Acceleration Of Hydration Research Articles

접착식 콘크리트 덧씌우기를 위한 초속경화 첨가재 현장 혼합 폴리머 개질 콘크리트의 적용성 연구

PURPOSES : Recently, bonded concrete overlay has been used as an alternative solution in concrete pavement rehabilitation since its material properties are similar to those of the existing concrete pavements. Deteriorated concrete pavements need rapid rehabilitation in order to prevent traffic jams on Korean expressways. Moreover, speedy and effective repair methods are required. Therefore, the use of bonded concrete overlay with ultra-rapid hardening cement has increased in an effort to reopen promptly the expressways in Korea. However, mobile mixer is required for ultra-rapid hardening cement concrete mixing in the construction site. The use of mobile mixer causes various disadvantages aforementioned such as limitation of the construction supply, open-air storage of mixing materials, increase in construction cost, and etc. In this study, therefore, hydration accelerator in-situ mixing on polymer modified concrete produced in concrete plant is attempted in order to avoid the disadvantages of existing bonded concrete overlay method using ultra-rapid hardening cement. METHODS : Bonded concrete overlay materials using ultra-rapid hardening cement should be meet all the requirements including structural characteristics, compatibility, durability for field application. Therefore, This study aimed to evaluate the application of hydration accelerator in-situ mixing on polymer modified concrete by evaluating structural characteristics, compatibility, durability and economic efficiency for bonded concrete overlay. RESULTS : Test results of structural characteristics showed that the compressive, flexural strength and bond strength were exceed 21MPa, 3.15MPa and 1.4MPa, respectively, which are the target strengths of four hours age for the purpose of prompt traffic reopening. In addition, tests of compatibility, such as drying shrinkage, coefficient of thermal expansion and modulus of elasticity, and durability (chloride ions penetration resistance, freezing-thawing resistance, scaling resistance, abrasion resistance and crack resistance), showed that the hydration accelerator in-situ mixing on polymer modified concrete were satisfied the required criteria. CONCLUSIONS : It was known that the hydration accelerator in-situ mixing on polymer modified concrete overlay method was applicable for bonded concrete overlay and was a good alternative method to substitute the existing bonded concrete overlay method since structural characteristics, compatibility, durability were satisfied the criteria and its economic efficiency was excellent compare to the existing bonded concrete overlay methods.

고강도 고함량 고로슬래그 혼합 시멘트 모르터의 수화 및 포졸란 반응에 미치는 석회석 미분말과 실리카퓸의 영향

본 연구는 고강도 고함량 고로슬래그 콘크리트의 특성에 미치는 석회석 미분말과 실리카퓸의 영향을 검토하기 위해 50%에서 최대 80%까지 고로슬래그를 다량 혼합하고, 석회석 미분말을 최대 20%, 실리카퓸을 최대 10%까지 혼합한 물-결합재비 20%의 고강도 시멘트 모르터의 유동성, 강도발현, 수화 및 포졸란 반응 특성, 공극율 및 공극 크기 분포 등을 분석하였다. 실험결과에 따르면 고함량 고로슬래그 배합은 포틀랜드 시멘트 배합에 비해 고로슬래그의 낮은 표면 마찰로 유동성이 크게 향상되고, 시멘트 수화에 필요한 자유수가 많아져 수화반응이 촉진되면서 초기강도가 증가하나, 너무 낮은 물-결합재비와 단위시멘트량으로 인해 수산화칼슘의 생성량이 부족하여 포졸란 반응이 충분히 활성화되지 못함에 따라 장기강도 발현이 억제된다. 석회석 미분말은 유동성에는 큰 영향을 주지 않고, 역시 시멘트의 초기 수화를 촉진하는 것으로 나타났으나, 수화를 가속하는 효과는 고로슬래그보다 높지 않고, 고로슬래그와 달리 수경성이 없기 때문에 오히려 석회석 미분말의 치환율이 높아질수록 압축강도가 낮아지는 것으로 나타났다. 또한 고분말의 고로슬래그를 사용하거나, 또는 실리카퓸으로 고로슬래그를 치환하는 경우 시멘트 수화에 필요한 자유수를 더 많이 흡착함으로써 유동성과 강도를 저하시키는 것으로 나타났다. 또한 고로슬래그를 사용한 배합의 공극율이 보통 포틀랜드 시멘트 배합보다 낮게 나타났으나, 석회석 미분말은 공극율에 뚜렷한 영향을 나타내지 않았고 실리카퓸은 낮은 시멘트 수화도로 인해 공극율을 오히려 증가시키는 것으로 나타났다. 반면 공극 크기 분포에 있어서는 고로슬래그와 실리카퓸를 혼합한 경우 미세공극이 증가하는 것으로 나타났다.

