Life Cycle Assessment and Environmental Load Management in the Cement Industry

Abstract

The cement industry is a significant contributor to global environmental impacts, and Life Cycle Assessment (LCA) has emerged as a critical tool for evaluating and managing these burdens. This review uniquely synthesizes recent advancements in the LCA methodology and provides a detailed comparison of cement production impacts across major producing regions, notably highlighting China’s role as the largest global emitter. It covers the core LCA phases, including goal and scope definition, inventory analysis, impact assessment, and interpretation, and emphasizes the role of LCA in quantifying cradle-to-gate impacts (typically around 0.9–1.0 t CO₂ per ton of cement), evaluating the emissions reductions provided by alternative cement types (such as ~30–45% lower emissions using limestone calcined clay cements), informing policy frameworks like emissions trading schemes, and guiding sustainability certifications. Strategies for environmental load reduction in cement manufacturing are quantitatively examined, including technological innovations (e.g., carbon capture technologies potentially cutting plant emissions by up to ~90%) and material substitutions. Persistent methodological challenges—such as data quality issues, scope limitations, and the limited real-world integration of LCA findings—are critically discussed. Finally, specific future research priorities are identified, including developing country-specific LCI databases, integrating techno-economic assessment into LCA frameworks, and creating user-friendly digital tools to enhance the practical implementation of LCA-driven strategies in the cement industry.

1. Introduction

Life cycle thinking has become indispensable in assessing and managing the environmental impacts of energy-intensive industries, and cement is no exception. Cement production today exceeds 4 billion tons per year globally, making it one of the world’s largest industrial activities [1]. It supplies the binders essential for construction, a sector responsible for roughly 40% of global final energy use and associated greenhouse gas (GHG) emissions [2]. In parallel with post-war urbanization, cement output has expanded dramatically—about 30-fold since 1950 and roughly 4-fold since 1990—driven overwhelmingly by new construction in emerging economies [3]. The cement industry now emits in the order of 0.9–1.0 ton of CO₂ for each ton of cement produced, stemming from both the calcination of limestone and fossil fuel combustion. In total, cement manufacturing accounts for approximately 5–8% of anthropogenic CO₂ emissions worldwide [4]. Emissions have surged in recent decades—in 2019, the sector released about 2.4 Gt CO₂ (roughly one-quarter of all energy-industry emissions)—and without intervention, could reach 1.8–2.5 Gt CO₂ annually by 2050 [5]. These trends underline cement’s outsized role in climate forcing. Moreover, the industry’s environmental impacts extend beyond carbon emissions, including the heavy consumption of raw materials and water [6] and local ecological disturbances (e.g., habitat disruption from quarrying and pollution affecting air quality and biodiversity) [7]. These wider burdens underscore the need for a holistic sustainability approach to cement production.

China dominates this picture. It is by far the world’s largest cement producer and CO₂ emitter. In 2022, China alone produced about 2.1 billion tons (over half of global output), and its cumulative cement use (2010–2012) has already exceeded the entire U.S. consumption throughout the 20th century [2]. Modernization has reduced China’s per-ton emissions, yet China’s absolute share remains extraordinarily high—roughly 56–57% of global cement production in 2018–2022 [8,9]. Even if Chinese production has plateaued since the mid-2010s, China still produces more cement in a few years than many countries do in a century. India (around 8–9% of global output) and the EU (~6%) are a distant second and third, and no other nation comes close to China’s scale. However, cement demand trends vary widely by region. Many high-income economies have seen consumption stagnate or decline, whereas low-and middle-income countries are continuing to experience growth. By 2050, global cement demand is projected to rise by about 12–23% above 2020 levels, driven largely by fast-growing markets in South and Southeast Asia and Africa as urbanization and infrastructure needs accelerate. For example, Ethiopia’s cement consumption is on track to more than double from 2018 to 2025 [4]. These regional shifts illustrate that while China currently dominates production, future growth will be increasingly centered in other emerging economies. Nonetheless, China’s cement trajectory remains pivotal for global outcomes given its sheer scale, meaning that global trends—including shifting patterns of urbanization, decarbonization policies, and circular economy measures—hinge critically on how China manages its cement sector.

The recognition of cement’s environmental footprint has run in parallel with the evolution of Life Cycle Assessment (LCA) as a rigorous methodology [10]. LCA was formalized in the 1990s through standardized frameworks (ISO 14040/44) and has since expanded beyond its early focus on energy and materials to include multiple impact categories, life cycle costing, and even social factors [11,12]. Influential reviews recount LCA’s growth from an industrial tool in the 1960s–1970s (notably a Coca Cola packaging study) to a mature science for holistic environmental analysis [10]. In the construction industry, in particular, LCA has become a key tool for evaluating the sustainability of materials and buildings [9]. Today, LCA is codified in international norms and underpins eco-labeling, carbon accounting, and product category rules worldwide. Its flexibility—from “cradle-to-gate” to full “cradle-to-grave” studies—makes it uniquely suited to gauge the environmental burdens of complex products and guide decarbonization strategies.

Applying LCA to cement products has proven especially valuable. Clinker production (the calcination of limestone into clinker) is consistently identified as the dominant impact hotspot in cement life cycles, accounting for roughly half of the industry’s GHG emissions (with fossil fuels and electricity providing most of the rest) [1]. Accordingly, numerous LCA studies have compared technologies (e.g., modern dry-kiln vs. older wet-kiln processes), raw material substitutions (using supplementary cementitious materials to replace a portion of clinker), alternative fuels (e.g., biomass or waste-derived fuels instead of coal), and emerging carbon-capture systems for cement plants. By quantifying impacts across supply chains, LCA helps manufacturers to locate “carbon hotspots” and evaluate trade-offs (for example, improved energy efficiency vs. lower-clinker formulations) in a systematic way. For instance, recent LCA-based roadmaps for European cement have assessed a suite of mitigation options—from optimizing kiln efficiency to fuel switching and CCS—showing that even the partial adoption of these measures could reduce regional cement CO₂ emissions by amounts in the order of tens of megatons per year [13]. Similarly, global analyses project that the aggressive use of low-clinker binders and waste fuels could shave 30–40% off typical cement carbon footprints, while the full application of next-generation capture technologies might approach net-zero under favorable conditions [14]. Beyond carbon, LCA studies are increasingly used to address other impact categories relevant to cement. For example, incorporating agricultural and marine waste materials into cement blends (such as rice husk ash and calcined oyster shells) has been shown to reduce CO₂ emissions while also lowering water and energy use in production [6]. Likewise, a comparative LCA of building systems indicated that recycling and material reuse can significantly cut local environmental impacts (land use, water consumption, toxicity, etc.) relative to conventional practices [7]. These insights underscore LCA’s value in revealing trade-offs and co-benefits, guiding the industry toward more sustainable production pathways.

Despite a long legacy of cement LCA research, several factors justify an updated review. First, cement technologies and energy sources have shifted markedly: most modern plants (especially in China) now use efficient suspension-preheater dry kilns; process fuel mixes have diversified; and concerns about non-CO₂ emissions (SO₂, NO_x, and particulate matter) and other environmental burdens have grown [15]. Second, the LCA methodology itself is evolving—new standards (e.g., ISO 14067 for product carbon footprints), improved life cycle inventory databases (e.g., ILCD), and advanced approaches like consequential LCA are becoming increasingly common. Third, global climate commitments have raised the bar: in the Paris Agreement era, stakeholders demand not just process-based CO₂ accounting, but a comprehensive assessment of embodied emissions and resource use throughout the cement–concrete–construction life cycle. Finally, existing reviews of cement LCA are becoming dated; new literature (including user-provided studies and recent global analyses) has emerged that needs synthesis.

Accordingly, this review re-examines LCA and environmental load management in the cement sector with fresh data and up-to-date studies. We begin by summarizing global cement production and emission trends—highlighting China’s dominant role—and outlining the formal LCA framework (its history, ISO standardization, and methodological scope). We then review how LCA has been applied to cement manufacturing and concrete products, identifying key impact drivers (e.g., clinker content and energy sources) and mitigation opportunities across the life cycle. We conclude by pinpointing knowledge gaps and suggesting directions for future research and policy, emphasizing how a life cycle perspective can inform more effective emission reduction pathways. In doing so, our goal is to update practitioners and decision makers on the state of cement-industry LCA, underscore its value for guiding decarbonization, and chart a path for further improvements.

