCA). The environmental impact showed a trend of first decreasing and then increasing, with eutrophication potential being the most influential indicator. The study provides a theoretical basis for multi-source waste treatment [19]. Huang et al. (2020) developed a life cycle thinking framework to identify key impacts and corresponding mitigation methods, providing information for building design and material selection and ensuring the effective treatment and recycling of construction and demolition waste [20]. Li et al. (2025) developed a comprehensive BIM-IoT platform for carbon emission assessment and tracking of prefabricated building materials to accurately assess and track carbon emissions in the process of prefabrication of construction projects in real time, and help stakeholders obtain comprehensive information throughout the life cycle of the building [21]. Zhang et al. (2025) used the life cycle assessment (LCA) method to build the carbon emission calculation model of Rac, and the results showed that the mix proportion optimization of Rac showed significant carbon emission reduction potential [22]. In other countries, Jasim et al. (2024) used life cycle cost assessment (LCCA) and life cycle assessment (LCA) methods to analyze the sustainability and cost-effectiveness of using recycled materials in asphalt pavement repairs, emphasizing their environmental advantages and challenges [23]. Hasheminezhad et al. (2024) comprehensively analyzed the environmental impact of recycled aggregate concrete (RAC) and natural aggregate concrete (NAC) by comparing their life cycle assessment (LCA), and found that RAC has significant advantages in reducing the consumption of natural resources and protecting the environment, but its environment efficiency is affected by factors such as transportation distance, transportation mode, and aggregate quality control [24]. Silvestre et al. (2014) focused on waste treatment during the life cycle of building materials and analyzed its maximum potential in the reuse or recycling industry [25]. Hossain et al. (2019) evaluated environmental impacts through multiple stages and explored the alleviating effect of waste material resource recovery on the environmental impact of the building life cycle [26]. Zulco et al. (2020) proposed a life cycle assessment of ornamental stone processing waste (OSPW) in the production of cement-based building materials, aiming to evaluate the impact of ornamental stone processing waste (OSPW) on environmental impact indicators such as global warming potential [27]. Piccardo et al. (2020) analyzed the main energy impacts of different material alternatives in the life cycle when retrofitting existing buildings to meet high-energy performance levels [28]. Honic et al. (2019) generated a Building Information Modeling (BIM)-supported Material Passport (MP) to assess the recycling potential and environmental impact of building materials [29]. Heidari et al. (2020) used energy consumption and carbon emissions as environmental impact assessment indicators and adopted the life cycle assessment method and life cycle cost analysis method to conduct environmental assessment and cost analysis research on recycled aggregate asphalt mixture pavements [30]. Hussain et al. (2023) developed a parametric life cycle carbon assessment (PLCCA) model, which combines a building information model (BIM) and life cycle assessment (LCA) to realize automatic data integration, dynamic calculation, and online carbon visualization [31]. Ahmad et al. (2025) quantified the reuse potential of precast concrete components in Swedish residential buildings through life cycle assessment. The results showed that the reuse of precast concrete components had greater potential to reduce carbon footprint than recycling, but its overall impact on the construction stock was still limited [32]. Hoang et al. (2025) revealed the recycling potential and market prospects of construction solid waste by estimating the supply, demand, and economic status of fixed and mobile concrete waste recycling plants in Hanoi, Vietnam [33]. Therefore, with the increasing awareness of environmental protection and policy support, the LCA method has become an important tool for researchers to evaluate the environmental benefits of products or services. Based on the evaluation results, more effective environmental improvement strategies can be further identified and formulated.

4. Goal and Scope Definition

As the primary step of life cycle assessment, it is crucial to clarify the purpose, object, and system boundaries of the research. This step involves selecting a functional unit, determining the measurement indicators for the inputs and outputs of the evaluation system, and setting conditions such as the time, location, and data quality of the study. By setting these conditions, data can be appropriately converted and standardized, and assumptions are defined to ensure the rationality of the research, enabling the comparison and standardization of the research results.

In this study, the LCA method is adopted to evaluate the environmental benefits during the recycling process of construction solid waste. By constructing two typical comparative models of construction solid waste treatment scenarios, carbon emission data under different treatment methods are analyzed. Due to the complex composition of construction solid waste and the diverse treatment methods, this study simplifies the actual situation and defines the specific evaluation scope. LCA can assist in evaluating the impacts of different treatment methods on environmental benefits such as resource recovery and carbon reduction in this process, providing a scientific basis for the recycling management of construction solid waste and optimizing the treatment pathway.

4.1. Scenario Construction

Construction solid waste mainly stems from the construction, renovation, and demolition processes of new buildings. Its components include waste concrete, mortar, waste metal, blocks, wood, and muck, among others. Different types of buildings and construction processes generate diverse kinds of construction solid waste. However, waste concrete, mortar, blocks, muck, and metals are generally the focal points for recycling. With the continuous development of the construction industry, the output of construction solid waste has been on the rise year by year. Although China started relatively late in the recycling of construction solid waste, driven by scientific research and policies, progress has gradually been made in the recycling treatment of construction solid waste. Typical recycled products such as recycled aggregates have begun to be mass-produced.

• Scenario 1: Simple Landfill

As a traditional non-recycling treatment method, in this scenario, no sorting is carried out at the construction site. All construction solid waste is directly transported to the solid waste landfill for unified landfilling.

• Scenario 2: Recycling Treatment

In this scenario, after pre-treatment (such as rough separation and sorting) at the recycling treatment plant for construction solid waste, materials that can be directly recycled (such as steel, wood, etc.) will be extracted and reused. After the mixed construction solid waste undergoes separation and crushing treatment, toxic and harmful components are separated, and the remaining inert substances such as concrete and masonry are processed into recycled aggregates, which are used to replace or partially replace natural aggregates.

The composition of solid construction waste is complex and diverse. In the actual process of resource utilization and non-resource utilization, corresponding treatment methods are usually selected based on the characteristics of their different components. Even under the two treatment methods of resource utilization and non-resource utilization, the treatment process and results of construction solid waste may differ due to differences in the sources, composition, participants, and methods of production. Given that this study adopts a comparative analysis method to calculate the difference in carbon emissions and environmental impact between two treatment methods under the comparative scenario, therefore, in the context of the same project, only the treatment method of building solid waste is changed, while other processes throughout the life cycle remain consistent. Based on the above considerations, in order to ensure comparability of scenarios and simplify calculations, the constructed scenario has the following characteristics:

(1)

Same origin of construction solid waste: The construction solid waste in two scenarios comes from the same demolition project and has the same composition.

(2)

Equivalent substitution of recycled aggregate and natural aggregate: The produced recycled aggregate can replace natural aggregate in a certain proportion and be used to produce finished concrete, concrete blocks, or other building materials. Under this setting, the proportion and quality of other auxiliary materials such as cement, water, and additives required for the production stage after substitution are the same as those in the natural aggregate scenario, and the production process remains consistent.

(3)

Consistency in the construction and usage processes of building material products: The conditions during the construction and usage processes of the building material products produced under the two scenarios are identical.

(4)

Mixed treatment of construction waste: It is stipulated that construction solid waste after building demolition is not subjected to on-site manual or mechanical sorting but undergoes entirely mixed treatment. Under the two scenarios, the quantity of transported construction solid waste is identical.

4.2. Determining the Scope

This study aims to evaluate the carbon reduction benefits of recycling treatment by comparatively analyzing the carbon emissions of two treatment methods for construction solid waste: simple landfill and recycling. The treatment of construction solid waste and the recycling of renewable resources involve a variety of materials, equipment, and production processes, forming a complete life cycle. To ensure the scientificity and accuracy of the evaluation results, this study needs to clarify the system boundaries and focus on comparing the main differences in carbon emissions between the two treatment methods.

