• Proceedings of the Korean Institute of Building Construction Conference
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• 2003.05a
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• pp.95-98
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• 2003

This paper presents the results of field experiment to apply the difference of setting tine method using super retarding agent for reducing hydration heat of mass concrete of foundation. According to the results, as the properties of fresh concrete, base concrete satisfies aimed slump and air content, and there is no difference of slump and air content with mixture of super retarding agent. The mixing ratio of super retarding agent is determined for setting time to be retarded by 12 hours in comparison with base concrete, but because the temperature of the air and concrete is low, the difference of setting time is retarded to 24 hours. In man concrete of foundation to which the difference of setting time method is applied, crack by hydration heat is not seen because the lower concrete of super retarding agent generates heat after generation of hydration heat of the upper concrete.

• Advances in concrete construction
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• v.6 no.6
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• pp.659-677
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• 2018

The use of some superplasticizers in the production of mortar or concrete influences the hydration kinetic and the amount of total heat. This results in a modification of some properties, namely mortar workability, mechanical strength and durability. Three superplasticizers were used; a polynaphthalenesulfonate (PNS), a melamine resin (PMS) and a polycarboxylate (PC). They have been incorporated into various amount in a standardized mortar based on limestone cement. The aim of this study was to evaluate the rheological, mechanical and Calorimeters properties of this mortar. This will select the most compatible product and more able to be used depending on the climate of the country and the cement used. The PNS is incompatible with this type of cement registering a decrease of strength but the PMS and the PC modify the kinetics of hydration with significant heat generation and improved mechanical strength. The measured heat flow is significantly influenced by the type and dosage of superplasticizer especially for low dosage. Hydration heat and compressive strength of the different mixtures can be evaluated by determining their ultimate values and ages to reach these values where the correlation coefficients are very satisfactory.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.05a
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• pp.203-204
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• 2016

In this research, it used cement power and reduction slag, which generates high hydration heat in hydration reation without heat cure below -5℃ degree. Purpose of final research is preventing freezing and thawing by making the compressive strength 5MPa in 3days below zero temperature due to own heat of concrete. and it is the result of physical characteristic and thermal property evaluation of reduction slag. Because reduction sag generates high hydration heat, compressive strength development is excellent. By generating highly Hydration heat by C₁₂A₇ and C₃A in reduction slag, compressive strength is developed in low temperature. In case of displacing only reduction slag without SO₃, it is indicated that quick-setting occurs by shortage of SO₃. For preventing quick-setting, gypsum is used essentially. According to this research result, in case of using reduction slag and gypsum as a ternary system, Compressive strength developed 5MPa in 3days below zero temperature. It is identified to prevent early frost damage of concrete below zero temperature.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.04a
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• pp.158-159
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• 2022

This study analyzed the temperature stress through mixtures mass concrete hydration heat analysis according to the replacement rates of FAC and CGS. As a result of the analysis, it was possible to confirm the effect of reducing hydration heat when CGS is substituted for the low heat mixture of mass concrete. However, the stress of the FAC+CGS combination exceeded the tensile stress. It is believed that it is necessary to apply the insulating sheet of the surface part and reduce the unit weight of cement.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.315-316
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• 2009

In this study, latent heat material was used to reduce hydration heating velocity of high-strength mass concrete. And the properties of hydration heat and autogenous shrinkage, and the relationship between hydration heat and autogenous shrinkage of high-strength mass concrete were numerically investigated.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.915-918
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• 2008

Hydration heat and autogenous shrinkage are generated essentially by the same hydration. Many researchers have studied the close relationship between hydration temperature and autogenous shrinkage but hardly any research has been undertaken to explain the specific numerical relation. In this study, early age properties of hydration heat and autogenous shrinkage of specimen whose section size was changed were analyzed, and relationship between hydration heat and autogenous shrinkage was investigated. In the results of the study, inner temperature and autogenous shrinkage increased as the section size increased. And rise and rise ratio of hydration temperature and autogenous shrinkage in hydration heating section and autogenous shrinking section are increased too. Temperature rise and autogenous shrinkage rise increased respectively, as hydration heating velocity and autogenous shrinking velocity increased. And autogenous shrinkage rise and autogenous shrinking velocity increased as hydration heating velocity increased.

• Journal of the Korea Concrete Institute
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• v.20 no.2
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• pp.157-164
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• 2008

In order to raise efficiency in construction, construction period, construction costs etc. that have been problematic in the methods of hydration heat reduction thus far, this study has developed a new method. The principle of the developed construction method involves the laying of a heat conducting medium such as the heat pipe in the concrete, and through the fast conduction of heat by the heat pipe, the hydration heat occurring within the mass concrete is transferred to the exterior by which the internal hydration heat is reduced. If the study results of the onsite test are summarized, on application of existing hydration heat reduction methods, the highest temperature was reached in about 2$\sim$4 days, but when the heat pipe of this study was used, the period was reduced to within 24 hours. Moreover, when the thermal crack index was calculated with the method using the heat pipe as developed in this study, a value of 1.2 or higher was revealed, which is a level that can restrict the occurrence of cracks. Therefore, when the hydration heat control method using the heat pipe as developed in this study is applied, not only the effects of construction efficiency and reduction in construction period, but also outstanding economical effects can be expected.

• Journal of the Korean Ceramic Society
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• v.25 no.5
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• pp.449-454
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• 1988

The effects of salts which was used as a catalysis in formation of $\alpha$-calciumusulfate hemihydrate from dicalcium sulfate hydrate were investigated on the hydration of $\alpha$-calciumsulfate hemihydrate. The hydration of $\alpha$-calciumsulfate hemihydrate was studied by the measurements of crystalline water, heat evolution. Also the hydrates were analyzed by XRD, DSC and SEM. The promotive effect each salts on the hydration was as follows: NaCl>NH4Cl>NaNO3>NH4NO3, and the hydration rate was accelerated with concentration of salts. The effect of Al2(SO4)3 and potassium sodium tartrate on the hydration was slmilar to water, whereas sodium succinate and gelatin retarded the hydration in comparision with water. These salts affected the hydration time but total heat evoution was similar.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.657-660
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• 2008

In this study, quantitative analysis on effect of hydration heat and autogenous shrinkage of concrete using BFS was studied. Especially, it analyze section data statistically which hydration heat and autogenous shrinkage rise, and it appeared the correlation of hydration heat and autogenous shrinkage as well as quantitative coefficients of the main properties. As a result, the section which hydration heat and autogenous shrinkage of BFS-50 rise rapidly is delayed than OPC, but the slope of hydration heat and autogenous shrinkage in that section appeared similar shape in each mixing. Finally it will be possible to control the amount of autogenous shrinkage because hydration heating velocity and autogenous shrinking velocity are decreased by using BFS.

• International Journal of Concrete Structures and Materials
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• v.19 no.1E
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• pp.33-39
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• 2007

The magnitude and distribution of hydration heat of concrete structures are related to the thermal properties of each component of the concrete, the initial temperature, the type of formwork, and the ambient temperature of exposed surfaces. Even though the reinforcing steel bar has completely different thermal properties, it has been excluded in the thermal analysis of the concrete structures for uncertain reasons. In this study, finite element analysis was performed on the concrete structures reinforced with steel bars in order to investigate the effect of reinforcing steel bars on the temperature and stress distribution due to the heat of hydration. As the steel content increased, the maximum temperature and the difference in the internal-external temperature decreased by 32.5% and 10.0%, respectively. It is clearly shown that the consideration of the influence of reinforcing steel bars in the heat of hydration analysis is necessary to obtain realistic solutions for the prediction of the maximum temperature and stresses of concrete structures.