2. Fundamentals of Life Cycle Assessment (LCA)

2.1. Definition and Principles of LCA

LCA is a structured, holistic methodology for quantifying the environmental impacts of a product or process over its entire life cycle—from raw material extraction, through production and use, to end-of-life disposal or recycling. In the cement industry, LCA has become an essential tool for evaluating and managing environmental loads, as it captures all major emissions and resource consumptions associated with cement production [16]. The core principle of LCA is life cycle thinking, which aims to avoid shifting environmental burdens from one stage or impact category to another. For cement, this means considering not only direct emissions (e.g., CO₂ from clinker calcination), but also the upstream impacts of fuel and raw material acquisition and downstream effects such as concrete use phase and demolition. Key LCA concepts include the functional unit (the reference flow to normalize comparisons, often one ton of cement or clinker in cement LCAs) and system boundaries (which define which processes are included—e.g., a “cradle-to-gate” LCA of cement covers impacts from raw material extraction to the cement factory gate, whereas a “cradle-to-grave” analysis would extend through concrete use and disposal). Adhering to these principles ensures a fair basis for comparing alternatives and identifying true hotspots of environmental impact. Several general findings have emerged from applying LCA to cement. Foremost, the clinker production (kiln) phase is consistently identified as the dominant contributor to impacts like climate change, largely due to limestone calcination and fuel combustion [17]. This aligns with the principle of targeting the major “hotspots” in the life cycle for improvement. Consequently, many mitigation strategies (e.g., alternative fuels, clinker substitution, and carbon capture) are focused on the clinker stage. At the same time, LCA principles emphasize that improvements in one aspect should not create new issues elsewhere. For example, using a bio-based alternative fuel could reduce fossil CO₂ emissions but might increase other impacts or demand more upstream land use; a proper LCA will illuminate such trade-offs so that net benefits can be confirmed before implementation. Another important principle is the integration of performance and functional quality: a low-carbon cement must still meet requirements for mechanical and durability performance. Recent studies stress coupling environmental assessment with performance evaluation so that sustainability gains do not come at the expense of cement quality or longevity [18]. For instance, optimizing cement formulations via experimental design has shown that it is possible to lower CO₂ emissions while maintaining strength [19]. Overall, the LCA framework provides a quantitative foundation to guide environmental load reduction in cement manufacturing, grounded in transparency and comprehensive system analysis.

In practice, however, adhering to the ISO framework can be challenging—especially for small- and medium-sized enterprises (SMEs) or in low- and middle-income regions. Key barriers include the high cost of data collection and software, lack of trained personnel, and limited data availability. For example, one recent review found that the three main obstacles to the SME adoption of LCA are exactly “lack of trained personnel, lack of data, and high costs” [7]. Thus, while ISO LCA standards lay out the principles of a comprehensive assessment, real-world applications often require streamlined or simplified approaches (e.g., screening LCAs) to address these practical constraints. In the construction sector, additional specialized frameworks have emerged to guide LCA: for instance, EN 15804 provides Product Category Rules for building materials and Environmental Product Declarations (EPDs) that concretely apply ISO 14040/44 to construction products. Likewise, software platforms (e.g., One Click LCA and ReCap) now offer automated LCA workflows that embed these standards—although such tools still rely on quality data and expert review. In summary, LCA’s core definition and four-stage procedure are standardized by ISO, but applying them effectively often requires adaptations (and incurs costs) beyond the purely theoretical framework [20].

2.2. Key Stages and ISO Standards

Figure 1 illustrates the generic ISO LCA framework: the four main phases (Goal and Scope Definition, Inventory, Impact Assessment, and Interpretation) are shown in sequence, with iterative arrows indicating feedback between stages. The diagram also notes typical applications of LCA (e.g., product design, strategic planning, and marketing). This figure embodies the theoretical LCA process as defined by ISO 14040/44: it emphasizes that an LCA study begins with clear goals and a defined functional unit, proceeds to compile life cycle data, then quantifies impacts, and finally interprets results for decision making [21]. However, the schematic is quite abstract. In a real LCA, one must concretely choose the functional unit and system boundaries and quantify each inventory flow. For example, in a cement production LCA, the functional unit is often one ton of cement (with a cradle-to-gate boundary covering raw materials through to cement output) [22]; by contrast, a building LCA might take an entire structure or a building area as the functional unit (e.g., 500 m² of warehouse cladding) and use a cradle-to-grave boundary to capture construction, use, and end-of-life phases. Thus, Figure 1 is useful conceptually, but applying it “in practice” requires tailoring the scope (what is included or excluded) and the functional unit to the case at hand, as illustrated by concrete LCA examples below.

In addition to the ISO 14040/44 framework, other standards and tools have emerged, especially in construction. For example, EN 15804 (and its updates) is a European standard that defines core rules for construction product LCAs and EPDs, effectively building on ISO 14040 by prescribing how to handle building-specific elements (modules, end-of-life scenarios, etc.). Commercial LCA software products (such as SimaPro and One Click LCA) implement these standards: they provide templates and databases that ensure conformity with ISO 14040/44 and EN 15804 when generating results [7]. One Click LCA, for instance, explicitly supports EN 15804-compliant EPD generation for cementitious and other building products (although these tools still require user input of the bills of materials and project data). Platforms like ReCap (a newer cloud-based LCA tool) likewise aim to streamline LCA for architects and engineers by embedding standard LCA rules. In short, ISO 14040/44 sets the generic life cycle framework while EN 15804 and industry tools operationalize it for buildings; understanding the differences between them is important for practitioners, especially in regions where these standards may not be well-known or are expensive to implement.

2.2.1. Goal and Scope Definition

The goal and scope phase defines the purpose, audience, and methodological basis of the LCA study. A clear goal helps to ensure that the analysis aligns with its intended use—whether for internal decision making, environmental declarations, or policy formulation. In the scope definition, practitioners specify the functional unit, system boundaries, allocation methods, and impact categories. In cement LCAs, the functional unit is typically one metric ton of cement or clinker, reflecting the product’s core function and enabling fair comparisons across systems. The system boundary is often set as cradle-to-gate, encompassing raw material extraction, fuel production, transportation, and cement manufacturing up to the factory gate. This focus on the production stage (which is responsible for the majority of emissions) is common, though some studies extend the boundary to include use and end of life for specific purposes.

When comparative LCAs are performed, it is crucial that system boundaries and functional units remain consistent to ensure an equivalent functional performance. Palermo et al. [23], for example, followed this principle in a comparative LCA of the Brazilian cement industry. They benchmarked three low-carbon 2030 scenarios against a business-as-usual case, with each scenario defined on a per ton of cement basis and covering all inputs and emissions from raw materials through cement production. In another study, Çankaya and Pekey defined an identical cradle-to-gate scope for both a traditional and alternative fuel/raw material scenario in Turkey, using one ton of clinker (and the resulting cement) as the functional unit. This rigorous scope definition allowed for a fair assessment of improvements—indeed, the alternative scenario showed an overall impact reduction of about 12% in clinker production [24]. Similarly, Li et al. [25] evaluated the inclusion of 5% municipal sludge in the kiln feed, expanding the system boundary to credit the sludge’s avoided landfill treatment and its dual roles as both fuel and raw material. By accounting for these additional factors, their study observed net reductions in multiple impact categories, including global warming potential (GWP) and acidification, relative to conventional cement. Consistent goal and scope definition is especially vital when unconventional materials or future scenarios are assessed, as it ensures that results are comparable and grounded in the same assumptions. For instance, an independent LCA showed that utilizing sewage sludge ash as a partial cement replacement could maintain concrete performance while reducing GWP by roughly 9% [26], underscoring how a well-defined scope (including the waste’s end-of-life avoidance) leads to actionable insights. These examples highlight that a rigorous goal and scope definition underpins relevant, comparable, and credible LCA results in the cement industry.

2.2.2. Inventory Analysis

Once the scope is defined, the Life Cycle Inventory (LCI) phase begins. This phase involves compiling and quantifying all input and output flows associated with the cement production system. The inventory encompasses raw materials (e.g., limestone, clay, and gypsum), energy carriers (electricity, coal, and alternative fuels like biomass or waste), process water, and all emissions and wastes. It accounts for direct plant emissions—such as CO₂ from limestone calcination and fuel combustion, NO_x and SO₂ from kiln exhaust, and particulates (dust)—as well as indirect emissions and resource uses from background processes (e.g., quarry operations and power generation for electricity), typically drawn from databases like Ecoinvent or prior studies. Practitioners often combine on-site measurements with secondary data to ensure completeness and transparency. For example, Ige et al. used both real-time plant data and forward projections to build inventory scenarios for South African cement production through to 2040, yielding policy-relevant insights into emission drivers [27]. Sambataro et al. similarly constructed a detailed cement LCI for Europe by aggregating data from over 300 Environmental Product Declarations, which helped to reveal the variability in emissions across different plants [28].

Beyond accounting for conventional fuels and emissions, inventory analysis must incorporate process innovations and alternative practices. For example, Chen et al. [17] applied DOE (design of experiments) techniques to optimize kiln performance, achieving a ~17% reduction in CO₂ emissions compared to baseline operations. Hadj Sadok et al. [29] showed that substituting 25% of clinker with calcined dredged sediments reduced the need for limestone and fossil fuel, cutting CO₂ emissions by about 17%. Arruda Junior et al. [30] evaluated LC³ cement (limestone calcined clay cement) made with kaolinitic clay from the Amazon; they found that although long transport distances for the clay slightly increased transportation impacts, the overall CO₂ per ton of cement fell by up to 38%. Such examples demonstrate how a meticulous LCI can capture the emission benefits of material and energy innovations.