Although carbon emissions occur in the whole process of the generation, treatment, and use of recycled products of construction waste, the focus of calculation is the stage with differences, so the calculation scope needs to be properly defined in the process of setting system boundaries. Since the difference between the simple landfill and recycling treatment scenarios is estimated, and the calculation boundary is defined as the stage where there is a significant difference in carbon emissions between the two scenarios, we simplified the stage where the difference is not obvious, focusing on the comparative accounting of the building materials production stage and the construction solid waste treatment and recycling stage. This method is based on the comprehensive consideration of data availability and research purpose in the actual research. Taking the construction waste generated during the construction or demolition of construction projects as the initial stage, although the transportation distance is an important factor, the transportation processes of the two scenarios are basically the same, and the models of dump trucks are the same. The carbon emissions during transportation are mainly related to the weight of building materials, but not related to the materials and sources of building materials. Therefore, it is assumed that the transportation distance of recycled building materials is the same as that of natural building materials, excluding the different effects of different material transportation processes on carbon emissions in the life cycle, and no accounting comparison of carbon emissions is conducted. As the raw materials of building materials are recycled aggregate and natural aggregate because the same building project follows the unified design and construction standards, the carbon emissions generated in the stage of producing building materials and putting them into construction are basically the same as those in the stage of building demolition, and the differences are mainly reflected in the stages of raw material production and construction waste disposal. According to the similarities and differences between the two scenarios, the system boundary of carbon emission calculation is defined as the production stage of building materials, and the treatment and recycling stage of construction waste. Therefore, this article will focus on comparing the carbon emissions differences between the production process of natural building materials under the simple landfill scenario and the production process of recycled building materials under the resource utilization scenario. Through this comparison, the essential differences in carbon emissions between the two treatment methods can be clearly revealed.

Through the above-defined system boundary, this study can quantify the carbon emission reduction potential of resource-based treatment methods compared to simple landfill treatment methods. This quantitative analysis provides a solid scientific foundation for advancing the resource-based utilization of construction solid waste, offering robust support for policy formulation, industry planning, and corporate decision making in promoting the sustainable treatment of construction solid waste. Thereby, it drives the construction industry toward low-carbon and environmentally friendly development, facilitates the efficient circular utilization of resources, and achieves the harmonious and sustainable development of the economy, society, and the environment.

Figure 1 shows the determination and comparison of system boundaries.

5. Life Cycle Inventory Analysis (LCI)

As the core step of life cycle assessment, it is responsible for collecting and analyzing the data of material inputs and environmental emissions in the product system. Through data collection, applicability testing, calculation, and result categorization, this step comprehensively describes the resource use and environmental impact of the system.

In this study, the environmental benefit evaluation mainly measures the environmental impact of each stage through the difference in carbon emissions, especially the comprehensive accounting of greenhouse gas emissions. The Guidelines for Accounting Methods and Reporting Greenhouse Gas Emissions of Enterprises in Other Sectors of Industry points out that emission sources and gas types include, but are not limited to, CO₂ emissions from fossil fuel combustion, CO₂ emissions during the use of carbonates, CO₂ emissions implicit in the net purchase of electricity and heat by enterprises, CH₄ emissions from anaerobic treatment of industrial wastewater, and the recovery, utilization, and destruction amounts of CO₂ and CH₄. In the scenarios of resource utilization and non-resource utilization of solid waste in construction, the main sources of carbon emissions include energy consumption of vehicles and equipment during transportation and production processes; the implicit carbon emissions generated by purchasing electricity; emissions during the process of simple landfilling and resource utilization of residual landfilling; and the implicit carbon emissions from consuming natural materials. The above-mentioned greenhouse gas emission data forms the quantitative basis for the carbon reduction benefits of this study.

5.1. Life Cycle Inventory Analysis

5.1.1. Greenhouse Gases

The main drivers of the greenhouse effect include carbon dioxide and other gases that absorb and emit infrared radiation. The Kyoto Protocol clearly lists six greenhouse gases to be controlled, including carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O), hydrofluorocarbons (HFC_S), perfluorocarbons (PFC_S), and sulfur hexafluoride (SF₆). In this study, three major greenhouse gases, carbon dioxide, methane, and nitrous oxide, were selected for analysis, considering the relatively large emission and environmental impact factors.

The global warming potential values are used to compare the radiation effects of different greenhouse gases relative to carbon dioxide over a certain period of time. The index assesses the relative impact of other greenhouse gases on climate change by converting their effects into equivalent amounts of carbon dioxide, which is also influenced by the length of time, with the commonly used time frame being 20 years, 100 years, or longer. Therefore, the GWP provides a way to convert the emissions of various gases into a uniform carbon dioxide equivalent for more scientific comparative analysis. Some of the global warming potential values published by the IPCC are shown in

Table 1. Global warming potential (kgCO₂/kg greenhouse gas).

	CO2	CH4	N2O	HFCS	PFCS	SF6
20 Years	1	62	275	9400	3900	15,100
100 Years	1	21	310	11,700	5700	22,200

[34].

According to the calculation method of carbon emissions during the whole life cycle of building materials, the product of different types of greenhouse gas emissions at each stage and their global warming potential value is the carbon dioxide equivalent that can be converted. In line with most international calculations, this paper calculates the global warming potential value of CO₂, CH₄, and N₂O greenhouse gases over a period of 100 years.

5.1.2. Carbon Emission Factors for Fossil Fuels

Fossil fuels, including coal, oil, natural gas, etc., are characterized by their non-renewability and are the main source of global energy consumption. The extraction and use of fossil fuels not only lead to resource depletion but also result in significant greenhouse gas emissions. This study focuses on the greenhouse gas emissions caused by fossil fuel combustion during the transportation and processing of construction waste while excluding emissions from chemical reactions and fuel leaks. In calculating carbon emissions, the energy emission factor is usually used as the base data, which represents the total amount of greenhouse gases emitted per unit of energy from extraction to final use, measured in terms of carbon dioxide equivalent. Although there are certain differences in the energy carbon emission factors released by different international and domestic institutions, this study mainly compares the carbon emission stages with significant differences between resource and non-resource scenarios when evaluating the carbon reduction benefits of the construction waste resource utilization process. Therefore, this study does not consider the carbon emissions from energy production. When selecting carbon emission factors for fossil fuels, this study used the default values of carbon dioxide emission factors provided by international institutions. As carbon emissions from fossil fuels are mainly affected by carbon content, regional differences have a relatively small impact. Zhang (2018) has compiled some greenhouse gas emission factors for fossil fuels released by the IPCC in 2006, as shown in Figure 2 [35].

5.1.3. Electricity Carbon Emission Factors

Electricity is an important energy source commonly used in production and processing. Although electricity is considered a clean energy source that does not directly cause greenhouse gas emissions during use, its carbon emission characteristics are dependent on the way it is produced. Especially relying on thermal power generation, this electricity production is the main source of carbon emissions related to electricity. Due to significant differences in energy structures among different regions, the carbon emissions from electricity are not consistent globally, which makes it difficult to directly apply the carbon emission factor for electricity internationally. Therefore, in order to accurately evaluate the carbon emission impact of electricity, it is necessary to consider the specific situation of electricity production and supply. Based on official data from the Ministry of Ecology and Environment, the National Bureau of Statistics, and other sources, the average carbon dioxide emission factors were calculated. In 2024, the national, regional, and provincial average carbon dioxide emission factors for electricity consumption were released for reference in calculating carbon dioxide emissions. Detailed data can be found in Figure 3 and Figure 4.

5.2. Functional Unit

In this study, recycled aggregate is selected as a typical method for the resource-efficient treatment of construction waste, and the carbon emissions differences between the resource utilization and non-resource utilization treatment scenarios are explored to comprehensively evaluate the environmental benefits. The functional unit set in the study is to process 1 ton of mixed construction waste that has not been sorted on-site and is directly generated.

5.2.1. Carbon Emissions in the Building Material Production Stage

In this study, the carbon emissions of the building materials production stage are considered under two scenarios. Based on the defined system boundary, the production of building materials involved in both scenarios mainly consists of the mining and transportation of natural aggregates.

(1)

Simple Landfill Scenario

In this scenario, natural aggregates are mainly used to meet the production needs of concrete or other building materials. Since the recycled aggregates can replace part of the natural aggregates in the production process, and other auxiliary materials such as the cement and its proportion used in the production process remain consistent. Therefore, the difference in carbon emissions in the production process is mainly reflected between the recycled aggregate produced by the treatment of 1 ton of construction waste and the same amount of natural aggregate.

