• Computers and Concrete
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• v.21 no.4
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• pp.367-376
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• 2018

This study reports the results of nondestructive monitoring of macro void developments in mortars manufactured with both ordinary Portland cement and sulfate resistant cement. Two types of curing were utilized; tap water curing and another curing environment that contains 5% $Na_2(SO_4)$ solution. Being the primary objective of this study, macro void developments of the mortar specimens were monitored by X-ray Medical Computerized Tomography. Compressive strength tests and water absorption tests were conducted on specimens that were kept in both curing environments for a duration of 560 days. Data analyses yielded consistent results among the three tests used in this experimental study. Macro void ratios of mortars decreased at the beginning of experiments for a certain period; afterwards, macro void ratios increased. The objective of this study was accomplished as anticipated since X-CT image analysis was able to nondestructively monitor macro void development process in cement mortars.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.681-684
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• 2008

The way to shorten a construction period is considered to an very important technology element as reducing the form work removal periods with promoting strength revelation own concrete. This study presents an experimental study on the development method, material for early strength concrete. The result is as follow : In OPC, the compressive strength has over 5MPa after 26hours at 20$^{\circ}C$ curing and another 36hours at 10$^{\circ}C$ curing. Used with early strength potland cement, the compressive strength has over 5MPa after 15hours at 20$^{\circ}C$ curing temperature and another 30hours at 10$^{\circ}C$ curing temperature.

• The Korean Journal of Food And Nutrition
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• v.12 no.4
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• pp.370-374
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• 1999

This study was carried out to some properties and curring effect of drip obtained from frozen-thawed park loin ham belly and imported belly by thawing process at 4$^{\circ}C$. Moisture content and pH value of drips were 88.05~90.85% and 5,72~6.05 and do not show significant differences between each samples. Protein contents were 11.07, 8.85, 8,76 and8,13% in the drips from domestic pork loin, ham, belly and imported belly, respectively. Approximately 99% of the drip were constituted with moisture and protein in any part of domestic pork and imported belly. Glutamic acid proline glycine, alanine and lysine were the predominant amino acid in the drips. Curing process of the drip by nitrite increased the pH value and total amino acid content. The residual nitrite decreased during the period of curing and total plate counts in drip with nitrite did not reach 1$\times$105CFU/g until 7 days.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.11a
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• pp.223-224
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• 2023

This study compared the curing temperature of the bubble sheet and the photothermal insulation sheet incorporating carbon-based photothermal materials to reduce concrete curing time as a part of shortening construction period. As a result of the experiment, bubble sheet with photothermal material B is judged to be effective in shortening the curing time under hot environment.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.965-968
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• 2008

The KS F 2403 method used on domestic sites for checking the compressive strength of a structure, sets the compressive strength of the concrete used in structural specimens as the compressive strength of testing specimens. Under this regulation, the curing method used for testing the specimens must be the standard ponding curing method (20$\pm$2$^{\circ}$C). However, because in-placed concrete is exposed to open air and cured under the seasonal temperature changes, the compressive strength of a real structure is different from the tested compressive strength. (Therefore,) This thesis first identifies the distinct characteristics of the strength development by applying the curing method listed under the KS and used for testing specimens on compressive strength tests; the atmospheric curing method, the sealed curing method, and the structural specimen core strength testing methods used for the in-sites quality checks including reckoning of the compressive strength of the structural specimens and form-demolding period; and the curing method suggested in this research, which sets the internal conditions of the structural specimens as the conditions of the applied curing method. Then, the thesis suggests the specimen curing method that most closely reenacts the compressive strength of the concrete used on the structural specimens

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.27 no.6
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• pp.295-302
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• 2017

In this study, the effect of pre-curing process on the enhancement of mechanical properties of IGCC-slag-based-geopolymer was studied. Pre-curing is a process in which the green geopolymer is left at room temperature for a certain period of time prior to the high-temperature curing, and it is known as increasing the strength of a specimen. Therefore, in this experiment, the compressive strength of the geopolymers was measured according to various pre-curing conditions, and microstructure and crystal phase changes were observed by SEM and XRD, respectively. The W/S ratio was determined to be 0.26, which can offer the maximum geopolymer strength with easy molding ability, and the concentration of the alkali solution was 15 M. Pre-curing was performed at room temperature for 0 to 27 days. Compressive strength of the geopolymer made with pre-curing process increased by 36~87 % compared with the specimens made with no pre-curing process. Those improved compressive strength for the pre-cured geopolymer was confirmed owing to promotion effect of pre-curing process on generation of C-S-H gel and zeolite phases, which were analyzed using by XRD and SEM measurement.

