Limestone Calcined Clay Research Articles

Harnessing iron tailings as supplementary cementitious materials in Limestone Calcined Clay Cement (LC3): An innovative approach towards sustainable construction

The increasing demand for sustainable construction materials has led to the exploration of iron tailings (ITs) as supplementary cementitious materials (SCMs) in Limestone Calcined Clay Cement (LC3). This study investigates the effects of varying ITs content in LC3 on compressive strength, microstructure, and environmental impact. Replacing 28 % of LC3 with ITs resulted in a 42 MPa compressive strength after 28 days, comparable to ordinary Portland cement (OPC), while reducing OPC content by 50 %. Microstructural analysis revealed that ITs contributed to the formation of additional C-(A)-S-H gel, enhancing the mechanical properties of the cement matrix. The findings also showed that concentrations of Zn (0.003–0.094 mg/L), Pb (0.002–0.090 mg/L), Cu (0.005–0.018 mg/L), Mn (0.115–0.712 mg/L), Ni (0.011–0.021 mg/L) in the leachates of LC3 containing ITs were below the critical limits for surface water and groundwater. Moreover, the life cycle assessment (LCA) demonstrated significant reductions in global warming potential (43.6 %), energy consumption (37.2 %), and cost (35.5 %). This study provides an innovative solution for waste utilization and environmentally friendly cement production.

Investigating the Interaction of Limestone Calcined Clay and OPC-Based Systems with a Methyl Hydroxyethyl Cellulose-Based Viscosity Modifier Used for 3D Printable Concrete

Investigating the Interaction of Limestone Calcined Clay and OPC-Based Systems with a Methyl Hydroxyethyl Cellulose-Based Viscosity Modifier Used for 3D Printable Concrete

A review on serviceability of foam concrete

In the face of the present global warming crisis, building energy conservation and emissions reduction have gained increasing attention. In the sustainable development of buildings, foam concrete has become increasingly popular in the construction industry due to its excellent thermal insulation, sound insulation and fire resistance. Foam concrete employed in buildingand construction (used as either a structural or non-structural member) must meet certain serviceability criteria. This paper reviews the serviceability of ordinary Portland cement (OPC) foam concrete, geopolymer foam concrete (GFC), sulphoaluminate cement (SAC) foam concrete, magnesium phosphate cement (MPC) foam concrete and limestone calcined clay cement (LC3) foam concrete, to include drying shrinkage, creep, thermal conductivity, water absorption and acoustic properties. Subsequently, it is proposed to change the initial curing conditions to reduce drying shrinkage, add glass fiber and basalt fiber to improve creep performance, increase heat flow direction resistance and extend the thermal conduction path to reduce thermal conductivity, control slump flow to regulate water absorption, and combine sound absorbing foam concrete with sound reflecting materials to achieve a comfortable and low noise living environment. Finally, ideas and suggestions for future work are proposed.

Rheological, mechanical, and environmental performance of printable graphene-enhanced cementitious composites with limestone and calcined clay

As extrusion-based 3D concrete printing gains wider acceptance in construction, there is a growing imperative to incorporate supplementary cementitious materials (SCMs) into printable mixtures to address their high cement content and promote sustainability. Conventional SCMs like fly ash and slag are becoming increasingly scarce, underscoring the need for alternative solutions such as limestone and calcined clay. Additionally, the utilization of nanomaterials in printable mixtures holds potential for enhancing the mechanical properties of 3D printed structures. These properties are often compromised by interlayer interfaces and void formations during printing, resulting in lower mechanical performance compared to conventionally cast concrete. Graphene nanoplatelets (GNPs), with their high aspect ratios and exceptional mechanical characteristics, offer promising avenues for reinforcing printable cementitious composites. This study explores the rheological, mechanical, and environmental aspects of graphene-enhanced cementitious composites incorporating limestone and calcined clay. Graphene nanoplatelets (GNPs) were dispersed utilizing a surfactant-assisted sonication technique, and their dispersion characteristics were evaluated through absorbance, particle size, and zeta potential measurements. Then, the influence of varying GNP concentrations on the rheological properties of limestone-calcined clay (LC2) cementitious composites was assessed. Compressive and flexural strength tests were conducted on 3D-printed LC2 samples with different GNP ratios, alongside cast specimens for comparison. Microstructural examination of failed specimens was performed using scanning electron microscopy. Furthermore, a life cycle assessment was conducted to compare the environmental impacts of printable LC2 mixtures to conventional printable mixtures. Incorporating GNPs at a ratio of 0.05 % by weight of cement in printable LC2 mixtures enhances compressive strength by 23 %, leading to a reduction of approximately 31 % in environmental impacts compared to conventional printed mixtures.

