• 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.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.163-166
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• 1999

In this paper, strength development of concrete using blast-furnace slag cement(BSC) and ordinary portland cement(OPC) are discussed under varius W/C and curing temperatures. According to the experimental results, strength development of BSC concrete is lower than that of OPC concrete in low temperature at early age and maturity. In high curing temperature, BSC concrete has higher strength development than that of low temperature regardless of the elapse of age and maturity. BSC has much effect on the strength development of concrete at the condition of mass concrete, hot weather concreting and the concrete products with the steam curing, which is influenced by high temperature.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2002.11a
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• pp.63-66
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• 2002

In this study, it does a high volume flyash substituted concrete experiments in two curing temperature circumstances - 35$^{\circ}C$, 2$0^{\circ}C$. High volume flyash concrete is tested in fresh concrete properties and hardeded concrete properties. In the fresh concrete test items, there is slump, air contents, concrete setting tests. 3, 7, and 28 days water curing compressive strength is measured in the hardened concrete test. The purpose of this study is to submit a various flyash concrete data for application to field. The result of this study is that the best strength is developed at the plain concrete cured 2$0^{\circ}C$ and Mixing F43 shows the best strength among specimens which cured at 35$^{\circ}C$

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.131-132
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• 2021

According to the domestic specification, the curing of the specimen for strength management used to determine the time of the mold deformity of the structure concrete in early spring and early autumn is cured in the field structure condition. However, when the seal curing is performed in the field, the temperature of the specimen is very low compared to the temperature of the actual structure, so the strength of the structure concrete predicted based on the strength of the specimen is much undervalued than the actual one, which causes the mold to be deformed. Therefore, this study analyzed the temperature history and compressive strength characteristics of the specimen for strength management through other sealing curing at 5℃ and concrete of the actual structure, and presented the most suitable curing method.

• Magazine of the Korean Society of Agricultural Engineers
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• v.44 no.2
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• pp.99-106
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• 2002

This study is performed to examine pH reduction by neutralization treatment and curing condition of porous concrete using rice straw ash for planting. Test results show that pH of porous concrete without neutralization treatment in the dry and water curing is 10.34 ∼ 10.57 and 9.42 ∼ 9.72, respectively. pH of porous concrete by neutralization treatment in the dry and water curing is 9.72 ∼ 10.03 and 9.00 ∼ 9.37, respectively. Accordingly, the best method for pH reduction of porous concrete for planting is to use water curing and neutralization treatment.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.273-274
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• 2009

The curing method used on domestic sites for checking the concrete compressive strength of a structure. 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 the curing method suggested in this research, which sets the internal conditions of the structural specimens as the conditions of the applied curing method. this thesis suggests the specimen curing method that most closely re-enacts the compressive strength of the concrete used on the structural specimens

• Journal of the Korea Institute of Building Construction
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• v.7 no.1 s.23
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• pp.91-98
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• 2007

In this study, the property and plastic cracking pattern of concrete were compared and analyzed with the replacement ratio of fly ash 0, 5, 10, 15, 20% by cement weight. And curing conditions of concrete were given variously such as indoors(with wind speed as 0, 300, 500m/min), outdoors and chamber. The hydration temperature had a tendency to decrease as the replacement ratio of fly ash increased, and in the case of the wind speed 0m/min, it was showed that the moment that the amount of evaporation of water from surface of reference concrete was more than the volume of bleeding was 90 min since casting concrete. The time that the crack initiated had a tendency to be more quickly as the replacement ratio of fly ash increased. The number, length, width and area of crack in the indoor curing, exposed outdoor curing, enclosed outdoor curing had a tendency to decrease as the replacement ratio of fly ash increased. The crack had a tendency to decrease in sequence of exposed outdoor, enclosed outdoor curing, indoors curing. The outbreak of cracking by the change of temperature and humidity was affected by relative humidity more than temperature and the cracking had a tendency to increase as relative humidity lowered.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.04a
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• pp.239-240
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• 2022

In winter, low outdoor temperature can casue reduction of concrete strength. Therefore, thermal protection is required when curing concrete in winter to maintain a certain level or higher surface temperature. Accordingly, in domestic construction sites, a curing method in which surrounds casting areas by tents and operates hot air blowers are widely applied. However, local low-temperature areas may occur due to airtightness of the curing tents. If additional heat is supplied to prevent occurrence of local low-temperature areas, energy consumption increases. Therefore in this study, a plan for improvement method of concrete curing was considered and the performance was evaluated through numerical analysis. A plan to improve the airtightness of the wall opening was applied, but the analysis showed that if only a part of the curing area is shielded, the temperature of the unshielded area decreases,making it inappropriate to improve curing performance.

• Tunnel and Underground Space
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• v.4 no.1
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• pp.31-37
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• 1994

The effects of blasting and ground vibratons on curing concrete have not been well studied. As a results unrealistic and costly ground vibration constraints have been placed on blasting and piling when it occurs in the vicinity of curing concrete. To study the effects of ground vibrations, a shaking table was made to produce peak particle velocities in the nearly same frequency range as found in construction blasting. Concrete blocks of 33.3X27.7X16.2cm were molded and placed on the shaking table. Different sets of concrete blocks were subjected to peak vibrations of 0.25, 0.5, 1.0, 5.0 and 10cm/sec. The impulses were applied at two hour intervals for thirty seconds. Along with unvibrated concrete blocks, the vibrated concrete samples with 60.3mm in diameters were measured for elastic moduli, sonic velocity, tensile and uniaxial compressive strength. Test results showed that the vibrations in curing concrete generally have effects on the uniaxial compressive strength or physical properties of the concrete.

• Advances in concrete construction
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• v.11 no.4
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• pp.347-356
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• 2021

To address the limitation of the commonly used steam curing of reactive powder concrete (SC-RPC) in engineering, a preparation technology of normal curing reactive powder concrete (NC-RPC) is proposed. In this study, an experimental comparative research on the mechanical properties of NC-RPC and SC-RPC under uniaxial tension is conducted. Under the premise of giving full play to the ultra-high performance of RPC, the paper tries to explore whether normal curing can replace steam curing. The results show that various mechanical indexes of NC-RPC (e.g., tensile strength, ultimate tensile strain, elastic modulus and deformation performance) could basically reach the mechanical index values in steam curing at 28d age, some performance is even better at a longer age. So it affirms the feasibility of normal curing. In this paper, the influence of normal curing age on the tensile properties of RPC is discussed, and the relationship between each index and age is introduced in detail. Based on the experimental data, the tensile mechanism of RPC is analyzed theoretically, and two kinds of tensile constitutive models for RPC are proposed, one is curvilinear model, and another one is polygonal line model. The validity of the two models is further verified by the test results of others.