• Journal of the Korea Concrete Institute
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• v.17 no.2 s.86
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• pp.273-297
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• 2005

In construction site, there are some occasions where concrete under initial curing is being affected by nitration from nearby vibration sources. To study these effects, in this paper, strength characteristics of concrete specimens subjected to continuous vibration up to 12 hours in vertical direction after concrete placement were observed. And through the vibration time control experiment where a number of time combinations consisted of times before and after applying vibration during initial curing period were used as experimental parameters, possibility of concrete strength improvement was investigated. From the experimental results, it could be seen that the concrete strengths were mostly decreased due to the increase of vibration velocity during initial curing period. But fluctuation ratio of concrete strength did not have any close correlations with the vibration times. And results of vibration time control experiment showed that if times before applying vibration sustains at least more than 3 hours, subsequent vibrations after that hours do not affect the concrete strength in any unfavorable ways.

• International Journal of Highway Engineering
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• v.18 no.1
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• pp.13-21
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• 2016

PURPOSES : In this study, we analyzed the compressive strength characteristics of lean base concrete in relation to changes in the outdoor temperature after analyzing the cold and hot weather temperature standards and calculated the minimum and maximum temperatures when pouring concrete. We examined the rate of strength development of lean base concrete in relation to the temperature change and derived an appropriate analysis formula for FRC base structures by assigning the accumulated strength data and existing maturity formula. METHODS : We measured the strength changes at three curing temperatures (5, 20, and $35^{\circ}C$) by curing the concrete in a temperature range that covered the lowest temperature of the cold period, $5^{\circ}C$, to the highest temperature of the hot period, $35^{\circ}C$. We assigned the general lean concrete and FRC as test variables. A strength test was planned to measure the strength after 3, 5, 7, 14, and 28 days. RESULTS : According to the results of compressive strength tests of plain concrete and FRC in relation to curing temperature, the plain concrete had a compressive strength greater than 5 MPa at all curing temperatures on day 5 and satisfied the lean concrete standard. In the case of FRC, because the initial strength was substantially reduced as a result of a 30% substitution of fly ash, it did not satisfy the strength standard of 5 MPa when it was cured at $5^{\circ}C$ on day 7. In addition, because the fly ash in the FRC caused a Pozzolanic reaction with the progress into late age, the amount of strength development increased. In the case of a curing temperature of $20^{\circ}C$, the FRC strength was about 66% on day 3 compared with the plain concrete, but it is increased to about 77% on day 28. In the case of a curing temperature of $35^{\circ}C$, the FRC strength development rate was about 63% on day 3 compared with the plain concrete, but it increased to about 88% on day 28. CONCLUSIONS : We derived a strength analysis formula using the maturity temperatures with all the strength data and presented the point in time when it reached the base concrete standard, which was 5 MPa for each air temperature. We believe that our findings could be utilized as a reference in the construction of base concrete for a site during a cold or hot weather period.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.2
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• pp.58-64
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• 2012

Due to the influence of global oil prices, industrial productivity, which oil consumption is high, was significantly reduced. AC type of high-strength PHC piles is being manufactured through twice the steam curing process and this have resulted in a significant rise for product's manufacturing costs. NAC way other types of file manufacturing process has the advantage of reducing manufacturing costs by a turn of the steam curing. Nevertheless, because the initial strength be poor than that of AC method, shipment is being after the curing period of approximately three days. In addition, the growth of the product enhance with curing period can not be avoided, as a result, cost of inventory is acting as the rise. Piles by the AC method is immediately shipped after curing, damaging problems does not occur when they are introduced to the field site (for example, pile on-site). In the case of NAC, however, at least after the curing period of three days and after expressing the strength of 80 MPa or more, they are shipped on the scene. Therefore, NAC type has problems as follows: (1) increase in moderate inventory holding costs with type and (2) breakage in the field due to lack of strength. In this study, for NAC-typed PHC files, mixing characteristics research for the strength development at 1 day equivalent to AC method were conducted and strength characteristics with changes of original materials were evaluated were also identified.

• 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.