Metakaolin Content Research Articles

Experimental study of the mechanical and thermal properties of metakaolin based geopolymer stabilized soil during low temperature curing

To address the challenges associated with significant thermal disturbance and carbon emissions resulting from the conventional stabilization of frozen soil using cement, geopolymer material is used to replace cement to stabilize frozen soil. The unconfined compressive strength (UCS) of the geopolymer stabilized soil was investigated in relation to the proportions of metakaolin (MK), calcium carbide slag (CCS), curing temperature, and curing age. Microscopic analysis was conducted to unveil the stabilized mechanism. The UCS, shear strength, thermal conductivity, hydration products and microstructure of geopolymer stabilized soil and cement soil were compared in parallel. A total of 240 experiments were conducted in this study. The outcomes indicate that the optimal content of MK and CCS is 10% and 6% respectively. The UCS of samples with the optimal content after 28d of curing at 20 °C, −2 °C, and − 10 °C are 3.783 MPa, 1.164 MPa, and 0.901 MPa respectively. The primary causes of the rise in UCS of the geopolymer stabilized soil are the production of amorphous calcium silicate hydrate and calcium aluminate hydrate gel as a result of the stimulation of MK based geopolymer with CCS. The UCS of the geopolymer stabilized soil decreases with a decrease in curing temperature. In frozen conditions, the expansion of ice crystals in the soil creates voids and promotes crack growth, leading to a decrease in the efficiency of geopolymerization reactions. After 28d of curing at room temperature and low temperature, the geopolymer stabilized soil with the optimal content exhibits higher UCS, failure strain, shear strength, cohesion, and internal friction angle compared to the cement soil. At all curing temperatures and ages, the geopolymer stabilized soil has a lower thermal conductivity than the cement soil. The geopolymer stabilized soil is less susceptible to low temperature curing than cement soil, demonstrating a larger amount of hydration products and a denser microstructure, according to experimental results from XRD and SEM. The results of this work offer a theoretical foundation for using geopolymer in place of cement to stabilize soils in permafrost regions.

PCE Superplasticizers for Calcined Clay Blended Cements – Challenges and Solutions

AbstractA high content of metakaolin in calcined clay blended cement has a positive effect on the early strength development, however, it also leads to a poor workability. Moreover, slump retention is more difficult to achieve in this system than in OPC or other composite cements. In this study, several approaches were investigated to achieve fluidizing ability of mortars prepared from composite cements holding 30 wt. % of calcined clay with varying amounts of metakaolin (∼ 23 wt.%, ∼ 51 wt.%). First, it was found that the slump retaining performance of a common industrial ready‐mix type HPEG PCE rapidly decreases when the content of metakaolin increases. Furthermore, a combination of the ready‐mix HPEG PCE and a retarder (sodium gluconate) which is commonly applied in ready‐mix concrete, also fails to improve fluidity retention in calcined clay blended cement with a high level of metakaolin, hence highlighting the difficulty of slump retention for such cements. To mitigate this problem, a unique admixture based on the combination of a precast type HPEG PCE and a novel PCE‐LDH nanocomposite is introduced. Mortar tests reveal that the high water‐reducing (precast) type HPEG PCE and the PCE‐LDH nanocomposite enables to achieve a remarkable improvement in fluidity retention of such calcined clay blended cements.

Study On Effect Of Marble Powder And Waste Foundry Sand As Fine Aggregates On The Properties Of Metakaolin-Cement Concrete

To bring an challenging and acceptable change in construction industry, upcoming graduates have to be much aware of alternate materials to be used in conventional concrete with improved performances and this study can be an encouraging approach to them. Many research studies have investigated the possible use of industrial by-products such as fly ash from thermal power plants, red mud from aluminium manufacturing industry, copper slag from copper smelting industry, GGBS from steel industry, and waste foundry sand from metal casting industries in cement concrete production. Here, it is investigated on the possibility of utilizing two industrial by-products in the production of concrete for achieving sustainable development. Metakaolin is used for replacing a specific percentage of cement, and waste marble powder and waste foundry sand are used to replace different percentages of conventional fine aggregates (sand) for producing a sustainable concrete. It is observed from the results that properties of cement concrete are influenced by the percentage content of metakaolin, waste marble powder and waste foundry sand.

