• Journal of the Korean Society of Safety
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• v.31 no.5
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• pp.109-116
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• 2016

This study presents the results of experiments to investigate the effect of polymer type and curing temperature on the mechanical properties of polymer mortar. Setting time of two types of polymers, hardening-delayed polymer(HDP) and rapid hardening polymer(RHP), was tested to check the working time. Additionally, flexural strength, compressive strength, and splitting tensile strength was investigated for mortars using these polymers. From these results, it was confirmed that, irrespective to curing temperature, RHP mortar at the curing age of 24h develops the similar mechanical properties to maximum properties and HDP mortar is more sensitive to the curing temperature. In addition, it should be noted that RHP mortar and HDP mortar are suitable in winter and summer, respectively.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2008.05a
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• pp.57-60
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• 2008

This study investigated the results of insulation heat curing method using double layer bubble sheet in slab concrete and mass concrete in cold weather environment. First of all, when double bubble sheets are applied, it was shown that slab concrete was protected from early freezing by remaining between 6 and 15℃ even in case outside temperature drops -9℃ below zero until the 2nd day from piling, and in the case of mass concrete, with the maximum temperature difference between the center and surface less than 4℃, crack occurrence index was close to 2 and no hydration heat crack occurred by internal constraint. The insulation heat preservation curing method using the double bubble sheet applied in this field prevented early freezing owing to stable curing temperature management, deterring concrete strength development delay at low temperature, and obtained the needed strength. Also, it was proven that the method is highly effective and economic for cold weather concrete quality maintenance through curing cost reduction like construction period shortening and labor cost reduction, etc by reducing the process of temporary equipment installation and disassembling.

• Journal of the Korean Society of Tobacco Science
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• v.20 no.2
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• pp.160-165
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• 1998

The Joint curing barns for flue-cured tobacco is a favorite with the tobacco farmers in Korea. However, most of farmer utilizing the joint curing barns indicated many problems such as high temperature and noise in the working room and a dry of cured leaves in the storage room. A structure of Joint curing barns has been modified to meet the needs of tobacco farmers. Compared with the unimproved joint curing barns, the improved one showed that the noise of workshop decreased about 7.7～10.8db, the amount of $CO_2$ decreased 40～50ppm in a working room and 80～100ppm in a machine room. Ammonia gas decreased 0.29mg/㎥ and the temperature of a working room dropped about 2.1～3.5$^{\circ}C$. The amount of air flow in a working room increased 23.2% at a site being 2m away from the entrance and 30.8% at a center. The inner temperature of the improved storage room showed that maximum temperature dropped about 3$^{\circ}C$, minimum temperature was high about 2$^{\circ}C$. The highest relative humidity was low 6%, the lowest one increased high about 10% when compared with the unimproved joint curing barns.

• Elastomers and Composites
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• v.52 no.4
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• pp.266-271
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• 2017

This study describes the influence of the amount of curing agent and curing temperature on the kinetics of polyurethane elastomers. The urethane prepolymer series was prepared by reacting toluene diisocyanate with polytetramethylene ether glycol at $80^{\circ}C$ for 1 h, and 4,4'-methylene bis(2-chloroaniline) was used as the curing agent. The ratio of the amine group of the curing agent to the isocyanate group of the urethane prepolymer was controlled from 0.85 to 1.05 at curing temperatures ranging from 80 to $120^{\circ}C$. The curing rate of the urethane prepolymer was monitored by observing the change in heat flow during the curing process using differential scanning calorimetry (DSC). As either the content of curing agent or the curing temperature was higher, the conversion rate to the polyurethane elastomer was high. The DSC results were compared with those obtained from using real-time FT-IR.

• Korean Journal of Food Science and Technology
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• v.28 no.3
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• pp.458-463
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• 1996

Fresh ginger harvested in Seosan, Choongchengnam-do, was used to investigate the pretreatment effect before long-term storage. Wounded ginger were cured at the temperature of 25, 30, $35^{\circ}C$ and the RH 83 and 93% for 1, 3, 5, 7 days, respectively Then the cured ginger were stored in the laboratory scale storage room ($12^{\circ}C,$ 95% RH) in order to find out the optimum curing condition. At a constant temperature and a RH. the longer ginger were cured, the more their weight was decreased; at a constant temperature and a curing period, the higher RH was, the less weight was lost. During the curing process, sprouting rate was accelerated at temperature higher than $30^{\circ}C$ and humidity higher than 90%; mold growing was observed at any temperature and humidity, but especially at $35^{\circ}C$ the rate was relatively faster when the curing time was increased. Hardness of wound surface cured at 93% RH was relatively higher than those cured at 83% RH at all temperatures. The weight loss of store ginger after curing was $2.0{\sim}8.2$ after 30 days and $7.2{\sim}14.2%$ after 60 days storage. Compared with all results through a screening procedure, the condition of 3-days curing at $25^{\circ}C$ and 93% RH showed th best result for minimizing quality changes during storage.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.4
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• pp.127-133
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• 2012

