Supplementary Cementitious Materials Research Articles

Embodied Carbon in Concrete: Insights from Indonesia and Comparative Analysis with UK and USA

Concrete is the most widely used construction material globally. However, its production, particularly that of cement, is a significant source of carbon dioxide (CO2) emissions, contributing to approximately 8% - 10% of the global anthropogenic CO2 emissions. This study aims to analyze and compare the embodied carbon (eCO2) of various concrete strength grades commonly utilized in Indonesia to offer insights for enhancing sustainability in the construction industry. The methodology involved designing concrete mixes according to Indonesian standards and calculating carbon emissions for each component. The findings revealed that the eCO2 in the Indonesian concrete mixes was significantly higher than that reported in the UK and US databases. This higher carbon footprint emerges primarily due to the greater cement content found in the Indonesian mixes. Nevertheless, the current study demonstrated that using fly ash as a supplementary cementitious material can substantially reduce the eCO2, with the mix containing fly ash showing a 42% reduction in emissions compared to the mix without fly ash. This research emphasizes the necessity for the Indonesian construction industry to adopt sustainable practices, including optimized mix designs and the use of low-carbon materials such as fly ash. In doing so, significant reductions in the carbon footprint of concrete can be achieved, contributing to the global efforts to mitigate climate change and to promote sustainability in construction practices.

From waste to sustainable production: Experimental design and optimization of sustainable concrete using response surface methodology and life cycle assessment

This study focuses on a holistic approach to investigate the engineering properties (microstructural, mechanical, environmental, and economic) of sustainable concretes produced using recycled aggregate and supplementary cementitious material (SCM). Compressive strength tests was conducted on 24 sustainable concrete series for the mechanical properties. Statistical analyses were performed using the response surface methodology, and mathematical models were developed considering the strength values obtained. Developed model-based optimization solutions were applied to determine the mix proportions of the optimization series containing lower cement dosage and SCM with the same hardened concrete properties as the reference concrete series. Considering these mix proportions, life cycle assessments were performed and environmental and economic properties were compared. A comparison of Ref-6 and Opt-6 series reveals that the global warming potential (GWP), energy consumption (EC), and waste generation (WG) values are 422.4-330.9 kg CO2 eq, 1294-1044 MJ, and 1294-1222 kg, respectively. This situation resulted in a reduction of 21.7% in GWP values, 19.3% in EC values, and 5.6% in WG values. Similarly, the economic comparison of these series indicates that the total cost values are 81.9-75.7 €, respectively, resulting in 7.7% reduction. Finally, Scanning Electron Microscopy analyses were conducted to examine the microstructural properties. The use of fly ash at 10% improved the microstructure properties and increased the C-S-H gel formation. It is thought that the process of transition from these waste materials to sustainable production is of critical importance, especially in places that are heavily damaged after devastating earthquakes and where large amounts of waste materials are generated.

Two-step process to recover metal and mineral residues from municipal solid waste incinerated (MSWI) ashes

The utilization potential of mineral fractions after metal recovery from fly ash and air pollution control residues from a municipal solid waste incineration plant was studied. Chemical leaching using acidic (H2SO4), and alkaline (NaOH) solutions was applied for metal recovery from fly ash and air pollution control residues from a municipal solid waste incineration plant. Subsequently, the feasibility of recycling both untreated and treated samples in cementitious materials was evaluated. This study aims to investigate the influences of chemical leaching on the structures and properties of MSWI residues as well as examine the utilization potential in cementitious materials of mineral residues after leaching, and their environmental risk. The use of acidic and alkaline leachants had good efficiency in critical metal recovery and unvalued/hazardous metal removal: 99 % of As, 72–80 % of Cd, 47–60 % of Zn, Cu, Co or Mn. After leaching, the chemical composition, physical properties, and mineralogical phases of the incinerated residues were substantially modified. The postleaching mineral residues showed potential for use in supplementary cementitious materials with enhanced reactivity and control of hydration kinetics. The compressive strength of cement pastes using 20 % of MSWI residues can obtain 14 MPa after 7 days. Detrimental impacts from potential toxic elements in incinerated residues can be alleviated through chemical leaching.