Cost-efficient natural apatite–metakaolin supported TiO2 mesoporous membrane for dye removal applications

The synthesis of a TiO2-tight ultrafiltration membrane supported on a low-cost ceramic substrate based on metakaolin and natural apatite was proposed in this study. To optimize the substrate composition, three samples were prepared by combining metakaolin and natural apatite with weight ratios of 25:75 (MK25), 50:50 (MK50), and 75:25 (MK75), and then sintered for 2h at 850, 900, 950, and 1000°C. The effect of sintering temperature and metakaolin content on the final properties of the prepared samples was studied in terms of microstructure, porosity, and mechanical strength. According to the results, the mechanical strength increased with increasing temperature and metakaolin content, but at the same time, the porosity decreased. MK50 composition and the temperature of 950°C were chosen as optimal conditions, and the support was prepared by extrusion. The prepared substrate presented a compressive strength of 4.4MPa, porosity of 33%, and an average pore size of 2.2μm. To prepare a crack-free ultrafiltration membrane, the deposition of the TiO2 top layer was favoured over an alumina intermediate layer. The obtained membrane has a pore size of 6.8nm and water permeability of 5.6Lh−1m−2bar−1. The membrane performance was tested for the removal of cationic and anionic dyes. The ultrafiltration experiments have shown a high removal rate for anionic and cationic dyes. Specifically, it was found that the removal rates of these dyes exceeded 75% without adjusting the pH of the solution.

Integration of monitoring indicators for self-sensing alkali activated cementitious materials: From electrical signals - resistivity to autogenous shrinkage

The chemical shrinkage and autogenous shrinkage of alkali-activated materials (AAMs) are usually more significant than that of ordinary Portland cement (OPC). Therefore, both searching for efficient methods to reduce shrinkage and exploring the shrinkage mechanism of AAMs are of great significance in promoting the application of AAMs. In this paper, metakaolin is used to reduce the chemical shrinkage and autogenous shrinkage of AAMs, while an innovative resistivity measurement is used to concretize the electrical signal of AAMs and the relationship between autogenous shrinkage and resistivity was explored. The early resistivity and heat of hydration curves of AAMs can be divided into five stages with high similarity, demonstrating the feasibility of indirectly quantifying the autogenous shrinkage and chemical shrinkage by resistivity. The results of TG-IR, MIP, and heat of hydration prove that the early reaction rate of AAMs decreases with the increase of metakaolin content, which further leads to the decrease of early chemical shrinkage and autogenous shrinkage. The reduction of autogenous shrinkage reached the maximum (49%) when the metakaolin content was 50%. A mathematical model between autogenous shrinkage and resistivity was established, which means that the resistivity of self-sensing materials can be used as an index to evaluate the early autogenous shrinkage of AAMs.

Hydration kinetics, microstructure and physicochemical performance of metakaolin-blended cementitious composites

This paper presents a comprehensive investigation on influences of metakaolin on the early and later performances of cementitious composites. Systematic measurements from hydration to physicochemical performance and thermodynamic modeling based on ternary compatible phase diagram were carried out. Different fineness of metakaolin with d50 of 25, 15.3 and 3.37 μm was adopted to replace ordinary Portland cement. The replacement level of metakaolin varied at 5 %, 10 %, 15 % and 20 %. Effects of metakaolin in view of pozzolanic activity and filling capacity on the microstructural formation of cementitious composites were quantified based on the Frattini test and the strength activity index. It is found that a higher addition or specific surface area of metakaolin decreases the fluidity of cementitious composites and meanwhile the setting time was delayed. The filling effect of metakaolin on cement hydration works primarily in the early 3 d while pozzolanic effect plays a major role afterwards. The relationship between particle size of MK and its pozzolanic activity becomes pronounced for metakaolin content greater than 10 %. The presence of metakaolin contributes to strength development mainly at late age. Finer particle size of metakaolin does not ensure a pronounced filling effect, which depends on the content of metakaolin. The metakaolin with high fineness d50 = 3.37 μm enables to promote cement hydration. The decrease of metakaolin particle size results in a higher content of C-A-S-H and high alumina-rich hydrates, as demonstrated by both experiments and simulation.

