• Journal of the Korean Ceramic Society
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• v.50 no.2
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• pp.149-156
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• 2013

This study examines the effects of limestone's factors on the fluidity of cement paste when of up to 15%. As the substitution ratio of limestone powder increases, the fluidity of the paste is also improved; however, it has no correlation to the $CaCO_3$ content of the limestone, fineness of the limestone, and fluidity of the pastes. Regardless of clay content of the limestone, it showed a similar mini-slump, so there was no correlation between the clay content and the fluidity of the paste. Also, the total organic carbon content of the limestone and the fluidity of the paste showed no correlation. Regardless of the limestone's grade or fineness, n value of powder gained by using the Rosin-Rammler distribution function showed that the fluidity of the paste increased as the n value reduced. It was also shown that particle size distribution of ordinary Portland cement with limestone powder had a major effect on the fluidity of the paste.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2005.11a
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• pp.57-61
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• 2005

Cement paste is originally the basic material and crucial factor consisting concrete. This study investigates the relationship between flow apparatuses, which are ring flow(R-F), flow cone(F-C) and mini slump(M-S), in order to estimate the fluidity of cement Paste. For quantitatively evaluating the measured data this study also investigated the calibration of the rheology consistent, such as yield value and plastic viscosity, of cement paste using viscometer For this purpose the present work discussed the influence of 3 type of ordinary portland cement with different companies, affecting the fluidity of cement paste. and it also demonstrated the influence of the various kinds of mineral admixtures, such as fly ash(FA), blast furnace slag(BS) and silica fume(SF) and that of incorporating ratio. The author concluded that using R-F apparatus is the most effective flow test method of cement paste and it is exactly proportional to other apparatus' rheological properties.

• Journal of the Korean Ceramic Society
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• v.45 no.6
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• pp.336-344
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• 2008

Rheological properties of cement pastes containing blast furnace slag (BFS: 3,900, $7,910\;cm^2/g$) or fly ash powder (FA: 4,120, $8,100\;cm^2/g$) according to the ratio of water/binder (W/B) and the dosage of polycarboxylate type superplasticizer (PC) were investigated by a mini slump and a coaxial cylinder viscometer. In this experiment, the ratio of replacing OPC with BFS or FA was 30 wt%, the W/B was from 30 to 70 wt%. As a result, the fluidity of cement paste containing BFS or FA was improved with increasing W/B and the dosage of PC. BFS or FA replaced cement paste with W/B 70% and PC 0.3% showed the highest fluidity. The segregation range of cement paste was occurred below $10\;d/cm^2$ of the yield stress and below 50 cPs of the plastic viscosity by the coaxial cylinder viscometer. And also it was formed that the plastic viscosity and the yield stress of FA replaced cement paste were higher than them of BFS replaced cement paste.

• Journal of the Korean Ceramic Society
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• v.42 no.11 s.282
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• pp.737-742
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• 2005

Rheological properties of ordinary portland cement (OPC) containing metakaoline (MK), granulated blast furnace slag (GBS) and polycarboxylate type superplasticizer (PCA) were investigated using a mini-slump test, sedimentation test and viscometer. Fluidity of cement pastes containing MK (OPC-MK, OPC-MK-GBS systems) with PCA were higher than those of the cement pastes without MK(OPC, OPC-GBS systems). Colloid suspensions with $0.1\%$ PCA were changed from stable sedimentation behaviors to flocculation behaviors in the OPC-MK, OPC-GBS and OPC-MK-GBS systems. The colloid suspensions showed stable sedimentation behaviors with PCA greater than $0.2\%$. The OPC system showed shear thinning behavior. However, the other systems showed weak shear thinning behaviors with PCA. Rheological properties of cement pastes were improved when MK and GBS were contained together. The rheological properties of OPC-MK, OPC-GBS and OPC-MK-GBS systems were improved by PCA added greater than $0.2\%$.

• Computers and Concrete
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• v.8 no.3
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• pp.279-292
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• 2011

The main purpose of this study includes investigation of the rheological properties of fresh self consolidating cement paste containing chemical and mineral additives using Artificial Neural Network (ANN) model. In order to develop the model, 200 different mixes are cast in the laboratory as a part of an extensive experimental research program. The data used in the ANN model are arranged in a format of fourteen input parameters covering water-binder ratio, four different mineral additives (calcium carbonate, metakaolin, silica fume, and limestone), five different superplasticizers based on the poly carboxylate and naphthalene and four different Viscosity Modified Admixtures (VMAs). Two common output parameters including the mini slump value and flow cone time are chosen for measuring the rheological properties of fresh self consolidating cement paste. Having validated the model, the influence of effective parameters on the rheological properties of fresh self consolidating cement paste is investigated based on the ANN model outputs. The output results of the model are then compared with the results of previous studies performed by other researchers. Ultimately, the analysis of the model outputs determines the optimal percentage of additives which has a strong influence on the rheological properties of fresh self consolidating cement paste. The proposed ANN model shows that metakaolin and silica fume affect the rheological properties in the same manner. In addition, for providing the suitable rheological properties, the ANN model introduces the optimal percentage of metakaolin, silica fume, calcium carbonate and limestone as 15, 15, 20 and 20% by cement weight, respectively.