Enhancing high-performance concrete with local andesite and calcined marl: Insights from heat treatment and untreated conditions

This study explores the incorporation of local Algerian andesite and calcined marl as supplementary cementitious materials in high-performance concrete (HPC), with a special focus on the effects of heat treatment. Advanced analytical techniques, including X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA), were used for material characterization. The Sherbrooke method was utilized for mix design optimization, and thermal curing effects were critically evaluated. Key results demonstrated that both andesite and calcined marl significantly enhance HPC performance. Fresh mixtures showed excellent workability and consistent density. In the hardened state, these admixtures reduced porosity and water absorption capacity, improving durability. Heat-treated samples exhibited substantial early strength gains, while non-heat-treated samples showed superior long-term strength due to ongoing pozzolanic activity. Ultrasonic pulse velocity (UPV) measurements confirmed the high quality of the concrete. Tomography revealed a dense pore structure and strong interfacial transition zones, contributing to overall performance. Statistical modeling using the Design of Experiments (DOE) methodology validated the experimental findings and identified optimal conditions for maximizing compressive strength. Sulfuric acid exposure tests indicated good chemical resistance, with balanced performance in maintaining residual strengths and managing weight losses. This research underscores the potential of using local andesite and calcined marl to enhance HPC, promoting sustainable construction practices in Algeria by reducing reliance on imports and utilizing regional resources. In summary, this study contributes to sustainable HPC development by demonstrating the effectiveness of local mineral admixtures. The dual benefits of heat treatment for early strength gain and non-heat-treated conditions for long-term durability offer valuable insights for optimizing HPC formulations, advancing our understanding of pozzolanic materials, and promoting environmental stewardship and economic efficiency in the construction industry.

An assessment of the pozzolanic potential and mechanical properties of Nigerian calcined clays for sustainable ternary cement blends

This study investigates the potential of calcined clays from Nigerian deposits as supplementary cementitious materials. Clay materials were obtained from three sites namely: Ikpeshi, Okpilla and Uzebba. The raw clay samples were then calcined at 700°C and 800°C. Chemical and mineralogical compositions were determined for the raw and calcined clay samples using XRF and XRD respectively. The chemical composition by XRF confirmed these clays as potential pozzolans with SiO2, Al2O3, and Fe2O3 collectively exceeding 70%. XRD analysis identified kaolinite and quartz as major mineral phases in the raw clays, which transformed into metakaolin upon calcination. Thermo Gravimetric Analysis (TGA) indicated varying lime consumption levels among the clays, with Ikpeshi clay displaying the highest pozzolanic reactivity and Uzebba clay the least. Compressive strength investigation on mortar cubes prepared with 50% substitution of Portland cement with the calcined clay and limestone, showed that Ikpeshi clay at 800°C had the best strength performance, with strength activity index of 0.92 (at age 28 days), demonstrating superior pozzolanic potential. Strength development was more significant between 7 and 28 days, indicating the pozzolanic reaction's contribution to long-term strength. However, initial strength at 3 days was lower than the reference Portland cement due to a delayed pozzolanic reaction. XRD analysis of blended pastes revealed typical phases of hydration like portlandite, calcium silicate hydrate phase, strätlingite, and ettringite, with the calcined clay blends showing reduced portlandite content, indicating absorption by the pozzolan's alumina phase.