Carbon emissions C_LP of simple landfill scenario in the production stage of building materials:

C_LP = C_tran + C_prod

(1)

where C_tran refers to the carbon dioxide equivalent value generated by the transport of natural aggregates to the production plant of finished building materials; C_prod refers to the carbon dioxide emission equivalent (tCO_2e) from the use of various energy sources during the extraction and production of natural aggregates.

C_tran = a_dLc_d

(2)

$${\mathrm{C}}_{\mathrm{prod}}={\sum }_{i=1}^n\left(a_i{M}_{trg}{C}_i\right)+\mathrm{e}{\mathrm{M}}_{\mathrm{t}\mathrm{r}\mathrm{g}}\mathrm{f}$$

(3)

where a_d is the diesel consumption per unit distance during the transportation of natural aggregates (kg/km); L is the total round-trip distance (km); and c_d is the carbon emission coefficient of diesel fuel (kgCO_2e/kg).

a_i represents the i-th energy consumption per unit of natural aggregate during the production process; M_trg is the amount of natural aggregate required for the replaced part (kg); c_i is the carbon emission coefficient of the i-th energy source; e is the power consumption during the production process of natural aggregate mining per unit (kW·h/kg); and f is the carbon emission factor for electricity.

(2)

Production of recycled aggregates from construction waste

In this scenario, recycled aggregates are used to replace a certain proportion of natural aggregates in finished building materials such as concrete. Based on the focus and scenario characteristics of this study, it is assumed that the production process of natural aggregates that have not been replaced has the same carbon emissions in the two scenarios. Therefore, in this scenario, the carbon emissions during the production stage only consider the production of recycled aggregates and are discussed under the treatment and recycling stage of construction waste.

5.2.2. Carbon Emissions During the Transportation, Construction, and Use Stages of Building Materials

The transportation phase of building materials involves the process of transporting finished building materials such as concrete and blocks from the manufacturer to the construction site. The construction and use stage of building materials refers to the entire process of applying finished building materials products to construction and putting them into use to achieve their functional use in buildings. According to the analysis of the system boundary in the previous text, it can be seen that the carbon emissions during the transportation, construction, and use stages of building materials are basically the same in the comparative scenario. Therefore, this study does not include them in the accounting scope.

5.2.3. Carbon Emissions During the Demolition Phase of Buildings

The demolition phase of a building refers to the stage when the building reaches its designed service life or needs to be demolished due to the loss of functional use, resulting in the destruction of the building structure and the complete generation of construction waste. Carbon emissions are mainly related to the energy consumption of construction machinery. Due to the fact that the background of construction waste generation in the two scenarios is the same in the comparative analysis, the carbon emissions at this stage are not included in the accounting scope of this study.

5.2.4. Carbon Emissions During the Construction Waste Treatment and Recycling Stage

The construction waste treatment and recycling stage mainly includes the process of transporting construction waste to landfills or resource treatment plants in two scenarios, as well as the process of crushing and screening construction waste in resource treatment plants to generate recycled aggregates.

(1)

Simple landfill of construction waste

This scenario mainly involves the carbon dioxide equivalent (C_tran) emitted from the transportation of construction waste to landfills, as well as the carbon dioxide equivalent (C_land) converted from greenhouse gases contained in the landfill gas generated from the construction waste landfill.

Carbon emissions C_LR of simple landfill scenario in the treatment and recycling stages:

C_LR = C_tran + C_land

(4)

C_tran = a_dLc_d

(5)

where a_d is the diesel consumption per unit distance during the transportation of construction waste to landfills (kg/km); L is the total round-trip distance (km); c_d is the carbon emission coefficient of diesel fuel (kgCO_2e/kg).

$${\mathrm{C}}_{\mathrm{land}}={\sum }_{i=1}^n{k}_i{M}_{GF}{\mathrm{G}\mathrm{W}\mathrm{P}}_{\mathrm{i}}$$

(6)

where k_i is the amount of i-th landfill gas generated per unit mass of construction waste; M_GF is the total amount of construction waste landfilled (kg); and GWP_i is the global warming potential value of the i-th greenhouse gas. The landfill gases considered in this paper mainly include CO₂, CH₄, and N₂O. Referring to the data in the database, the amount of CO₂ landfill gas produced by landfilling 1 ton of unit mass construction waste is 2.73 × 10⁻¹ kg, the amount of CH₄ landfill gas produced is 1.75 × 10⁻² kg, and the amount of N₂O landfill gas produced is 3.23 × 10⁻⁶ kg.

(2)

Production of recycled aggregates from construction waste

The carbon emissions during the recycling and treatment stage of construction waste in the context of resource utilization mainly involve the process of transporting construction waste back to the resource utilization plant, as well as the entire process of crushing and screening construction waste to generate recycled aggregates. This includes carbon emissions from diesel consumption in transportation vehicles, as well as carbon emissions from fossil energy and electricity consumption in transportation equipment and equipment used in resource utilization production. At the same time, the resource production is accompanied by the production of residue, and finally, the residue that cannot be treated and utilized needs to be transported to a landfill. C_RR of carbon emissions in the treatment and recycling stage of the resource scenario:

C_RR = C_tran + C_revi + C_land

(7)

where C_tran refers to the carbon dioxide equivalent value generated during the transportation of construction waste to resource recycling plants; C_revi refers to the carbon dioxide equivalent value generated during the entire process of recycling construction waste into recycled aggregates in the recycling plant; and C_land refers to the carbon dioxide equivalent value generated by the transportation and landfill of residues that cannot be recycled during the process of resource utilization.

C_tran = a_dLc_d

(8)

where a_d is the diesel consumption per unit distance during the transportation of construction waste to the resource utilization plant (kg/km); L is the total round-trip distance (km); and c_d is the carbon emission coefficient of diesel fuel (kgCO_2e/kg).

$${\mathrm{C}}_{\mathrm{revi}}={\sum }_{i=1}^n\left(a_i{M}_{GF}{C}_i\right)+{\mathrm{e}\mathrm{M}}_{\mathrm{G}\mathrm{F}}\mathrm{f}$$

(9)

where a_i represents the i-th energy consumption per unit of recycled aggregate during the production process; M_GF refers to the total amount of construction waste (kg) that is recycled to the resource treatment plant for resource utilization; C_i is the carbon emission coefficient of the i-th energy source (kgCO_2e/kg); e is the power consumption during the production process of recycled aggregates per unit (kW·h/kg); and f is the carbon emission factor for electricity.

$${\mathrm{C}}_{\mathrm{land}}={\sum }_{j=1}^n\left(k_j{m}_w{GWP}_j\right)+{\mathrm{a}}_{\mathrm{d}\mathrm{w}}{\mathrm{L}}_{\mathrm{w}}{\mathrm{c}}_{\mathrm{d}}$$

(10)

where k_j is the amount of j-th landfill gas produced per unit mass of residue landfill; m_w is the total amount of landfill residue (kg); and ${GWP}_j$ is the global warming potential value of the j-th landfill gas. Landfill gas mainly includes CO₂, CH₄, and N₂O; a_dw is the diesel consumption per unit distance during the transportation of residue to the landfill site (kg/km); and Lw is the total round-trip distance (km).

5.3. Accounting Model for Carbon Emission Reduction Benefits of Construction Waste Resource Utilization

The paper aims to explore the differences in life cycle carbon emissions of construction waste treatment under two scenarios: resource utilization and non-resource utilization, and analyze the carbon reduction benefits of building waste resource utilization in order to provide a basis for environmental benefit assessment. Therefore, this study did not conduct a detailed exploration of the full life cycle carbon emissions for each scenario separately. Instead, the carbon emission calculations for each stage mentioned in the previous analysis were summarized, and the differences between the two scenarios were calculated to estimate the carbon reduction benefits of the resource utilization treatment method. The following is a carbon emission reduction benefit evaluation model for construction waste under the scenario of resource utilization:

C’ = C_LP + C_LR − C_RR

(11)

where C_LP represents the carbon emissions during the production stage of building materials in a simple landfill scenario, C_LR represents the carbon emissions during the processing and recycling stage in a simple landfill scenario, and C_RR represents the carbon emissions during the processing and recycling stage in a resource utilization scenario. C’ is the difference in carbon dioxide equivalent between the resource utilization and non-resource utilization processes of construction waste in the simplified model. If C’ > 0, it indicates that the resource utilization treatment of construction waste has certain carbon reduction and environmental benefits. The larger the value of C’, the more significant the carbon reduction benefits.