Additional studies reinforce the importance of a robust inventory in quantifying improvement potential. Khan et al., 2021, examined the effects of replacing a portion of coal with solid recovered fuel (SRF) derived from waste in an OPC plant. They found that increasing the SRF share to about 53% of fuel energy cut GHG emissions from ~1036 to 832 kg CO₂-eq per ton of cement (~20% reduction), and projected that an 80% SRF share could achieve roughly a 30% reduction (to ~725 kg CO₂-eq/ton) [31]. In another case, Georgiopoulou and Lyberatos developed seven fuel mix scenarios for producing one ton of clinker by partially substituting coal with alternatives like refuse-derived fuel (RDF), scrap tires, and biomass sludge. Their LCA inventory showed notable differences: the scenario using a high fraction of RDF was identified as the most environmentally favorable, whereas the scenario relying heavily on biological sludge was least preferable [32]. This outcome was driven by the energy content and emissions profile of each alternative fuel mix. These detailed inventory analyses reveal how choices of raw materials and fuels translate into environmental impacts. With a robust LCI foundation, cement producers and policymakers can better quantify, compare, and optimize the emission reduction potential of various interventions (e.g., alternative fuels, clinker substitutes, and efficiency improvements), making the subsequent impact assessment more reliable.

2.2.3. Impact Assessment

In the LCIA stage, the compiled inventory is translated into indicators of potential environmental impact. This involves classifying each inventory flow into an impact category and characterizing its contribution to category indicators using science-based factors. For example, all greenhouse gas emissions (CO₂, CH₄, N₂O, etc.) are assigned to the climate change category and converted to CO₂-equivalents using their 100-year GWP factors. Similarly, NO_x and SO₂ emissions are classified under acidification potential and characterized (e.g., into moles of H⁺ potential). Cement LCAs typically report GWP (kg CO₂-eq per functional unit) as a headline result, but a full LCIA provides a multi-dimensional environmental profile of the system, helping to identify trade-offs among impact categories.

For example, Gallego Davila et al. [33] analyzed a Danish cement plant equipped with carbon capture technology and found that while GWP was reduced by over 100% (i.e., net-negative CO₂ emissions), other impacts—such as human toxicity and fossil resource depletion—increased due to the additional energy and chemical inputs required for capture. Similarly, Meshram et al. [34] compared a fly ash-based geopolymer cement to traditional Portland cement and reported large decreases in GWP (61–70% lower), fossil fuel depletion (49% lower), and terrestrial ecotoxicity (77% lower) for the geopolymer. However, they also observed a slight increase in ozone depletion potential attributable to the production of alkali activators for the geopolymer. These findings demonstrate the value of LCIA in revealing both the environmental benefits and limitations (or burden shifting) of low-carbon cement strategies.

Recent studies on emerging technologies further illustrate the importance of a broad impact perspective. Tomatis et al. assessed a cement kiln using a novel solar–thermal calcination system, comparing it to a conventional kiln. Their results showed that the solar-driven system reduced impacts in 14 of 17 categories, including a ~48% reduction in climate change impact, as well as major decreases in fossil fuel depletion (75% less), smog formation, and terrestrial ecotoxicity. However, the solar approach also introduced some trade-offs: the construction of solar infrastructure led to a 102% increase in human toxicity (cancer) and a 6% increase in metals/minerals depletion, and it required roughly twice the land area per functional unit. Coupling the solar calciner with carbon capture was identified as an even more effective climate mitigation option (an 81% GWP reduction relative to conventional practice, versus 48% with solar alone), but would further accentuate non-GWP impacts [35]. As another example, LCAs of geopolymer cements have confirmed substantial GWP reductions from clinker replacement, while noting that certain categories can worsen. In one comparative study, a slag-based geopolymer concrete had significantly lower impacts than ordinary concrete in all categories except ozone layer depletion, where the geopolymer’s use of chemical activators led to a relatively higher impact [36]. This underscores how a holistic impact assessment is crucial: focusing on a single metric like CO₂ could overlook increases in other environmental burdens. By examining a range of impact categories, the LCIA phase ensures that improvements (e.g., in GWP) are not outweighed by unintended impacts in areas like toxicity, resource use, and ozone depletion. Such comprehensive assessment is instrumental in guiding truly sustainable cement production strategies.

2.2.4. Interpretation

As the final phase of the LCA framework, interpretation serves to synthesize the results from the inventory and impact assessments into actionable insights and recommendations. In cement industry applications, this phase entails identifying environmental hotspots, checking the robustness of the results (through sensitivity or uncertainty analysis), and suggesting improvement strategies while keeping in mind technical and economic feasibility. The interpretation step is crucial for validating that the LCA’s findings are both technically sound and practically relevant to decision making.

For instance, Malacarne et al. [37] evaluated LC3 (limestone calcined clay cement) production in Brazil and found that regional factors such as raw material availability and transport distances greatly influence environmental outcomes. In their interpretation, they noted that using waste-derived kaolinitic clay as an SCM can yield substantial CO₂ and energy reductions (in the order of 30% compared to ordinary Portland cement) [30], but the net benefits depend on minimizing transport impacts and ensuring local supply. This highlights the need for localized data and careful boundary choices when assessing new cement formulations—what works as an improvement in one region might not in another. In another study, Akintayo et al. [38] conducted a comparative LCA of ten different cement production methods and combined it with a multi-criteria decision analysis. Their interpretation emphasized that while several low-clinker cements offered large GWP reductions, there were trade-offs in other impact categories and in technical performance. They recommended a multi-indicator approach to optimization, rather than focusing solely on CO₂. Notably, the LCA + MCDM framework identified a blast-furnace slag cement (CEM III/A) as the most sustainable option overall, with significantly lower impacts than OPC across 18 midpoint categories. Clinker production was confirmed as a dominant hotspot (responsible for ~55% of total GWP in their analysis), underscoring the importance of clinker substitution in reducing impacts.

In a different approach, Bacatelo et al. [39] integrated LCA with a Techno-Economic Assessment (TEA) to evaluate CO₂ capture technologies for a Portuguese cement plant. Their interpretation revealed that while calcium looping had the highest potential environmental benefit (achieving the greatest CO₂ reductions among the options considered), its implementation was highly sensitive to the energy source and capital expenditure assumptions. In fact, under favorable assumptions, the calcium looping process was deemed the most feasible carbon capture route for that plant—but if low-carbon electricity was not available or if upfront costs were too high, the advantage could diminish. This example illustrates how combining environmental and economic analysis can guide technology selection: a solution needs to be green and financially viable to be truly sustainable. In all these cases, the interpretation phase was essential in translating LCA results into real-world guidance. By examining the influence of key parameters, exploring “what-if” scenarios, and aligning the findings with practical constraints, this phase ensures that LCA recommendations for the cement industry are robust, balanced (considering multiple impacts), and tuned to the priorities of stakeholders and policymakers.

3. LCA Applications in the Cement Industry

3.1. Cradle-to-Gate Assessments of Cement Production

LCA has been widely applied at both the plant level and national level in the cement industry to establish baseline impacts and evaluate improvement scenarios. Cradle-to-gate LCAs (covering raw material extraction through to cement production) consistently identify clinker production as the dominant environmental hotspot, responsible for ~90–95% of cement’s CO₂ emissions and major shares of other impacts. For example, Myanmar’s first cement LCA found that clinker making contributed ~96% of total CO₂ and ~98% of toxicity potential, with a GWP ranging from 872 to 1440 kg CO₂-equivalent per ton cement across eight plants. Wet-process kilns had significantly higher emissions than modern dry-process kilns. Even the best dry kilns showed trade-offs (e.g., higher SO₂ from coal power). Such baseline studies inform retrofit and policy strategies: in Myanmar’s case, recommendations included upgrading all kilns to dry-process with precalciners, increasing clinker substitution (using fly ash, slag, etc.), implementing waste heat recovery (WHR), and switching to alternative fuels. These measures would reduce both fuel-derived and process-derived emissions [40].

At the national scale, LCAs coupled with industry data enable scenario modeling. In South Africa, an integrated LCA–system dynamics model projected that without new interventions, cement-related pollution and GHG outputs would double by 2040, exacerbating global warming impacts. This outlook, essentially a business-as-usual baseline, underscored the need for aggressive mitigation. The same study explored policy-driven scenarios, suggesting that maintaining strict emissions regulations and introducing measures like eco-blended cements, carbon budgets, and a carbon tax could dramatically alter the predicted trajectory. In other words, LCA provided a quantitative basis for national policy: for South Africa, it indicated that blending just ~15% clinker substitutes industry-wide or implementing a modest carbon price could stabilize or reduce CO₂ per ton of cement instead of allowing a doubling by 2040 [27].

