• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.11a
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• pp.27-28
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• 2019

In this study, the characteristics of compressive strength of ultra high strength concrete supplied with moisture from outside by vacuum water absorbing curing method were investigated. Specimens were prepared by replacing the binder(Silifa fume and GGBS) by 25 wt% with respect to the weight of cement at W/B 0.16. Each specimen was subjected to water Vacuum absorbing curing time 0 min, 30 min, 60 min, 90 min and 120 minutes immediately after the demolding. Curing was performed at $20^{\circ}C$ Air-dry curing, $90^{\circ}C$ steam curing, $90^{\circ}C$ steam curing and $180^{\circ}C$ autoclave curing. Experimental results showed that water absorbing degree increased with increasing water absorbing curing time, and BS25 sample had higher water absorbing degree than SF25 sample at same time. Compressive strength tended to increase up to about 40% in water absorbing degree, but compressive strength decreased again in water absorbing more than 40%.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.11a
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• pp.107-108
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• 2017

The purpose of this study is to derive the optimum water absorbing curing time. It was found that the cement paste compressive strength was increased with the water absorbing ratio up to 40%, but the compressive strength was slightly lower when the catch level was over 50%. It is considered that the superfluous water did not react and remained in the inside of the specimen, causing microcracks in the inside due to the high temperature curing, resulting in a decrease in strength. Therefore, it is considered that the optimum catcher curing time for improving the strength through catcher curing is when the catcher reaches 40%.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.2
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• pp.50-59
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• 2020

Superabsorbent Polymer (SAP) expands inside concrete by absorbing water and contracts as it discharges water. Through this process, concrete can achieve the internal curing effect, but the space occupied by the expanded SAP remains as a void. In this study, the effects of SAP internal curing and voids were evaluated by evaluating the fundamental properties and chloride penetration resistance of SAP mixed concrete. Also, to evaluate the internal curing effect by SAP, the tests were carried out under water and sealed curing conditions, respectively. From the result, the compressive strength of water curing did not differ significantly according to the mixing ratio of SAP. In the case of sealed curing, however, the compressive strength tended to increase as the mixing ratio of SAP increased. The internal curing effect of sealed curing was considered to have influenced the increase in compressive strength. In the case of the chloride diffusion coefficient, the diffusion coefficient tended to decrease as the mixing ratio of SAP increased. In particular, as the sealed curing is applied, the chloride penetration resistance is further improved due to internal curing effect. If the curing conditions are different, it is considered inappropriate to estimate the chloride penetration resistance by the surface electrical resistivity.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.2
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• pp.49-56
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• 2018

The use of highly absorptive materials in cement-based materials is increasing for internal curing purpose. However, calculation of correct absorption capacity of such materials is not easy, which leads to change in the effective water-to-cement ratio of cement paste by either absorbing or releasing water. In this study, effective absorption capacity of a highly absorptive material was found using isothermal calorimetry. Moreover, the effect of specific surface area was investigated. It was found that the method was capable of finding effective water absorption capacity of activated carbon fiber. For the activated carbon fiber used in this research, the effect of specific surface area was negligible because the high BET surface area was due to micropores less than 1nm, which does not affect the rate of hydration curve. Thus, the effective absorption capacity of such materials can be found successfully using this method.