A sustainability evaluation method for low-carbon concrete based on LCA

Abstract

This application discloses a sustainability evaluation method for low-carbon concrete based on LCA (Limited Carbon Calculation), comprising: obtaining the mechanical performance indicators of low-carbon concrete samples; obtaining a system list for each stage of low-carbon concrete; performing characteristic calculations on the system list for each stage of low-carbon concrete and analyzing its environmental impact potential; monetizing the environmental impact potential to obtain a comprehensive environmental evaluation index for low-carbon concrete; calculating the environmental and economic effect indicators of each mechanical performance indicator; normalizing the results to obtain the normalized results; calculating the sustainability index of low-carbon concrete; performing sensitivity analysis on the sustainability index of low-carbon concrete to evaluate its sustainability and obtain the optimal mix proportion of low-carbon concrete. This application is applicable to the sustainability evaluation of low-carbon concrete and other low-carbon products, providing a quantitative assessment method, optimizing the mix proportion of low-carbon concrete, and providing a scientific basis for its performance improvement and widespread application.

Description

Technical Field

[0001] This application relates to the field of building materials technology, specifically to a method for evaluating the sustainability of low-carbon concrete based on LCA. Background Technology

[0002] Concrete is the most widely used building material globally, and its traditional production process, especially the calcination of cement clinker, is a significant source of carbon emissions, accounting for approximately 7%-8% of global emissions. In response to the national "dual-carbon" strategy, utilizing industrial solid waste such as slag and fly ash to replace cement, and using recycled aggregates from waste concrete to replace natural aggregates to prepare low-carbon concrete, has become an important technological path in the industry. This path not only significantly reduces carbon emissions and conserves natural resources but also achieves efficient recycling of industrial and construction solid waste. It is worth noting that high-quality low-carbon concrete not only possesses significant environmental advantages but also often exhibits superior mechanical properties and long-term durability compared to ordinary concrete. In particular, the incorporation of reinforcing materials such as steel fibers effectively improves its brittleness and poor ductility, enabling it to meet the requirements of large-scale engineering projects and demonstrating broad application prospects.

[0003] Life Cycle Assessment (LCA) is a quantitative methodology for evaluating the environmental impact of a product throughout its entire life cycle. This methodology primarily comprises four steps: defining the purpose and scope, inventory analysis, impact assessment, and interpretation of results. However, current assessment systems for concrete have significant limitations and are difficult to apply to complex low-carbon concrete. First, most LCA assessments of concrete are limited to evaluating material carbon emissions, unit cost, and energy consumption, lacking a comprehensive analytical framework that couples mechanical properties, environmental effects, and economic benefits. Second, for ordinary concrete, its performance, carbon emissions, and cost are typically simply positively correlated; for example, higher cement content leads to higher compressive strength, but also higher carbon emissions and unit cost. However, low-carbon concrete exhibits characteristics of high strength, low emissions, and uncertain costs. These three factors present a non-linear and complex game-theoretic relationship, rendering traditional assessment logic inapplicable. Therefore, there is an urgent need to establish a sustainability assessment method for low-carbon concrete that comprehensively considers material performance, environmental effects, and economic effects.

[0004] With the rapid development and engineering application of low-carbon concrete materials, constructing a precise sustainability evaluation system to match them has become crucial for promoting their large-scale application. However, due to the wide range of raw material sources, complex composition, and diversified cementitious systems, it is difficult to accurately obtain data on raw materials for low-carbon concrete. Existing evaluation methods do not consider all factors comprehensively and cannot provide a comprehensive evaluation approach. This directly leads to insufficient usability of evaluation results, thus posing challenges to the objective assessment of materials and their engineering applications. Therefore, it is urgent to establish a sustainability evaluation method for low-carbon concrete that comprehensively considers material performance, environmental effects, and economic effects. Summary of the Invention

[0005] To address the aforementioned technical problems, this application provides a sustainability evaluation method for low-carbon concrete based on LCA (Limited Carbon Aggregate Analysis). This method considers the mechanical properties of low-carbon concrete, analyzes its energy consumption, air pollution, environmental impact potential, and unit cost. Based on this, it comprehensively evaluates the sustainability of low-carbon concrete with different recycled aggregate replacement rates and different steel fiber volume fractions, ultimately obtaining the optimal mix proportion for low-carbon concrete.

[0006] Firstly, this application provides a method for evaluating the sustainability of low-carbon concrete based on LCA, including: Obtain the mechanical property indicators of low-carbon concrete samples. Select low-carbon concrete, determine the life cycle system boundary, establish a low-carbon concrete material life cycle database, and obtain a system list for each stage of low-carbon concrete. The system inventory of low-carbon concrete at each stage is characterized and the environmental impact potential is analyzed. The social willingness-to-pay method is used to monetize the environmental impact potential and obtain the comprehensive environmental assessment index of low-carbon concrete. Based on the comprehensive environmental evaluation index of low-carbon concrete, the environmental and economic effects of each mechanical performance index are calculated; the results are then normalized. The sustainability index of low-carbon concrete was calculated based on the normalization results. Sensitivity analysis was conducted on the sustainability indicators of low-carbon concrete to evaluate its sustainability and obtain the optimal mix proportion.