6. Life Cycle Impact Assessment

Based on life cycle inventory analysis, the purpose of this stage is to identify and evaluate potential environmental impacts within the research scope. By qualitatively or quantitatively evaluating the environmental impact of each part of the research object, the specific degree of impact of each link on the environment can be accurately described. On the basis of inventory analysis and impact assessment, a comprehensive evaluation and explanation of energy consumption and environmental impact throughout the entire life cycle process is conducted. The purpose is to identify the main factors that contribute to environmental impact, identify opportunities for improvement, and propose strategies to reduce resource consumption and environmental impact. Ultimately, a structured report and implementation recommendations will be formed to guide future environmental management practice decisions and promote continuous environmental improvement.

6.1. Building Material Production Stage

When using the simple landfill method for disposal, it is necessary to calculate the production stage of natural aggregates. When dealing with resource utilization, the production of recycled aggregates is included in the calculation of the processing and recycling stages. In the comparative scenario, the physical quantity of natural aggregates used for accounting is the same as the amount of recycled aggregates generated from all construction waste. Assuming that the components of construction waste such as waste concrete, crushed stone, and building blocks no longer contain other impurities, and that recycled aggregates mainly come from these components, it is believed that the production of recycled aggregates can be calculated based on the proportion of these components. The research results of Zhang (2016) and Wan et al. (2003) show that when recycling construction solid waste through screening, crushing, and dust removal, 65% recycled coarse aggregate, 33% recycled fine aggregate, and 2% fine powder can be produced per unit mass of construction solid waste [36,37]. A total of 100 tons of construction waste can generate 98 tons of recycled aggregate, with a residue amount of approximately 2 tons. The natural aggregate M_trg required for the simple landfill method is 98 tons. Assuming that a 25 t dump truck is used for transportation, according to statistical calculations, the comprehensive fuel consumption is 1.28 L/100 km·t. The estimated transportation distance is 25 km. According to the actual measurement and recorded data of an enterprise in Miyun District, Beijing, the equipment information required for the production of natural aggregates is shown in Figure 5. The equipment information required for the production of natural aggregates is shown in Figure 5. The equipment for producing natural aggregates includes excavators and loaders, and the calculated unit fuel consumption for producing natural aggregates is 0.21 kg/t. Due to the different processing capabilities of each device, the most critical sand-making machine has a processing bottleneck capacity of 120 t/h, which means that the bottleneck processing capacity for each device to start simultaneously per hour is 120 t. Without considering equipment load and wear, calculated based on the upper limit of the equipment power range, the unit power consumption is 7.77 kW·h/t. The power carbon emission factors used in this article are based on data from the North China region in 2022. The energy consumption during the production stage of natural aggregates is calculated to be 53.31 kg of transportation diesel, 20.58 kg of production diesel, and 761.46 kW·h of production electricity. According to Formulas (2) and (3), the carbon dioxide equivalent emitted from transporting natural aggregates is calculated to be 165.8 kgCO_2e, and the carbon dioxide equivalent emitted from producing natural aggregates is calculated to be 579.97 kgCO_2e. The total carbon dioxide equivalent C_LP emitted from producing natural aggregates under the simple landfill method is 745.77 kgCO_2e.

6.2. Processing and Recycling Stage

(1)

Simple landfill

The carbon emissions under the simple landfill method mainly come from the transportation of construction waste and the greenhouse gas emissions from landfill gas. Assuming a one-way transportation distance of 25 km for construction waste, using a 25 t dump truck for transportation, with a comprehensive fuel consumption of 1.28 L/100 km·t, and a total of 100 t of construction waste to be buried, according to Formula (5), the diesel consumption during the transportation of construction waste is 54.4 kg, and the CO₂ equivalent generated during transportation is 169.18 kgCO_2e.

Another part of carbon emissions comes from landfill gas. According to the landfill gas production of unit construction waste, the greenhouse gas carbon dioxide equivalents generated during CO₂, CH₄, and N₂O landfills are calculated to be 27.3 kg, 36.75 kgCO_2e, and 0.10013 kgCO_2e, respectively. According to Formula (6), the carbon dioxide equivalent generated during construction waste landfill is calculated to be 64.15 kgCO_2e. The calculation shows that when the project adopts the simple landfill method to treat construction waste, the total carbon emissions during the treatment and recycling stages are 233.33 kgCO_2e.

(2)

Resource-based production of recycled aggregates

The carbon emissions generated by the resource utilization of construction waste mainly come from the transportation of construction waste, the production of recycled aggregates, and the landfill of residues. The one-way transportation of construction waste to the resource utilization treatment plant is 25 km, with a unit fuel consumption of 1.28 L/100 km·t set to be the same as that of construction waste transportation vehicles.

The equipment information required for the production of recycled aggregates is shown in Figure 6.

Due to the different processing capabilities of each device, the most critical ones, the wind and magnetic separators, have a processing bottleneck capacity of 200 t/h, which means that the bottleneck processing capacity for each device to start simultaneously per hour is 200 t. Without considering equipment load and wear, the upper limit of the equipment power range is used for calculation. Based on data analysis, the estimated electricity consumption per unit of construction waste resource production is 2.51 kW·h/t. The fuel consumption in the production process of recycled aggregates mainly comes from the loader transporting garbage to the production line and finished products to the material warehouse. Based on the actual hourly fuel consumption and output of the case, the average fuel consumption is calculated to be 0.18 kg/t. In addition to crushed stone, concrete, and other components used for producing aggregates, metal, wood, and other components are also sorted and recycled during the production process, leaving behind non-recyclable residues. As mentioned earlier, the residue rate of crushed stone, concrete, etc., is about 2%. Therefore, 100 tons of construction waste can generate 98 tons of recycled aggregates, with a residue amount of about 2 tons. The residue will be concentrated in the factory and transported to the nearest landfill site for burial. The landfill site is 25 km away from the resource utilization treatment site, and the unit fuel consumption is set to 1.28 L/100 km·t, which is the same as that of construction waste transportation vehicles.

We calculated the carbon emissions of each part according to Formulas (8), (9) and (10), respectively. The final calculation shows that the energy consumption in the process of resource utilization for producing recycled aggregates is 54.4 kg of transportation diesel, the carbon emissions generated from the transportation of construction waste are 169.18 kg CO_2e, the production diesel consumption is 18 kg, and the production electricity consumption is 251 kW·h. According to the formula, the carbon emissions generated during the process of resource-based production of recycled aggregates are 226.06 kg CO_2e.

The other part of carbon emissions is the carbon emissions generated by residual landfill gas. We calculated the greenhouse gases generated during the landfill of CO₂, CH₄, and N₂O based on the amount of landfill gas produced per unit of residue. We set the global warming potential values for CH₄ to 21 kgCO₂/kg and N₂O to 310 kgCO₂/kg, and calculated the carbon emissions generated during residue transportation and landfill as 4.67 kgCO_2e according to the formula. The final calculation shows that the total carbon emissions (C_RR) generated during the processing and recycling stages of the project when using resource-based methods to treat construction waste is 399.91 kgCO_2e.

6.3. Interpretation of Data Sources and Error Values

To minimize variable interference, the data in this study were sourced from on-site actual measurements and recorded data of an enterprise in Miyun District, Beijing. The data were collected from the construction solid waste treatment and recycling processes of the same building project, which adheres to unified design and construction standards, with building materials conforming to identical specifications and quality requirements. Based on this framework, this study comprehensively and systematically organized the key parameters of data collection and measurement information employed for different equipment, such as data acquisition forms, sampling time spans, type of measurement instruments, and data verification methods. Specifically, the energy consumption types of the equipment primarily included diesel and electricity. For electricity consumption measurement, this study utilized industrial-grade standard precision electricity meters equipped with real-time intelligent data acquisition and feedback capabilities to monitor power consumption and load characteristics. Diesel consumption was measured using fuel level gauges, with real-time data verification through these instruments and manual compilation of aggregated information. These key parameters and measurement details have been systematically organized and presented in tabular form. The data collection and measurement information are shown in

Table 2. Data collection and measurement information.

