The construction sector faces multiple challenges in carbon emissions from cement manufacturing and excessive utilization of natural resources as raw materials, which harm the environment. In the current investigation, an alkali-activated binder was used to produce sustainable M35-grade paver blocks and was compared with a conventional paver block. The solid precursors were industrial wastes such as fly ash, ground granulated blast furnace slag (GGBFS), and calcium carbide residue (CCR), which were activated by sodium silicate (Na2SiO3) and sodium hydroxide (NaOH) as activators. Compared to conventional paver blocks, the alkali-activated paver blocks demonstrated better durability properties such as decreased water absorption and better abrasion resistance. The compressive strength of the M35-grade alkali-activated paver blocks was found to be 12% higher than the commercially available blocks of the same grade. The other mechanical properties, such as flexure and split tensile strength, also performed better when compared to the commercial paver block used for light-traffic conditions. Water absorption and abrasive wear of the alkali-activated paver blocks were superior to the commercially available paver blocks.

The progress of industrialization and rising electricity demand have significantly impacted various aspects of our lives, leading to a prioritization of green electricity sources such as wind turbines. However, managing the waste from end-of-life turbine blades poses a significant challenge, particularly as the first generation of wind turbines in Europe, primarily made of glass fibre-reinforced thermosets, reaches the end of service life. Unfortunately, landfilling and incineration remain common disposal methods in many EU countries. Co-processing end-of-life blades in cement manufacturing offers a promising alternative by enabling energy and material recovery. This method aligns with sustainable development and circular economy goals. Cement production, known for its high CO 2 emissions and extensive raw material consumption, can benefit from substituting ground or shredded turbine blades, which contain organic and inorganic components. This study conducts a comparative life-cycle assessment of incineration and co-processing across different European countries to identify the disposal method with the least environmental impact. The evaluation focuses on carbon footprint reduction and water conservation as key benefits. Findings reveal that while incineration poses risks to global warming, it can help preserve water. In contrast, co-processing yields environmental benefits across all assessed categories by conserving raw materials for cement production. The normalized results indicate that human health is the most impacted area of protection for both processes, with resource benefits influenced by the type of energy produced in the examined countries. The Global Warming Potential values for co-processing are similar across the four countries (−525 kg CO2-eq for Germany, −523 kg CO2-eq for Spain, −533 kg CO2-eq for Italy, −494 kg CO2-eq for the Netherlands), representing an environmental benefit from substituting the raw mineral feedstock with EoL turbine blades. Moreover, the results show that, in terms of Human Health and Ecosystems, co-processing produces environmental benefits, whereas incineration generates damage (positive impact values) due to emissions that are harmful to living species regardless of geographical location. • Comparative life-cycle quantitative assessment between different waste management possibilities for EoL wind turbine blade. • The assessment is carried out in different European countries. • Description of the co-processing recycling procedure of EoL turbine blades is presented. • The environmental impacts have been presented in terms of GWP, AWERE, human health, natural resource, and ecosystem.

Utilisation of calcium carbonate derived from pilot-scale indirect CO2 mineral carbonation of waste concrete: Impacts on mechanical and microstructural properties of mortar

Resource recovery for sustainable construction: Strength and microstructure characteristics of municipal solid waste incineration ash as a green alternative to cement in cementitious composites

Limestone calcined clay cement (LC 3 ) with 50% clinker content represents a significant advancement in low-carbon binders but further clinker reduction is limited by insufficient portlandite (CH) availability to sustain pozzolanic reactions. Commercial CH addition defeats the low-carbon purpose due to its carbon emission higher than clinker. This study addresses this dual challenge by valorizing industrial carbide slag (CS), a CH-rich (80%) waste by-product – as a circular calcium source to enable low-clinker LC 3 formulations with 30% and 40% clinker factors. Six paste mixes were systematically evaluated, comparing raw CS and calcined CS against conventional LC 3 -50 and OPC controls. A multi-technique characterization framework was employed to establish the hydration kinetics, phase assemblage, C-(A)-S-H gel chemistry, and pore structure evolution. The results reveal a synergistic trade-off mechanism: although the addition of both CS forms inhibits the hydration of clinker silicates (C 3 S/C 2 S), this inhibition is effectively compensated by sustained pozzolanic reactions driven by the supplemental calcium and the formation of Al rich C–(A)–S–H gel with shorter silicate chains, alongside stable carboaluminate phases. Consequently, LC 3 -40-CaO achieves a 28-day compressive strength of 52.5 MPa, equivalent to LC 3 -50, while utilizing 10% less clinker. All CS-modified pastes exhibit refined pore structures (critical pore entry radii of 14–17 nm), comparable to LC 3 -50 (11 nm) and substantially finer than OPC (77 nm). Environmental performance indicators demonstrated 16% reduction in embodied CO 2 per MPa compared to LC 3 -50. This work establishes waste carbide slag as a viable, low-carbon CH source enabling mechanically robust LC 3 binders with clinker factors below 50%, advancing circular economy principles in sustainable cement production. • Multi-scale mechanistic framework explains dual calcium source pathways • Waste carbide slag enables <50% clinker content in LC 3 • Calcined carbide slag outperforms raw slag in the mechanical performance • 15-20% embodied CO 2 reduction versus LC 3 -50 through combined clinker reduction and waste valorization