[0007] In one possible implementation, the mechanical properties include compressive strength, splitting tensile strength, flexural strength, and bending toughness.

[0008] In one possible implementation, the system boundary is the environmental and economic benefits generated by low-carbon concrete throughout its entire lifecycle, from raw material production to concrete preparation.

[0009] In one possible implementation, the low-carbon concrete material lifecycle database includes a raw material production stage database, a transportation stage database, and a concrete preparation stage database; wherein the concrete preparation stage database includes an energy consumption and air pollution database.

[0010] In one possible implementation, the system inventory for each stage of low-carbon concrete is an inventory of energy consumption and air pollution per unit volume of low-carbon concrete at each stage of its life cycle.

[0011] In one possible implementation, the environmental impact potential includes: greenhouse gas (GWP), human toxicity (HTP), photochemical ozone synthesis (POFP), particulate matter formation (PMFP), acidification (AP), ocean eutrophication (MEP), abiotic resource depletion (ADP), and fossil fuel depletion (FDP). The characteristic calculation formula is:

[0012] In the formula, EI m,i For the first m The first type of concrete i Environmental impact potential; M j For the first j The amount of a substance consumed or emitted; EF j For the first j Characteristic factors of a substance; Q k For the first k The amount of each material used; ET ik For the first k The first material transported i Environmental impact potential; d k For the first k The transportation distance of the materials; E m,i,pre For the first m The first stage of concrete preparation i Environmental influence potential.

[0013] In one possible implementation, the comprehensive environmental assessment index of the low-carbon concrete is calculated as follows:

[0014] In the formula, CEI is the comprehensive environmental evaluation index of low-carbon concrete, in yuan; EI i For the first i Environmental impact potential; δ i For the first i Monetization weights of environmental impact potential; The environmental assessment indicators are divided into natural environmental pollution indicators and natural resource depletion indicators, and their monetization weights are calculated as follows: Indicators related to natural environmental pollution:

[0015] In the formula, δ i For the first iThe weight of environmental influence on potential; t i For the first i Environmental protection tax per unit equivalent index for each category of environmental impact, in yuan; p j The potential impact of a single pollutant; k j To influence the potential coefficient, This is related to the pollutant's pollution capacity and emissions; q j This refers to the average annual emissions of pollutants. Indicators related to natural resource depletion:

[0016] In the formula, δ i For the first i The weight of environmental influence on potential; t ij For the first i The first environmental impact category j Resource tax for this type of resource, in yuan; r ij For the first i The first environmental impact category j The average annual reserves of this type of resource.

[0017] In one possible implementation, the environmental effect index is calculated as follows: , , ,

[0018] In the formula, CI, SI, FI, and TI are the environmental effect indicators of concrete's compressive strength, splitting tensile strength, flexural strength, and toughness, respectively; CEI represents the comprehensive environmental evaluation index of low-carbon concrete per cubic meter. f c , f t , f f , K These are the compressive strength, splitting tensile strength, flexural strength, and flexural toughness of low-carbon concrete. The formula for calculating the economic effect indicator is as follows: , , ,

[0019] In the formula, CI cost SI cost FI costTI cost These are the economic indicators for the compressive strength, splitting tensile strength, flexural strength, and toughness of concrete, respectively. C m To reduce the unit cost of low-carbon concrete, ;in, C m The unit cost of low-carbon concrete; C m,i The unit price of each raw material is in yuan / kg; W m,i For the quality of each raw material; s Transportation distances for each raw material, in km; T k The unit price for truck transportation is yuan / km.

[0020] In one possible implementation, the sustainability index of the low-carbon concrete is calculated using the following formula:

[0021] In the formula, ECO i This is the i-th type of sustainability indicator for low-carbon concrete. α i and β i The first i The environmental and economic effects of low-carbon concrete are allocated by a coefficient, the sum of which is 1. E i and C i These are normalized environmental and economic indicators, respectively.

[0022] In one possible implementation, the sensitivity analysis of the sustainability indicators of low-carbon concrete, the evaluation of the sustainability of low-carbon concrete, and the determination of the optimal mix proportion of low-carbon concrete include: Factorial analysis was used, with various sustainability indicators set as responses and the mix design variables of low-carbon concrete set as influencing factors, to obtain the results of the factorial analysis. The range analysis method was used to obtain the results of the range analysis for the comprehensive evaluation of multiple sustainability indicators; By analyzing the factorial and range results corresponding to the comprehensive evaluation of multiple sustainability indicators, the optimal mix proportion of concrete is obtained.

[0023] The beneficial effects of this application are: 1) The method provided in this application considers the basic mechanical properties, environmental benefits, and economic efficiency of concrete materials, breaking through the limitation of the simple positive correlation between mechanical properties and sustainability indicators in traditional evaluation methods. It achieves a scientific quantification of the comprehensive performance of low-carbon concrete, significantly improving its practical usability. This method can systematically analyze the energy consumption, air pollution, environmental impact potential, and economic indicators of low-carbon concrete under different mix proportions, comprehensively assessing its sustainability and providing theoretical support for the optimization and engineering selection of low-carbon concrete materials.