Equipment	Data Acquisition Form	Sampling Time Span	Type of Measuring Instrument	Data Validation Method
Dump Truck	Semi-auto	Single	Fuel level gauges	Diesel oil consumption Fuel level gauges check
Excavator	Semi-auto	Single	Loader electronic scale Fuel level gauges
Loader	Semi-auto	Single
Vibrating Feeder	Auto	Real-time	Ordinary precision electric meter Electronic scale Power analyzer Sensor	Power consumption Demand billing
Hammer Crusher (Cone Crusher)	Auto	Real-time
Shaping Crusher (Jaw Crusher)	Auto	Real-time
Sand Making Machine	Auto	Real-time
Winnowing Machine	Auto	Real-time
Magnetic Separator	Auto	Real-time
Belt Conveyor	Auto	Real-time
Vibrating Screen	Auto	Real-time

.

Within the same regional boundaries, the same building experiences relatively consistent natural factors such as weathering and corrosion during its usage. Even over long-term use, the composition and quality of solid waste from the same building project remain highly stable. The selection of homogeneous buildings aims to minimize uncertainties arising from differences in waste composition and quality, thereby ensuring data accuracy and research reliability. These data include equipment usage during processing, energy power consumption, and waste generation volume. Excluding indicators such as carbon emission coefficient and carbon emission impact factors, the equipment processing capacity is reflected as the maximum error value in this study, thereby affecting power.

Table 3. Equipment processing capacity comparison for natural and recycled aggregates (t/h).

Equipment	Natural Aggregate Production Processing Capacity (t/h)	Recycled Aggregate Production Processing Capacity (t/h)
Vibrating Feeder	±13.51%	±35.71%
Hammer Crusher (Cone Crusher)	±13.51%	(±44.12%)
Shaping Crusher (Jaw Crusher)	±14.29%	(±26.67%)
Sand Making Machine	±20%	——
Winnowing Machine	——	±97.04%
Magnetic Separator	——	±25%
Belt Conveyor	±0%	±0%
Vibrating Screen	±26.83%	±21.18%

describes the comparison of error values between natural aggregates and recycled aggregates in terms of equipment processing capacity.

7. Life Cycle Interpretation

7.1. Calculation Results

The benefits of recycling carbon emission reduction in construction waste mainly come from the corresponding value of carbon dioxide emission reduction under the comparison of recycling scenario and non-recycling scenario. According to the analysis and calculation results, the carbon emission generated by simple landfill treatment is 979.10 kgCO_2e, and the carbon emissions generated by the recycling production and recycling orthopedic treatment were 399.91 kgCO_2e. According to Formula (11), the carbon emission reduction benefit of recycling construction waste can be calculated, and the project can reduce the emission of 579.19 kgCO_2e by recycling construction waste treatment, accounting for about 59.16% of the total amount within the accounting scope, and the carbon emission reduction benefit is obvious. For details, refer to

Table 4. Summary of comparison results (kgCO_2e).

Stage	Natural Aggregate (kgCO2e)	Recycled Aggregate (kgCO2e)
Production Stage	695.77	226.06
Treatment and Recycling Stage	233.33	173.85
Total	979.10	399.91

.

7.2. Result Analysis

The resource utilization of construction solid waste has significant carbon emission reduction benefits, which can effectively reduce carbon emissions during the treatment process of construction solid waste. By converting building solid waste into reusable resources such as recycled aggregates, not only does it reduce the large amount of greenhouse gas emissions caused by traditional disposal methods such as landfilling, but it also avoids the additional carbon emissions caused by the extraction of raw materials such as natural aggregates. This resource utilization method not only reduces the negative impact of waste on the environment, but also promotes the recycling of resources, improves resource utilization efficiency, reduces dependence on natural resources, and is of great significance for achieving carbon reduction goals. It provides an effective way for the construction industry to achieve sustainable development, helps promote the transition of the entire society to a low-carbon economy, and makes positive contributions to addressing climate change.

7.3. Parameter Sensitivity Analysis

To explore the extent to which changes in energy consumption parameters affect the life cycle carbon emissions in non-resource and resource utilization scenarios, this study conducted a sensitivity analysis of key parameters. The scenarios for the sensitivity analysis were set by fluctuating fossil energy consumption by 10%, 20%, and 30%, respectively, and the carbon emission data were used as the calculation results to quantitatively analyze the changes in carbon emissions under different scenarios when fluctuations occur.

The results show that, under different scenarios, when considering the fluctuation in fossil energy consumption as an interfering factor, the carbon emission reduction advantage of resource utilization still exists. The gap in carbon emissions between the non-resource and resource utilization scenarios gradually widens. When the fluctuation in fossil energy consumption reaches 30%, the resource utilization of construction waste still shows carbon emission reduction benefits, and the carbon emissions in the resource utilization scenario become more significantly affected by the scenario fluctuations, effectively reducing carbon emissions in the process of construction waste treatment. This further proves that resource utilization has robustness and superiority in carbon emission reduction. Therefore, in the actual decision making for construction solid waste treatment, priority should be given to optimizing the energy structure and combining it with resource utilization methods, which is an effective way to reduce carbon emissions. When facing the uncertainty of energy consumption growth, the resource utilization method is of great significance for reducing carbon emissions (as shown in Figure 7).

8. Discussion on Economic Benefits

8.1. Cost Comparative

8.1.1. Comparison of Production Costs

There are differences in the production costs of recycled aggregates and natural aggregates, which are mainly determined by factors such as raw material acquisition, processing, transportation, and labor costs. The production of native building materials (such as natural sand and gravel, cement, etc.) highly relies on natural resource extraction, and their extraction costs increase exponentially with resource depletion. The extraction process involves a large amount of energy consumption and environmental damage, and the cost of raw materials is significantly affected by resource reserves and transportation distance. In contrast, the raw materials for recycled building materials mainly come from the resource utilization of construction waste, which has lower production costs than natural aggregates, and can shorten transportation radius and reduce transportation costs through localized processing. Therefore, the initial cost of recycled building materials is lower. However, sorting, crushing, screening, and pollutant removal during the processing requires certain equipment and labor costs, and the cost of technology research and development is higher than that of traditional processes. Therefore, although recycled aggregates have the advantage of saving raw material costs in the production process, their overall production cost is still limited by factors such as processing technology and facility investment.

8.1.2. Comparison of Service Life and Maintenance Costs

The service life and maintenance costs of building materials directly affect the overall economic benefits. Natural aggregates generally possess high strength and stability, thus having a relatively long service life in construction projects. For example, native building materials such as natural stone and high-quality steel can maintain good performance for many years under normal usage conditions, and do not require frequent replacement or maintenance during their service life. In contrast, recycled aggregates face lower strength and durability in engineering applications under high loads or special environments, which to some extent affects their service life. However, with the continuous development of recycled aggregate technology, product performance has gradually approached or exceeded the standards of natural aggregates, thereby reducing the impact of differences in service life on costs. In terms of maintenance costs, structures made from natural aggregates are less prone to cracking, damage, and other issues, while recycled aggregates require more maintenance and repair work in their initial application. With the improvement in the quality of recycled aggregates, the corresponding maintenance cost difference gradually narrows. Buildings using recycled aggregates can reduce resource consumption and environmental burden in the long run, ultimately reducing total costs. For example, Wang (2024) et al. pointed out that when the recycled fine aggregate completely replaces the natural fine aggregate and the fly ash content is high, the recycled high-ductility cement composite (R-HDCC) shows the best comprehensive advantages in environment efficiency, economy, and performance; its carbon footprint and energy consumption are significantly reduced; the cost is reduced; and it has good ductility and bending resistance [38]. Omid Aghamohammadi et al. (2024) developed a new type of environmentally friendly high-strength concrete, which uses calcium oxide-activated slag instead of cement, and partially replaces aggregates with rubber powder and PET particles. The environmental performance is significantly better than that of ordinary high-strength concrete, but the compressive strength and flexural strength decrease with increasing rubber and PET contents. They also pointed out that introducing recycled slag as a substitute for concrete cement in high-strength concrete is an economically sustainable method [39]. Ling et al. (2024) pointed out that architects can prevent waste by upgrading recycled metals and providing unique building components such as discarded shipping containers or recycled metal panels. Generally speaking, recycling metals not only saves resources but also strengthens the structure and extends its lifespan [40].