Regional case studies further illustrate how LCA is used to model improvements. In China, recent LCA research has explored the substitution of traditional raw materials with industrial by-products to reduce emissions at the source. Liu et al., 2023, conducted a cradle-to-gate LCA evaluating the environmental impact of using calcium carbide sludge (CCS) as a partial replacement for limestone in clinker production. The study found that using CCS in the place of natural limestone could reduce the GWP by up to 31%, primarily due to the avoidance of CO₂ emissions from limestone calcination and improved thermal efficiency during processing. Among three modeled scenarios, the most environmentally favorable involved the mechanical dehydration of CCS followed by drying in a coal-fired dryer, achieving significant reductions in energy use and emissions. An additional optimization, using waste heat from kiln exhaust gases to dry CCS, further improved environmental performance by reducing fossil fuel dependence and associated impacts. This case highlights the potential of non-carbonate industrial waste as a raw material substitute in China’s cement industry and demonstrates how localized LCA studies can guide targeted decarbonization strategies [41].

In Brazil, researchers performed a prospective LCA comparing a 2014 baseline with three mitigation scenarios for 2030. The scenarios assumed an increased use of alternative fuels (e.g., biomass and waste) and greater clinker replacement in cement. The results showed broad reductions across 17 of 18 impact categories. Notably, fossil resource depletion fell by up to 39% and GWP dropped by 14% in the moderate scenario and ~33% in ambitious scenarios. The clinkerization process remained the largest contributor to climate impacts in all cases, and raw material extraction dominated toxicity impacts. This confirms that lowering the clinker factor is pivotal: replacing a portion of clinker with fillers or pozzolans directly cuts process CO₂. The Brazilian study concluded that the mitigation scenarios would outperform a business-as-usual path, not only in reducing GHG emissions beyond expectations, but also in lowering other environmental burdens. Such nation-scale LCAs support sectoral roadmaps (Brazil’s 2030 plan, in this case) by quantifying the benefits of specific measures like alternative fuels and energy efficiency [23].

In Indonesia, LCA has been combined with decision analysis to compare the sustainability of different cement plants and fuel mixes. Putra et al., 2020, evaluated three cement factories via an integrated LCA and Analytic Hierarchy Process (AHP). The LCA (focusing on CO₂, human health, and acidification) revealed that Plant 1—despite having older technology—had the lowest CO₂ emissions and overall impacts because it burned medium–high-quality coal and used alternative fuels (e.g., oil). The AHP then ranked the plants by environmental, social, and economic criteria, ultimately selecting that same plant as the most sustainable (score 0.456). This result reinforces that fuel quality and diversification can outweigh even technology age in environmental performance. The study’s recommendations were to improve fuel quality across the board, increase the use of alternative fuels, and upgrade process technology where possible. Here, LCA provided environmental metrics for the AHP decision model, guiding industry stakeholders on which plant configuration was preferable when considering multi-criteria sustainability [42].

In Europe, industry-wide LCAs have examined the impact of deploying industrial symbiosis (IS) practices (e.g., using industrial by-products as raw feed or fuel in cement plants). Capucha et al., 2023, assessed several IS measures for European cement production, including alternative raw materials, alternative fuels, and clinker substitution, both individually and combined, in a 2030 scenario. The LCA showed that such measures could cut cement’s GHG emissions by up to ~12% at the production stage, with clinker substitution yielding the largest single benefit. However, the study also highlighted the importance of LCA methodological choices—for instance, assumptions about biogenic CO₂ neutrality influenced results. The authors concluded that while incremental improvements through IS are valuable, achieving carbon neutrality (net-zero cement) by 2050 will require breakthrough technologies like carbon capture, utilization, and storage (CCUS) beyond the scope of IS alone. This European analysis provides a regional benchmark: even with the maximum feasible use of waste-derived fuels and materials by 2030, the cement industry would still need greater innovations (e.g., CCS) to meet mid-century climate targets [43].

Overall, cradle-to-gate LCA applications establish critical performance baselines (e.g., CO₂ per ton cement) for different regions and technologies and then model how changes in fuel, technology, or material inputs can improve these metrics.

Table 1. Cradle-to-gate LCA case studies in cement production (regional examples).

Region (Scope)	Baseline Findings	Modeled Improvements	Recommended Actions	References
Myanmar (8 plants)	Clinker ~96% of CO2; GWP 0.87–1.44 t CO2/ton; wet kilns worst.	Dry kilns cut GHG vs. wet; however, coal power drove SO2 up.	Convert wet→dry kilns (with precalciner); increase fly ash/slag in cement; add waste heat recovery; switch to alt fuels.	Tun et al., 2020 [40]
South Africa (national)	~0.9–1.0 t CO2/ton (est.); emissions could double by 2040 under BAU.	Scenarios with blended cement, fuel mix changes flatten CO2 growth.	Implement carbon tax and budgets; mandate eco-blended cements (clinker factor reduction) to curb growth.	Ige et al., 2022 [27]
China (plant level)	Replacing limestone with CCS reduced GWP by up to 31%; best scenario involved mechanical dehydration + coal drying.	Further GWP reduction achieved by drying CCS using kiln waste heat.	Promote use of calcium carbide sludge as raw feed; utilize kiln exhaust for CCS drying.	Liu et al., 2023 [41]
Brazil (industry 2030)	Clinker main source of GHG; transport and fuel also notable.	+Alt fuels + SCMs in cement lead to 14–33% lower GWP; up to 39% less fossil fuel use.	Increase biomass and waste fuel use; promote high-SCM blended cements to meet 2030 mitigation targets.	Palermo et al., 2022 [23]
Indonesia (3 plants)	Older kiln with higher coal grade and some waste fuel had lowest impacts.	N/A (comparison study across plants rather than time scenarios).	Use higher-quality fuels; co-fire alternative fuels; prioritize efficiency over just age of plant.	Putra et al., 2020 [42]
Europe (industry 2030)	Avg ~0.6–0.8 t CO2/ton with current practices; ~5–7% GHG cut already from waste fuels.	Industrial symbiosis measures (alt raw, fuel, SCMs) can yield ~12% CO2 reduction by 2030.	Expand clinker substitution (e.g., calcined clay, fly ash); use more biomass fuels. Simultaneously invest in CCUS for post-2030 deep cuts.	Capucha et al., 2023 [43]

summarizes key findings from regional LCA case studies. A striking observation is the range of CO₂ intensities and improvement potentials: older inefficient processes (e.g., wet kilns in Myanmar) can emit well over 1.3 t CO₂/t cement, whereas modern operations with alternative fuels or additives (e.g., in Europe or Brazil) can reach ~0.6–0.8 t. Such analyses guide both industry and policymakers by quantifying the benefits of upgrades. Importantly, they also highlight co-benefits and trade-offs—for example, a dry kiln retrofit reduces CO₂ and energy use, but might slightly increase NO_x/SO₂ if coal power is used. Thus, LCA-based scenario studies provide a data-driven foundation for crafting improvement strategies at the plant and national levels.

3.2. Comparison of Different Cement Types

Blended cement types with a reduced clinker content systematically exhibit lower environmental impacts than plain OPC. In particular, cements with high proportions of SCMs show substantial savings. For example, Ige et al. found that replacing about 20–35% of clinker with limestone or slag could cut cradle-to-gate GWP by roughly 14–35% relative to pure OPC. In that South African LCA, a CEM II/B–L cement (15% limestone) gave a ≈14% lower GWP, while a CEM III/A (high blast-furnace slag) achieved a ≈35% lower GWP [44]. These high-SCM cements also reduced acidification, eutrophication, and resource use in tandem with GHG savings, because calcination (the dominant CO₂ source) was proportionally lower. A Turkish LCA similarly showed that a slag- or pozzolan-rich cement had an overall impact in the order of ~20% lower than OPC [36]. In general, acidification and eutrophication potentials track CO₂ reductions (since both stem mainly from fuel combustion), and blended Portland-composites (CEM II–V) consistently outperform OPC across most midpoint categories. Emerging low-clinker binders follow the same trend. LC3, for instance, typically uses ~50% clinker and has been reported to cut CO₂ by roughly one-third compared to OPC (in the order of 30–40% GWP reduction). Likewise, alkali-activated “geopolymer” cements (0% clinker) can reduce GWP by 60–80% (albeit with a different chemistry) [38]. In practice, the environmental gain depends on the local SCM source and energy mix. Nevertheless, any cement with 30–50% clinker generally yields GWP and energy use reductions in the order of tens of percent. Waste-derived and specialty cements can yield even greater relative improvements. Thermo-activated recycled cement (RCC), made by reclaiming and re-calcining concrete debris, shows dramatic GWP reductions. Real et al. report that RCC’s cradle-to-gate GWP is only about 22–92% of OPC’s, depending on processing route. For example, a dry-process RCC (no washing) had roughly one-quarter the CO₂ of OPC (≈22–25% of OPC GWP), whereas a wet-process RCC (with washing and drying) was still ≈8% lower (≈92% of OPC) [45]. In all cases, RCC avoids quarrying and uses the original concrete as its raw feed, so its fossil energy use and related impacts (acidification and particulate) are much lower than those for OPC. Similarly, adding large amounts of mineral waste into cement can significantly cut emissions. Sánchez et al. showed that substituting ~35% of raw materials with marble waste (an “eco-cement”) reduced the cement’s GWP by ≈34% and halved particulate emissions relative to OPC. In these low-impact cements, fossil fuel use falls (since the calcination of virgin limestone is avoided) and CO₂ from calcination is cut; acidification and eutrophication benefits accrue accordingly [46]. The overall picture is clear: any substantial reduction in clinker content delivers proportional reductions in GWP and co-impacts. In practice, replacing 10–20% of clinker typically yields ~10–20% GWP savings, while replacing 30–50% yields ~30–50% savings [47]. Most impact categories move together—for example, blends that cut CO₂ also cut fossil resource use and particulate formation. Some trade-offs may arise (e.g., the transport of SCMs or catalyst use), but, in general, “greener” cements outperform OPC across the board. This comparison is summarized below in

Table 2. Environmental comparison of cement types.