Investigation on the sulfate attack of metakaolin blended recycled concrete based on percolation theory

Recycled aggregate concrete (RAC) is one of the most important ways to achieve sustainable development for concrete industry. However, the research on durability, especially on sulfate transport and erosion mechanism, of RAC needs deep investigation. Pore structure evolution is a vital parameter for sulfate transport, which is difficult to be traced. To investigate the dynamic changes of pore structure in metakaolin blended RAC under sulfate erosion, percolation theory is addressed in this study. Firstly, dry and wet cycle was applied to accelerate the sulfate transport in metakaolin (MK) blended RAC systems. Then the compressive strength of the samples after sulfate attack was measured to evaluate the sulfate erosion degree. Furthermore, backscattered electron imaging (BSE) was used to acquire the percolation parameters, such as wet site ratio, percolation probability and so forth. Finally, sulfate content and compressive strength of the sample were related to the percolation probability. Results present that MK exhibits excellent resistance to sulfate erosion and can be used to enhance the performance of RAC. There is a certain correlation between the degree of sulfate erosion, compressive strength, and percolation parameters. The influence of the number of dry–wet cycles and MK content on sulfate ion transport can be demonstrated using percolation theory, which can be employed for predicting sulfate transport and revealing erosion mechanisms. This enables a clear understanding of the ion transport mechanisms within concrete and holds significant importance on the investigation of durability issues of RAC.

Effect of Metakaolin on the Water Resistance of Magnesium Phosphate Cement Mortar

In order to study the effect of metakaolin on the water resistance of magnesium phosphate cement mortar, we took four factors as research objects: the setting time, fluidity, compressive strength, and water resistance of magnesium phosphate cement mortar. These were studied after adding equal gradations of metakaolin, and we then carried out SEM microcosmic experiments on the best group. The results showed that with the increase in metakaolin content, the setting time of magnesium phosphate cement decreased gradually, and the fluidity of the mortar decreased as a whole. The effect of metakaolin on the fluidity of the magnesium phosphate cement mortar was not significant when the content of metakaolin was less than 8%. Metakaolin was able to improve the pore structure of magnesium phosphate cement mortar; for example, it improved its compressive strength and water resistance due to both chemical and physical interactions. The water resistance of mortar samples in the same timeframe increased first and then decreased with the increase in metakaolin content. When the content of metakaolin was 12%, the water resistance of magnesium phosphate cement mortar achieved the optimal results. A 50.32% improvement of the 56 d strength retention rate and a 54.89% improvement of the 90 d strength retention rate proves its effective long-term water resistance.

Optimizing raw material composition and alkali content in low silicon-aluminum tailings-based geopolymers

This study delves into the effective utilization of low silicon–aluminum tailings, exploring their potential for large-scale applications in one-part (‘just add water’) geopolymers. Optimizing the raw material composition and alkali content is crucial. Higher slag content enhanced gel production and polymerization, resulting in a more homogeneous structure dominated by C-(A)-S-H gels with stronger bonding. While increased metakaolin content forms more zeolite phases and exhibited an incompatible structure filled with N-A-S-H gels with weaker bonding. Alkali concentrations also play a significant role in promoting tailings dissolution and gel polymerization. Excessive levels, however, hinder the process and restrict strength development. Ultimately, a reasonable mechanical strength of 52.8 MPa was achieved. The geopolymer paste effectively immobilizes Pb and Zn, demonstrating impressive immobilization rates of 97% and 91%, respectively. The chemical speciation analysis reveals the conversion from unstable to stable state. These findings highlight the potential applicability of low silicon–aluminum tailings in geopolymers.

Enhancing the mechanical and environmental performance of engineered cementitious composite with metakaolin, silica fume, and graphene nanoplatelets

Engineering cementitious composites are designed to offer high ductility, enhanced strength, and enhanced impact resistance as rehabilitation materials for various support structures and equipment. ECC is an inventive material for construction with tensile strain hardened properties and multiple fracture behaviors, which is highly encouraged in the construction industry. The objective of this study was to create an eco-efficient engineered cementitious composite (ECC) with binary systems of cement with metakaolin (MK) and silica fume (SF) and an optimized dosage of graphene nanoplatelets (GNPs). To optimize mixture proportion, an experimental design was developed using the response surface method. We analyzed the compressive strength, split tensile strength, flexural strength, dried density, embodied carbon, and eco-strength efficiency of the optimal mixture proportion to determine its mechanical properties and low-carbon footprint. Results analysis showed a total of 10% content of SF and MK is optimum for an eco-friendly (low carbon profile) and mechanically strong ECC mixture. If it exceeds 10%, the mechanical strength of the composite decreases. Furthermore, 0.02%to 0.03% GNP concentration improved mechanical characteristics even further. According to the results of the multi-objective optimization, the optimal values for the variables Mk, SF, and GNPs are 9.19%, 4.83%, and 0.03%, respectively.

