• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.4
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• pp.358-366
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• 2019

The purpose of this study is to explore the possibility of estimating optimum surface finishing work time of the fresh concrete placed at the job site by applying a surface hardness test meter(Durometer). Tests are carried out by measuring and comparing the Proctor penetration resistance test and hardness test by Durometer. Correlations between Procter penetration test and hardness test by Durometer were obtained. Two different types Durometer were applied to estimate setting time. Test results indicate that the measurement of the Durometer and the test of the Proctor penetration resistance are highly correlated. When measuring the initial setting time with Durometer, initial setting time is reached when the hardness value by the type C Durometer is reached around 42HD, and when final setting is measured with the type D Durometer, the surface finishing work time limit and curing time can be estimated with 10HD of Durometer.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.1
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• pp.33-38
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• 2020

The aim of the research is to evaluate the feasibility of durometer for assessing setting time of the concrete by comparing it with the currently used proctor penetration test method to improve the surface finishing timing determining method generally determined based on the experience of the worker. As a research result, the correlation between suggesting method using durometer with currently used proctor penetration test method was high enough. Hence, on the surface of the concrete, the initial setting time and the final setting time could be designated as 41 HD with C-type, and 11 HD with D-type, respectively. Therefore, the durometer can be used as a portable setting time evaluation device with the easiness of handling and measuring for determining concrete surface finishing timing quantitatively.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.11a
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• pp.118-119
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• 2019

In this study, we compared the proctor penetration resistance test value of the concrete using CGS for Fine Aggregate and the hardness value of the Durometer. The results are summarized as follows. 1) Surface finish The Durometer C type setting time measurement value was about 45 HD, and the hardness value of the Durometer D type was about 5HD. 2) The proctor penetration resistance test value and the hardness value of the Durometer are highly correlated and are expected to be easy to use.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.11a
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• pp.81-82
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• 2019

In this study, the Proctor penetration resistance test value and the hardness value of the improved Durometer were compared and analyzed for the change in the FA replacement rate of the concrete using CGS fine aggregate. The results are summarized as follows. It is. 1) The Proctor penetration resistance test value and the hardness value of the improved Durometer showed a high correlation in the form of a curve. 2) About surface finish Super-resolution with the improved Durometer is considered to be useful when using about 50 HD and about 80 HD in the end to determine the surface finishing work time.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.11a
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• pp.116-117
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• 2019

In this research, Proctor insertion resistance test values and Durometer A type hardness values were compared and analyzed between the setting times of the concrete using CGS for Fine Aggregate, and the results are summarized as follows. 1) The Proctor penetration resistance test value and the hardness value of Durometer A type showed a high correlation in the form of a curve. 2) About surface finish The resolution exceeding the hardness value of the Durometer A type uses about 25 HD, and in the case of termination, about 35 HD, and is considered to be effective for determining the surface finishing work time. The possibility to do is expected.

• Journal of the Korea Institute of Building Construction
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• v.20 no.5
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• pp.433-440
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• 2020

In this study, a new type of Durometer was invented by modifying the currently used Durometer with the hemisphere shaped needle to columnar shaped needle. The aim of the study is, hence, to provide the feasibility of the advanced Durometer for assessing setting time of the concrete. Generally, the finishing of concrete surface should be conducted to secure the smooth surface, improve the permeability, and prevent the plastic shrinkage cracking. Although this surface finishing work should be conducted during the plastic phase between initial and final setting, currently in practical situations, the timing of starting the finishing work was determined by the sense of the worker. To improve this situation, Kato Junji suggested to use the hemisphere and needle shaped Durometers to determine the initial and final setting time, respectively. However, in this case, there are difficulties of using two different Durometers and of occurring failure of the Durometer due to the intruded cement paste. To prove the feasibility of new typed Durometer, setting time and surface hardness were evaluated by applying for the concrete with various replacing ratios of fly-ash and coal gasification slag as an aggregate.