Cement Type	Clinker Content	GWP vs. OPC	Key Impact Differences	Notes/Issues
OPC (CEM I)	~95–100%	Baseline (0% change)	–	Standard reference; highest CO2 and energy use.
CEM II/B–L (limestone)	~80–90% (10–20% limestone)	≈15% lower GWP	Slightly lower acidification/eutrophication (≈same)	Minor reductions; small energy savings.
CEM II/B–S (slag)	~65–80% (20–35% slag)	~20–30% lower GWP	Reduced fossil fuel use; lower heavy metal toxicity	Good CO2 reduction; some metallic content in slag.
CEM III/A (BFS)	~35–50% (50–65% slag)	≈35% lower GWP	Large drop in CO2, fossil use; lower ozone formation and toxicity	Best performer among common cements.
CEM IV (pozzolan)	~50–70% (30–50% pozzolan)	~20–30% lower GWP	Lower CO2; similar acidification benefit	Reduces fossil fuel use; may need curing.
CEM V (composite)	~50–70% (slag+pozz, etc.)	~30–40% lower GWP	Similar to CEM III/IV blends	Mixed SCMs; performance varies by blend.
LC3 (limestone+calcined clay)	≈50%	~30–40% lower GWP	Reduced CO2 and energy; improved durability properties	Emerging technology; raw materials widely available.
RCC (recycled cement)	0% virgin limestone (recycled clinker)	~25–75% lower GWP	Much lower fossil fuel use; large GWP drop	Process-dependent (dry vs. wet routes).
Marble-blended	~60–94% (6–35% marble)	~34% lower GWP	Lower CO2; ~50% less particulate	Uses waste CaCO3; minor effect on concrete quality.
Other alternatives	Varies	Geopolymers: 60–80% lower (estimated)	Even lower calcination CO2, but potential slag source impacts	Alkali-activated and novel cements (data emerging).

, contrasting key cement types, their clinker fractions, GWP relative to OPC, and notable impact differences.

Overall, high-SCM cements (CEM III/V and LC3) and waste-derived cements (RCC and marble cements) consistently deliver the lowest impacts. Blended CEM II types yield moderate improvements, and geopolymers can be extreme cases. Acidification and eutrophication track roughly with these trends (since fuel combustion causes both); e.g., OPC’s acidification is ~20–30% higher than that for CEM III/A. In summary, reducing the clinker fraction by 10–20% typically cuts GWP by 10–20%, and so on, illustrating clear and roughly linear benefits for all key impact categories.

3.3. Use of LCA in Policy Making and Environmental Certifications

LCA has become a key decision-making tool in formulating environmental policy for the cement sector. It provides quantitative evidence on GHG and resource impacts that can underpin regulatory targets and standards. For example, Rihner et al. emphasize that LCA is a “key decision lever” in industrial decarbonization strategies, supporting evidence-based choices across energy-intensive sectors, including cement [48]. In practice, governments are embedding life cycle metrics into policy frameworks. In China, for instance, researchers have modeled a carbon trading system for cement based on LCA outputs: an “LCA-RCOT” model (LCA combined with a Rectangular Choice Of Technologies framework) showed how a cap-and-trade scheme with a 5% emissions reduction target could optimally guide technology deployment in Chinese cement manufacturing [49]. Likewise, Lu et al., 2004, argue that building codes should incorporate whole-life carbon standards—e.g., requiring embodied carbon reductions by 2030—to align the construction sector with China’s carbon-neutrality goals [50]. These examples illustrate how LCA underlies both market-based instruments (like emissions trading) and command-and-control standards (like energy/carbon performance requirements) in national policy.

Cement-specific environmental standards are evolving to reflect LCA findings. International bodies (ISO/CEN) and national regulators have created product rules and codes that allow for greater use of SCMs based on life cycle benefits. A recent European case is the revision of the EN 197 standard: in 2021, a new Part 5 was published to formally include two ternary cements (CEM II/C-M and CEM VI) with a much lower clinker content [51]. These changes followed LCA-based research showing that such blends substantially cut CO₂ per ton of cement. Similarly, China’s building material standards are being updated to include carbon footprints and life cycle benchmarks for cement products. For example, a national implementation plan now mandates the development of product carbon footprint accounting rules for cement, reflecting a shift toward performance-based regulation rooted in life cycle analysis. In all these cases, LCA provides a scientific basis for policymakers to set quantitative limits on emissions (e.g., maximum CO₂ per ton of cement) or approve new low-carbon cement grades in codes.

Governments are increasingly embedding life cycle metrics into regulations and standards. For example, China—after modeling an LCA-based cap-and-trade for cement—has now officially expanded its national ETS to include the cement industry (first compliance by end-2025 for 2024 emissions). LCA data also feed voluntary labeling and certification schemes that influence market demand. Environmental Product Declarations (EPDs)—ISO 14025 Type III labels—are widely used in construction to make life cycle impacts transparent. Sectoral EPDs (consensus LCA data sets for a whole industry) have been developed in several regions to guide regulations and green building design [52]. In the United States, states like California have enacted “Buy Clean” laws, requiring contractors to only use materials (including cement and concrete) with documented low embodied carbon via Environmental Product Declarations (EPDs) [53]. Studies show that these U.S. Buy Clean policies (focused on material carbon intensity) can reduce the embodied carbon of concrete by only an order of ~9–16% without complementary measures [54], highlighting the need for performance-based building standards. In Europe, pending building code reforms (e.g., France’s 2022 RE2020 regulation) similarly mandate whole-life LCA reporting or limits on CO₂ per square meter for new construction. Together, such laws and codes use LCA data to set numeric carbon targets or benchmarks (kg CO₂ per ton of cement or per building area), ensuring that procurement and design choices reward lower-carbon options.

Cement-product standards and industry norms have also evolved on an LCA basis. For instance, the European cement standard EN 197-1 was recently revised to formally allow new “ternary” cements (CEM II/C-M and CEM VI) with a much lower clinker content, reflecting LCA research showing that these blends cut CO₂ per ton of cement. In Germany, a landmark voluntary agreement with the government (1995–2012) on energy and CO₂ reductions led the cement association (VDZ) to systematically collect plant data. This effort culminated in the 2012 publication of a sector-average cement EPD: essentially, a Type III eco-label created from nearly all German cement works’ 2010 LCI data. This generic EPD (and underlying LCA) now serves as a benchmark in design and regulation. Beyond Germany, industry programs have spurred EPD creation: in 2016, the U.S. Portland Cement Association used the WBCSD/CSI EPD tool to generate three generic cement EPDs (covering 92% of U.S. capacity), and one of these industry-average EPDs was incorporated into the National Ready Mixed Concrete Association’s sector-wide concrete EPD. In practice, these sectoral EPDs (backed by LCA data) support national product category rules and carbon label schemes. For example, key markets now allow credit for concrete products with verified EPDs in green building ratings (LEED, BREEAM, Green Star, etc.). Cement plants that invest in SCMs or alternative fuels and, thus, lower their LCA carbon footprint can gain a market advantage through EPDs—a dynamic that encourages continuous improvement [53].

Beyond building certification, public procurement policies are also incorporating LCA. Some governments now require that cement or concrete bids include a validated LCA or meet a CO₂ intensity threshold. For example, California’s Buy Clean Act sets maximum GWP values for concrete and steel in public works. In China, emerging “low-carbon concrete” labels and green procurement rules similarly push developers to demand cement with lower life cycle emissions. Thus, LCA has become a bridge between environmental goals and market practice: it creates objective benchmarks (e.g., kg CO₂ per ton of cement) that suppliers and specifiers use to compare products. Over time, these mechanisms drive continuous improvement. Cement producers that outperform baseline life cycle emissions can claim eco-labels or credits, while heavy emitters face carbon pricing or exclusion from green markets.