Effects of Mineral Trioxide Aggregate Mixed with Hydration Accelerators on Osteoblastic Differentiation

IntroductionDespite good physical and biological properties, mineral trioxide aggregate (MTA) has a long setting time. A hydration accelerator could decrease the setting time of MTA. This study assessed the biocompatibility of MTA mixed with hydration accelerators (calcium chloride and low-dose citric acid) and investigated the effect of these materials on osteoblast differentiation. MethodsCell viability was evaluated by the EZ-Cytox assay kit (Daeil Lab Service, Seoul, Korea). The gene expressions of osteocalcin and bone sialoprotein were detected by reverse-transcription polymerase chain reaction and real-time polymerase chain reaction. The mineralization behavior was evaluated with alizarin red staining. ResultsThere was no statistically significant difference in cell viability between experimental groups. The messenger RNA level of osteogenic genes significantly increased in MTA mixed with hydration accelerators compared with the control and MTA mixed with water. MTA mixed with the hydration accelerators resulted in similar mineralization compared with MTA mixed with water. ConclusionsHydration accelerators increase the osteogenic effect and show a similar effect on the mineralization of MTA, which may have clinical applications.

Effect of Colloidal Nano-Silica on the Mechanical and Durability Performances of Mortar

s. The mechanical and durability properties of cement mortars with colloidal nanosilica (CNS) were investigated experimentally. Reference mortar with a low water-to-cement ratio of 0.30 was used in this study. The influence of CNS was evaluated by adding 0.5, 1.0, 1.5 and 2.0% of CNS by weight of cement. CNS was first stirred in the mixing water for 2 minutes before added to cement and sand. Superplasticizer was used to maintain the same flowability. Results showed that the compressive strength consistently increases with higher dosage of CNS at all the curing ages, due to both hydration acceleration and pozzolanic reaction. With the increase in CNS, the migration coefficient and water sorptivity consistently decreased; with 2% of CNS, the migration coefficient and water sorptivity were reduced by 45% and 30% respectively in comparison with the reference mortar. The improved durability could be explained by the reduction and refinement in the porosity, which can be attributed to nanofiller effect and pozzolanic reaction of nanosilica. Furthermore, the addition of CNS could reduce the drying shrinkage by densifying the microstructure in the cement paste, which has not been reported previously.

조기강도 개선형 시멘트 및 초기수화 촉진 혼화제를 사용한 콘크리트의 조기압축강도 발현특성 평가

본 연구에서는 콘크리트의 조기강도 확보를 통해 골조공기를 단축하는 것을 목표로 하여 시멘트 종류, 고성능감수제의 감수율, 초기수화 촉진 혼화제의 혼입에 따른 콘크리트의 조기강도 발현성능을 검토하였다. 조기강도 개선형 시멘트와 Sodium persulfate, Potassium hydroxide의 초기수화 촉진물질에 의해 12시간에 5MPa, 18시간에 14MPa의 조기강도를 확보할 수 있는 것으로 나타났다. 이를 통해 건설현장에서 거푸집의 골조공기를 단축시켜 원가절감이 가능할 것으로 기대된다. In this study, revelation performance of concrete at early age according to types of cement, water reducing ratio of high performance superplasticizer and mixing of accelerator for early hydration was examined aiming for reduction of construction period of framework through securing strength at early age of concrete. It was observed that strength at early age, 5MPa in 12hours, 14MPa in 18hours, is secured by early strength improvement type cement and using promotion admixture for early hydration which are Sodium persulfate, Potassium hydroxide. Therefore cost reduction is expected to be possible in construction site by reducing construction period of frame work.