[0024] 2) The method provided in this application introduces a variety of sensitivity analysis methods to conduct sensitivity analysis on the sustainability indicators of low-carbon concrete. It can identify the significance level and degree of influence of each influencing factor on the sustainability indicators, clarify the key control parameters, and provide scientific basis and directional guidance for the mix design optimization of low-carbon concrete.

[0025] 3) The method provided in this application has good scalability and applicability. It can be used not only for the sustainability evaluation of a single concrete technology solution, but also extended to the comprehensive evaluation at the component level and even the overall project level, realizing the quantitative determination of the sustainability of the evaluation object from materials to structure, thereby improving the green building evaluation system and having important theoretical value and practical significance for promoting the engineering application of low-carbon concrete. Attached Figure Description

[0026] Figure 1 A schematic diagram illustrating the process of evaluating the sustainability of low-carbon concrete, provided as an embodiment of this application; Figure 2 This is the system boundary of the method described in the embodiments of this application.

[0027] Figure 3 This refers to the environmental impact potential of low-carbon concrete throughout its life cycle in step S3 of the method described in this application embodiment.

[0028] Figure 4 This is the total cost of each type of low-carbon concrete in step S4 of the method described in this application embodiment.

[0029] Figure 5 These are the environmental and economic indicators of various types of low-carbon concrete in step S4 of the method described in this application embodiment. Detailed Implementation

[0030] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0031] In the description of this application, the term "for example" is used to mean "used as an example, illustration, or description." Any embodiment described as "for example" in this application is not necessarily to be construed as being more preferred or advantageous than other embodiments. The following description is provided to enable any person skilled in the art to make and use this application. Details are set forth in the following description for purposes of explanation. It should be understood that those skilled in the art will recognize that this application can be made without using these specific details. In other instances, well-known structures and processes will not be described in detail to avoid unnecessarily obscuring the description of this application. Therefore, this application is not intended to be limited to the embodiments shown, but is consistent with the broadest scope of the principles and features disclosed in this application.

[0032] Low-carbon concrete, due to its wide range of raw material sources, complex composition, and diverse cementitious systems, makes it difficult to accurately obtain a complete list of raw material data. Existing evaluation methods do not consider all factors comprehensively and cannot provide a holistic evaluation approach. These problems result in insufficient usability of the evaluation results, failing to accurately reflect the actual situation.

[0033] In view of this, this application provides a method for evaluating the sustainability of low-carbon concrete.

[0034] See Figure 1 The present application provides a method for evaluating the sustainability of low-carbon concrete, comprising the following steps: S101. Obtain the mechanical property indicators of low-carbon concrete samples.

[0035] In one possible implementation, the mechanical properties include compressive strength, splitting tensile strength, flexural strength, and bending toughness.

[0036] In one possible implementation, the low-carbon concrete sample is made by replacing cement with industrial solid waste (such as slag, fly ash, etc.) and incorporating fibers and recycled concrete aggregates. The recycled concrete aggregates are prepared from construction waste concrete feedstock; the fibers include steel fibers, polypropylene fibers, basalt fibers, plant fibers, etc., used to improve brittleness.

[0037] S102. Select low-carbon concrete, determine the life cycle system boundary, establish a low-carbon concrete material life cycle database, and obtain a system list for each stage of low-carbon concrete.

[0038] In one possible implementation, the system boundary is the environmental and economic benefits generated by low-carbon concrete throughout its entire lifecycle, from raw material production to concrete preparation.

[0039] It should be noted that the system boundary determined in step S102 is the environmental and economic benefits generated by low-carbon concrete throughout its life cycle from "cradle" (raw material production) to "gate" (concrete preparation completion), without considering the impact of energy generation, production equipment, and building facilities on the environment and economy.

[0040] In one possible implementation, the low-carbon concrete material lifecycle database includes a raw material production stage database, a transportation stage database, and a concrete preparation stage database.

[0041] Furthermore, the low-carbon concrete material lifecycle database includes a 1 kg raw material production stage database, a 2-ton light gasoline truck transportation stage database, and a 1 m 3 Database on concrete preparation stages.

[0042] Specifically, the production stage database only considers the impact of raw materials; since all raw materials are sourced locally, considering the size of a typical city, it is assumed that the transportation distance from the slag, aggregate, and other production sites to the concrete mixing plant is 30 km, and the transportation distance of water and water-reducing agents is ignored; the concrete preparation stage database only considers the electrical energy consumed by the mixer during the concrete mixing process.

[0043] In one possible implementation, the system inventory for each stage of low-carbon concrete is determined by the unit volume (1m³). 3 The energy consumption and air pollution inventory of low-carbon concrete at each stage of its life cycle.

[0044] Furthermore, the energy consumption includes the consumption of raw coal, crude oil, and natural gas; the air pollution inventory includes CO2, SO2, and NO. x Emissions of CO, CH4, particulate matter and NMVOC.

