• Cement
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• s.106
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• pp.62-68
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• 1987

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.1
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• pp.84-92
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• 2014

The purpose of study is to analyze mechanism with early high portland cement and hardening accelerator. As the result, it was concluded that hardening accelerator makes accelerates appearance of $Ca(OH)_2$ through experiment using TG-DTA when it hydrates with cement. On the result of compressive strength, as increasing the amount of hardening accelerator used, early compressive strength was improved. Also, as a result of hydration heat, hardening accelerator accelerates hydration of $C_3S$ that is cement's component. On the result of XRD's analyzation, hydration product for each age could be check and it was shown that as increasing the amount of hardening accelerator used, peak point of hydration product was recorded high. As the result of SEM, appearance of C-S-H was shown as the amount of $Ca(OH)_2$'s appearance and each age according to additive contents of hardening accelerator. Therefore hardening accelerator used on this study is effective on getting early compressive strength.

• Journal of the Korea Institute of Building Construction
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• v.13 no.3
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• pp.218-226
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• 2013

Of construction materials, cement and steel are the representative material that carbon dioxide. to reduce carbon emissions in the use of these materials The purpose of this study is low heat type blended cement, which is manufactured using a amount of cement than ordinary low heat blended cement. Low heat blended cement, mixing ratio of 10%, was investigated hydration properties and adiabatic temperature of concrete. The study in order to activate the reaction mineral admixture, a separate source of CaO and $SO_3$ areneeded. gypsum and lime, it expected amount of cement, low-carbon low-heat blended cement could reduce the hydration heat concrete than currentlyused low heat blended cement.

• Cement Symposium
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• s.39
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• pp.128-136
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• 2012

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.813-816
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• 2008

Polycarboxylate-type superplasticizer is widely used for producing self-compacting and high-strength concrete and improving concrete durability. This paper discusses the influence of molecular structure of polycarboxylate-type superplasticizer on the fluidity and the rate of heat liberation of ordinary Portland cement paste. The fluidity of cement paste was increased by addition of polycarboxylate-type superplasticizer. The arrival time up to the maximum rate of heat liberation was increased by addition of polycarboxylate-type superplasticizer. The fluidity and the arrival time up to the maximum rate of heat liberation were more influenced by addition of polycarboxylate-type superplasticizer having shorter grafted chain than that having longer grafted chain.

• Cement Symposium
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• no.17
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• pp.15-21
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• 1989

시멘트 모르타르에 EVAc 에멀젼 및 계면활성제(Sodium Dodecylbenzenesulfonate)를 첨가하여 압축강도, 흡수율, 화학적 저항성, 수화발열속도, 전자현미경 등으로 그 물성을 관찰하였다. EVAc를 시멘트에 첨가할 경우 5-15wt$\%$, SDBF는 0.03wt$\%$를 첨가하고 혼수량을 flow value로써 기준하는 것이 최적조검임을 알 수 있었다. 그리고 EVAc emulsion을 첨가함으로써 혼수량 및 흡수율의 감소 효과를 거둘 수가 있었으며 또한 화학적 저항성도 증가되었다. EVAc emulsion을 과다 첨가할 경우에는 기포가 많이 형성되어 강도가 저하하나, 여기에 계면활성제(Sodium Dodecylbenzenesulfonate)를 가하면 강도가 증가하였으며, 한편 수화 속도는 지연되었다.

• Journal of the Korean Geotechnical Society
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• v.20 no.9
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• pp.25-32
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• 2004

Some amount of cements can be added into the soil with high water content to improve the engineering properties. In such a case, it is difficult to predict and figure out the phase changes of the soil-cement mixture which is closely associated with workability of the soil-cement mixture. Changes in heat of hydration and hardness of the cement pastes are known to provide the useful information about the phase changes of the soil-cement mixtures. In this study, heat of hydration and cone penetration depth were measured from the specimens of cement paste and 3 soil-cement mixtures. From the experimental results, it was found that the phase changes of the soil-cement mixtures are the same as those of cement paste, and that shear strength of the mixtures abruptly increases when the heat of hydration is minimum. Initial setting time of the mixtures coincides with the state when fall cone penetration depth was 1.0 mm and it is defined as plastic limit of the mixtures. Initial setting time of the mixtures is retarded as soil/cement ratio is increased. Measurements of heat of hydration and fall cone apparatus could be the useful tools to predict the phase changes of tile soil-cement mixtures.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.5
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• pp.17-25
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• 2010

We studied on the watertightness improvement of cementitious material for durability enhancement of concrete. For improvement of watertightness of OPC and OPC with fly ash, we used various materials with watertightness properties to OPC and OPC with fly ash. The performance of watertightness improvement of cementitious materials closely related to formation of CSH by pozzolanic reaction and to reducing of size of contact angle in cement pore by using organic fatty acid. And volume of CSH formation at early hydration have an influence of watertightness improvement and reduction of long-term water absorption rate. In using of fly ash, improvement of workability by using the spherical fly ash caused to densify on the structures of cement material and CSH formation by pozzolanic reaction and cement using fly ash also caused watertightness improvement of cementitious materials. For improvement of concrete durability by watertightness, cementitious materials need using watertightness materials and at using fly ash, also it have to the effect of improvement of watertightness of cementitious materials by pozzolanic reaction.

• Journal of the Korea Concrete Institute
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• v.27 no.2
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• pp.115-125
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• 2015

This study investigated the fluidity, heat of hydration, setting time, strength development, and characteristics of hydration and pozzolanic reactions of high-strength high-volume ground granulated blast-furnace slag(GGBFS) blended cement pasts with the water-to-binder ratio of 20% by experiments, and analyzed the effects of the replacement ratio and fineness of GGBFS on the hydration and pozzolanic reaction. The results show that, in the high-strength mixtures with low water-to-binder ratio, the initial hydration is accelerated due to the "dilution effect" which means that the free water to react with cement increases by the replacement of cement by GGBFS, and thus, strengths at from 3 to 28 days were higher than those of plain mixtures with ordinary Portland cement only. Whereas it was found that the long term strength development is limited because the hydration reaction rates rapidly decreases with ages and the degree of pozzolanic reaction is lowered due to insufficient supply of calcium hydroxide according to large replacement of cement by GGBFS. Also, the GGBFS with higher fineness absorbs more free water, and thus it decreases the fluidity, the degree of hydration, and strength. These results are different with those of normal strength concrete, and therefore, should be verified for concrete mixtures. Also, to develop the high-strength concrete with high-volume of GGBFS, the future research to enhance the long-term strength development is needed.

• Resources Recycling
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• v.27 no.1
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• pp.92-105
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• 2018

The present study was carried out to find a suitable drying method for measuring non-evaporable water contents of various hydraulic inorganic materials. In Part 1 of the paper, the case Ordinary Portland cement is discussed. Various drying methods including vacuum and oven drying, and an ignition, were used for the OPC paste and mortar having different w/c. The sole vacuum drying under room temperature led a fluctuation on measurement of hydration degree, while the sole oven drying also yielded unwanted hydration promotion at the early age. A combination of the vacuum and oven drying was considered as a suitable drying method for the OPC case.