• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2000.10a
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• pp.266-271
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• 2000

This study was performed to find out how much water the cement hydration reaction need. It is real situation that it is difficult to find out the amount of chemical combined water with stoichiometric chemical reaction form. Because several variation occurred during hydration reaction it's not easy to divide water which used at cement paste mixture. In this study high temperature(105$^{\circ}C$) dry method was used to divide evaporable water and non-evaporable water. The last is combined water chemically and some free water absorbed to products of hydration physically. The test was processed with variation of water cement ratio from 10% to 45% with 5% intervals. The weight of cement paste specimens were measured after dry for 72hours at each checking time(0.5, 1, 3, 5, 10, 24, 48, 72, 168hour). In this study some conclusions such as follows were derived. Firstly, Pure combined water contents required at cement hydration result in 23.3percent of the weight of cement. Secondly, The sufficient mixing water needed to fully hydrated cement result in about 40∼45percent of weight of cement. That is, gel pores water could be about 16.7∼21.7percent of weight of cement.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2005.10a
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• pp.123-127
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• 2005

EVA Powder modified high strength concretes were prepared by varying polymer/binder mass ratio with a constant water/binder mass ratio of 0.3. The effect of EVA powder on the slump, hydration heat, compressive and flexural strength, toughness and water absorption ratio was studied. In hydration heat test, temperature of hydration reaction displayed almost fixed level regardless of containing rate of EVA powder, but peak time of hydration reaction displayed late inclination as containing rate of powder increases. With the same water/binder mass ratio, the compressive strength and water absorption of EVA powder modified concretes decreased slightly when EVA powder was added and the flexural strength of EVA powder modified concretes rised slightly when EVA powder was added. Also, the toughness of the modified concretes can be improved markedly. The interpenetrating structure between the polymeric phase and cement hydrates formed at a $2{\sim}6%$(containing rate of EVA powder). The properties of the polymer modified concretes were influenced by the polymer film, cement hydrates and the combined structure between the organic and inorganic phases.

• Journal of Urban Science
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• v.9 no.1
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• pp.7-16
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• 2020

Application of nanomaterials to cementitious composites has been attempted with the rapid development of nanotechnology since the 1990s. Various nanomaterials such as carbon nanotube, graphene, nano-SiO₂, nano-TiO₂, nano-Al₂O₃, nano-Clay, and nano-Magnetite have been applied to cementitious composites to improve the mechanical properties and the durability, and to impart a variety of functionality. In-depth information on the effect of nanomaterials on the hydration reaction, the microstructure, and the mechanical properties of cementitious nanocomposites is provided in the present study. Specifically, this paper mostly deals with the previous studies on the heat evolution characteristics of cementitious nanomaterials at an early age of curing, and the pore and the compressive strength characteristics of cementitious nanocomposites. Furthermore, the effect of nanomaterials on the cementitious nanocomposites was systematically discussed with the reviews.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.261-262
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• 2010

The Reaction structure in POSCO Global R&D center has to be investigated to minimize the crack especially by the hydration heat. In this study, several methods to control the hydration heat are suggested and the computational analysis of hydration heat is performed. The main variables are kinds of concrete, the interval of placement.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.25-28
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• 2006

This study investigated pre-mixed cement combined with ordinary portland cement, BF and SF, in order to manufacture cement binder, which is possible to produce 150MPa ultra high strength concrete. The BF used in this study reduces and control hydration heat. It can also improve concrete fluidity, while AP increases hydration product and accelerates reaction of BF. SF has micro filler effect and makes pozzolanic reaction. It also fabricates high density internal organization. This developed pre-mixed cement can reduce hydration heat and increase hydration product. It is possible to fabricate high density organization and to secure homogeneity. The mock-up test of ultra high strength concrete showed excellent dispersibility and workability and indicated compressive strength more than 150MPa at 28 days.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.06a
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• pp.153-154
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• 2020

The purpose of this paper is to examine the characteristics of heat and hydration of concrete according to formwork materials. As a result of the experiment, it was found that there were no problems such as concrete heat loss and delay in hydration reaction due to the use of synthetic resin formwork.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.11a
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• pp.129-130
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• 2020

This paper attempted to examine the characteristics of heat of hydration and calorific value of concrete according to the formwork material in Hot weather environment. As a result of the experiment, it was found that there were no problems such as temperature cracking and delay in hydration reaction when a synthetic resin form was used.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.1
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• pp.15-22
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• 2022

In this study, the hydration reaction and strength characteristic of cement mortar with spent coffee ground(SCG) was investigated. As a result of the study, it was found that as the firing temperature of the SCG increased, the mass loss due to the combustion of organic matter increased, but the density increased. In addition, when the SCG were mixed, SCG interfered with the hydration reaction and the compressive strength was significantly lowered. On the other hand, the coffee grounds ash(SCG_Ash) calcined at 800 ℃ showed a hydration reaction and a compressive strength equivalent to or higher than that of OPC mortar.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.565-566
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• 2009

Supplementary cementing materials (SCM), such as silica fume, slag, and low-calcium fly ash, have been widely used as mineral admixtures in high strength and high performance concrete. Due to the chemical and physical effect of SCM on hydration, compared with Portland cement, hydration process of cement incorporating SCM is much more complex. This paper presents a numerical hydration model which is based on multi-component concept and can simulate hydration of cement incorporating SCM. The proposed model starts with mixture proportion of concrete and considers both chemical and physical effect of SCM on hydration. Using this proposed model, this paper predicts the following properties of hydrating cement-SCM blends as a function of hydration time: reaction ratio of SCM, calcium hydroxide content, heat evolution, porosity, chemically bound water and the development of the compressive strength of concrete. The prediction results agree well with experiment results.

• Journal of the Korean Ceramic Society
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• v.35 no.2
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• pp.185-195
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• 1998

This experiment carried out in order to investigate the effect of the chemical activators for acceleration of hydration the system of Fly ash-Cao The paste was consisted of 80wt% Fly ash and 20wt% CaO with 1. 3. 5wt% of 4 activators(N{{{{ alpha _2 }}S{{{{ OMICRON _4 }}, CaC{{{{ {l }_{2 } }}, NaOH, Ca(N{{{{ OMICRON _3 {)}_{2 } }} and W/S ratio of 0.42 After curing for 1, 3, 7, 14, 28 days the paste hydration was characterized by the measurement of compressive strength XRD analysis SEM observation the combined water and the reaction amount of Ca(OH)2 determination. As a result of this ex-periment all of the system which involved Na2SO4 or NaOH had a god compressive strength. In the case of 7 days curing a system which added CaCl2 showed the highest compressive strength among all especially NaOH system showed a high increase in strength as a dosage of it increased. Hydration products were different according to activatores added. Only C-S-H was observed in NaOH system. As the reaction amount of Ca(OH)2 and combined water were increased the compressive strength increased. There were few differences in the comparision of strength between ignited loss 3.1% and loss 9.3% of fly ash.