In summary, LCA now underpins a broad suite of cement-sector policies and voluntary standards. It informs the setting of emissions targets and material substitution rules in regulations, shapes product category rules and EPD programs, and provides the criteria for environmental certifications and procurement. Through these channels, LCA aligns industry practices with national and global climate objectives: quantitative life cycle data ensure that policies reward genuinely lower-carbon cements and encourage innovation rather than relying on arbitrary spec changes. As policymakers have noted, embedding LCA into standards and codes—from ISO frameworks to local building regulations—helps the cement industry to meet “dual carbon” targets on the basis of scientific analysis. In turn, this integration of LCA into the regulatory and market framework has already led to measurable improvements (for example, increased SCM usage and lower clinker ratios in many countries), illustrating the practical impact of LCA-driven policy.

4. Environmental Load Management Strategies

Modern cement production faces intense pressure to reduce its environmental footprint. This chapter reviews key strategies for managing environmental loads in the cement industry, focusing on technological and material innovations and real-world case studies of successful implementation. These strategies are examined through the lens of LCA to quantify their benefits and trade-offs across impact categories.

4.1. Technological Innovations: Energy Efficiency, Alternative Fuels, and Carbon Capture

One pillar of environmental load management in cement is technological innovation at the plant level. Energy efficiency improvements have been achieved through high-efficiency kiln designs, multi-stage preheaters, precalciners, and WHR systems. Preheater–precalciner kilns use cyclone towers to recover heat from flue gases, reducing fuel per ton clinker. Precalciners divert a portion of fuel to a separate combustion chamber to calcine the meal before it enters the rotary kiln, which raises thermal efficiency and boosts throughput. Modern dry-process plants with precalciners consume ~3.0–3.4 GJ/ton clinker, markedly lower than older wet kilns (>5 GJ/t). Low-NO_x burners and staged combustion in precalciners further cut NO_x emissions by creating fuel-rich zones. These measures, now standard in new plants, have nearly maxed out gains—the environmental impact rises sharply if less efficient kiln systems are used.

WHR systems are another innovation to improve energy efficiency. They capture exhaust heat from kiln off-gases or clinker coolers to generate electricity or preheat raw materials. For example, installing a WHR power system in a Jordan cement plant recovered ~340 kW, reducing petroleum coke use by 22,000 t/year and CO₂ emissions by ~68,900 t/year. WHR can typically supply 20–30% of a plant’s electricity needs, thereby offsetting grid power and cutting indirect emissions [55]. However, WHR performance depends on having sufficiently hot and steady gas streams; modern cool kilns with multi-stage preheaters leave less waste heat available. Nonetheless, LCA studies show that WHR provides net GHG reductions by displacing fossil power, albeit with significant capital cost and moderate emission savings relative to total cement CO₂.

Carbon-neutral wastes can also be utilized. Biodegradable wastes (biomass and cellulose residues) are considered CO₂-neutral fuels. However, their collection, drying, and processing require additional energy and water. Additionally, biomass combustion may increase the emissions of nitrogen oxides (NO_x) and particulate matter, indicating the need for detailed LCAs that address these secondary impacts. An LCA study demonstrated that replacing 20% fuel with tires and 10% with sewage sludge reduced total GHG and resource depletion, but slightly elevated certain environmental impacts such as toxicity [56].

Alternative fuel use (co-processing waste) is one of the most impactful technological strategies for direct emissions reduction. Many cement plants now burn biomass and waste-derived fuels—such as refuse-derived fuel (RDF), sewage sludge, used tires, and liquid hazardous waste—in the place of coal or petcoke. These fuels are often considered carbon-neutral (biomass CO₂ is biogenic) or carbon-negative when they avoid methane from waste decay. Co-processing not only safely destroys wastes at high kiln temperatures, but also lowers fossil CO₂ emissions per ton of clinker. For instance, one LCA study in the U.S. found that replacing coal with high-energy liquid hazardous waste cut the GWP by ~16% and also reduced acidification and ecotoxicity impacts. Another study modeling a modern precalciner kiln showed that co-firing 20% scrap tires, 20% industrial waste, 10% sludge, etc., reduced net GHG emissions and resource depletion without significant new impacts. Europe leads in alternative fuels, with substitution rates averaging ~53% (reaching >90% in some plants). This yields substantial CO₂ savings, though diminishing returns occur beyond 40–50% replacement due to a lower fuel energy content and potential modest increases in NO_x or other emissions [57]. Policy (e.g., landfill bans) and cement kiln permitting have been key enablers of the high alternative fuel usage in Europe.

Selective non-catalytic reduction (SNCR) and ammonia use are also potential strategies. SNCR technology effectively reduces NO_x emissions through ammonia or urea injection, but it carries the risk of ammonia slip. Unreacted ammonia can end up in fly ash or wastewater streams. An LCA of SNCR implementation showed that environmental impacts from ammonia emissions could outweigh the NO_x reduction benefits, increasing acidification and eutrophication. In a “worst-case scenario”, poor ammonia handling rendered SNCR environmentally disadvantageous overall [58]. Additionally, excess ammonia can form ammonium salts in fly ash, potentially releasing toxic NH₃ upon ash reuse [59]. Thus, low-NO_x burners and SNCR, while effective in reducing NO_x, require rigorous ammonia management to mitigate secondary impacts.

CCUS is an emerging technological innovation to manage the cement industry’s process emissions. Because ~60% of CO₂ from cement comes from limestone calcination (and ~40% from fuel), CCUS is considered essential for deep decarbonization beyond efficiency and fuel switching. Several capture pathways are under development, as follows: (a) post-combustion capture (scrubbing CO₂ from flue gas via solvents or membranes), (b) oxy-fuel combustion (burning fuel in pure oxygen to produce a CO₂-rich exhaust), and (c) pre-combustion or process-integrated capture (e.g., calcium looping). Post-combustion amine scrubbing is the most mature and can retrofit existing kilns. It can capture ~85–95% of CO₂ from flue gas, but imposes a high energy penalty (~2.5–4 GJ/t CO₂ captured for solvent regeneration) and requires extensive gas cleanup (SO_x/NO_x removal) to protect amines [60].

Oxy-fuel technology, in which the precalciner or kiln is fired with oxygen instead of air, yields an exhaust of ~80% CO₂ that can be purified. Trials have shown that oxy-fuel can reach ~90% capture rates, but challenges remain in maintaining kiln product quality and in the capital cost of the air separation unit. Finally, calcium looping (CaL) involves diverting CO₂ into a separate reactor where lime (CaO) absorbs it, then regenerating CO₂ in a calciner; this can integrate with the kiln by using the spent sorbent as feed. A recent LCA of integrating Ca looping in a cement plant found that it could cut GHG emissions by ~74–91% compared to baseline. However, CCUS implementations carry upstream penalties: increased fuel or electricity use for capture can offset part of the gains if the energy is not from low-carbon sources. Thus, prospective LCAs stress that the net benefit of CCUS depends on future cleaner energy grids and that capture alone may not guarantee carbon-neutral cement [61].

Table 3. Key technological options, their typical performance, and trade-offs.

Technology Innovation	Typical CO2 Reduction and Efficiency Impacts	Trade-Offs/Notes
High-efficiency kiln (preheater + precalciner)	~30–50% less fuel per ton vs. old wet kilns; lowers overall GWP per ton clinker.	Requires high capital; now standard BAT in new plants (ROI via fuel savings).
Waste Heat Recovery (WHR)	Up to ~30% of plant power from waste heat, cutting ~5–10% of total CO2.	High install cost; effectiveness limited by modern kiln heat efficiency.
Alternative fuels (biomass, RDF, etc.)	Replaces coal/petcoke CO2; 50% substitution can cut ~20–30% net GHG.	Need waste preprocessing and stable supply; can slightly alter emissions profile (e.g., chlorine, trace metals).
Low-NOx burners + SNCR	20–70% NOx reduction in kiln exhaust.	Minor energy penalty for ammonia injection (SNCR); addresses local air quality (NOx).
Post-combustion CO2 capture (amines)	85–95% CO2 removal from flue gas; can cut overall plant emissions ~50–80%.	Large energy penalty for solvent regeneration; requires new equipment ~25–40% of plant cost.
Oxy-fuel combustion	~90% CO2 capture at kiln; nearly pure CO2 stream output.	Requires oxygen plant (high power use); kiln retrofit complexity—not yet commercial.
Calcium Looping (integrated)	70–90% CO2 reduction in recent pilots; less extra energy if integrated with kiln heat.	Needs additional reactors; increases limestone consumption (for sorbent); technology at pilot stage.

summarizes key technological options, their typical performance, and trade-offs.

By combining these innovations, a “technology stack” approach can drastically reduce the environmental load of clinker production. For instance, a plant might use a state-of-the-art precalciner kiln with 60% alternative fuels and WHR and plan to retrofit amine scrubbers by 2030. Such a combination addresses energy, fuel, and process emissions simultaneously. LCA-based decision tools help to optimize these trade-offs, e.g., whether to invest in WHR or in photovoltaic power to supply a capture unit. Ultimately, technological measures alone likely cannot achieve net-zero cement, but they form the necessary foundation for deeper decarbonization when coupled with material changes and carbon utilization.