[0045] It should be noted that the energy consumption and air pollution inventory of low-carbon concrete at each stage of its life cycle includes inventories for the raw material production stage, the transportation stage, and the concrete preparation stage, with each stage including an inventory of energy consumption and air pollution.

[0046] Furthermore, the inventory database for the production stages of the raw materials (cement, slag, fly ash, silica fume, sand, stone, coarse aggregate, water-reducing agent, etc.) mainly comes from national standards and relevant literature. In addition, considering the differences in data from different regions, literature sources, and scholars, a data-driven approach is adopted to accurately obtain the inventory data for the raw materials.

[0047] S103. Calculate the system inventory characteristics of low-carbon concrete at each stage and analyze the environmental impact potential; use the social willingness-to-pay method to monetize the environmental impact potential and obtain the comprehensive environmental assessment index of low-carbon concrete.

[0048] In one possible implementation, the environmental impact potential includes: greenhouse gas (GWP), human toxicity (HTP), photochemical ozone synthesis (POFP), particulate matter formation (PMFP), acidification (AP), ocean eutrophication (MEP), abiotic resource depletion (ADP), and fossil fuel depletion (FDP). The characteristic calculation formula is:

[0049] In the formula, EI m,i For the first m The first type of concrete i Environmental impact potential; M j For the first j The amount of a substance consumed or emitted; EF j For the first j Characteristic factors of a substance; Q k For the first k The amount of each material used; ET ik For the first k The first material transported i Environmental impact potential; d k For the first k The transportation distance of the materials; E m,i,pre For the first m The first stage of concrete preparation i Environmental influence potential.

[0050] Understandably, the aforementioned first m The term "concrete type" actually refers to the different types of low-carbon concrete prepared with different mix proportions.

[0051] S104. Based on the comprehensive environmental evaluation index of low-carbon concrete, calculate the environmental effect index and economic effect index of each mechanical performance index; normalize the results to obtain the normalized results.

[0052] In one possible implementation, the comprehensive environmental assessment index of the low-carbon concrete is calculated as follows:

[0053] In the formula, CEI is the comprehensive environmental evaluation index of low-carbon concrete, in yuan; EI i For the first i Environmental impact potential; δ i For the first iMonetization weights of environmental impact potential; The environmental assessment indicators are divided into natural environmental pollution indicators and natural resource depletion indicators, and their monetization weights are calculated as follows: Indicators related to natural environmental pollution:

[0054] In the formula, δ i For the first i The weight of environmental influence on potential; t i For the first i Environmental protection tax per unit equivalent index for each category of environmental impact, in yuan; p j The potential impact of a single pollutant; k j To influence the potential coefficient, This is related to the pollutant's pollution capacity and emissions; q j This refers to the average annual emissions of pollutants. Indicators related to natural resource depletion:

[0055] In the formula, δ i For the first i The weight of environmental influence on potential; t ij For the first i The first environmental impact category j Resource tax for this type of resource, in yuan; r ij For the first i The first environmental impact category j The average annual reserves of this type of resource.

[0056] In one possible implementation, the environmental effect index is calculated as follows: , , ,

[0057] In the formula, CI, SI, FI, and TI are the environmental effect indicators of concrete's compressive strength, splitting tensile strength, flexural strength, and toughness, respectively; CEI represents the comprehensive environmental evaluation index of low-carbon concrete per cubic meter. f c , f t , f f , KThese are the compressive strength, splitting tensile strength, flexural strength, and flexural toughness of low-carbon concrete.

[0058] The formula for calculating the economic effect indicator is as follows: , , ,

[0059] In the formula, CI cost SI cost FI cost TI cost These are the economic indicators for the compressive strength, splitting tensile strength, flexural strength, and toughness of concrete, respectively. C m To reduce the unit cost of low-carbon concrete, ;in, C m The unit cost of low-carbon concrete; C m,i The unit price of each raw material is in yuan / kg; W m,i For the quality of each raw material; s Transportation distances for each raw material, in km; T k The unit price for truck transportation is yuan / km.

[0060] In one possible implementation, the normalization is calculated as follows:

[0061] Normalization of environmental and economic indicators yields the normalized results for environmental indicators. E i Normalization results of economic effect indicators C i .

[0062] S105. Calculate the sustainability index of low-carbon concrete based on the normalization results.

[0063] In one possible implementation, the sustainability index of the low-carbon concrete is calculated using the following formula:

[0064] In the formula, ECO i This is the i-th type of sustainability indicator for low-carbon concrete. α i and β i The first i The environmental and economic effects of low-carbon concrete are allocated by a coefficient, the sum of which is 1.E i and C i These are normalized environmental and economic indicators, respectively.

[0065] For example, the Generally speaking, if the allocation coefficients for both are equal, it means that the environmental and economic effects are equally important; if the focus is on the economic effect, the allocation coefficient should be increased; the same applies if the focus is on the environmental effect.

[0066] S106. Conduct sensitivity analysis on the sustainability indicators of low-carbon concrete, evaluate the sustainability of low-carbon concrete, and obtain the optimal mix proportion of low-carbon concrete.