Strength behavior of metakaolin and fly ash treated dredged clay at high water content

This study investigated the strength behaviors of dredged clays treated with metakaolin (MK) and fly ash (FA). A series of laboratory tests including direct shear and unconfined compressive strength tests were performed on MK and FA-treated dredged clay at various MK contents and different curing times. The direct shear test results showed that the shear stress and displacement curves for all specimens tested are strain-softening types and influenced by MK content and curing time. The variation curve at a higher MK content or higher curing time is always higher than that at a lower one. The shear strength from the direct shear test at a given vertical stress consistently increases linearly with the increase of MK content while increasing parabolically with curing time. This indicates both curing time and MK content contribute to the development of the shear strength. Both strength parameters c and φ grow with increasing MK content and curing time. Unconfined compressive strength test results show the strain-softening behavior for all tested specimens. Compared with adding FA alone or MK alone, adding both fly ash and MK exhibited a better treatment effect in the unconfined compressive strength, which increases with increasing MK content and curing time.

Sustainable Alternatives to Cement: Synthesizing Metakaolin-Based Geopolymer Concrete Using Nano-Silica

The emission of carbon dioxide gas from the cement manufacturing industry has raised concerns about global warming. Geopolymer concrete (GC) is gaining attention as a sustainable and environmentally friendly alternative to traditional cement concrete. The current study focused on using local clay to synthesize and characterize metakaolin-based GC with varying percentages of nanosilica (NS) (1.5%, 3.0%, 4.5%, 6.0%, and 7.5% by weight of MK content) using NaOH/sodium silicate. The geopolymer specimens were cured at room temperature for 28 days, and their workability, compressive, tensile, and flexural strengths were measured to evaluate the influence of NS on the concrete’s mechanical properties. The study found that the compressive, tensile, and flexural strengths of the GC increased gradually up to 6.0% NS, but any further increase in its ratio resulted in a reduction in mechanical characteristics. The study concludes that the addition of 6.0% NS in metakaolin (MK)-based GC produces the highest mechanical properties, improving the compressive strength of the GC mix by 34.3% compared to the control GC mix and improving the flexural and split tensile strengths by 39% and 37%, respectively, compared to control GC strengths. Furthermore, the statistical analysis confirms nano-silica’s significant impact on geopolymer concrete’s mechanical properties, emphasizing its role in improving performance and sustainability as an alternative to cement-based materials.

Enhancing Freeze-Thaw Resistance of Alkali-Activated Slag by Metakaolin.

Incorporating metakaolin (MK) into slag to prepare alkali-activated materials can reduce shrinkage and improve the durability of alkali-activated slag (AAS). But its durability under freeze-thaw conditions is unknown. In this paper, the effects of MK content on the freeze-thaw properties of AAS were investigated from the perspective of gel composition and pore solution. The experimental results showed that the addition of MK generates a gel mixture of C-A-S-H and N-A-S-H with a cross-linked structure and decreases the content of bound water and pore water absorption. With the increase of alkali dosage, water absorption decreased to 0.28% and then increased to 0.97%, and the leaching rate of ions was Ca2+ > Al3+ > Na+ > OH-. When the alkali dosage was 8 wt % and the MK content was 30 wt %, the compressive strength loss rate of AAS was 0.58% and the mass loss rate was 0.25% after 50 freeze-thaw cycles.

Static and dynamic mechanical properties of magnesium phosphate cement modified by metakaolin after high-temperature treatment

Magnesium phosphate cement (MPC) is widely used in fields of construction and fire-retardant coatings due to its excellent properties. The hydration properties of MPCs at high temperatures are the points of interests. In this work metakaolin was used to improve workability and mechanical properties of MPC, and static and dynamic mechanical properties and hydration products of the MPC after high temperature treatment were investigated. The results showed that the incorporation of metakaolin in MPC allows extending and importantly tuning the setting time of MPC. Notably, 40% replacement of dead burnt magnesia with metakaolin in MPC could extend the setting time of MPC to about 24 min. While the fluidity of MPC significantly decreased with increasing metakaolin content. Typically, increasing the temperature leads the deterioration of mechanical properties of the MPC. However, static and dynamic strength enhancement was also observed at 600℃. The main hydration products of MPC with metakaolin are struvite (MgNH4PO4·6H2O), unreacted MgO, aluminum phosphate (APH) and possibly amorphous substance containing aluminum. Moreover, the impact resistance of MPC at high temperatures were significantly improved with incorporation of metakaolin.