8.2. Market Demand Comparison

8.2.1. Consumer Preferences

Natural aggregates are widely favored by consumers due to their stable performance and high quality, and have a deep historical foundation and extensive market trust in the construction industry. Consumers have a higher awareness of natural aggregates and are more inclined to use materials that have been validated for a long time when choosing building materials. Consumers generally believe that natural aggregates can provide reliable building quality assurance and reduce risks caused by material issues, which to some extent limits the market promotion of recycled building materials. Oberender et al. (2024) pointed out that recyclable building products have not yet been launched globally, and expanding recycling in this sector depends on whether consumers accept the use of recycled and reclaimed products [41].

But, with the enhancement in environmental awareness, more and more consumers have begun to pay attention to the environmental efficiency of building materials. Consumers’ preference for building materials products is shifting from single functionality to composite value, and recycled aggregates have become a key choice due to their compatibility with the “dual carbon” goal. Some consumers are willing to pay higher prices for environmentally friendly building materials, especially in green building projects. For example, the proportion of recycled aggregates used in some green building projects is gradually increasing, indicating that consumers’ acceptance of environmentally friendly building materials is gradually improving. According to the analysis report on the current situation and future development trend of the green building material industry from 2024 to 2029, the market scale of green building materials in China has reached CNY 202.41 billion in 2023, with a year-on-year increase of 19.17%. It is estimated that the annual operating revenue of green building materials will exceed CNY 300 billion by 2026, with an average annual growth rate of more than 10% from 2024 to 2026. Despite increasing environmental awareness, consumers still have doubts about the quality and performance of recycled aggregates. Some recycled building materials may have slightly lower strength, durability, and appearance than natural aggregates. For example, the strength and durability of recycled concrete may be affected by the quality of raw materials, while the appearance and dimensional accuracy of recycled bricks may not be as good as that of native bricks. Moreover, the application history of recycled aggregates is relatively short, and there is a lack of relevant popular science education, resulting in limited consumer understanding of them.

8.2.2. Industrial Chain

The stakeholders of green buildings primarily include consumers, building material manufacturers, design institutes, supervisory units, developers, consulting firms, property management entities, and other participants. He et al. (2024) employed a multi-player quantum game theory approach to analyze the interest entanglement among developers, general contractors, and building material suppliers in advancing green building development. The results indicate that during green building construction, the entanglement of interests among stakeholders can effectively prevent betrayal and establish an “entanglement treaty” among them, which holds significant importance for encouraging active participation in green building initiatives [42]. Currently, various stakeholders of green building in China have different goals and expectations for green building projects.

As the main implementers of green building development, developers’ willingness to develop green buildings directly affects the development of the green building industry chain. Real estate developers will comprehensively consider factors such as cost, quality, performance, and market demand when choosing building materials. For natural building materials, due to their stable quality, reliable performance, and mature supply system in the market, developers are more confident when choosing. For recycled building materials, developers need to comprehensively evaluate their cost-effectiveness and market acceptance. Some developers actively adopt recycled building materials in order to meet the requirements of green building certification or respond to government environmental policies. But, in some projects with strict cost control, developers may have concerns about the high cost of recycled building materials.

When designing a building, the design unit will choose suitable building materials based on the functional requirements, structural features, and owner’s requirements of the building. For natural building materials, design units have rich design experience and mature design standards, which can ensure the safety and reliability of buildings. For recycled building materials, design units need to conduct in-depth understanding and research on their performance to ensure their applicability and safety in design. At the same time, design units will actively promote the application of recycled building materials based on market demand and environmental requirements.

Contractors will select suitable building materials based on design requirements and construction standards during the construction process. For natural building materials, contractors have mature construction techniques and experience, which can ensure construction quality and progress. For recycled building materials, contractors need to evaluate and test their construction performance to ensure the feasibility and reliability of the construction. In addition, contractors will also pay attention to the cost and supply stability of recycled building materials to avoid construction delays and cost increases caused by material issues.

Therefore, the coordination mechanism in the green building material industry chain is influenced by the differing objectives of stakeholders and relies on the multi-dimensional integration of policy mandates, technical standards, and market drivers. Significant differences exist between upstream and downstream entities in terms of risk preferences and price expectations. As the implementing entity, developers need to balance the selection of recycled building materials between meeting green building certification requirements, responding to environmental policies, and controlling project costs. Their risk preferences are reflected in their dependence on stable quality and mature supply of natural building materials, as well as a cautious evaluation of the cost-effectiveness and market acceptance of recycled building materials. Price expectations are prone to concerns due to the high short-term costs of recycled building materials. Design units need to break through their reliance on mature design experience of natural building materials and conduct in-depth research on the performance of recycled building materials to ensure design applicability and safety. They can use green building standards (such as LEED/BREEAM) to force the adaptation of recycled building materials technology, but they need to rely on third-party certification to solve performance doubts. The risk focus is on whether the material performance meets the design specifications. Contractors, based on the maturity of construction technology and schedule assurance, are highly sensitive to the construction performance and supply stability of recycled building materials, and value the direct impact of material costs on construction costs in price expectations. Overall, the synergistic efficiency of information sharing, technical standard integration, and cost transmission mechanism among the three determines the actual acceptance and application depth of recycled building materials in the industry chain.

8.2.3. Policy Impact

The production and use of natural aggregates are subject to certain policy restrictions, mainly to protect natural resources and reduce environmental impact. For example, ore mining requires strict approval and environmental assessment to reduce damage to the ecological environment. The regulatory support for natural aggregates focuses on collection and environmental protection, strictly regulating the environmental impact caused by natural aggregate mining, and promoting the green transformation of the construction industry. The government does not have any specific incentive policies for the use of natural aggregates, but in some infrastructure projects, natural aggregates are still the preferred choice mainly because their performance and quality can meet the strict requirements of the project.

The government has introduced a series of policies to encourage the resource utilization of construction waste and the production and use of recycled aggregates. These policies include tax incentives, fiscal subsidies, priority procurement, etc. For example, Europe, Japan, and the United States not only strictly regulate the disposal of construction solid waste through legislation, but also promote the development and application of recycling technology through incentive policies. Mike et al. (2019) summarized and classified the construction waste recycling management policies and measures in countries such as Japan and the Netherlands, and analyzed the policy measures that may be applicable to developing countries and low- and middle-income countries. They believed that combining different policies would be more effective [43]. Tangtinthai et al. (2019) summarized the successful experiences of the UK in policies and taxes related to construction waste recycling, and combined material flow analysis with policy impact analysis, pointing the way towards achieving the goals of construction waste reduction and recycling [44]. Beijing gives 30% investment subsidies to construction waste recycling enterprises, and the district government gives 22.4 CNY/t subsidies to recycling enterprises. These policies not only promote the market development of recycled aggregates, but also reduce the amount of construction waste landfilled and lower the exploitation of natural resources. In addition, the promotion of green building standards such as Leadership in Energy and Environmental Design (LEED) has also had a positive impact on the market demand for recycled aggregates. Green building projects typically require the use of a certain proportion of recycled aggregates to reduce carbon emissions and resource consumption. Therefore, the support of policies and regulations is a key element in promoting market development, among which policy incentives for recycled aggregates have a significant effect on improving market penetration and acceptance.

8.2.4. Product Acceptance

Natural aggregates have a high acceptance in the construction industry, mainly due to their mature technology and stable performance. The acceptance of natural aggregates is influenced by industry standards and specifications, and many construction projects’ design and construction specifications explicitly require the use of natural aggregates that meet specific standards. The long-term usage habits of natural aggregates in the construction industry have also to some extent affected their market acceptance. Builders and homeowners tend to use natural aggregates that have been validated for a long time when selecting materials to ensure the safety and durability of the building.