4.2. Material Innovations: Use of Supplementary Cementitious Materials and Waste-Derived Inputs

In parallel with process innovations, material innovations play a crucial role in reducing the life cycle impacts of cement and concrete. The clinker factor (percentage of Portland clinker in cement) can be reduced by using SCMs—industrial by-products or natural pozzolans that partially substitute the clinker in cement or concrete. SCMs directly lower CO₂ emissions and resource use per ton of cement by avoiding a portion of the energy- and limestone-intensive clinker production [46].

Prominent SCMs include fly ash from coal power plants, ground granulated blast furnace slag (GGBS) from steel production, silica fume, calcined clays (e.g., metakaolin), natural pozzolans (volcanic ash and pumice), limestone fines, and agricultural residues like rice husk ash (RHA). Many of these SCMs are already widely used in blended cements (e.g., fly ash and slag cements) [62]. Recent developments focus on high-performance SCMs and novel blends to maximize clinker displacement while maintaining cement quality [63].

For example, LC3 is a new blend with ~50% clinker, 30% calcined clay, 15% limestone, and 5% gypsum. LC3 can achieve a strength comparable to OPC at a much lower clinker content. An LCA study in Brazil found that substituting 45–60% of OPC with calcined kaolinitic clay + limestone (producing LC3) reduced total CO₂ emissions by up to 38% (including clay calcination) and reduced overall energy use by ~28%. This illustrates the considerable mitigation potential of new SCM blends [64].

SCMs often also improve other impact categories.

Table 4. Environmental performance of various SCM-based cements compared to OPC.

Cement Type	Clinker %	GWP (CO2 eq.)	Energy Use	Particulate Matter	Water Use
Ordinary Portland Cement (OPC)	95%	100% (baseline)	100%	100%	100%
Limestone Calcined Clay Cement (LC3)	50% clinker (30% calcined clay, 15% limestone)	~62%	~72% (28% less)	~90% (est.)	~80% (est.)
Fly Ash Blended Cement (PPC)	65% clinker (30% fly ash)	~70–85%	~75–90%	~80%	~95%
Slag Cement (PSC)	50% clinker (45% GGBS)	~60–70%	~70%	~85%	~90%
Marble Waste “Eco-cement”	65–94% clinker (6–35% marble sludge)	~66% (at 35% repl.)	~66%	~50% (dust)	~40%
Rice Husk Ash Blended CAC	95% clinker (5% RHA in CAC)	~81%	~95%	~95%	~100%

Impacts are relative to OPC (100%). Lower numbers are better.

shows an LCA comparison of OPC versus cements with various SCMs (indicating relative impacts on key categories).

As seen, clinker substitution can yield 20–40% reductions in GWP for high-substitution cements (slag and LC3) and proportionally lower impacts in energy use and air pollution. In one study, incorporating 35% marble waste (largely CaCO₃) to replace natural limestone and some clinker led to a 34% reduction in GHG emissions and halved particulate emissions. Even a modest SCM like 5% RHA in calcium aluminate cement was found to cut CO₂ by ~19% and ozone depletion by 31% [65]. These improvements are because the SCM’s “embodied impacts” are lower than the clinker it replaces—often being industrial waste, its production impact is allocated to the primary product.

However, SCM use can involve trade-offs. Some SCMs have supply constraints or variability (high-quality fly ash is limited as coal power declines). The transport of heavy bulk materials like slag or natural pozzolan can add impacts; indeed, the Brazil LC3 study noted that transport emissions rose for high-replacement mixes. Also, some impacts like resource depletion can shift, e.g., calcined clay requires clay mining and fuel for calcination, though its net CO₂ is still far lower than making equivalent clinker. There can also be performance trade-offs: certain SCMs cure slower or require chemical activators. LCA must account for functional performance—if lower-clinker cement requires more cement in concrete to reach the same strength, some of the environmental benefit is lost. Overall, though, most SCMs show clear environmental advantages at the material production stage.

Another material innovation is increased circularity through industrial waste utilization. Apart from SCMs used as cement components, wastes can replace raw feed or serve other functions. For instance, copper slag or spent foundry sand can substitute some raw materials in the kiln feed, reducing virgin quarrying. Recycled concrete fines or cement paste from demolished concrete can be processed into new cement or used as supplementary material—this is an emerging area (often termed “recycled cement”). Such approaches close material loops and reduce life cycle resource depletion and landfill burden. Pilot projects on clinker made with recycled concrete fines have shown CO₂ savings, though careful LCA is needed to ensure that trucking and processing the old concrete does not outweigh benefits.

Material innovations like SCM adoption and waste-derived inputs demonstrably reduce the life cycle GWP of cement (often 20–40% reduction) and also tend to lower air pollution (NO_x and PM) and resource consumption impacts. They align with broader circular economy goals by valorizing by-products (fly ash, slag, and ash) and reducing the need for new raw materials. When implemented alongside process optimizations, these material strategies multiply environmental gains—for example, using LC3 cement (material change) in a structure means that each ton of cement has a smaller carbon footprint, and if that cement was made in a plant with WHR and alternative fuels (process change), the benefits compound [32]. LCA studies consistently highlight clinker factor reduction as one of the most effective levers for lowering cement’s embodied impacts, with the caution that performance and regional availability must be managed. Future research will expand SCM options (e.g., engineered clays, agricultural ashes, and even carbonated industrial wastes that store CO₂ in cement)—blending such approaches could yield cements that are not only lower-carbon, but potentially carbon-neutral or carbon-absorbing over their life cycle.

4.3. Case Studies of Successful Implementations

Real-world case studies illustrate how combining the above strategies can achieve significant environmental load reductions in practice. This section highlights successful implementations across different regions—each demonstrating an integration of technology, materials, and supportive frameworks (policy, economics, and collaboration).

Table 5. LCA comparison of OPC versus cements with various SCMs.

Region (Project)	Key Strategies Implemented	CO2 Reduction	Co-Benefits and Enablers	References
Brazil (LC3 Cement Demo)	45–50% clinker replaced with calcined clay + limestone (LC3 cement); process fuel shift to biomass	~38% per ton cement (vs. OPC)	28% energy savings; utilizes local clay waste; supported by academia–industry partnership and gov’t R&D funding.	Malacarne et al., 2021 (Constr. Build. Mater.) [37]
China (AI control Adoption)	Digitalization/AI-based process control (smart factory technologies)	~2–5% reduction in energy use (reflecting comparable cuts in CO2 emissions)	Improved energy efficiency, reduced labor intensity (>20%), enhanced quality stability and equipment reliability through full-scale digitalization and smart control systems.	Tong et al., 2023 (Cem. Concr. Res.) [66]
Denmark (Aalborg CCUS Pilot)	Post-combustion CO2 capture (~20–30% capture rate initially) with plan for 100% by 2030; CO2 utilization in fuels; 60% alternative fuel in kiln	Projected 80–90% reduction by 2030 (net carbon-neutral cement)	Participation in Horizon2020 consortium; gov’t investment of EUR 15M; aligns with national climate policy and future green fuel market.	Gallego et al., 2023 (J. Clean. Prod.) [33]
USA (Hazardous Waste Fuel Program)	25–30% of kiln fuel replaced with liquid hazardous waste (solvents) in a preheater kiln; emissions monitoring upgrades	~16–19% net GHG reduction (scope 1)	Reduced landfill/incineration of hazardous waste; cost savings on fuel; achieved with EPA regulatory support (BIF permit) and community engagement.	Holt et al., 2018 (Cem. Concr. Res.) [57]

provides an overview of several projects and their outcomes.

Brazil—LC3 Pilot and Adoption: Brazil has abundant kaolinitic clay, and a recent project in Brazil developed and trialed limestone LC3 on an industrial scale. In this case, a cement plant in Brazil’s Amazon region replaced 45% of its clinker with calcined clay and limestone. The LCA results showed a ~38% reduction in CO₂ emissions per ton of cement, even accounting for the transport of clay. Energy demand dropped by ~28% and other impact categories saw improvements, demonstrating the successful implementation of a novel SCM blend in a developing economy context. The case was enabled by collaboration between academia (Federal University researchers) and industry (cement companies), with support from government programs aiming to utilize local clay waste and reduce deforestation-driven biomass fuel use. This LC3 cement is now commercially branded and used in some construction projects in Brazil, validating its performance in tropical climates [37].

Chinese cement makers are deploying “smart factory” technologies to cut emissions. For example, Tong et al., 2023, report a full-scale Chinese cement plant where advanced digital controls were installed—including integrated robotics, AI-based classifiers (XGBoost), and cloud-based process monitoring. This smart-plant setup optimized the kiln and preheater controls in real time. As a result, the plant achieved an energy reduction of about 2–5% through improved process control. (This energy saving directly translates into lower CO₂ emissions per ton of cement.) The case demonstrates a practical, implemented sustainability strategy: by using AI and data analytics to fine-tune operations, the plant lowered its environmental load without major hardware changes [66].