Metakaolin‐based geopolymer concretes for nuclear protection: On the perspective of physicochemical, durability, and microstructure

AbstractAs a striking contribution of metakaolin to geopolymer concretes, the varying contents of metakaolin with quartz powder are included the mixtures with ground granulated blast furnace slag, and quartz sand to observe the mechanical, physical, transport, microstructure, and nuclear protection parameters of the samples, within this study. The geopolymer concrete samples are tested for the mechanical transport and physical properties depending on the curing time, curing temperature, and the raw/by‐product material type. The results show that the samples containing the most metakaolin performed well with a 24‐h compressive strength of 131.78 MPa. Increasing the curing temperature and curing time affected both mechanical, physical and transport properties. In addition, the microstructure of the samples was analyzed by scanning electron microscopy, x‐ray diffraction, and Fourier transform infrared spectroscopy. Moreover, the effect of increasing metakaolin reinforcement on the nuclear protection capacity of the produced geopolymer concretes with experimental gamma transmission and neutron dose measurements was investigated. The M3 sample with high content of both metakaolin and granulated blast‐furnace slag showed the highest resistance to gamma photons in the energy range of 0.081–0.383 MeV. The produced geopolymer samples absorbed almost 40% of the fast neutrons with 4.5 MeV energy. Neutron removal cross sections of the produced geopolymer concretes are in the range of 0.0952–0.0949 cm−1 and are larger than those of B4C, graphite, and boric acid. The findings of this study revealed that the addition of metakaolin improved the mechanical, nuclear shielding and structural properties of geopolymer concretes.

Fly-ash-based geopolymer modified by metakaolin for greener grouting material

Fly ash usually requires high-temperature maintenance owing to its low volcanic ash activity, which greatly limits its application. In this study, fly-ash-based geopolymer grouting materials were prepared by modifying them with suitable alkali activators and metakaolin at room temperature. The results of the orthogonal experiments showed that the content of metakaolin had the most significant effect on the 1-, 7- and 28-day mechanical properties of the material. The optimum mix proportion was determined as metakaolin content (m MK/m P) = 15%, sodium silicate modulus (M s) = 1.0 and sodium silicate content (m SS/m P) = 50%. The compressive strengths of the materials at 1, 7 and 28 days were 12.6, 24.9 and 36.3 MPa, respectively. The results of X-ray diffraction, Fourier transform infrared spectroscopy, mercury intrusion porosimetry and scanning electron microscopy showed that the reaction mechanism of fly ash was subject to a bidirectional alkaline attack. Meanwhile, the unreacted fly ash particles proved the inertness of fly ash, while metakaolin mostly dissolved and formed hydrated sodium aluminosilicate gel to increase the mechanical strength of the geopolymer. The material developed in this study can meet the specification requirements of inorganic cementitious material for road grouting in terms of compressive strength and fluidity, increasing the usage of fly ash and contributing to environmental protection.

A Comparative Study of Metakaolin and Silica Fume on the Properties and Microstructure of Ultrafine Dredged Sand Mortars

The main objective of this study is to improve the performance of ultrafine dredged sand mortars by using metakaolin (MK) and silica fume (SF) mixed with high-content FA. The mechanical properties and microstructure of the ultrafine dredged sand mortars were analyzed. The results show that the strong growth rate of the mortars with 5%, 10%, and 15% MK and SF contents, respectively, exceeds 30% at the age of 7 d. Compared with an ordinary Portland cement dredged mortar, the shrinkage of the specimens with 5% and 15% MK increases prior to 7 d and decreases by 16.9% and 13.8%, respectively, at 90 d. The addition of MK shows a better enhancement effect than that of SF, with the splitting tensile strength increased by 41.4% to 2.15 MPa with 15% MK compared with the mortar with a 50% FA content at 3 d. MK shows a higher enhancement effect than SF due to its uniquely active Al2O3. Moreover, a microstructural investigation based on scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP) confirms that the physical filling and pozzolanic effects of MK and SF can optimize the microstructure of the slurry, improve the interfacial combination of different phases, and refine the pore size distribution of cement paste. The test results prove that high-content FA ternary cementitious systems containing MK or SF represent a sustainable solution to the resource utilization of building materials based on ultrafine dredged sand.