[0067] In one possible implementation, S106 includes: S106a. Using factorial analysis, various sustainability indicators were set as responses, and the mix design variables of low-carbon concrete were set as influencing factors to obtain the results of factorial analysis. S106b. The range analysis method is used to obtain the results of the range analysis for the comprehensive evaluation of multiple sustainability indicators; S106c. By analyzing the factorial and range results corresponding to the comprehensive evaluation of multiple sustainability indicators, the optimal mix proportion of concrete is obtained.

[0068] Furthermore, both factorial analysis and range analysis were performed using Minitab statistical software.

[0069] Specifically, the factorial analysis steps are as follows: Select "Statistics" Analysis of variance General linear model "Fit a general linear model" to obtain the results of factorial analysis, namely the significance level of each variable on the sustainability index; Specifically, the steps for range analysis are as follows: Select "Statistics" DOE Taguchi By analyzing the Taguchi design, the results of the range analysis are obtained, which shows the order of importance of each factor's influence on the sustainability index of concrete. Through further analysis, the optimal mix proportion of concrete can be obtained.

[0070] The content of this application will be further explained below with specific examples.

[0071] S1: Obtain the mechanical property indicators of the low-carbon concrete sample.

[0072] According to the design requirements, considering the volumetric steel fiber content (0%, 0.5%, 1.0%, 1.5%) and the recycled aggregate replacement rate (0%, 25%, 50%, 75%, 100%), 12 groups of low-carbon concrete samples with different mix proportions were prepared. The mix proportions are shown in Table 1. The measured compressive strength, splitting tensile strength, flexural strength and flexural toughness are shown in Table 2.

[0073] It should be noted that the total aggregate mass of low-carbon concrete is fixed, and the recycled aggregate replacement rate refers to the percentage of mass that is replaced by natural aggregate. For example, in Table 1, for the R25S00 specimen, the total aggregate mass per cubic meter is 1086 kg, the recycled aggregate is 271.5 kg, and the recycled aggregate replacement rate = 271.5 / 1086 = 0.25.

[0074] Furthermore, to illustrate the advantages of low-carbon concrete, the examples of this invention include a comparative analysis with conventional concrete (PC).

[0075] Table 1. Mix proportions of low-carbon concrete (kg / m³) 3 )

[0076] Note: R00, R25, R50, R75, and R100 refer to the recycled aggregate replacement rates of 0%, 25%, 50%, 75%, and 100%, respectively; S05, S10, and S15 refer to the steel fiber volume content of 0.5%, 1.0%, and 1.5%, respectively.

[0077] Table 2. Test results of mechanical properties of low-carbon concrete

[0078] S2: Select low-carbon concrete, determine the life cycle system boundary, establish a low-carbon concrete material life cycle database, and obtain a system list for each stage of low-carbon concrete.

[0079] This application's embodiment selects 1 m 3 The low-carbon concrete of the functional unit was analyzed.

[0080] Based on domestic and international standards and relevant literature, and using a data-driven approach, considering factors such as material location and economic differences, a low-carbon concrete material lifecycle database is established according to the system boundary determined in step S2. Figure 2 The results are shown in Tables 3 and 4. The production stage database only considers the impact of raw materials. Since all raw materials are locally sourced, considering the size of a typical city, the transportation distance from slag, aggregate, etc., to the concrete mixing plant is assumed to be 30 km, and the transportation distance for water and water-reducing agents is ignored. The concrete preparation stage only considers the electrical energy consumed by the mixer during the concrete mixing process.

[0081] Table 3 Lifecycle Library of Low-Carbon Concrete Material Production Stages

[0082] Note: In Table 3, 2.06E-01 indicates This indicates the amount of crude oil consumed in the energy required to produce 1 kg of cement.

[0083] Table 4. Lifecycle Library of Low-Carbon Concrete Materials in Transportation and Preparation Stages

[0084] Furthermore, based on the lifecycle database established in step S2, a system inventory for each stage of low-carbon concrete is obtained, including the raw material production stage, concrete transportation stage, and preparation stage, as shown in Table 5-7. In the system inventory analysis, 1m... 3 An inventory of energy consumption and air pollution at each stage of the life cycle of low-carbon concrete functional units. Energy consumption includes the consumption of raw coal, crude oil, and natural gas; air pollution includes CO2, SO2, and NO. x Emissions of CO, CH4, particulate matter and NMVOC.

[0085] Table 5 List of Raw Material Production Stages

[0086] Table 6 List of Raw Material Transportation Stages

[0087] Table 7 List of Stages in Low-Carbon Concrete Preparation

[0088] S3: Collect environmental impact characterization factors from the CLCD database and literature, listed in Table 8. Perform characterization calculations on the system inventory of low-carbon concrete obtained in step S3 to analyze its environmental impact potential, including greenhouse effect (GWP), human toxicity (HTP), photochemical ozone synthesis (POFP), particulate matter formation (PMFP), acidification (AP), marine eutrophication (MEP), depletion of abiotic resources (ADP), and fossil fuel depletion (FDP). Based on the determination of objectives and scope, the environmental impact potential of various types of low-carbon concrete materials throughout their life cycle can be calculated using the following formula.