Influence of silica fume on pore structure, mechanical properties and carbon emission of reactive powder concrete prepared by ice crystal homogenization technology

Under ultra-low water-to-binder ratio conditions, the liquid-bridge effect between powders seriously restricts the development of reactive powder concrete (RPC). Ice crystal homogenization technology fundamentally solves the liquid-bridge problem between powders. However, high carbon emissions still constrain the application of RPC. This paper introduces an innovative RPC material incorporating silica fume (SF) as a supplementary cementitious material to solve environmental concerns and alleviate powder aggregation challenges based on the ice crystal homogenization technology. Experimental results show that there was a significant improvement in compressive and flexural strengths observed, particularly in RPC material containing 15% SF, which exhibited the most notable enhancements: a 19.7% increase in compressive strength to 296.3MPa and a 23.6% increase in flexural strength to 43.8MPa. Moreover, the optimized microstructure was reflected in a substantial reduction in water absorption rate and cumulative pore volume by 44.7% and 54.4%, respectively. Besides, RPC incorporating 15% SF achieved the lowest carbon emissions efficiency, with carbon emissions efficiency could be reduced by 79%~93% compared with conventional UHPC. In conclusion, the use of SF and ice crystal homogenization technology in RPC provides the great potential for developing sustainable construction materials and promoting carbon reduction strategies.

Study on the Influence of Carbonation on the Microstructure of Cement-based Materials Based on BSE Technique

Background: The influence of carbonation on the interfacial transition zone (ITZ) microstructure of cement-based materials was significant. However, the width of ITZ is about tens of microns, and studying its micro-characteristics (such as porosity, hydration products, content of unhydrated cement, etc.) by macro test was difficult. Methods: Backscattered electron (BSE) imaging technology and gray scale analysis method were used to analyze the cement-based materials with water-binder (W/B) ratios of 0.53 and 0.35, respectively. Results: BSE and gray scale analysis showed that in the ITZ, the porosity of 0.53P (Portland cement paste), 0.35P (Portland cement paste), 0.53F (fly ash), and 0.35F (fly ash) decreased by 24.1%, 28.9%, 49.5%, and 64.2% respectively, whereas the content of hydration products increases after carbonation, and the matrix also shows the same rule. At the same time, the smaller W/B ratio, the greater the porosity reduction, and the filling effect of carbonation on the specimens with supplementary cementitious material (SCM) was more significant than that of pure cement specimens. Conclusion: The porosity of the ITZ decreased after carbonation, however it remained higher than that of the matrix. Consequently, the ITZ remained a vulnerable zone with a greater diffusion rate of CO2 compared to the matrix even after carbonation.

Effects of CaO-based expansive agent on carbonation resistance of marine concrete

Marine concrete contains a high volume of supplementary cementitious materials, which benefits low-carbon concrete production. However, they may also increase the risk of cracking and accelerate the carbonation due to the pozzolanic reaction. Theoretically, the CaO-based expansive agent (CEA) can inhibit shrinkage cracks and introduce external calcium sources that aid in the carbonation resistance of concrete. A comprehensive understanding of the impact of CEA on the carbonation resistance of marine concrete is currently scarce.In this study, marine concretes with varying dosages of CEA were exposed to 20% CO2 for 28 days. The carbonation depth, carbonation coefficient, air permeability, pore structure characteristics and CO2 buffer capacity of concrete were investigated. When the CEA dosage was less than 6%, the carbonation resistance and air permeability approached the reference groups in normal-strength concrete (NSC) and high-strength concrete (HSC). However, more than 6% CEA significantly decreased the carbonation resistance of concrete, particularly for HSC. For NSC, there was an excellent correlation between the carbonation coefficient and compressive strength, while for HSC, the carbonation coefficient correlated well with porosity. Also, CO2 buffer capacity was essential to assess the carbonation resistance of marine concrete.