Europe (Denmark)—Carbon Capture and Utilization Pilot: In Northern Europe, policy drivers for carbon neutrality by 2050 have spurred a high-profile case at Aalborg Portland’s cement plant in Denmark. This plant, the largest cement producer in Denmark, launched a pilot project in 2021 to integrate CCUS with its operations. The project, part of an EU Horizon 2020 consortium, is installing a post-combustion CO₂ capture unit aiming to capture ~400,000 t CO₂/year, about 20–30% of the plant’s emissions in phase 1. A unique aspect is the plan to utilize a portion of the captured CO₂ for green fuels: the CO₂ will be combined with hydrogen (from renewables) to produce e-methanol, while the rest is destined for geological storage under the North Sea. An LCA study of this CCUS chain (capture + methanol) found an ~74–90% reduction in net CO₂ emissions, depending on energy sources. Importantly, the study showed that using Denmark’s increasingly renewable grid for capture operations improved the LCA outcome significantly. The Danish case is a prime example of stakeholder collaboration: it involves the cement company, energy companies (for hydrogen supply), universities conducting LCA/TEA, and government funding. While still in the early stages (the capture plant is expected to be fully operational by the mid-2020s), it demonstrates a holistic approach—combining alternative fuels (the plant already uses ~60% waste fuels), efficiency upgrades, and carbon capture with utilization. The success of this project could provide a template for other European plants, especially in regions with CO₂ infrastructure and policy support (e.g., Norway’s Brevik project) [33].

United States—Alternative Fuel Co-processing in Cement: A case from the USA highlights successful hazardous waste co-processing. In this example, a large Midwestern cement kiln partnered with a waste management firm to use high-BTU liquid hazardous wastes (like solvents and paint residues) as kiln fuel. Over a decade, the plant ramped up to replace ~30% of its fuel heat input with these liquid wastes. According to an LCA case study, the shift resulted in a 19% reduction in GWP and sizable decreases in toxins and acidification potential compared to the baseline coal-fired scenario. The project’s success was due to strict feed control (ensuring a consistent calorific value and low mercury/chlorine in waste) and regulatory support—the EPA provided permits under the Boiler and Industrial Furnace (BIF) rules to allow burning hazardous waste with continuous emissions monitoring. Community stakeholders were engaged to address concerns, emphasizing that overall emissions (NO_x and SO₂) did not increase and some (SO₂) even dropped due to the inherent sorbents in the waste. This USA case underscores how policy flexibility and stakeholder engagement enabled an environmental win–win: the cement plant reduced fossil CO₂ and fuel costs, while hazardous waste found a productive use with the destruction of harmful constituents at high kiln temperatures [57].

These case studies illustrate that integrated approaches yield the best outcomes. Each project tackled multiple facets: Brazil combined material substitution with biomass fuel, China showed that even modest improvements from digital optimization can yield measurable sustainability gains, Denmark paired fuel shift with carbon capture and utilization, the U.S. addressed both waste management and fuel sourcing, and Europe pushed the limits of waste fuel replacement. Common enabling factors include strong policy support (e.g., renewable energy mandates, waste co-processing permits, and R&D funding), favorable economics (e.g., cost savings from waste fuels or carbon credits for CCUS), and stakeholder collaboration (industry partnerships and public acceptance).

These implementations indicate that the cement industry’s decarbonization is achievable through incremental innovation scaled up by systemic support. Each case contributes to a growing knowledge base. As more plants adopt similar measures, the industry moves closer to its goal of minimizing environmental loads across the life cycle, in line with global climate and sustainability targets.

5. Challenges, Limitations, and Research Opportunities

While Life Cycle Assessment (LCA) in the cement industry has significantly evolved, critical methodological, practical, and data-related challenges still constrain its effectiveness and adoption. Addressing these issues is essential to improve the accuracy, relevance, and applicability of LCA, particularly for real-world decision making in industry and policy.

A primary limitation in current cement LCA studies lies in the system boundary definition. Most assessments are conducted on a cradle-to-gate basis, covering impacts only up to the point that the cement leaves the factory. While this approach provides valuable insights into manufacturing-stage emissions, it neglects downstream phases such as transportation, concrete production, use, and demolition. As a result, key environmental burdens associated with service life performance, repair frequency, and end-of-life processing are excluded. This restricts the capacity of LCA to inform holistic decarbonization strategies. Full cradle-to-grave studies are essential to reflect the true environmental load of cement-based products and guide decisions such as material durability or circular economy interventions.

Another fundamental issue is data availability and quality. Many studies depend extensively on international databases (e.g., Ecoinvent and GaBi), lacking region-specific validation. Countries with substantial cement production like China and India frequently suffer from incomplete or generalized datasets, causing discrepancies in representing local conditions such as fuel mixes, raw material sourcing, and plant technologies. Developing regionally validated, comprehensive Life Cycle Inventory (LCI) databases is, thus, crucial to ensure accurate and actionable LCA results.

Moreover, few studies systematically address data uncertainties or perform sensitivity analyses to confirm robustness. Methodological inconsistencies, especially regarding allocation methods for emissions from alternative fuels or co-products, further complicate result comparability across studies. Increased emphasis on harmonized standards, transparent reporting, and standardized uncertainty assessments is needed to strengthen reliability and facilitate benchmarking across the cement industry.

A significant shortcoming highlighted by this review is the limited economic perspective in current LCA approaches. Traditional LCAs predominantly focus on environmental impacts while overlooking economic dimensions like investment feasibility, operating costs, and broader economic implications. Integrating TEA and LCC methods with LCA could address this gap by enabling more informed trade-offs between environmental benefits and financial viability. Such hybrid frameworks would significantly improve the decision support capability of LCA, making it more attractive and practical for industry stakeholders.

While “regionalized LCA models” have been proposed to address localized variations, validation mechanisms for these models remain poorly defined. Future research must establish clear validation protocols, incorporating local monitoring data, benchmarking against regional industry practices, and conducting stakeholder consultations to ensure that these regionalized models reflect actual operational conditions and can reliably guide local sustainability policies.

Additionally, comprehensive impact assessments that consider pollutants associated with alternative fuels and materials (e.g., dioxins, heavy metals, and PAHs) are critical. Current LCA practices often underreport or omit these secondary environmental impacts. Expanding the LCA methodology to thoroughly evaluate the fate and transport of hazardous substances will improve environmental risk assessments and support safer waste utilization practices.

Technological accessibility represents another barrier, especially in developing economies and among small-to-medium enterprises (SMEs). Existing LCA software often lacks customization to local data structures, regulatory frameworks, and economic contexts. Developing user-friendly, localized LCA tools—such as domestic software modules tailored specifically for national cement industries—would greatly enhance LCA adoption by reducing complexity, lowering implementation costs, and facilitating broader industry participation.

To overcome these challenges, future research should prioritize expanding system boundaries to include downstream life cycle phases, integrating rigorous economic assessments with LCA methodologies, and establishing validated, region-specific LCI databases. Efforts should also aim at improving transparency, methodological standardization, and developing accessible LCA tools. Interdisciplinary collaborations among environmental scientists, engineers, economists, and policymakers will be instrumental in addressing these gaps, ultimately fostering a more comprehensive, credible, and practical implementation of LCA within the cement sector.

6. Conclusions

This review synthesized current knowledge on the application of LCA and environmental load management strategies in the cement industry, highlighting significant advancements in methodologies, technological and material innovations, and practical implementations across diverse regional contexts. Important findings include the following:

(1)

Clinker production remains the primary environmental hotspot, contributing approximately 90–95% of cement’s CO₂ emissions.

(2)

Technological innovations, such as high-efficiency kilns, alternative fuels, and waste heat recovery, demonstrate potential emissions reductions of 20–50%.

(3)

Supplementary cementitious materials (SCMs), like slag and fly ash, can effectively reduce CO₂ emissions by 20–40% while improving other environmental indicators.

(4)

LCA-based policies, including emissions trading schemes and green procurement standards, have effectively driven industry-wide environmental improvements.

Despite significant progress, challenges such as incomplete data, methodological inconsistencies, and inadequate economic integration persist. To overcome these limitations, future research should focus on the following:

(1)

Developing and validating regionalized and dynamic LCA models through local data and industry engagement.

(2)

Integrating economic assessments (TEA and LCC) within environmental LCA frameworks for practical decision making.

(3)

Enhancing methodological transparency, standardizing allocation approaches, and systematically conducting sensitivity analyses.

(4)

Creating user-friendly, localized LCA tools to facilitate broader industry adoption.

Addressing these areas will further solidify LCA as an essential tool for achieving sustainability and decarbonization goals in the cement sector.