Clay-based cementitious materials with high performance and low carbon emissions have gained considerable interest in recent years. This study develops a new marine soft clay-based cementitious material derived from calcium carbide residue (CCR) and waste tile powder (WTP). Systematic characterisation is conducted through macro- and micro-scale tests, including unconfined compressive strength (UCS) testing, orthogonal experiments, mercury intrusion porosimetry (MIP), X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The UCS of specimens under varying influence factors (WTP content, temperature, CCR content and curing time) was evaluated. Furthermore, stress-strain behaviour, failure strain, liquid and plastic limits, microstructure and carbon footprint were investigated. Experimental results reveal that CCR and WTP promote strength improvement. When 17% CCR and 15% WTP are mixed with clay, the 28-d strength reaches 2210.19kPa. The optimal proportions of NaOH, WTP and CCR are 14%, 14% and 0.8%, respectively, as determined by orthogonal experiments. SEM-EDS results indicate that cementitious products are clearly observed with the addition of WTP and CCR. The microscopic mechanism is also discussed. This research demonstrates that the clay-based cementitious system derived from CCR and WTP is an environmentally friendly material with excellent properties, providing a new approach for solid waste recycling.

Clay soils in cold regions are highly vulnerable to repeated freeze-thaw cycles (FTCs), yet sustainable and effective stabilization methods that simultaneously enhance mechanical performance, frost durability, and environmental footprint remain underexplored. This study addresses this gap by investigating the synergistic stabilization of frost-susceptible clay using waste marble (WM) powder, nanozeolite (NZ), and polyvinyl alcohol fibers (PVAFs). A comprehensive experimental program evaluated unconfined compressive strength (UCS), indirect tensile strength (ITS), California bearing ratio (CBR), and durability index (DI), of untreated and treated soils (10% WM, up to 2% NZ, and up to 2% PVAF) subjected to up to 10 FTCs, complemented by microstructural analyses using X-ray diffraction (XRD) as well as scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDS). In addition, a comparative life cycle assessment (LCA) quantified environmental performance. The optimal mixture (10% WM, 1.5% NZ, 1.5% PVAF) achieved a UCS of 7.8MPa (≈ 37 times that of untreated clay), an ITS of 654kPa, and a soaked CBR of 108%. After 10 FTCs, more than 95% of compressive strength and over 80% of bearing capacity were retained. Multi-scale microstructural analyses confirmed the formation of cementitious hydration products and a cohesive fiber-reinforced matrix. An apparent linear correlation between UCS and CBR supports practical strength estimation. The LCA showed reductions of approximately 59% in global warming potential and over 89% in mineral resource scarcity compared to conventional cement-based stabilization. These findings demonstrate that WM-NZ-PVAF stabilization offers a sustainable, frost-resilient solution for cold-region geotechnical applications, though field validation remains necessary.

To address the practical engineering challenges of compaction difficulty and low efficiency associated with traditional backfilling methods for narrow and confined urban foundation trenches, this study proposes an eco-friendly backfill material: sodium silicate-activated fly ash-cement composite fluidized stabilized soil, using in-situ loess from the Xiong'an New Area as raw material. Material components were optimized through curing agent ratio determination and single-factor tests. The development laws of mechanical properties, the micro-scale solidification mechanism, and the flow-filling characteristics within narrow trenches were systematically elucidated by integrating scanning electron microscopy and computational fluid dynamics (CFD) simulations. The results indicate that a fly ash-to-cement mass ratio of 1:1 serves as the critical benchmark for optimizing the composite curing agent proportion. This ratio effectively inhibits excessively rapid early water evaporation and provides a stable hydration environment for the later pozzolanic reaction of fly ash. The optimal mix proportion achieves a balance between high fluidity and high strength. A water content of 51.25% ensures sufficient cementitious reactions. A sodium silicate content of 2.0% strikes a balance between activating fly ash and avoiding excessive slurry viscosity. A curing agent content of 35% facilitates the formation of a continuous and dense cementitious network. Under the optimal proportion, the material exhibits a spread flow of 175mm and a 14-day compressive strength of 4.53MPa, meeting the requirements for pumping construction and strength. The compressive strength of fluidized stabilized soil results from the synergistic interaction of fluidity, molding compactness, and water loss behavior. This is manifested microscopically by the generation of cementitious products, pore filling, and particle cementation, and macroscopically reflected in the coupled effects of physical water migration and chemical water consumption. Adopting a single-pour length covering three utility tunnel Sect. (9m) and a pouring speed of 5m/s combined with a terminal speed reduction process can significantly enhance the compactness and construction quality of trench backfilling. This approach facilitates the formation of a stable flow field and reduces air bubble retention in corners. Field application demonstrates that this process can meet the dual requirements of construction efficiency and quality. The research findings provide a theoretical foundation and key technical guidance for the construction of underground comprehensive utility tunnels in the Xiong'an New Area.