Improved chloride binding capacity in sustainable metakaolin blended seawater cement mortar: Effect of external alternative electric field

Seawater is a promising substitution of fresh water in concrete production to relieve the resource crisis, especially for the concrete fabricated in harsh environment with less freshwater supply, while the excessive chloride ion (Cl-) in seawater may induce severe durability issue. In this work, metakaolin (MK) was used as supplementary cementitious material to prepare seawater cement mortar (SWCM), and ohmic heating (OH) curing was utilized to fabricate MK-SWCM at -20 °C by creating high temperature curing condition, with conductive carbon fibers (CFs) as electrical reinforcement media. The CFs fraction was numerically and experimentally obtained as 1.0 vol%, the electrical resistivity, electric voltage and curing temperature change during OH process was disclosed. Results showed that MK inclusion and OH curing both contributed to enhancing the Cl- binding capacity with higher hydration degree and denser pore structure. To be specific, OH cured SWCM with 10% MK content endowed the Cl- binding ratio of 35.4%, meeting the increase of 97.8% compared to that of room temperature cured SWCM with no MK addition. Moreover, the mechanical strengths were further proven excellent for winter production in cold environment, which were all above 60 MPa with the aid of OH curing. A systematical analysis was conducted to roundly clarify the benefits for MK-SWCM fabrication in cold region from the aspects of Cl- binding capacity efficiency, environmental benefits and mechanical strength.

Simultaneously comparing various CO2-mineralized steelmaking slags as supplementary cementitious materials via high gravity carbonation

The integration of accelerated carbonation with the utilization of steelmaking slags presents a vital strategy for CO2 mineralization towards net-zero scheme. This study simultaneously evaluates basic oxygen furnace slag (BOFS), refining slag (RFS), and electric arc furnace reducing (EAFRS) and oxidizing slags (EAFOS) as potential partial replacements for ordinary Portland cement, at substitution levels ranging from 5 % to 15 % as supplementary cementitious materials (SCMs). These slags were pretreated through aqueous accelerated carbonation in a high-gravity rotating packed bed. We assessed several parameters, including carbonation conversion, CO2 capture capacity, workability, strength, and durability. The results demonstrated that EAFRS achieved the highest CO2 capture capacity, reaching 0.193 kg-CO2/kg-slag with a maximum carbonation conversion of 46 % under 197 times high-gravity conditions and a liquid-to-solid ratio of 20. While the incorporation of carbonated slags had minimal impact on the setting properties of cement pastes, higher substitution ratios necessitated increased water demand. The strength of blended cement containing 5 %, 10 %, and 15 % of carbonated BOFS, RFS, and EAFRS met standard requirements at 28th day. Additionally, a mathematical model was developed to predict the mechanical strength of cement mortars. The introduction of carbonated BOFS, RFS, and EAFRS facilitated hydration due to the formation of calcium carbonates, although it resulted in slower strength development kinetics. Notably, the replacement of cement with carbonated EAFOS exhibited a higher expansion rate, likely due to its elevated silicon dioxide and alkaline species content, which may lead to alkali-aggregate reactions, resulting in expansion and cracking.

Compressive strength and regional supply implications of rice straw and rice hull ashes used as supplementary cementitious materials

Substituting Portland cement (PC) with supplementary cementitious materials (SCMs) is a key strategy for reducing greenhouse gas (GHG) emissions. Considering alternative SCMs requires a holistic understanding of changes to material performance, emissions reduction potential, and regional availability. Four rice hull ashes (RHAs) and one rice straw ash (RSA) were evaluated to replace PC in mortars (10% untreated ash and 30% blast furnace slag; 15% untreated ash; or 15% milled ash). The 28-day compressive strengths with 0.59 water-to-binder ratio for fly-RHAs (38.0–49.8 MPa) and RSA (37.7 - 44.1 MPa) did not vary significantly from the PC control (43.2 MPa) based on an ANOVA. Modeling rice biomass generation in six U.S. states shows RSA could triple the supply of rice-biomass ash, but in states with substantial PC demand, i.e., California and Texas, the potential GHG reduction may remain small (∼1–2%). RSA and RHA may hold promise in lowering concrete GHG emissions.