[0089]

[0090] In the formula, EI m,i For the first m The first type of concrete i Environmental impact potential; Mj For the first j The amount of a substance consumed or emitted; EF j For the first j Characteristic factors of a substance; Q k For the first k The amount of each material used kg ; ET ik For the first k The first material transported i Environmental impact potential; d k For the first k The transportation distance of the materials km ; E m,i,pre The first m The first stage of concrete preparation i Environmental influence potential.

[0091] Table 8. Characterization factors of relevant substances

[0092] Calculate the environmental impact potential of low-carbon concrete over its life cycle, such as Figure 3 As shown.

[0093] Furthermore, based on the environmental impact potential obtained in step S3, the comprehensive environmental assessment index of low-carbon concrete is calculated:

[0094] In the formula, CEI is the comprehensive environmental evaluation index of low-carbon concrete, in yuan; EF i For the first i Environmental impact potential; δ i For the first i Monetization weight of environmental impact potential.

[0095] Among them, the various environmental indicators are divided into natural environmental pollution indicators and natural resource depletion indicators. Their monetization weights are calculated as follows, and the calculation results are shown in Tables 9 and 10.

[0096] Indicators related to natural environmental pollution:

[0097] In the formula, δ i For the first i The weight of environmental influence on potential; t i For the first iEnvironmental protection tax per unit equivalent index for each category of environmental impact, in yuan; p j The potential impact of a single pollutant; k j The potential coefficient is related to the pollutant's pollution capacity and emissions; q j This represents the average annual emissions of pollutants.

[0098] Indicators related to natural resource depletion:

[0099] In the formula, δ i For the first i The weight of environmental influence on potential; t ij For the first i The first environmental impact category j Resource tax for this type of resource, in yuan; r ij For the first i The first environmental impact category j The average annual reserves of this type of resource.

[0100] Table 9 Natural Environment Pollution Indicators

[0101] Table 10 Natural Resource Depletion Indicators

[0102] Finally, based on the above parameters, the comprehensive environmental evaluation index of low-carbon concrete was obtained, as shown in Table 11.

[0103] Table 11 Comprehensive Environmental Assessment Results of Low-Carbon Concrete

[0104] S4: Based on the comprehensive environmental evaluation index of low-carbon concrete, calculate the environmental and economic effects of each mechanical performance index; normalize the results to obtain the normalized results.

[0105] The economic cost of low-carbon concrete is calculated using the following formula. The price list of materials, sourced from manufacturers or distributors, is shown in Table 12. The contribution of each raw material to the total cost of low-carbon concrete is as follows: Figure 4 As shown.

[0106]

[0107] In the formula, C m The unit cost of low-carbon concrete; Cm,i The unit price of each raw material is in yuan / kg; W m,i For the quality of each raw material; s Transportation distances for each raw material, in km; T k The unit price for truck transportation is yuan / km.

[0108] Table 12 List of Raw Materials and Transportation Prices for Low-Carbon Concrete (RMB)

[0109] Next, environmental and economic impact indicators are calculated and normalized to obtain the normalized results.

[0110] The calculation results of the environmental and economic effect indicators of low-carbon concrete are shown in Table 11 and... Figure 4 As shown.

[0111] Depend on Figure 5 It can be seen that the comprehensive environmental effect index of low-carbon concrete changes by no more than 12% with the increase of recycled aggregate replacement rate, and by 1%-6% with the increase of steel fiber volume content. When the steel fiber volume content is 1.5%, the comprehensive environmental effect index of LC-HPRAC is the smallest. Its economic effect index generally increases with the increase of recycled aggregate replacement rate and steel fiber volume content, but the economic effect index of flexural toughness decreases with the increase of steel fiber volume content. When the steel fiber volume content is 0.5%, the comprehensive economic effect index of low-carbon concrete is the lowest and the economy is the best.

[0112] S5: Calculate the sustainability index of low-carbon concrete based on the normalization results.

[0113] The calculation results of various mechanical properties sustainability indicators of low-carbon concrete are shown in Table 13.

[0114] Table 13 Sustainability Indicators

[0115] It should be noted that, The calculation of other parameters is the same.

[0116] S6: Conduct sensitivity analysis on multiple sustainability indicators of low-carbon concrete, evaluate the sustainability of low-carbon concrete, and obtain the optimal mix proportion of low-carbon concrete.

[0117] Sensitivity analysis of sustainability indicators of low-carbon concrete was conducted using factorial analysis and range analysis to complete the sustainability evaluation of low-carbon concrete and obtain the optimal mix proportion of low-carbon concrete.

[0118] Factorial analysis involves studying all combinations of levels of the experimental factor in each repeated trial to analyze the significance of the experimental variable.

[0119] Range analysis refers to the difference between the maximum and minimum values ​​in the test results, which is used to determine the order of importance of the influence of various factors on the sustainability index of concrete.