The manufacture of cement contributes significantly to carbon dioxide (CO2) emissions into the atmosphere. The effects of mineral admixtures (iron dust, glass fines, metakaolin, and limestone fines) make them suitable for reducing carbon emissions as a replacement for cement. All mineral admixtures (MA) are byproducts of primary materials, and natural fiber is included. This study focuses on a sustainable material that does not compromise strength. This paper analyzes the properties of self-healing concrete developed using MA Bacillus tropicus and sisal fiber. Three different percentages of MA, 10%, 20%, and 30%, and 1% of sisal fiber were used by weight of cement. Bacteria were incorporated into the concrete using the direct addition method, in which the healing solution (a combination of a 1:9 bacterial-to-nutrient ratio) was added directly to the concrete. A total of five mixes of concrete control C0, bacterial control CB, 10% MA CB10, 20% MA CB20, and 30% MA CB30 were cast. Thus, 1% sisal fiber was constant for all mixes. The self-healing concrete's (SHC) performance was assessed through sorptivity, porosity, water absorption, acid resistance, crack-healing efficiency (CHE), compressive strength (CS), splitting tensile strength (STS), regain compressive strength (RCS), and microstructural morphology analysis. The economic and environmental benefits are evaluated. A comparative analysis of the experimental results showed positive results up to a 20% replacement after declination, but not to a level below the reference mix. Adding fiber significantly increases tensile strength, achieving a 3 to 13% improvement over the control mix, and supports bacterial survival within the concrete environment. Optimal concrete mixtures of 20% were suggested, and the specimens showed improvements of 15.45% in CS, 12.53% in STS, and 90.96% in RCS compared to control concrete specimens. The recovery ratio can exceed 80% for all mixes except the control specimen. The economic analyses identified reduced maintenance costs and lower carbon emissions. The microstructural analysis confirms the presence of bacteria, as well as calcium carbonate and calcite.

Cement manufacturing is a significant source of CO2 emissions in the world, with approximately 8% of the global emissions being due to cement manufacturing, mainly through clinker manufacturing. In order to reduce its environmental effects, this paper examines the use of silica fume (SF) and Alccofine (AF) as additional cementitious materials (SCMs) to improve the mechanical and durability characteristics of concrete. The first stage involved the addition of SF at 5, 7.5 and 10% replacement levels to establish the optimum dosage and the second stage involved the addition of AF at 5, 10 and 15% with the optimum SF content maintained. Mechanical properties such as compressive strength, flexural strength, and split tensile strength and durability properties such as water sorptivity and rapid chloride penetrability (RCP) were tested. The best combination of 7.5% SF and 10% AF was 34.7% increase in compressive strength, 16.1% increase in flexural strength and 16% increase in split tensile strength over the control mix. This blend showed a 43.7% decrease in water sorptivity and a 42.8% decrease in RCP in terms of durability, which is significant in terms of resistance to water ingress and chloride penetration. Compressive strength was well predicted by machine learning models, with the most significant variables being cement content and AF. Life cycle assessment (LCA) indicated that the optimum blend had a global warming potential that was reduced by a factor of about 10% relative to OPC. These findings indicate that the integration of SF and AF does not only improve the performance of concrete but also minimizes its environmental impact, which is a promising avenue to sustainable and high-performance construction materials.