Promoting Sustainability in the Cement Industry: Evaluating the Potential of Portuguese Calcined Clays as Clinker Substitutes for Sustainable Cement Production

The cement industry significantly contributes to global CO2 emissions, posing several challenges for a future low-carbon economy. In order to achieve the target established by the European Sustainable Development Goals of reaching carbon neutrality by 2050, the European Cement Association (Cembureau) has devised a comprehensive roadmap based on five key approaches, referred to as the 5C strategies. Portland clinker is one of the crucial concerns, since its production emits over 60% of the cement manufacturing emissions. Therefore, supplementary cementitious materials (SCMs) to partially replace clinker content in cement have gained significant attention in providing alternatives to traditional clinker in cement production. This paper evaluates the potential of Portuguese calcined clays (CCs) as viable substitutes for clinker to enhance sustainability in cement manufacturing. More than 50 clays were characterised through chemical and mineralogical analyses to assess their reactivity and suitability for calcination using the strength activity index (SAI), along with XRD, XRF, and TGA techniques. This study investigated the calcination conditions that provide the best clay reactivity, which were subsequently used for calcination. This investigation is part of a project to evaluate the behaviour of calcined clays through mechanical, hydration, and durability properties. The findings indicate that Portuguese calcined clays exhibit promising pozzolanic activity. Furthermore, these clays could significantly reduce CO2 emissions and raw material consumption in cement production. This research underscores the potential of local calcined clays as a sustainable clinker substitute, promoting eco-friendly practices in the construction industry.

Potential Reuse of Ladle Furnace Slag as Cementitious Material: A Literature Review of Generation, Characterization, and Processing Methods

Ladle furnace slag (LFS), a by-product of steel refining, shows a promising reuse pathway as an alternative additive or substitute for Portland cement due to its high alkalinity and similar chemical composition to clinkers. However, LFS is often stored in large, open surface areas, leading to many environmental issues. To tackle waste management challenges, LFS can be recycled as supplementary cementitious material (SCM) in many cementitious composites. However, LFS contains some mineral phases that hinder its reactivity (dicalcium silicate (γ-C2S)) and pose long-term durability issues in the cured cemented final product (free lime (f-CaO) and free magnesia (f-MgO)). Therefore, LFS needs to be adequately treated to enhance its reactivity and ensure long-term durability in the structures of the cementitious materials. This literature review assesses possible LFS treatments to enhance its suitability for valorization. Traditional reviews are often multidisciplinary and explore all types of iron and steel slags, sometimes including the recycling of LFS in the steel industry. As the reuse of industrial by-products requires a knowledge of their characteristics, this paper focuses first on LFS characterization, then on the obstacles to its use, and finally compiles an exhaustive inventory of previously investigated treatments. The main parameters for treatment evaluation are the mineralogical composition of treated LFS and the unconfined compressive strength (UCS) of the final geo-composite in the short and long term. This review indicates that the treatment of LFS using rapid air/water quenching at the end-of-refining process is most appropriate, allowing a nearly amorphous slag to be obtained, which is therefore suitable for use as a SCM. Moreover, the open-air watering treatment leads to an optimal content of treated LFS. Recycling LFS in this manner can reduce OPC consumption, solve the problem of limited availability of blast furnace slag (GGBFS) by partially replacing this material, conserve natural resources, and reduce the carbon footprint of cementitious material operations.

Investigation on rheological performance of indigenously developed sustainable low clinker hybrid cementing binders

Cement production is a chief source of greenhouse gas emissions and is responsible for 5–8 % of anthropogenic CO2 emissions to the atmosphere worldwide. Incorporating Supplementary cementitious materials (SCMs) into cement production can lessen the need for parent materials and also reduce about 30 % of carbon dioxide (CO2) footprint. This study examines the rheological performance of the indigenously developed low-clinker hybrid cementing binders. The rheological behavior of blends could vary with different factors like the quantity of cement replacement, the type of mineral additive, the water-to-binder ratio, and the age of the paste. The rheological performance was learned through flow curves, constant shear rate, and small amplitude oscillatory shear tests. The results obtained from samples revealed that the binary blended (BB) mix exhibited higher shear stress, and the ternary (TB) and quaternary blends (QB) exposed low shear stress. From the analysis, the dynamic yield stress was increased by increasing the SCM proportion. Constant shear rate test results showed that the BB has the highest static yield stress, then other blends. Samples showed significant elasticity and linear viscoelasticity region. The resulting compressive strength of 28 days of curing showed that the quaternary mix QB1 had the highest ultimate compressive strength (52 MPa) increased by 101.9 %. While the BB has shown the least strength (80.3 %) among other blends. The characterization studies were opted to identify the properties of SCMs. The morphological study was conducted to recognize the effect of SCMs leading to the formation of denser structures to enhance compressive strength.