Use of nanocrystal seeding chemical admixture in improving Portland cement strength development: application for precast concrete industry

This paper summarises an investigation into the potential advantages to the precast concrete industry of using a new ‘seeding’ type of chemical admixture in Portland cement (PC) based concrete mixes. Results indicated that the addition of 2–4% nanocrystal seeding chemical (NCS) admixture by weight of PC can provide a doubling of early strength, particularly at 6 and 12 h. This strength gain could lead to the turnover of moulds in precast concrete plants being completed twice in 24 h, thus increasing production capacity. Isothermal conduction calorimetry, X-ray diffraction and thermogravimetric analysis techniques were used to investigate the reasons for the improvement in compressive strength development. Results indicated that the increase in early compressive strength is due to an acceleration of early hydration of PC in presence of the NCS. Indeed, after 6 h, the degree of hydration was more than 50% greater when NCS was used. This paper also highlights the possibility of the NCS chemical admixture being used in conjunction with supplementary cementitious materials (SCMs) in PC blended concrete mixes. 2% NCS was added to a blend containing 70% PC and 30% ground granulated blast furnace slag (GGBS). Results indicated that early strength values were greater compared to the blend without NCS and comparable to the 100% PC mix.

Nanosilicas as Accelerators in Oilwell Cementing at Low Temperatures

Summary Accelerators are important cementing additives in deepwater wells where low temperatures can lengthen the wait-on-cement (WOC) time, potentially increasing the cost of operations. The cement-set accelerators traditionally used for shortening WOC times are inorganic salts, such as calcium chloride (CaCl2). These accelerators are known to have the potentially negative side effect of increasing the set-cement permeability. Nanosilicas, on the other hand, can be advantageous compared with conventional cement-set accelerators because they reduce the permeability and increase the mechanical strength of cement-based materials. For this reason, nanosilicas are known to be particularly good candidates as replacement materials for traditional salt accelerators. This study investigates the feasibility of the use of different sizes and aspect ratios of nanosilicas as cement hydration accelerators under low-temperature conditions of 59°F (15°C). The nanosilica activities are herein defined through their comparative advantages with respect to traditional accelerators, as well as through the advantages and disadvantages of the different nanosilicas resulting from their various sizes and shapes. Although hydration of oilwell cement is known to be accelerated by the addition of nanosilica, the effects of nanosilica particle shape on cement hydration kinetics has not been previously investigated. The isothermal calorimetry experiments conducted in this study reveal that just as smaller nanosilica particle sizes increase the cement-set acceleration, so do higher nanosilica aspect ratios. The effects of slurry density on the relative merits of CaCl2 and nanosilicas are also investigated. In regular-weight slurries, the effectiveness of nanosilica acceleration appears to be weaker than that of CaCl2, especially during early ages (≤ 3 days). In lightweight slurries, the effectiveness of nanosilica acceleration can be much stronger than that of CaCl2, especially when mid- to long-term properties (≥ 2 days) are considered. Smaller particle sizes and higher aspect ratios enhance the acceleration effect of nanosilicas. The compressive-strength development of lightweight oilwell cements with and without accelerators was also investigated. Lightweight cements accelerated with nanosilica displayed 7-day compressive strengths up to 136% higher than those accelerated with CaCl2.

Cement Composites Reinforced with Functionalized Carbon Nanotubes

ABSTRACTThis paper reports on the effect of surface functionalization of multi-wall carbon nanotubes on the strength and structure of portland cement composites. Reference nanotubes and nanotubes functionalized by carboxylic groups are used in this research.Grafting of functional groups on the surface of the nanotubes allows the acceleration of cement hydration. It is established that the use of carboxylated nanotubes contributed to early strength development. The multi-wall carbon nanotubes reinforced composites are characterized by the high content of the calcium silicate hydrates and a very dense structure.

Influence of heavy metals on the early hydration of calcium sulfoaluminate

The hydration of calcium sulfoaluminate \( ( {\text{C}}_{4} {\text{A}}_{3} \overline{\text{S}} ) \) in the presence of heavy metal is essential not only for applying the cement in solidification/stabilization (s/s) process, but also for preparing modern green cements from wastes containing heavy metals. In this study, the influence of gypsum, types, and concentrations of heavy metal nitrates (Pb(NO3)2, Cr(NO3)3·9H2O, Cu(NO3)2·3H2O, Zn(NO3)2·6H2O) on the hydration of \( {\text{C}}_{4} {\text{A}}_{3} \overline{\text{S}} \) during the first 24 h were investigated by isothermal conduction calorimetry, X-ray diffraction, and thermogravimetric analysis. The addition of 20 % of gypsum to \( {\text{C}}_{4} {\text{A}}_{3} \overline{\text{S}} \) leads to a rapid formation of ettringite against monosulfate and acceleration of hydration. The effects of heavy metals on the hydration of \( {\text{C}}_{4} {\text{A}}_{3} \overline{\text{S}} \) depend on the types of heavy metals and the addition of gypsum. Without any gypsum addition, heavy metal nitrates such as Cr, Cu, and Zn promote the hydration of \( {\text{C}}_{4} {\text{A}}_{3} \overline{\text{S}} \), whereas Pb presents a strong retardation effect at the early age of \( {\text{C}}_{4} {\text{A}}_{3} \overline{\text{S}} \) hydration. When 20 % of gypsum is added to \( {\text{C}}_{4} {\text{A}}_{3} \overline{\text{S}} \), heavy metals tend to accelerate the hydration of the blended pastes except Zn. However, heavy metal containing phases were not detected in this work, which needs to be supplemented by further investigations.