[0120] Range analysis and factorial analysis of concrete sustainability indices were performed using Minitab statistical software. The significance of steel fiber volume content and recycled aggregate replacement rate on the sustainability of low-carbon concrete and the optimal mix proportion within the experimental range were calculated. The calculation results are shown in Tables 15 and 16.

[0121] The factorial analysis steps are as follows: Select "Statistics" Analysis of variance General linear model "Fit a general linear model", setting the sustainability index as "response" and the mix design variable of low-carbon concrete as "factor", to obtain the results of factorial analysis, i.e., the significance level of each variable with respect to the sustainability index; the steps of range analysis are as follows: Select "Statistical" DOE Taguchi By analyzing the Taguchi design, the results of the range analysis are obtained, which shows the order of importance of each factor's influence on the sustainability index of concrete. Through further analysis, the optimal mix proportion of concrete can be obtained.

[0122] Table 14 Factor Level Table

[0123] Table 15 Response of Steel Fiber Volume Content and Recycled Aggregate Replacement Rate

[0124] Note: In Table 15, the cell value corresponding to Level 1 and the recycled aggregate replacement rate is 0.7675, indicating that the response value of the comprehensive evaluation of multiple indicators is 0.7675 when the recycled aggregate replacement rate is 0%. The cell value corresponding to Delta and the recycled aggregate replacement rate is 0.2800, which represents the range of the factor recycled aggregate replacement rate. It is calculated by subtracting the minimum value from the maximum value, i.e., 0.7675-0.4875=0.2800, reflecting the influence of the level change of this factor on the comprehensive evaluation value of sustainability. The larger the value, the stronger the influence of this factor on the final result. The ranking represents the ranking of the degree of influence from high to low.

[0125] It should be noted that the calculation method for the response value of a comprehensive evaluation of multiple indicators includes: The formula for calculating the comprehensive sustainability evaluation index for each specimen of a certain factor in the Taguchi experiment is as follows: ; The mean of the comprehensive sustainability evaluation index for this factor was calculated for all specimens in the Taguchi experiment. The range and rank of the response values ​​were calculated based on the comprehensive evaluation of multiple indicators.

[0126] For example, taking a response value of 0.7675 as an example, the calculation process is as follows: First, the comprehensive sustainability evaluation index of the R00S00 specimen with a recycled aggregate replacement rate of 0 is calculated as (1+0.91+1+0.25) / 4=0.79; then, in the Taguchi test, there is another R00S10 specimen with a recycled aggregate replacement rate of 0, whose comprehensive sustainability evaluation index is 0.745; finally, the mean of the two specimens is calculated as (0.79+0.745) / 2=0.7675, which is the response value.

[0127] Table 16 Factorial Analysis

[0128] Note:" "" indicates that the result is significant.

[0129] Table 16 shows that the replacement rate of recycled aggregate significantly affects the compressive strength and toughness indicators; the steel fiber content significantly affects all indicators. Table 15 shows that when the steel fiber volume content is level 2 and the recycled aggregate replacement rate is level 1, i.e., the steel fiber volume content is 0.5% and there is no recycled aggregate, the sustainability of concrete reaches the optimal level. However, considering the resource utilization of abandoned buildings, and the sustainability level when the recycled aggregate replacement rate is 50% is close to that when there is no recycled aggregate, both around 0.7, the recycled aggregate replacement rate can be increased to 50%. Taking into account the three factors of environment, cost, and strength, the mix proportion of low-carbon concrete is optimal when the steel fiber volume content is 0.5% and the recycled aggregate replacement rate is 50%.

[0130] The method provided in this application considers the macroscopic mechanical properties of materials and constructs a sustainability evaluation method for low-carbon concrete based on the LCA method. The advantages of this method are: 1) It comprehensively considers the material's performance, environmental effects, and economic efficiency, establishing a more reasonable sustainability evaluation system for low-carbon concrete materials; 2) Based on a data-driven strategy, it accurately obtains a list of environmental and economic data for low-carbon concrete raw materials, ensuring calculation accuracy and the rationality of the evaluation; 3) It systematically analyzes the influence of factors such as recycled aggregate replacement rate and steel fiber content on environmental and economic efficiency, and uses factorial analysis and range analysis to conduct sensitivity analysis on the sustainability indicators of low-carbon concrete, considering the environmental and cost factors of materials, and optimizing the design mix proportions of low-carbon concrete; 4) This method is not only used for the sustainability evaluation of low-carbon concrete but can also be used in the evaluation of other types of concrete materials, possessing wide applicability and significant implications for the design and application of concrete materials.

[0131] It should be understood that any parts not described in detail in this specification belong to the prior art.