Performance of limestone calcined clay cement (LC3) made with CO2-mineralized concrete slurry waste

Concrete slurry waste (CSW) is an under-recycled material with great potential to be substitute ordinary Portland cement (OPC) after proper treatment. In this study, dehydrated CSW (DCSW) was used to mineralize CO2 and the carbonated product was used to prepare limestone calcined clay cement (LC3). The results showed that the CaCO3 content of carbonated DCSW (CDCSW) reached ∼57.7% after mineralization for 8.5 h. During carbonation the Portlandite peak disappeared after 1.5 h, and the Mc_AFm peak disappeared after 3.5 h. The alite and belite peaks gradually diminished, with a weak diffraction remaining at 8.5 h. Replacing limestone with CDCSW led to a decrease of 14.7% in fluidity, at a plasticizer dosage of 1.3%. The compressive strength of LC3-cdcsw mortar specimens was higher than those of LC3-limestone specimens at all ages. The effective chloride diffusion coefficient of LC3-cdcsw was also promisingly small (1.08 × 10−11 m2/s). The comprehensive properties (grey correlation degree) of LC3-cdcsw were 17.82% lower than that of OPC, but 17.73% higher than that of ordinary LC3. At 28 d, the contents of monocarboaluminate for LC3-cdcsw and LC3-limestone are 11.2% and 9.5%, respectively. The fourth thermal decomposition peak of LC3 system is higher than that of OPC, and the peak intensity of LC3-cdcsw is lower than that of LC3-limestone. Our work explores the pathway of carbon sequestration in concrete slurry waste for the preparation low-carbon and durable cementitious materials.

Mechanical and environmental performance of high-strength strain-hardening cementitious composites with high-dosage ternary supplementary cementitious materials: Fly ash, limestone, and calcined clay

Strain-Hardening/Engineered Cementitious Composites (SHCC/ECC) are emerging as cementitious composites with high deformation capacity and excellent crack control ability. However, the high cement dosage (typically 1000–1500 kg/m3) in conventional high-strength SHCC leads to high environmental impacts, while using high-dosage conventional supplementary cementitious materials (SCM) to replace cement typically leads to low strength. This study aims to solve this conflict by using ternary SCM to develop high-strength SHCC with satisfactory mechanical properties and environmental performance. High dosages of ternary SCM (50–80 % by weight of binder) were explored, with 10–70 % fly ash and 0–40 % limestone calcined clay (LCC). Test results showed that with 30 % Portland cement, 50 % fly ash, and 20 % LCC, SHCC achieved compressive strength of 96.89 MPa, tensile strength of 11.24 MPa, ultimate tensile strain of 6.71 %, and average crack width of 78 µm. Additionally, the embodied carbon and energy per unit tensile strength of the developed SHCC is much lower than that of conventional SHCC. To assess the overall performance of SHCC for sustainable construction, seven key performance indices were comprehensively compared, encompassing mechanical properties, environmental impact and economic viability. This new version of sustainable high-strength SHCC holds great potential for reducing carbon footprint in various practical applications.

Enhancement of mortar’s properties by combining recycled sand and limestone calcined clay cement

The use of Recycled Fine Aggregate (RFA) combined with Limestone-Calcined Clay Cement (LC3) is one of the low-carbon options for replacing ordinary mortar, leading to an eco-friendly and sustainable construction material, and providing a solution for waste management. In this paper, a comprehensive investigation concerning the mechanical properties and microstructural characteristics of LC3 mortar, using different proportions of limestone, calcined clay, cement clinker, and two types of RFA (namely RS1 and RS2), was carried out. The results highlight that a binder with 17.55 wt% calcined clay, 8.77 wt% limestone, and 73.68 wt% CEM I shows superior mechanical properties compared to CEM I with both natural sand and high-quality recycled sand, and similarly it shows better mechanical properties than CEM II at all levels of substitution of natural sand with recycle sands of high and normal quality. The replacement of commercial cement with LC3 mitigates the negative impact of RFA on water absorption, enhances pore size distribution, reduces total porosity, and boosts mechanical strength. The combination of RFA with LC3 is an effective approach to reduce the environmental impacts of cement production, to well manage wastes generated by construction and demolition, and to improve material’s performances.