Investigations on phase constitution, mechanical properties and hydration kinetics of aluminous cements containing magnesium aluminate spinel

Abstract Aluminous cement containing magnesium aluminate (ACMA) spinel was prepared in situ by sintering mixtures of limestone, magnesia and bauxite. The phase constitution, micro-morphology, and hydration kinetics of ACMA were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM) and isothermal calorimeter measurements, respectively. Magnesium aluminate (MA) spinel, calcium monoaluminate (CA) and calcium bialuminate (CA 2 ) are the primary phases of the obtained ACMA. In addition, trace amount of calcium silicoaluminate (C 2 AS) and residual alumina (Al 2 O 3 ) were detected. MA, mainly exists in the form of octahedron on the order of 2–5 μm and forms agglomerates with the tabular or flaky-shaped CA in the clinker. The compressive strength of the ACMA castables increased remarkably as a function of CA content. The measurement of hydration heat demonstrated a five stage hydration process, namely, pre-induction, induction, acceleration, deceleration and stabilization. The N value was calculated to be lower than 1 in acceleration stage which indicates a nucleation controlled hydration process. On the other hand, it was higher than 1 in stabilization stage showing a diffusion controlled process.

Chloride-induced corrosion behavior of reinforcing steel in spent fluid cracking catalyst modified mortars

Concrete properties can be improved by various additives. Nowadays there is a strong interest concerning the use of spent fluid catalytic cracking catalyst (SFCC) as an admixture to improve mechanical properties of concrete. This work aims at studying the corrosion resistance of steel rebars in SFCC modified mortar specimens. Results of physicochemical characterization indicate the acceleration of cement hydration due to pozzolanic activity of SFCC. Electrochemical measurements show that the addition of the SFCC enhances corrosion resistance by delaying its corrosion onset and decreasing the corrosion rate. These benefits can be attributed to the reduction of the mortar permeability.

Biocompatibility of Mineral Trioxide Aggregate Mixed with Hydration Accelerators

IntroductionThe aim of this study was to evaluate the biocompatibility of mineral trioxide aggregate mixed with selective hydration accelerators such as calcium chloride (CaCl2), citric acid (CA), and calcium lactate gluconate solution (CLG). MethodsInductively coupled plasma-atomic emission spectrometry analysis was used to measure calcium ions in the extracts of test materials. The 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino)carbonyl]-2H-tetrazolium hydroxide assay was performed using MG-63 cells to examine the cytotoxicity of the test materials. The surface of each sample and the growth pattern of the attached cells were observed using scanning electron microscopy (SEM). ResultsMTA mixed with 10 wt% CaCl2 and MTA mixed with 43.4 wt% CLG released a higher amount of calcium ions than the other groups. The 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino)carbonyl]-2H-tetrazolium hydroxide assay revealed that the cell viability of MTA mixed with 0.1 wt% CA was significantly higher than pure MTA on 7-day extract (P < .05). MTA mixed with 43.4 wt% CLG showed significantly higher cell viability than the other groups on 1-day extract (P < .05). MTA mixed with 10 wt% CaCl2 in all groups showed the lowest cell viability at all time points (P < .05). Under SEM, elongated and confluent cells were observed in all samples except in samples of MTA mixed with 10 wt% CaCl2. ConclusionsMTA mixed with 0.1 wt% CA showed good biocompatibility. MTA mixed with 43.4 wt% CLG showed favorable biocompatibility on 1 day. MTA mixed with 10 wt% CaCl2 in all groups showed the lowest cell viability at every time point and poor cell attachment under SEM.