[0132] It should be understood that the above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined in this specification may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, the present invention will not be limited to the embodiments shown in this specification, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A sustainability evaluation method for low-carbon concrete based on LCA, characterized in that, include: Obtain the mechanical property indicators of low-carbon concrete samples. Select low-carbon concrete, determine the life cycle system boundary, establish a low-carbon concrete material life cycle database, and obtain a system list for each stage of low-carbon concrete. The system inventory of low-carbon concrete at each stage is characterized and the environmental impact potential is analyzed. The social willingness-to-pay method is used to monetize the environmental impact potential and obtain the comprehensive environmental assessment index of low-carbon concrete. Based on the comprehensive environmental evaluation index of low-carbon concrete, the environmental and economic effects of each mechanical performance index are calculated. Normalization is performed to obtain the normalized result; The sustainability index of low-carbon concrete was calculated based on the normalization results. Sensitivity analysis was conducted on the sustainability indicators of low-carbon concrete to evaluate its sustainability and obtain the optimal mix proportion.

2. The method according to claim 1, characterized in that, The mechanical properties include compressive strength, splitting tensile strength, flexural strength, and bending toughness.

3. The method according to claim 1, characterized in that, The system boundary refers to the environmental and economic benefits generated by low-carbon concrete throughout its entire life cycle, from raw material production to concrete preparation.

4. The method according to claim 1, characterized in that, The low-carbon concrete material life cycle database includes a raw material production stage database, a transportation stage database, and a concrete preparation stage database; among which, the concrete preparation stage database includes energy consumption and air pollution databases.

5. The method according to claim 1, characterized in that, The system list for each stage of low-carbon concrete is a list of energy consumption and air pollution per unit volume of low-carbon concrete at each stage of its life cycle.

6. The method according to claim 1, characterized in that, The environmental impact potentials include: greenhouse gas (GWP), human toxicity (HTP), photochemical ozone synthesis (POFP), particulate matter formation (PMFP), acidification (AP), marine eutrophication (MEP), abiotic resource depletion (ADP), and fossil fuel depletion (FDP). The characteristic calculation formula is: In the formula, EI m,i For the first m The first type of concrete i Environmental impact potential; M j For the first j The amount of a substance consumed or emitted; EF j For the first j Characteristic factors of a substance; Q k For the first k The amount of each material used; ET ik For the first k The first material transported i Environmental impact potential; d k For the first k The transportation distance of the materials; E m,i,pre For the first m The first stage of concrete preparation i Environmental influence potential.

7. The method according to claim 1, characterized in that, The comprehensive environmental assessment index of the low-carbon concrete is calculated as follows: In the formula, CEI is the comprehensive environmental evaluation index of low-carbon concrete, in yuan; EI i For the first i Environmental impact potential; δ i For the first i Monetization weights of environmental impact potential; The environmental assessment indicators are divided into natural environmental pollution indicators and natural resource depletion indicators, and their monetization weights are calculated as follows: Indicators related to natural environmental pollution: In the formula, δ i For the first i The weight of environmental influence on potential; t i For the first i Environmental protection tax per unit equivalent index for each category of environmental impact, in yuan; p j The potential impact of a single pollutant; k j To influence the potential coefficient, This is related to the pollutant's pollution capacity and emissions; q j This refers to the average annual emissions of pollutants. Indicators related to natural resource depletion: In the formula, δ i For the first i The weight of environmental influence on potential; t ij For the first i The first environmental impact category j Resource tax for this type of resource, in yuan; r ij For the first i The first environmental impact category j The average annual reserves of this type of resource.

8. The method according to claim 1, characterized in that, The formula for calculating the environmental effect index is: ， ， ， In the formula, CI, SI, FI, and TI are the environmental effect indicators of concrete's compressive strength, splitting tensile strength, flexural strength, and toughness, respectively; CEI represents the comprehensive environmental evaluation index of low-carbon concrete per cubic meter. f c , f t , f f , K These are the compressive strength, splitting tensile strength, flexural strength, and flexural toughness of low-carbon concrete. The formula for calculating the economic effect indicator is as follows: ， ， ， In the formula, CI cost SI cost FI cost TI cost These are the economic indicators for the compressive strength, splitting tensile strength, flexural strength, and toughness of concrete, respectively. C m To reduce the unit cost of low-carbon concrete, ;in, C m The unit cost of low-carbon concrete; C m,i The unit price of each raw material is in yuan / kg; W m,i For the quality of each raw material; s Transportation distances for each raw material, in km; T k The unit price for truck transportation is yuan / km.

9. The method according to claim 1, characterized in that, The formula for calculating the sustainability index of the low-carbon concrete is as follows: In the formula, ECO i This is the i-th type of sustainability indicator for low-carbon concrete. α i and β i The first i The environmental and economic effects of low-carbon concrete are allocated by a coefficient, the sum of which is 1. E i and C i These are normalized environmental and economic indicators, respectively.

10. The method according to claim 1, characterized in that, The process involves sensitivity analysis of sustainability indicators for low-carbon concrete, evaluation of its sustainability, and determination of the optimal mix proportions. Factorial analysis was used, with various sustainability indicators set as responses and the mix design variables of low-carbon concrete set as influencing factors, to obtain the results of the factorial analysis. The range analysis method was used to obtain the results of the range analysis for the comprehensive evaluation of multiple sustainability indicators; By analyzing the factorial and range results corresponding to the comprehensive evaluation of multiple sustainability indicators, the optimal mix proportion of concrete is obtained.

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