Performance of cementitious systems containing calcined clay in a chloride-rich environment: a review by TC-282 CCL

In this review by TC- 282 CCL, a comprehensive examination of various facets of chloride ingress in calcined clay-based concrete in aggressive chloride-rich environments is presented due to its significance in making reinforced concrete structures susceptible to chloride-induced corrosion damages. The review presents a summary of available literature focusing on materials characteristics influencing the chloride resistance of calcined clay-based concrete, such as different clay purity, kaolinite content and other clay minerals, underscoring the significance of pore refinement, pore solution composition, and chloride binding mechanisms. Further, the studies dealing with the performance at the concrete scale, with a particular emphasis on transport properties, curing methods, and mix design, are highlighted. Benchmarking calcined clay mixes with fly ash or slag-based concrete mixes that are widely used in aggressive chloride conditions instead of OPC is recommended. Such comparison could extend the usage of calcined clay as a performance-enhancing mineral admixture in the form of calcined clay or LC2 (limestone-calcined clay). The chloride diffusion coefficient in calcined clay concrete is reported to be significantly lower (about 5–10 times in most literature available so far) compared to OPC, and even lower compared to fly ash and slag-based concrete at early curing ages reported across recent literature made with different types of cements and concrete mixes. Limited studies dealing with reinforcement corrosion point out that calcined clay delays corrosion initiation and reduces corrosion rates despite the reduction in critical chloride threshold. Most of these results on corrosion performance are mainly from laboratory studies and warrant field evaluation in future. Finally, two case studies demonstrating the application of calcined clay-based concrete in real-world marine exposure conditions are discussed to showcase the promising potential of employing low-purity calcined clay-based concrete for reducing carbon footprint and improving durability performance in chloride exposure.

Sulphate resistance of low-clinker engineered cementitious composites examined by MicroXRF imaging.

Engineered cementitious composites (ECC) are a class of high-performing fibre-reinforced cementitious materials recognised for their increased ductility and durability compared to conventional cement-based materials, owing to their autogenously controlled tight crack widths, even when subjected to high strains. To reduce ECC's environmental impact, this research examines the use of a low-clinker binder - limestone-calcined clay cement (LC3) - as an alternative to portland cement (PC), along with fly ash to further reduce the clinker proportion and the embodied CO2 of the formulations. In conventional concrete, LC3 hydrates to a denser microstructure resulting from the synergistic reaction between limestone and calcined clay. At the lower water contents typical of ECC and with the presence of fly ash, the influence of the binder composition on the microstructure is difficult to anticipate. To examine the influence of these compositional variables on microstructure, permeability and durability, the sulphate resistance of LC3-based ECC is explored. Specifically, the ECC-LC3 blends are designed with high clinker replacement rate of 75% by mass of binder and contain either conventional fly ash or reclaimed fly ash at 50% by mass of binder. Expansion of ECC-LC3 samples subjected to standard sodium sulphate test conditions was measured up to 12 months and the depth of penetration of sulphates into the ECC-LC3 of varying compositions was quantified using micro-X-Ray Fluorescence (microXRF) imaging and modelling. The expansion results show that the ECC-LC3 formulations performed better than the PC samples and can provide adequate resistance to external sulphate attack, even when reclaimed fly ashes are used in place of the conventional ash. In addition, the shallow penetration of sulphate into these cementitious composites demonstrates the low diffusion coefficients values that were determined using the quantitative data from MicroXRF imaging.