Evaluation of the effect of blood contamination on the compressive strength of MTA modified with hydration accelerators

ObjectivesThis study was performed to evaluate the effect of blood contamination on the compressive strength (CS) of Root MTA (RMTA) modified with Calcium chloride (CaCl2) and Disodium hydrogen phosphate (Na2HPO4) as setting accelerators over time.Materials and MethodsA total of 110 cylindrical specimens of RMTA were divided into 6 experimental groups as follows: Group1, RMTA; Group 2, RMTA modified with CaCl2 (RMTA-C); Group 3, RMTA modified with Na2HPO4 (RMTA-N); Group 4, RMTA contaminated with blood; Group 5, RMTA-C contaminated with blood; Group 6, RMTA-N contaminated with blood. The CS of specimens in all groups was evaluated after 3 hr, 24 hr, and 1 wk. In the modified groups (groups 2, 3, 5, and 6) the CS of five specimens per group was also evaluated after 1 hr.ResultsBlood contamination significantly reduced the CS of all materials at all time intervals (p < 0.05). After 3 hr, the CS of specimens in the RMTA groups (with and without blood contamination) was significantly lower than those in the RMTA-C and RMTA-N groups (p < 0.05). The CS values were not significantly different at the other time intervals. In all groups, the CS of specimens significantly increased over time (p < 0.05).ConclusionsBlood contamination decreased the CS of both original and accelerated RMTA.

A study on Fluoroanhydrite; a solid waste of the chemical industry: Characterization and valorization attempts

In the present work the characterization of a fluoroanhydrite which is a by-product of a Tunisian plant for fluorhydric acid preparation and a formulation of a self-leveling composition for floor toppings were reported. The fluoroanhydrite was characterized by x-ray diffraction (XRD), Infra-red (IR) and differential scanning calorimetry (DSC) techniques. These analyses confirmed that the by-product is the anhydrite II. The formulation was mainly, based on a fluoroanhydrite. It also contains aggregates such as a neutralizing agent, a hydration accelerator and a plasticizer. The optimization of four responses (plasticity, compressive strength, initial and final setting times) has been carried out using preliminary experiments. This retained composition aimed at obtaining a product with the required characteristics requested by the users of this kind of material. The optimized formula has the following composition: 39.85% binder (ICF-Fluoroanhydrite; particle size 1200 μm), 39.85% aggregates (silica sand), 4.40% neutralizing agent (CaCO3), 0.52% hydration accelerator (K2SO4), 0.23% plasticizer (sodium lingosulfonate) and 15.15% water.

Rheological properties of oil well cement slurries

The rheological properties, including yield stress, plastic viscosity, thixotropy and gel strength of oil well cement slurries incorporating six different chemical admixtures were investigated at different temperatures in the range of 23 to 60°C using an advanced shear-stress/shear-strain controlled rheometer. The compatibility and interactions between the binder and chemical admixtures were explored. The aim of the present study was to effectively use chemical admixtures to develop slurries with satisfactory properties in order to overcome difficulties encountered in oil well cementing such as the rapid loss of workability, pumping problems, acceleration of cement hydration, fast evaporation of mixing water and zonal isolation. It was found that the rheological properties of oil well cement slurries are highly dependent on temperature, water/cement ratio and the type of admixture used. Coupled effects of temperature and chemical admixtures had a substantial effect on the flow properties of the slurries. Among the six admixtures used, the new generation polycarboxylate-based high-range, water-reducing admixture (PCH) was found to be more effective in improving the rheological properties of oil well cement slurries at all test temperatures.

Early Stage Hydration Process of Hydroxypropyl Methyl Cellulose Ether Modified Cement Pastes

Effect of hydroxypropyl methyl cellulose ether (HPMC) on early stage process of cement pastes and its mechanism were studied by hydration heat, chemical combined water, calcium ion concentration, TG-DTG and Ca (OH) 2 content. Results show that HPMC can significantly delay hydration acceleration period of cement pastes. Hydration acceleration period of cement pastes gradually goes back, with the dosage increasing. However, changes of HPMC dosage has little effect on deceleration period and stabilization period of cement hydration. When hydration time is less than 6 hours, chemical combined water slowly increases. Chemical combined water dramatically increases when hydration time is between 6 hours and 24 hours. After 4 hours hydration, calcium ion concentration reaches maximum 26.8mm/L in blank sample. Calcium ion concentration gradually decreases when hydration time is more than 4 hours and reach minimum 9.2 mm/L after 24 hours hydration. Calcium ion concentration of cement pastes which modified with HPMC showed the same change law. When hydration time is less than 4 hours, the content of Ca (OH) 2 in cement pastes slowly enlarges along with hydration time prolonging. The content of Ca (OH) 2 significantly increases when hydration time is more than 4 hours. At the same age, the more the dosage of HPMC is, the less the chemical combined water, calcium ion concentration and Ca (OH) 2 content.