Coated granular materials are involved in numerous industrial processes, including powder handling in pharmaceuticals, additive manufacturing, cement production, and food processing, where surface treatments control flowability, prevent agglomeration, and improve product consistency. Despite their widespread use, the influence of coatings on the collective behavior of granular materials remains poorly understood. While dry granular flows are well described by the μ(I) rheology for frictional, noncohesive particles, many real-world systems involve additional interparticle interactions that fall outside this framework. Here, we investigate how polymer coatings on silica grains modify dry granular rheology by introducing non-Coulombic frictional behavior at the particle scale. Pressure-imposed rheological experiments reveal that coatings activate a low-friction regime in which the bulk friction coefficient and packing fraction approach values typical of frictionless grains. The transition from this lubricated state to a conventional frictional regime depends on both normal stress and shear rate, indicating stress- and velocity-dependent contact mechanics. Tribological measurements show that interparticle friction decreases with coating thickness and sliding velocity, but increases with normal load. Building on these findings, we develop a mean-field rheological model that extends the classical μ(I) framework to include coating-dependent, non-Coulombic friction. Discrete Element Method simulations incorporating the measured friction law capture the key qualitative features observed experimentally. These results demonstrate that controlled surface coatings provide a powerful route to engineer granular rheology and enhance flowability across various industrial applications.

Comparative prospective life cycle assessment of decarbonization strategies in the Saudi cement industry

Calcium sulfoaluminate-belite (CSAB) cement has gained interest as an alternative low-CO2 cement to conventional portland cement (PC) for various applications, offering beneficial properties such as reduced setting time, rapid strength development, and shrinkage compensation. CSAB cement production requires less limestone, lower clinkering temperature, and lower clinker grinding energy compared to PC. The reduced limestone requirement is attributed to the chemical composition of CSAB cement—having lower CaO and higher Al2O3 contents. The surplus limestone rejected by PC plants due to low CaO content presents an opportunity for its use in CSAB clinker production, potentially offering a sustainable approach to alleviate the strain on limestone reserves for future cement manufacturing. This study investigates the suitability of limestones having clayey and siliceous impurities with less than 40% CaO content (by weight) for producing high ye’elimite CSAB cement. The chemical compatibility and scale of utilization of limestone are discussed by comparing the performance of produced cements with a commercial CSAB cement having similar composition. The amount of gehlenite phase was dependent on the free-CaO available for clinkering reactions, restricting the utilization of low-grade limestone to 15%–20%. The experimentally observed phase compositions were found to be in reasonable agreement with the phase assemblage predicted by FactSage modeling. A modified formula for the lime saturation factor was proposed for raw mix proportioning of CSAB clinkers. This study reports the development of laboratory-synthesized CSAB cements of optimal compositions exhibiting similar heat of hydration, microstructure evolution, and strength development as that of commercial CSAB cement.

Decarbonization of cement production in Türkiye: a techno-economic and risk analysis of CO2 capture technologies

Towards Sustainable Cement Production in Iraq: Life Cycle Assessment and the Impact of Clinker Substitution

Synergistic effects of graphene nanoplatelets and palm oil fuel ash on the mechanical properties and carbon footprint of concrete

Firms in Tororo, Uganda. This study examined the influence of inventory management practices lean inventory systems, Economic Order Quantity (EOQ), and Just-in-Time (JIT) control on financial performance among cement manufacturers in Tororo, Uganda. Guided by Profit Maximization Theory and the EOQ model, the study adopted a pragmatic philosophy and a cross-sectional mixed-methods design. Data were collected from senior and middle-level managers using stratified random sampling, while key informants were purposively selected. Quantitative data were analyzed using descriptive statistics, correlation, and hierarchical regression analysis, while qualitative data were analyzed through thematic coding. The findings revealed that inventory management practices significantly influence financial performance among cement manufacturers. EOQ emerged as the most dominant predictor, followed by lean inventory systems, while JIT showed a positive but comparatively weaker effect. Overall, the results indicate that effective inventory management improves financial performance by reducing costs, improving resource utilization, and enhancing operational efficiency. The study concludes that strengthening EOQ-based ordering systems, improving JIT implementation through reliable supplier coordination, and adopting lean inventory practices can enhance profitability, efficiency, and return on assets. Inventory management is therefore a critical strategic function for improving performance in the cement manufacturing sector.