The role of chemistry and fineness of metakaolin on the fresh properties and heat resistance of blended fly ash-based geopolymer

Sensible thermal energy storage using concrete as a storage medium is a promising technology that helps minimize energy in power plant. The purpose of this study is to evaluate the potential benefits of metakaolin (MK) as a partial substitute for fly ash-based geopolymer for heat resistance. As a partial substitute (5 and 20 wt.%) for fly ash (FA), nine metakaolins containing different alumina contents were selected. In order to assess their potential for storing high-temperature thermal energy, physical and microstructural analyses were performed before and after heat exposure up to 500 °C. Low packing density limits the workability of some metakaolins and increases water demand in pastes. The mechanical properties of geopolymer weaken as the temperature is raised (< 500 °C). The high alumina content of some metakaolins, however, helps to mitigate strength loss during high temperatures. A higher dosage of metakaolin has also shown to prevent this deterioration of strength. A reduction in strength under heating is caused by both dehydration and dehydroxylation. The higher fineness and alumina content of MK have demonstrated significant potential to enhance the heat resistance of FA-based geopolymers. As a result, the geopolymer paste developed is suitable for being used in heat-resistant applications.Article HighlightsFly ash was the main precursor of as prepared alkali-activated binders.Adding metakaolin enhances the resistance of hardened materials under thermal load.The higher the alumina content inside metakaolin is, the higher the performance is.

Impact of Limestone–Metakaolin Ratio on the Performance and Hydration of Ternary Blended Cement

Once sulfates become limited, the interaction of limestone with metakaolin (MK) is initiated, resulting in the formation of carboaluminates in a blended cement system. In this study, two different types of MKs (sourced from coal mining residue and soft clay) were adopted to examine limestone–MK ratios of 1:8, 1:4, 1:2, 1:1, and 2:1, by fixing the cement and MK content at 55% and 15%, respectively. The optimal limestone–MK ratio of 1:4 was found (equal to limestone content of 3.8%) to achieve the highest compressive strength of 60 MPa due to the formation of more carboaluminate content in both MK blended cement systems. This finding was corroborated with the thermodynamic modeling that the highest hydrates volume was achieved at the optimal limestone–MK ratio of 1:4. An overdosage of limestone reduces its reaction degree, reflecting the fact that excessive limestone content could only acts as filler in the system.

Mechanical properties and hydration of ultra-high-performance seawater sea-sand concrete (UHPSSC) with limestone calcined clay cement (LC3)

Ultra-high-performance seawater sea-sand concrete (UHPSSC) has attracted increasing attentions over the past few years as it exhibits exceptional mechanical and durability properties similar to conventional ultra-high-performance concrete (UHPC). Comparing to conventional UHPC, UHPSSC has great advantages when applied in marine engineering, particularly in offshore projects where construction materials are not easily accessible, and the transportation is costly. Nonetheless, current production of UHPSSC still necessitates large amounts of cement due to its low water/binder ratio. The larger demands of cement in manufacturing UHPSSC/UHPC than ordinary concrete can lead to substantial increase in the carbon emission. Therefore, an eco-friendly UHPSSC is developed in this paper by incorporating a promising ternary binder system (LC3) that consists of limestone (LS), calcined clay (metakaolin) and cement. The influence of the metakaolin (MK) dosage on the mechanical, hydration and microstructure properties of UHPSSC is comprehensively studied by carrying out a variety of experiments including mechanical test, isothermal conduction calorimetry test, TGA, XRD, SEM etc. The results showed that the UHPSSC mixed with LC3 exhibited lower early-age compressive strength than the reference mix, but its long-term strength was better than the reference group owing to the formation of more hydrates at the late age by the pozzolanic reaction of MK and the synergistic reaction between LS, MK and cement. Based on this study, the coupled replacement rate of cement by LS and MK could reach up to 40% without strength compromise. Nonetheless, 20% MK and 10% LS appeared to be the optimum substitution rate (total substitution rate of 30%) where the highest long-term strength was achieved. The main exothermic peak and total heat of hydration normalized per binder weight decreased with the increase of MK content level, but the main peak occurred earlier. Moreover, the addition of seawater can promote the hydration, leading to a greater main exothermic peak.