Using ceramic demolition wastes for CO2-reduced cement production

This study focuses on assessing the pozzolanic potential of two types of ceramic demolition waste, namely terracotta roof tiles and sanitary porcelain, as substitutes for traditional calcined clays in blended and limestone calcined clay (LC3) cement production. Experimental methods employed include the modified Chapelle test and XRD for pozzolanic activity evaluation, flexural and compressive strength tests, capillary absorption measurements, and SEM for microstructure analysis. Mortars containing 10%, 20%, and 30% ceramic powders and 5%, 10%, or 15% limestone filler were tested. The findings showed that porcelain powders exhibited lower pozzolanic activity due to their lower surface area and higher firing temperature of the material. Up to 20% substitution of OPC with terracotta had minimal strength impact, with a 103% strength activity index (SAI) at 90 days. Ultrafine terracotta powder showed promise in LC3 production with up to 30% OPC substitution, achieving a 97% SAI after 90 days. The poor mechanical properties of porcelain-containing mortars were explained by surfactants present in sanitary porcelain. This research informs the cement and processing industries on the potential use of specific ceramic demolition waste materials in eco-cement production, offering insights into blended pozzolanic cements and LC3 formulations, with the goal of reducing the carbon footprint of cement manufacturing.

Lower-carbon concrete technologies

In this article, we introduce the IStructE's new concrete technology tracker, which has been compiled to inform members about the development of lower-carbon alternatives to conventional Portland cement-based concrete. We also look in more detail at four emerging technologies: Limestone Calcined Clay Cement, Seratech, Cambridge Electric Cement, and Brimstone.

Use of spent fluid catalytic cracking catalyst (FCC) in Limestone Calcined Clay Cement (LC3) systems: Studies in pastes and mortars

This study evaluates the substitution of calcined clay for a waste from the petrochemical industry, spent fluid catalytic cracking catalyst (FCC), as a source of reactive aluminosilicates in Limestone Calcined Clay Cements (LC3) systems. Three carbonate types were used to make cement-type LC3: a high-purity calcium carbonate, waste from the marble industry, and another from a dolomite soil source. LC3 blends were prepared by mixing 50 wt% OPC, 5 wt% calcium sulfate dihydrate, 30 wt% FCC and 15 wt% from each carbonate source. A mixture than substituting the carbonate source for a siliceous source was prepared to analyse the influence of carbonate phases in LC3 systems. The hydration process of the LC3 blends was studied by X-ray diffraction, thermogravimetric analyses, isothermal calorimetry and FESEM. Mechanical properties were studied by measuring compressive strength at 7, 28 and 90 days. The obtained results corroborated that the mortars prepared with LC3 cements using the FCC obtained higher compressive strength than the control mortar prepared with ordinary Portland cement (OPC) at 28 and 90 curing days. It has been demonstrated that FCC is a by-product that can substitute calcined clay, and the different sources of carbonates such as high purity, waste or contaminated with magnesium do not interfere with the performance of this type of cement.

Performance of a Single Source of Low-Grade Clay in a Limestone Calcined Clay Cement Mortar

The high kaolinite content of metakaolin makes it valuable to other industries, thereby affecting its availability and affordability for the production of limestone calcined clay cement (LC3). This work presents a study on the potential utilization of low-grade clay in place of pure metakaolin in the preparation of LC3 for mortar formulations. CEM I was partially substituted with calcined clay and limestone by 20, 30, 40, and 50 wt.%. The weight ratio of calcined clay and limestone was maintained at 2:1 for all mixes and the water-to-binder ratio was 0.48. X-ray diffraction (XRD), thermogravimetric analysis (TGA), and isothermal conduction calorimetry were used to study the hydration process and products after 28 days. Mechanical and durability assessments of the LC3 mortar specimens were conducted. LC3 specimens (marked LC20%, LC30%, LC40%, and LC50%) trailed the control sample by 1.2%, 4%, 9.8%, and 18%, respectively, at 28 days and 1.6%, 2.3%, 3.6%, and 5.5%, respectively, at 91 days. The optimum replacement of OPC clinker, calcined clay, and limestone was 20% (LC20%).