The influence of nano-silica on the hydration of ordinary Portland cement

Nucleation seeding is a new approach to control the kinetics of cement hydration. It is known that nano-silica has an accelerating effect on cement hydration. It is assumed that the surface of these particles act as a nucleation site for C–S–H-seeds which then accelerate the cement hydration. In this case the acceleration should depend on the particles surface area. To verify this, nano-silica particles of different sizes and specific surface areas were synthesised. The acceleration of cement hydration clearly correlates with the total surface size of the added particles, which was varied by either using smaller particles or higher concentration of particles in the cement lime. Additional in situ-XRD experiments show that the consumption of C3S and the formation of portlandite are accelerated by the addition of nano-silica. In both cases the surface size is the major factor for the hydration kinetics.

Improvement of the Properties of Mineral Trioxide Aggregate by Mixing with Hydration Accelerators

Introduction Mineral trioxide aggregate (MTA) is used widely in endodontic therapy. This study examined the setting time, compressive strength, and pH of MTA mixed with several hydration accelerators (calcium chloride, low-dose citric acid, calcium lactate gluconate solution). Methods Group 1 (control) was obtained by mixing MTA with distilled water. In group 2, MTA containing 10% calcium chloride was mixed with distilled water. In group 3, MTA was mixed with 0.1% citric acid. In group 4, MTA was mixed with a calcium lactate gluconate solution. The setting time, compressive strength, and pH were examined. Results The setting time of MTA mixed with hydration accelerators was significantly shorter than that of MTA mixed with water ( P < .01). In particular, replacing distilled water with a calcium lactate gluconate solution provided a significant decrease in setting time. The compressive strengths of MTA mixed with hydration accelerators were significantly lower than that of MTA mixed with water ( P < .01), but those values increased with time. The pH of MTA mixed with hydration accelerators was significantly lower than that of MTA mixed with water ( P < .01) but stable at a high level (pH 11–12). Conclusions Hydration accelerators improved the setting time of MTA. Nevertheless, more study will be needed to improve MTA without impairing its preexisting advantages.

A 43Ca and 13C NMR study of the chemical interaction between poly(ethylene–vinyl acetate) and white cement during hydration

43Ca and 13C NMR methods were used to study the chemical interaction of poly(ethylene–vinyl acetate) (PEVAc) admixture in commercial-grade white cement. From 43Ca NMR it is shown both that PEVAc induces modest changes in the hydrated cement structure, and that hydrated commercial cement is significantly more complex than models that have been used for its structure in past work. The 13C NMR results show that the PEVAc hydrolysis occurs early in the cement hydration acceleration period, with a rate well-fit by an exponential decay using a time constant of 6±1 days.

Influence of metakaolin and silica fume on the heat of hydration and compressive strength development of mortar

In this study, two metakaolins (MK1 & MK2) were investigated for use as supplementary cementitious materials in cement-based systems. The MK vary in their surface area (17 to 19 m 2/g), but are almost similar in chemical composition. Total of four series of mortar mixes were made. First was control mix. Second and third mixes contained 10% of each of the MK as partial replacement of cement. In fourth mix, cement was replaced with 10% silica fume (SF). Water-to-cementitious materials ratio was kept constant as 0.36. Performances of MK mixes were compared with control mix, and mixes incorporating SF. Tests were conducted for early-age properties of fresh mortar and compressive strength. Early age investigation was aimed to determine the reactivity (temperature and heat of hydration of MK), and its effect on fresh mixture (slump flow). Test results have indicated that (i) blended mortar with MK can reach higher temperature with respect to 100% ordinary Portland cement; (ii) MK exhibits lower pozzolanic activity than SF. Hydration heat of SF is greater than that of MK; (iii) it is supposed that there are three elementary factors which influence the contribution that MK makes to mortar strength when it partially replaces cement in mortar. These are the filler effect, the acceleration of ordinary Portland cement hydration and the pozzolanic reaction of MK with calcium hydroxide.