• Magazine of the Korea Concrete Institute
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• v.9 no.3
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• pp.149-156
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• 1997

In order to improve compressive strength of cement mortar, powder admixture(FAS) was mmufactured by mixing fly ash. Il-anhydite and silica hume, and superplasticizer was used for the control of fluidity reduction with the use of this admixture. Cement was substituted by 10, 20wt% of FAS respectively. At W/S = 0.40, the fluidity of' cement paste substituted by PAS was decreased. NSF and NT-2 were very effective fbr the control of fluidity reduction. As the particle size of U -anhydrite was fine, the fluidity of cement mortar was increased. The fluidity reduction of cement mortar substituted by 10wt% of FAS was controlled. The compressive strength of cement mortar substituted by 10wt% of FAS showed higher. value than that of 20wt%, expecially specimen(C1) substituted by 10wt% of $\gamma$ had the highest compressive strength value.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.5
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• pp.12-20
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• 2017

This report presents the results of an investigation on the fundamental properties of mortars high fluidity high volume slag cement(HVSC) activated with sodium silicate($Na_2SiO_3$). The ordinary Portland cement(OPC) was replaced by ground granulated blast furnace slag(GGBFS) from 40% to 80% and calcium sulfoaluminate(CSA) was 2.5% or 5.0% mass. The $Na_2SiO_3$ was added at 2% and 4% by total binder(OPC+GGBFS+CSA) weight. A constant water-to-binder ratio(w/b)=0.35 was used for all mixtures. The research carried out the mini slump, V-funnel, setting time, compressive strength and drying shrinkage. The experimental results showed that the contents of superplasticizer, V-funnel, setting time and drying shrinkage increased as the contents of CSA and $Na_2SiO_3$ increase. The compressive strength increases with and an increase in CSA and $Na_2SiO_3$. One of the major reason for these results is the accelerated reactivity of GGBFS with CSA and $Na_2SiO_3$. The maximum performance was CSA 5.0% + $Na_2SiO_3$ 4% specimens.

• Journal of the Korea Concrete Institute
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• v.18 no.4 s.94
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• pp.489-496
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• 2006

Graft copolymerized polycarboxylate(PC)-type superplasticizers which have carboxylic acid with $\pi$ bond among the molecular structure and polyethyleneglycol methyl ether methacrylate(PMEM) were synthesized by free radical reaction. To investigate their chemical structures and molecular weights, PCs were analyzed by FT-IR(fourier transform spectrometer), C-NMR(nuclear magnetic resonance spectrometer) and GPC(gel permeation chromatograpy). When types of carboxylic acids(methacrylic acid, acrylic acid, maleic anhydride, and itaconic acid) and molar ratios of carboxylic acid/PMEM) were varied, adsorptive and fluid characteristics in cement paste were discussed. As the molar ratio of carboxylic acid/PMEM) was higher, amount adsorbed on the cement particles and the fluidity of cement paste by mini-slump spread testing method were increased. When main chain of PC was methacrylic acid, a larger amount was adsorbed on the cement particles. PCs with acrylic acid as main chain showed higher dispersing power. However, it was confirmed that PCs with dicarboxylic acids(maleic anhydride, itaconic acid) didn't have good adsorption and dispersibility.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.8
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• pp.5636-5645
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• 2015

Physical characteristics of aggregates affect the workability and strength of mortar and concrete, which include their fineness ratio, particle size distribution and water absorption. The workability of construction materials decreases if the incorporated fine aggregates show improper size distribution of their particles. This study shows the particle size effect on the rheological behavior of mortar and provides basic information for evaluating its workability. A mini-slump flow test was adopted to evaluate the workability of mortar. In addition, its plastic viscosity and yield stress were measured using a rheometer for building materials. The sand samples were prepared by sieving river sand and sorting out with their particle sizes. As a result, it was observed that the fines less than 0.7 mm increases the yield stress and plastic viscosity of the mortar samples. If the fines are less than 0.34 mm, the water absorption of the fines dominates change on the workability.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.6
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• pp.74-82
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• 2017

This research presents the results of the strength and drying shrinkage properties to study the effect of ground granulated blast furnace slag(GGBFS), fly ash(FA) and calcium sulfoaluminate(CSA) for activated ternary blended slag cement. The activated ternary blended cement(ATBC) mortar were prepared having a constant water-cementitious materials ratios of 0.4. The GGBFS contents ratios of 100%, 80%, 70% and 60%, FA replacement ratios of 10%, 20%, 30% and 40%, CSA ratios of 0%, 10%, 20% and 30% were designed. The superplasticizer of polycarboxylate type were used. The activator was used of 10% sodium hydroxide(NaOH) + 10% sodium silicate($Na_2SiO_3$) by weight of binder. Test were conducted for mini slump, setting time, V-funnel, water absorption, compressive strength and drying shrinkage. According to the experimental results, the contents of superplasticizer, V-funnel and compressive strength increases with an increase in CSA contents for all mixtures. Moreover, the setting time, water absorption ratios and drying shrinkage ratio decrease with and increase in CSA. One of the major reason for the increase of strength and decrease of drying shrinkage is the accelerated reactivity of GGBFS with alkali activator and CSA. The CSA contents is the main parameter to explain the strength development and decreased drying shrinkage in the ATBC.