• Proceedings of the Korea Concrete Institute Conference
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• 1995.10a
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• pp.329-333
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• 1995

The usual methods for the temperature control of mass-concrete structures include the use of low-heat cement, pre-cooling, or pipe-cooling. In order to control the heat of hydration of mass-concrete structures such as massive pier or anchor block, and mat foundation, the pipe cooling method is widely acceptable for pratical use. In this paper, method of analysis using the Finite Element Method was applied to analyze the heat exchange on the field of three dimensional thermal conduction. The result of analysis Well agreed with experimentally measurement data by "KUMATANI". The method of this analysis will be used widely to control the heat of hydration by the pipe cooling in mass-concrete.-concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.297-302
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• 2001

SRC pier at KTE 6-1 construction area is a very important structure. Precise control of quality is needed. This pier has 3.50m$\times$3.73m section and 38.20m length. So this structure must be treated as mass concrete and thermal crack caused by hydration heat should be controled. In this project belite cement concrete is used to control the thermal crack. As a result of adapting belite cement concrete perfect control is achieved. Finally, hydration heat FEM analysis of horizontal element is executed for Ordinary Portland Cement concrete and belite cement concrete. In comparison of two results, it is confirmed that using low heat portland cement concrete is necessary.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.345-348
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• 2005

This paper presents the result of adiabetic temperature rise and fundamental properties of concrete combining admixtures. According to results, difference of setting time with I5.5hours is observed between S-P and R-F30 mixture. Based on the adiabetic temperature rise test, 8$^{circ}C$of heat producted occurs between E-P and R-F30 mixture. is applied to estimate the temperature rising under adiabetic curing condition, which exhibits closer consistency with tested value. The function mentioned above can account for the effect of dormant period in hydration process at early stage on hydration heat production. It reveals that the consideration of placing layer based on the mixture adjustment(E-P mixture at top layer and R-F30 mixture at bottom layer) in mass concreting will contribute to reduce hydration heat as well as alleviate tensile stress discrepancy between placing layer.

• 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.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.24 no.1
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• pp.27-32
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• 2014

This study analyzed the fundamental characteristics of concrete according to a ternary system mixing in order to reduce hydration heat of mass concrete and to improve early age strength. The results are as follows. The fluidity of unconsolidated concrete satisfied the target scope regardless of the binder conditions. When the replacement ratio between FA and BS increased, the slump of low heat-A mix and low heat-B mix increased, and air content was not affected by the change of binders. As for setting time, low heat cement mix had the fastest regardless of W/B, and high early strength low heat mix achieved 6 hours' reduction compared with low heat-B mix at initial set, and 12 hours' reduction at the final set respectively. As for the simple hydration heat, the low mix peak temperature was the highest and low heat-B mix had the lowest temperature. And high early strength low heat mix was similar with that of low heat-B. The compressive strength of hardened concrete had similar strength scope in all mixes except for low heat-B mix at early ages, and had unexceptionally similar one without huge differences at long-term ages.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2008.11a
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• pp.31-36
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• 2008

This study aims to examine the effects of thickness of the concrete members and curing temperature on the properties of low heat concrete through heat of hydration analysis. Type of the members that was analyzed in the experiment is ternary mixture of ordinary portland cement, blast-furnace slag incorporating ratio(20%) and fly ash incorporating ratio(30%), which formed a mat foundation. Thicknesses of the concrete members were 1, 2 and 3(m) and three levels of curing temperatures were 10, 20 and 30(℃). They were applied to analyze the effects on the temperature and thermal cracking index. As a result, for temperature history, temperature difference between the central area and the surface tended to decrease as the thickness of the concrete members get thinner. For the temperature cracking index, on the other hand, the risk of cracking tended to decrease as the curing temperature gets higher and as the thickness gets thinner.

• Computers and Concrete
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• v.11 no.4
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• pp.271-289
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• 2013

In this research, a developed microstructural model of cement particles was presented to describe the cement hydration procedure. To simplify the hydration process, the whole hydration was analyzed in a series of sub-steps. In each step, the hydration degree, as well as the microstructural size of the hydration cell, was calculated as a function of the radius of the unreacted cement particles. With the consideration of the water consumption and the reduction of the interfacial area between water and hydration products, the micro-level expressions of the cement hydration kinetics were established. Then the heat released and temperature history of the concrete was carried out with the hydration degree obtained from each sub-steps. The equivalent age method based on the Arrhenius law was introduced in this research. Based on the equivalent age method, a maturity model was applied to describe the evolution of the mechanical properties of the material during the hydration process. The finite element program ANSYS was used to analyze the temperature field in concrete structures. Then thermal stress field was calculated using the elasticity modulus obtained from code formulate. And the risk of thermal cracking was estimated by the comparison of thermal stress and concrete tensile strength.

• 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.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.95-100
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• 2003

The shrinkage of high strength/high performance concrete is very important property for the good working of a structure since it very often generates early age cracking due to thermal and autogenous shrinkage. Autogenous shrinkage occurs as a result of internal moisture depletion due to hydration and temperature-induced effects. The level of autogenous shrinkage occurring due to hydration also depends on temperature history at very early age. It is necessary that effect of temperature on autogenous shrinkage is investigated since the stress generated due to autogenous shrinkage is quantified. In this study, Effect of hydration heat evolution on autogenous shrinkage of high strength concretes with W/C=25-40% was investigated.

• Magazine of the Korea Concrete Institute
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• v.7 no.6
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• pp.176-185
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• 1995

The heat generation of hydration of cement causes the internal temperature rise and volum& change at early age, particularly in massive concrete structures. As the results of the temperature rise and external restraint conditions, the thermal stress may induce cracks in concrete. Therefore, various techniques of the thermal stress control of the mass concrete have been wid'dy used. One of them is pipecooling which reduces the temperature of concrete with flowing water. The objective of this paper' is to develop a finite element program which is capable of simulating the temperature history considering pipe-cooling effect. The numerical results in this study are in good agreement with experimental data measured in the footing(l1 x22m). Therefore, this study may provide available method to predict the hydration temperature of concrete with pip:-cooling.