The acceptance of recycled aggregate products is relatively low, mainly due to the uncertainty of their performance and quality. Some recycled aggregates may have slightly lower strength, durability, and appearance than natural aggregates. The market promotion of recycled aggregates still faces the problem of insufficient consumer awareness. Many builders and homeowners have a limited understanding of recycled building materials and have doubts about their performance and quality. This results in a lower acceptance of recycled aggregates in the market and a relatively limited range of applications. However, with the advancement in technology and the promotion of policies, the performance and quality of recycled building materials are gradually improving, and their market acceptance is also gradually increasing.

8.3. Long-Term Benefit Comparison

The analysis of long-term economic benefits not only needs to focus on direct costs and benefits, but also needs to comprehensively consider the long-term impact of resource scarcity, externalities, technological progress, and market dynamics on economic behavior. In the comparison between recycled aggregates and natural aggregates, this multi-dimensional analysis is particularly important.

(1)

From the perspective of resource scarcity, natural aggregates rely on limited natural resources, and the market supply–demand imbalance caused by resource scarcity will lead to price fluctuations. In the long run, this upward trend in costs will pose a serious challenge to the economic sustainability of enterprises and industries that rely on natural aggregates. In contrast, the raw materials for recycled aggregates mainly come from construction waste, and their supply is relatively stable and renewable, which can reduce the cost risks caused by resource scarcity in the long run.

(2)

From an external perspective, the production process of natural aggregates often comes with high energy consumption, carbon emissions, and environmental pollution. These negative externalities not only cause damage to the environment, but may also lead to an increase in social costs, such as natural disaster losses caused by climate change and health problems caused by environmental pollution. In the long run, these externalities will be transformed into economic costs for enterprises through policies, regulations, tax adjustments, and social responsibility requirements. The production process of recycled aggregates has significant positive externalities, and its resource recycling mode can reduce waste landfill and carbon emissions, making positive contributions to environmental protection and sustainable development. This positive externality will be transformed into an increase in social value in the long run, which will then bring additional economic benefits to recycled aggregate enterprises through policy incentives, market recognition, and other means.

(3)

From the perspective of technology and long-term competitiveness, the recycled aggregate industry is in a rapid development stage, and the continuous progress of technology has gradually brought its performance and quality closer to or even surpassing that of native building materials. In the long run, technological innovation in recycled aggregates will continuously reduce their production costs, improve production efficiency, and expand their application scope. Therefore, in terms of long-term competitiveness, technological advancements in recycled aggregates will give them a more advantageous position in the market.

(4)

From the perspective of market dynamics, as the global emphasis on sustainable development continues to increase, consumers’ demand for environmentally friendly building materials will continue to grow. In the long run, the market potential of recycled aggregates is enormous, and its market share will continue to expand with the improvement in consumer awareness and technological progress. In addition, the support of policies and regulations will also provide strong guarantees for the development of recycled aggregates. This will further promote the market penetration rate of recycled building materials and reduce the operational risks of enterprises. In terms of long-term returns, recycled aggregate enterprises will benefit from the growth in market demand and the cost reduction brought about by technological progress, achieving a higher return on investment.

Overall, recycled aggregates have significant advantages in long-term economic benefits: its circular utilization mode of resources can reduce the cost risk caused by resource scarcity; its positive externality will be transformed into an increase in social value, thereby bringing additional economic benefits to the enterprise; its technological progress will continuously reduce production costs, improve production efficiency, and expand its application scope; and its market potential is enormous and will benefit from the improvement in consumer awareness and the support of policies and regulations. In contrast, the natural aggregate industry faces many challenges in terms of resource scarcity, environmental costs, policy risks, etc., and its long-term economic benefits will be greatly limited.

9. Countermeasures and Suggestions

The resource utilization system of solid waste in China’s construction industry is still in its infancy, and its core technological bottlenecks mainly lie in the physical and chemical performance shortcomings of recycled building materials, limitations in engineering application scenarios, and insufficient market competitiveness. This dual constraint of technology and economy has led to the lack of large-scale application in this field, and there is a significant gap compared to the mature recycling system in developed countries. Based on the comprehensive benefit evaluation model constructed in this study, combined with the quantitative analysis of environmental impact and cost–benefit accounting from the perspective of the life cycle, this study proposes the following countermeasures and suggestions to provide a reference for promoting energy conservation, emission reduction, and circular economy development.

9.1. Improve Laws and Regulations, Management Policies, and Technical Specifications, and Optimize the Governance Framework of the Entire Industry Chain

The government should accelerate the formulation and improvement of relevant laws and regulations, and clarify the responsibilities and obligations of various links such as the source, transportation process, treatment methods, and application of recycled products of construction waste. Fang et al. (2017) pointed out that the research and application of building solid waste management started earlier globally, especially in many developed countries where relatively mature systems have been established. Their successful experience shows that systematic policy support and technological innovation are key factors in promoting the resource utilization of building solid waste [45]. Sun et al. (2022) conducted an analysis based on a system dynamics simulation model, and the results showed that the level of green technology research and development, as well as the completeness of policies, laws, and regulations, play a key role in the development of green buildings [46].

The revised “Green Building Evaluation Standards” (GB/T 50378-2024) [47] in China in 2024 will include the proportion of green building materials in the mandatory provisions of star-rated building evaluation, requiring that the proportion of green building materials used in one-star to three-star green buildings should not be less than 30%, 40%, and 50%, respectively. Although the policy specifies the requirements for the application of recycled building materials, there are still market segmentation issues caused by local protectionism in actual implementation. In this regard, it is necessary to include the procurement of recycled building materials in the local government’s green performance assessment system to curb regional market barriers at the institutional level. The existing standard system has problems such as insufficient connection between recycled building material product standards (e.g., GB/T 25177 [48] “Recycled Coarse Aggregates for Concrete”) and engineering application specifications (e.g., GB 50010 [49] “Code for Design of Concrete Structures”), as well as significant differences in local standards, which lead to market confusion. Therefore, the government should guide the industry to accelerate the development of unified green building materials standards and technical specifications, establish a certification system covering product quality and environmental performance, and enhance consumer trust by improving market transparency.

On the implementation path, the government can implement a pre-review system for construction waste disposal plans during the project initiation stage, requiring the submission of waste disposal plans before the start of construction projects, implementing refined classification and recycling, and ensuring that construction waste enters the standardized disposal process from the beginning of its generation. Supporting industry regulatory policies will be introduced to strengthen the supervision of the resource utilization industry, ensuring orderly competition and sustainable development of the industry. In addition, detailed technical specifications and standards should be developed to provide clear technical guidance for the resource utilization of construction waste. In domestic practice, many governments have carried out beneficial explorations. For example, Hangzhou has established the “Green Building Promotion Association” to build a collaborative platform between the government, developers, building materials enterprises, and research institutions, promoting the development of green buildings through policy support and financial subsidies; Sichuan Province has established a Green Building Development Fund to provide financial support for projects to reduce economic costs; and Beijing, on the other hand, collaborates with building materials enterprises to guide developers to choose green building materials through incentive policies and subsidy measures, forming a promotion model that combines policy guidance with market mechanisms. These practices provide regional experience references for building a governance framework for the entire industry chain.

9.2. Diversified Policy Coordination Promotes Path Optimization of Construction Waste Resource Utilization Treatment

The government needs to use a diversified combination of policy tools to break down cost barriers and cognitive barriers in the promotion of recycled building materials, and drive industry transformation through differentiated efficiency of fiscal subsidies, green credit, and green building rating mechanisms. Cao et al. (2022) demonstrated through the establishment of relationship network models and evolutionary game models that enterprise subsidy policies, preferential policies, and restrictive policies on traditional housing can effectively promote the development of green housing [50]. He et al. (2021) pointed out that policy subsidies have a positive incentive effect on the development of green buildings while subsidizing developers and consumers helps to maximize profits and social welfare. However, the incentive effect of subsidies on consumers is better than that on developers. Through effective policy subsidy measures, the growth in the green building market can be promoted, and more developers and consumers can participate in green building projects, thus achieving a win–win situation of environmental protection and economic benefits [51].