Experimental Evaluation of Heat of Hydration in Concrete Incorporating Supplementary Cementitious Materials

Experimental Evaluation of Heat of Hydration in Concrete Incorporating Supplementary Cementitious Materials

Utilizing spodumene slag as a supplementary cementitious material: A quantitative study

This study investigates the potential of spodumene slag (SPS) as a supplementary cementitious material (SCM). Firstly, the comprehensive characterization results show that SPS consists of quartz, gypsum, calcite, lazurite, and alumino-silicates, with 34 % amorphous content. Next, the hydration characterization indicates that SPS has limited self-cementing properties; however, it inhibits the initial dissolution of C3S, C3A, and C4AF due to the gypsum. This inhibition for C3S is counteracted by the dilution effect of SPS. Over time, the hydration degrees of the clinker phases improve as SPS provides additional nucleation sites and retains more free water for cement hydration. Additionally, thermodynamic modelling was established and validated by experimental data to capture the reaction process and phase changes. AFt forms in all systems, but AFm phases decrease and disappear at 40 % and 50 % SPS levels. Engineering tests reveal that 50 % SPS addition extends initial setting time by 60 %, and reduces fluidity by 20 %. Compressive strength remains acceptable up to 20 % SPS replacement, with an activity index of more than 80 %. Overall, SPS shows potential as a supplementary cementitious material, but careful adjustment of replacement levels is essential to minimize its disadvantages.

Development of sustainable self-healing engineered cementitious composites incorporating maximum amounts of natural pozzolan

In light of the scarcity of the most commonly used supplementary cementitious materials in Engineered Cementitious Composites (ECC), there is a pressing need to explore alternative materials to replace them. This paper considers the influence of integrating high amounts of natural Pozzolan (NP) on the sound and self-healing characteristics of ECC, including compressive and flexural strengths, deflections, cracking behavior, ultrasonic pulse velocity, rapid chloride permeability, and microstructure both before and after pre-cracking and recovery periods. NP contents at Portland cement (PC) ratios of 1.2, 1.5, 1.8, and 2.2 were explored, along with a combination of (50 % NP + 50 % slag)-to-PC ratio of 2.2. The results obtained indicate that superior self-healing properties can be achieved with the use of NP instead of slag, particularly at higher NP/PC ratios. Furthermore, the ductility of ECC significantly increased with the inclusion of NP, reaching more than twice the deflection capacity of the control specimens at various ages. The results of this research confirm the formation of additional C-A-S-H-type healing products as the outcome of the NP incorporation on the self-healing ability of ECC. In addition, the life cycle assessment analysis (LCA) highlights the significant reductions in energy consumption, CO2 emissions, and cost of ECC mixtures prepared with increased inclusion of NP, up to a 2.2 NP/PC ratio.