Characteristics of the açai seed (Euterpe precatoria Martius) after thermal processing and its potential in soil-cement brick

The management of the açai palm, a species of the Euterpe genus, has grown in recent years mainly for the extraction of palm heart and the pulp of the fruit called açai. After the extraction of the’ pulp, there is a significant generation of residues, as the discarded seeds account for approximately 85% of the fruit. Therefore, this research aims to characterize the açai seed after fruit processing, as well as to evaluate the potential of thermally processed seed for use in soil-cement bricks. The seed morpho-anatomy tests were performed, including moisture content, loss of ignition, ash content, thermogravimetry, fluorescence, and X-ray diffraction of the ground seeds. Tests on thermally processed seeds included readings by X-ray diffraction and laser granulometry. After evaluating the properties of the ash, it was incorporated into soil-cement mixtures in proportions of 5%, 10%, 15%, and 20%, replacing the clinker content of LC3 (Limestone Calcined Clay Cement). Based on the results obtained, soil-cement bricks were produced with a composition of 90% soil and 10% LC3, with the LC3 cement clinker being replaced by 20% açai seed ash. The results indicate the potential for the application of açai seed ash in soil-cement bricks on a practical scale, demonstrating that the ash enhances soil stabilization and increases the compressive strength of the soil-cement matrix due to its smaller particle size compared to that of the soil grains. This not only reduces the amount of cement required for the matrix but also offers environmental sustainability through the utilization of seed waste. The study underscores the potential of applying açai seed ash in the context of environmentally significant alternative technologies and sustainable practices, emphasizing the promise of the properties found in discarded açai seeds.

Impact of Admixtures on Environmental Footprint, Rheological and Mechanical Properties of LC3 Cemented Paste Backfill Systems

This study investigates the time-dependent rheological behavior of cemented paste backfill (CPB) that contains calcined clay as a binder, particularly with LC3 (Limestone Calcined Clay Cement) compositions, using two different PCEs (Polycarboxylate Ether) superplasticizers. Rheological measurements have been conducted on four different mix designs using the Bingham model to describe the CPB mixtures. Both yield stress and plastic viscosity have been reported, and the impact of the admixture on these parameters has been investigated. Unconfined compressive strength (UCS) was measured over 182 days for all mix designs. Both admixtures showed better workability in all cases, with significantly improved yield stress and plastic viscosity compared to the reference, while showing little to no negative impact on strength over time. This study highlights that both from a binder and an admixture point of view, relevant to the industry, these calcined clay systems are ready to be used in a CPB and could make a significant impact on the sustainability of a mining operation in the near future.

Mechanical strength and Life Cycle Assessment (LCA) of soil-cement: comparison between mixtures of soil with ASTM type III cement, LC3, and the incorporation of by products and agroindustrial residues

Soil stabilization with binders is based on the binder action on soil particles, in turn causing an improvement in the mechanical behavior of the soil. Thus, this study aims to analyze the mechanical and environmental properties of soil-cement mixtures using Portland ASTM type III cement as binders and comparing to LC3 (Limestone Calcined Clay Cement), as well as incorporating extra raw materials such as silica fume, fly ash, sugarcane bagasse ash (Saccharum officinarum L) and açai seed ash (Euterpe precatoria Martius). The mixtures of soil, binder, extra raw materials were performed manually, and the cylindrical specimens (100 mm internal ø) were molded based on the AASHTO Normal Test. The results showed that the highest values of compressive strength ranged between 10 and 11 MPa, which were recorded for reference, soil-LC³ and soil-LC-açai seed ash mixtures. Life Cycle Assessment (LCA) was performed using the CML 2001 method with the aid of the OpenLCA software. Additionally, it was observed that the main emissions and consequences for the environment were from mixtures containing higher clinker contents.

Limestone calcined clay cement (LC3): A sustainable solution for mitigating environmental impact in the construction sector

The impact of global warming on the construction sector is a serious issue in today's world; this might be attributed to the emission of greenhouse gas (GHG) during the production process of Portland cement. Due to its advantages, cement plays a major role in the construction of civil infrastructures. Cement production is not only responsible for global warming and also creates a risk of raw material deficiency. To reduce the over exploitation of virgin materials, Limestone Calcined Clay Cement (LC3), with a proportion of Clinker 50 %, Limestone 30 %, Calcined Clay 15 % and gypsum 5 %, is found to be a suitable and sustainable alternative to preserve the ecosystem. As a result, attempts were undertaken in this work to create a mixture design approach for LC3 with the primary objective of developing higher compressive strength (CS) in a cost-effective manner. The relationship between the water to binder ratios and 28-d CS has been examined to suggest a conceptual mixture design strategy for LC3 rationally. The 28-day CS of 46.2 MPa has been observed. The suggested design technique has been presented step by step and validated using an example based on the guidelines illustrated by IS 10,262. The design technique aims to produce a concrete mix that meets specific strength, workability, and durability requirements while considering the environmental conditions and properties of materials available. The study emphasizes a systematic approach to concrete mix design, considering various factors like water-cement ratio, aggregate proportions, and workability requirements to ensure the resulting concrete meets the desired performance standards. Compliance with IS 10,262:2019 ensures that concrete used in construction is designed systematically and according to established guidelines, leading to higher quality and more predictable performance in structural applications. Further, to access the sustainability of the developed LC3 mix Life-Cycle Assessment (LCA) of LC3 was reported starting from raw material procurement to the production of concrete as the final product. In this LCA analysis, the monetary cost involved in the production of concrete, energy demand and GHG emission of the LC3 was compared with the conventional concrete. The result from the analysis revealed that LC3 possess superior performance in terms of energy requirement and GHG emission than the OPC concrete.