To address the loose structure and insufficient dynamic stability of collapsible loess subgrades in Gangu, Gansu Province, as well as the engineering and environmental concerns associated with conventional stabilizers (high energy consumption and carbon emissions), this study proposes a composite stabilization strategy using an eco-friendly curing agent (EFCA) and P·O 42.5 Portland cement. Unconfined compressive strength (UCS) tests and dynamic triaxial tests were performed, and scanning electron microscopy (SEM) image processing together with fractal theory was employed to systematically elucidate the macroscopic dynamic response and the microscopic pore-reconstruction and evolution mechanisms of the composite-improved loess. The results indicate that the optimal mix proportion determined by an orthogonal design is "6% cement + 0.02% curing agent", yielding a 28-day UCS of 2.51MPa, which is 483% higher than that of the untreated loess. The dynamic resilient modulus (Ed) increases markedly and reaches 826.49MPa under a confining pressure of 60kPa and a dynamic stress of 30kPa (an 8.07-fold increase). Nonlinear regression analysis confirms that the Ni model, by jointly accounting for the coupled effects of mean and deviatoric stresses, provides exceptionally high predictive accuracy for Ed of the composite-improved loess, with an average relative error of only 0.026. Quantitative microstructural analysis reveals that the synergistic effects of chemical cementation and hydration products promote the transformation of loess particles into dense aggregates, resulting in a decrease in the pore fractal dimension (D) from 1.323 to 1.249. This topological reconstruction from connected macropores to discrete micropores fundamentally reduces the structural complexity of the soil. The study clarifies a cross-scale physical-mechanical mechanism whereby "microstructural pore-fractal dimensionality reduction" drives a "macroscopic surge in dynamic stiffness", providing theoretical and data support for green, low-carbon subgrade construction and long-term dynamic stability evaluation in loess regions.

Supersulfated cement (SSC), a low carbon dioxide binder utilising 80–90% ground granulated blast-furnace slag (GGBS), faces a critical challenge in balancing mechanical performance and carbon dioxide footprint reduction when incorporating basic oxygen furnace slag (BOFS) – a steelmaking byproduct with underutilised potential. However, adding more than 10% BOFS to SSC causes a significant reduction in strength, which limits both its broader application and its potential for further reducing carbon dioxide emissions. This study explores the synergistic effect of sodium lactate in BOFS-modified SSC (BSC) to address this limitation. The results show that even a small addition of 0.5% sodium lactate significantly improves the 7-day and 28-day strength of BSC. Hydration heat tests reveal that the combined use of BOFS and sodium lactate significantly inhibits early hydration, leading to a more porous initial microstructure. This porosity facilitates the dissolution of slag during the later stages of hydration. Furthermore, the chelating properties of lactate ions promote the dissolution of ions from both GGBS and BOFS, increasing the formation of ettringite and enhancing the hydration of SSC. These findings demonstrate that the simultaneous use of sodium lactate and BOFS offers a significant improvement in both the performance and environmental benefits of SSC, making it a more viable option for sustainable cement production.

The growing demand for sustainable construction materials has accelerated research into eco-friendly alternatives to traditional Portland cement. This research explores the potential of geopolymer concrete formulated from agricultural-waste ashes as a sustainable replacement for conventional Portland cement. Banana peel ash (BPA) and sugarcane bagasse ash (SCBA) were employed as aluminosilicate precursors, and their combined effects were systematically examined through controlled variations in blend proportion, alkaline activator molarity, sodium silicate-to-sodium hydroxide (SS/SH) ratio, and aggregate-to-binder ratio. The influence of these parameters on fresh and hardened properties-including workability, compressive strength, and flexural strength-was rigorously evaluated. Within the defined experimental domain, an optimal formulation comprising 52.5% SCBA and 47.5% BPA activated with 10M NaOH achieved compressive and flexural strengths of 33.17MPa and 9.95MPa, respectively, demonstrating structural-grade performance suitable for practical applications. Detailed microstructural investigations employing SEM-EDS, XRD, FTIR and TGA techniques confirmed that both ashes exhibit high silica content, significant pozzolanic behaviour, and that increased activator concentration enhanced the dissolution of aluminosilicate phases leading to a denser geopolymeric matrix with improved durability. To further strengthen the analytical framework and enable predictive mix optimization, artificial intelligence-based models-Gene Expression Programming (GEP) and Artificial Neural Networks (ANN)-were developed. Both models achieved excellent predictive performance (R2 > 0.98) with respect to slump Flexural and compressive strength; however, the GEP model consistently exhibited superior accuracy, lower error indices and better alignment with measured results than the ANN. Performance was validated through statistical metrics including Mean Square Error (MSE), Root Mean Square Error (RMSE), Mean Absolute Error (MAE) and coefficient of determination (R2), confirming the robustness of the machine-learning framework in capturing the complex, non-linear interactions among mix variables. The novelty of this study lies in demonstrating that low-value agricultural waste ashes can be engineered into reliable, structural-grade geopolymer binders, producing a high-performance BPA-SCBA concrete that repurposes agricultural residues and reduces the carbon footprint of cement production. Additionally, the integration of AI-based optimization provides a robust decision-support tool for mix design, enabling data-driven, sustainable construction practices.