In this paper, tests were carried out to monitor the effect of the curing temperature on autogenous shrinkage of the high strength cement mortar incorporating silica fume, blast furnace slag and fly ash ranged from 10%~30% by mass of cement. The curing temperatures were varied from $5^{\circ}C$ to $35^{\circ}C$, respectively. According to results, the setting time exhibited to delay with increase of admixture and drop of temperature. As for the effect of curing temperature on autogenous shrinkage, the increase of SF and BS resulted in an increase of autogenous shrinkage, while the use of FA decrease. The higher the curing temperature is, the greater the autogenous shrinkage is. This is due to the accelerated hydration rate of cement. It is found that the maturity does not consider the effect of curing temperature on autogenous shrinkage.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.11a
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• pp.175-176
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• 2022

By studying the characteristics of matrix insulated through heat generated through oxidation of iron powder, the basic research results on the possibility of buffering and applicability of Cold weather concrete as a curing method are presented. In order to prevent freezing due to a sharp decrease in temperature in the initial stage of curing, iron powder (Fe), powder activated carbon, which is a small amount of porous carbonaceous adsorbent, and salt (NaCl) as an oxidizing agent are replaced with iron powder admixture. As the curing temperature increases, the strength tends to increase, and when replacing the admixture at the same curing temperature, the strength slightly decreases. This is determined as a result of generating iron oxide through an oxidation reaction of iron powder, activated carbon, and NaCl generating a large amount of pores in the matrix. In addition, the internal temperature tends to increase as the mixing substitution rate increases, and it is judged that the oxidation heat of the iron powder mixture affects the increase of the internal temperature during curing. The higher the replacement rate of the iron powder mixture, the slightly lower the strength, but it is determined that freezing and melting that may occur in the early stage of curing can be prevented due to an increase in the initial internal temperature.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2007.04a
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• pp.1-4
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• 2007

This study investigated the applicability of insulation curing method with double layer bubble sheets to the man concrete subjected to cold weather. Temperature history of the mass concrete indicated that the highest temperature of center section was exhibited at $34^{\circ}C$ while the that of surface section was $25^{\circ}C$. Difference between center and surface was shown to be less $10^{\circ}C$ when the temperature of center section was peak section, and thereby associated temperature cracking index was calculated 1.5, and occurrence probability of temperature cracking was 5%, so there was no temperature cracking caused by internal restraint. No temperature crack was observed by naked eye. It was clear that early frost demage and temperature cracking could be restrained due to reducing temperature difference between inner part and outside in the case double bubble sheets applied to insulation curing method in cold weather. The maturity of mass concrete is higher than outside about $72\sim89^{\circ}$ DD, so it was demonstrated to prevent early frost demage and ensure strength excellently. Insulation curing method with double bubble sheets was more economic than heating curing method.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.04a
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• pp.107-111
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• 1996

The testing specimens were made from the standard mix proportion according to those of domestic PC factories to establish a basic data for the Accelerated Curing Effect. The experimental tests were conducted according to the conditions of each sub-curing periods. By comparing the results of compression tests on de-molded and 28-day water-curing specimens, we find that the most effective curing condition to obtain more than the required design strength after 28 days of water curing may be as follwings; the presteaming period does not affect seriously and less than $30^{\circ}C$/hr-the rate of temperature rise and less than $82^{\circ}C$ - maximum temperature are necessary. It seems that post-curing procedure is very important factor to increase the effect of accelerated curing.

• Proceedings of the Korean Institute of Building Construction Conference
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• v.y2004m10
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• pp.11-14
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• 2004

The object of this study is vibrating compaction and curing method in the production process of Design concrete for precast concrete(Design-PC) product. From change of vibrating compaction time and pre-curing time. curing temperature which would be factors of product quality in Design-PC concrete production. and research of optimized steam curing condition from relations between curing condition and strength development. basic data of vibrating compaction time and concrete steam curing method for Design-PC will be presented.