Multidisciplinary approach for the prediction of cement paste rheological properties: physical analysis, experimental rheology and microstructural modelling

AbstractIn this contribution, an interdisciplinary approach was employed to investigate and describe the fresh rheology of cementitious pastes, using analytical techniques, microstructural modelling, and experimental rheometry. The pastes, based on Ordinary Portland Cement and Limestone Calcined Clay Cement at a solid volume fraction of Φ = 0.45, were subjected to various analyses. Physical and chemical analyses were conducted including laser granulometry and isothermal heat flow calorimetry. Dynamic rotational rheometry and static oscillatory rheometry, along with viscoplastic and viscoelastic rheological modelling were used to support the characterization of the pastes. A physics‐based Monte‐Carlo algorithm was developed to numerically describe rheological properties such as structural buildup and yield stress. The results showed that as the physical properties of the pastes became more complex, the correlation of several analysis methods went more challenging. However, the combination of analytical, experimental, and phenomenological rheology allowed for a more distinct characterization of the cement paste. These findings can serve as a basis for further multidisciplinary rheological characterization of cementitious building materials.

Performance and hydration of ternary cements based on Portland clinker, carbonated recycled concrete paste (cRCP) and calcined clay

This study explored composite cements consisting of Portland clinker, two pozzolans (alumina-silica gel in carbonated Recycled Concrete Paste (cRCP) and metakaolin), and calcium carbonate. The rapid reactivity of alumina-silica gel resulted in full reaction within 28 days, while metakaolin exhibited slower reactivity. cRCP played a significant role in strength development between 1 and 7 days, with metakaolin becoming prominent thereafter. The combination of materials preserved their distinct characteristics. Early hydration was mainly influenced by clinker and cRCP, leading to high early compressive strength. After alumina-silica gel dissolved, metakaolin forms a microstructure, reducing porosity and allowing for continued strength improvement over time. The pozzolans did not hinder their respective reactions, and calcium carbonate from cRCP stabilized ettringite content, similar to limestone-calcined clay systems. This study’s findings offer insights for developing multi-component cement with cRCP and calcined clays, resulting in higher strength and reduced CO2 footprint compared to calcined clay-limestone cements.

Strain hardening composite made of LC3 binder and mineral impregnated carbon yarn: effect of crystalline admixture on mechanical characteristics and microstructure

The addition of crystalline admixtures in the cementitious composite is instrumental in imparting water tightness, enhancing strength, and achieving self-healing abilities in various construction applications. In this work, the viability of using crystalline admixtures in heat-cured strain-hardening cementitious composites (SHCC) and their impact on specimens subjected to alkaline and aqueous environments are examined. In SHCC, lime stone-calcined clay cement (LC3) is used in the matrix and mineral-impregnated carbon yarns are used as reinforcement. The usefulness of heat curing for SHCC to water curing is initially assessed by analyzing the mechanical characteristics and connecting them to the microstructural components by SEM examination. Investigations reveal that the crystalline admixture increases compressive strength in water- and heat-cured specimens by 30–37%, respectively. Subsequently, a uniaxial tensile test is conducted on heat-cured SHCC specimens and on pre-damaged ones that are submerged in tap water and also in alkaline water. The impact of crystalline admixture on the SHCC's tensile response was examined, and the results were correlated with SEM examination. The maximal stress is increased by approximately 14% and 26% when pre-damaged SHCC specimens with crystalline admixture are submerged in water and an alkaline environment, respectively.