Study on the interaction between limestone filler and rice husk ash on the rheological properties of cement composite pastes

As an active supplementary cementitious material, rice husk ash (RHA) can improve several properties of cement paste. However, it has a significant negative impact on the flowability of cement pastes. This study aims to improve the rheological properties of cement-RHA paste by adding an additional admixture: limestone filler (LF). The rheological curve was measured using a rheometer, and the effects of LF and RHA on the rheological properties (dynamic and static yield stresses, consistency, and structural build-up) were investigated. The calculation and analysis of water film thickness (WFT) and the interaction forces between the particles in the paste were conducted to reveal the intrinsic mechanism. The results show that LF can effectively eliminate the adverse effect of RHA on rheological properties. When the RHA content is 10 %, the addition of 5 %, 10 %, and 20 % LF reduces the yield stress by 43.86 %, 69.64 %, and 87.11 %, respectively, and decreases the consistency by 28.17 %, 40.85 %, and 73.24 %, respectively. The high porosity of RHA leads to significant water absorption, which affects the WFT between paste particles much more than LF. The WFT decreases with RHA, resulting in a higher yield stress. The higher specific surface area (SSA) of RHA reduces the spacing between paste particles, and the enhanced interactions between particles significantly increase the initial yield stress (20 min). The addition of LF reduces the inter-particle forces and the structural build-up, lowering the yield stress, which results in a good complementary effect between LF and RHA on the rheological properties. This study can provide guidance for the design of mix proportions considering the workability of the cement-LF-RHA composite system.

Challenges and Performance of Filter Dusts as a Supplementary Cementitious Material.

Global industry relies on a linear approach for economic growth. One step towards transformation is the implementation of a circular economy and the reclamation of anthropogenic deposits. This study examines two filter dusts, one German and one Argentinian, from the production of calcined clays, representing such deposits. Investigations and comparisons of untreated and calcined filter dust and the industrial base product pave the way for using waste product filter dust as supplementary cementitious material (SCM). In the future, some twenty thousand tons of contemporary waste could potentially be used annually as SCM. The results confirm the suitability of one material as a full-fledged SCM without further treatment and a measured pozzolanic reactivity on par with fly ash. Sample materials were classified into two groups: one was found to be a reactive pozzolanic material; the other was characterized as filler material with minor pozzolanic reactivity. Additionally, important insights into the physical properties of oven dust and heat-treated oven dust were obtained. For both material groups, an inversely proportional relationship with rising calcination temperatures was found for the specific surface area and water demand. The impact of the calcination temperature on both the particle size distribution and the potential to optimize the reactivity performance is presented.

Sustainable Utilization of Calcined Granite Powder as Partial Replacement for Cement in Concrete Mixtures: A Mechanical and Environmental Assessment

<p class="heading1" style="line-height:150%;margin-bottom:0cm;margin-right:0cm;margin-top:0cm;tab-stops:36.0pt;text-align:justify;text-justify:inter-ideograph;"><span style="font-size:11.0pt;font-weight:normal;line-height:150%;">The escalating environmental concerns associated with cement production have prompted to explore alternative materials for partial replacement, aiming to reduce the carbon footprint of the construction industry. This research investigates the incorporation of calcined granite powder, a byproduct of granite processing, as a sustainable supplementary cementitious material. The granite powder, which is conventionally disposed of in landfills, was collected directly from the industry and subjected to calcination to enhance its pozzolanic properties.The experimental investigation involved replacing cement with calcined granite powder in varying proportions (0-50%) in concrete mixes of M30 grade. Mechanical properties such as compressive strength, flexural strength, and durability were assessed to evaluate the performance of the formulated mixes. Remarkably, the mix containing 70% cement and 30% calcined granite powder exhibited a substantial increase in </span><span style="color:#00B0F0;font-size:11.0pt;font-weight:normal;line-height:150%;">compressive strength by 7 %,  flexural strength by 11 % and 13 % increase in tensile strength </span><span style="font-size:11.0pt;font-weight:normal;line-height:150%;">compared to the conventional M30 mix. Furthermore, a life cycle assessment (LCA) was conducted using SimaPro software to analyze the environmental impact of the formulated concrete mixes. The results indicated that the concrete mix with 40% calcined granite powder and 60% cement not only demonstrated superior mechanical properties but also proved to be environmentally sustainable, exhibiting reduced global warming potential. This finding underscores the potential of calcined granite powder as a viable and eco-friendly alternative, contributing to the sustainable evolution of concrete production.</span></p>