The government should play a demonstrative role, reward and punish, and use them to promote the transformation of handling methods. For example, the UK has introduced the “Landfill Tax”, which proposes a disposal fee of GBP 56 per ton for construction companies directly burying construction waste. The characteristic of this measure is that the government will allocate 90% of the tax revenue to support research in the field of reusing construction waste. After conducting a robust evaluation and comparison of different waste management schemes in Italy, Yi et al. (2024) proposed that decision-makers could consider implementing subsidies to promote an economically sustainable recycling market [52]. Therefore, for enterprises that actively carry out the resource utilization of construction waste, tax incentives, financial subsidies, and other reward measures can be given to reduce their operating costs and increase their enthusiasm for participating in resource utilization. For example, in order to support and develop comprehensive utilization projects of construction waste, Guangzhou city adopts the subsidy methods of construction waste disposal subsidy funds and production land subsidy funds. The former provides subsidies based on the actual utilization of construction waste in recycled building materials products, with a subsidy standard of 2 CNY/ton; The latter provides subsidies for the factory land of eligible enterprises, taking into account the processing scale of the enterprises, with a subsidy standard of 3 CNY/square meter per month. Li et al. (2022) studied the impact of local government subsidy policies on the decision-making strategies of construction units based on an evolutionary game analysis model. The research results showed that in the long run, the government’s inspection efforts and the indirect benefits of construction units directly affect the probability of construction units choosing to apply for green building projects [53]. Ning et al. (2023) pointed out that government regulatory penalties are far more effective in regulating the behavior of green housing market entities than consumer feedback [54]. Therefore, for the illegal discharge and disposal of construction waste, it is necessary to strengthen supervision, strictly punish according to law, increase the cost of violations, and form a strong deterrent.

In addition, green credit policies indirectly incentivize companies to participate in green projects by reducing financing costs. WANG et al. (2018) pointed out that in the field of green buildings, preferential development loan interest rates, plot ratio incentives, development tax incentives, and preferential housing loan interest rates are four sensitive policy measures that can effectively motivate relevant parties to participate in green building projects. The greater the degree of financial subsidies tilted toward developers, the more significant the promotion effect [55]. The green building certification system such as Leadership in Energy and Environmental Design (LEED) promotes the management and resource utilization of building waste from the design and construction stages by setting performance standards and evaluation indicators. In the process of promoting green building certification, the government should regard the resource utilization of construction waste as an important evaluation indicator, and encourage construction projects to actively apply for green building certification through policy guidance and incentive measures, thereby promoting the green transformation of the entire industry.

In summary, fiscal subsidies and green credit focus on short-term incentives and financing support, while the long-term and standardized nature of green building certification systems and scoring mechanisms has unique advantages in promoting industry green transformation. Therefore, through the synergistic effect of policy tools such as fiscal subsidies, green loans, and green building ratings, a sound policy system can be constructed to promote the sustainable development of construction waste resource utilization.

9.3. Conduct Reasonable Site Selection Planning to Reduce Traffic Volume

The site selection planning of construction waste resource treatment facilities is crucial. Reasonable site selection can not only reduce transportation costs, but also reduce carbon emissions during transportation. Araz Hasheminezhad et al. (2024) proposed that the impact of the production stage of recycled aggregate concrete (RAC) with cement and aggregates is slightly greater than that of natural aggregate concrete (NAC). The transportation distance and mode significantly affect the impact on the environment. Recycling and energy savings are possible, but depend on specific conditions, especially transportation distance [24]. When selecting a site, comprehensive consideration should be given to the sources of construction waste and the demand for recycled products, and efforts should be made to choose areas near densely populated buildings. Meanwhile, optimizing transportation routes and modes is also an effective means of reducing traffic volume. Using advanced logistics management systems and geographic information systems, the shortest and smoothest transportation routes should be planned, and suitable transportation vehicles and loading methods should be selected based on the characteristics and transportation requirements of construction waste to improve transportation efficiency and reduce energy consumption.

9.4. Research and Develop Advanced Equipment and Processes to Reduce Energy Consumption

Advanced equipment and technology are key to improving the efficiency and quality of construction waste resource utilization. Enterprises should increase their investment in technology research and development; establish close cooperative relationships with research institutions, universities, etc.; and jointly carry out equipment and process research and development work. At the same time, attention should be paid to the energy-saving design of equipment, adopting efficient motors, drive systems, etc., to reduce energy consumption during equipment operation. In terms of technology, innovative treatment processes should be explored, resource recovery and product quality should be improved, treatment costs and energy consumption should be reduced, and resource-based treatment should be made more competitive in terms of economic and environmental efficiency.

9.5. Improve Data Collection and Management

The construction industry should establish a comprehensive data collection system, covering information such as the amount, types, composition, and disposal methods of the waste generated. For example, Yuvraj R. Patil et al. (2024) explored the performance, challenges, and opportunities of recycling concrete aggregates, and pointed out the shortcomings in the current quantitative management of construction and demolition (C&D) waste and sustainable policy frameworks, calling for the establishment of detailed localized databases to improve waste management [56]. Therefore, the construction industry can utilize technologies such as the Internet of Things and big data analysis to monitor the generation and processing of solid waste in real time, achieving data sharing and integration. Resource utilization processes should be optimized through data analysis to improve resource recovery rates.

10. Conclusions and Future Research Directions

This research systematically combed the current situation and related concepts of construction waste recycling, and used the life cycle assessment method to build a comparative scenario based on typical construction waste disposal methods, analyze the carbon emissions of different disposal methods, and establish a calculation model to quantitatively assess the carbon emission reduction benefits of construction waste recycling, providing an important basis for its environment efficiency and economic benefits assessment. The research results indicate that the resource utilization of construction solid waste has significant environmental benefits. This study further comprehensively evaluates the economic benefits of natural and recycled aggregates from the dimensions of production cost, service life, maintenance cost, and market demand. It not only focuses on short-term production costs but also examines long-term market competitiveness and potential benefits. In addition, by analyzing the linkage mechanism between the construction waste resource utilization industry and upstream and downstream industries, a market potential analysis method based on industry synergy was proposed to identify the competitive advantages and development bottlenecks of recycled building materials in the circular economy system. Based on this, the path optimization strategy is proposed to provide theoretical support and practical guidance for promoting the internalization of environment efficiency, economic feasibility improvement, and market promotion of construction waste recycling.

This study has the following improvement directions and future research focuses:

(1)

This article adopts a comparative analysis of resource utilization and non-resource utilization, assuming that the transportation stage of building materials, the construction and use stage, and the demolition stage, which have similar processes in the scenario, are no longer included in the accounting scope. Therefore, it is not possible to account for all carbon emissions throughout the entire life cycle and compare them with carbon emission reductions. In future research, it should be improved, and long-term environmental impact tracking assessments of resource utilization should be carried out to enhance the time dimension of the LCA model.

(2)

In actual construction waste treatment, the composition is complex and there are various methods for resource utilization. This article only focuses on the component with the largest proportion for the purpose of simplifying calculations, and only studies the production of recycled aggregates, which is the most widely used resource utilization method. It is difficult to accurately measure the carbon emissions in actual situations.

(3)

This study focuses on the impact of greenhouse gases that cause global warming without addressing environmental impact types such as photochemical smog, acidification, eutrophication, and ecological toxicity, as well as the differential emission characteristics of pollutants such as SO₂, NO_x, C_XH_Y, and dust. In the future, a multi-factor environmental impact assessment framework needs to be constructed to supplement the comparative analysis of emission inventories of multiple pollutants under different disposal methods.

(4)

This study did not consider the spatial heterogeneity of regional economic levels, environmental standards, and policy tools, and lacked an in-depth deconstruction of localized practical experience. In the future, an evaluation index system that includes regional characteristics can be established to compare resource utilization models in different economic gradient regions. By analyzing successful experiences and key obstacles through typical cases, empirical support can be provided for differentiated policy design and technical route selection.