• Journal of the Korea Institute of Building Construction
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• v.12 no.5
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• pp.510-517
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• 2012

This study evaluated the recycling potential of in-site waste soil as pile back filling material (PBFM). We performed experiments to check workability, segregation resistance, bond strength, direct shear stress test, and dynamic load test using in-site waste soil in coastal areas. We found that PBFM showed better performance than general cement paste in terms of workability, segregation resistance, and bond strength. On the other hand, the structural performance of PBFM was slightly lower than that of general cement paste due to the skin friction force of pile by Pile Driving Analyzer and direct shear stress. However, because this type of performance degradation in terms of structure can be improved through the use of piles with larger diameter or by changing the type of pile, considering the economics and environment, we considered that recycling of PBFM has sufficient value.

• KIEAE Journal
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• v.13 no.2
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• pp.33-38
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• 2013

Limited resources for construction material in the Mae-Hae region, a remote Northern Thailand, acted as an impetus to introduce a new way for constructing their dwellings. The new construction material brought new construction methodology, namely, using earth and bamboo which are indigenous materials, readily available for them to use. Using indigenous material at Mae-Hae region was most ecological and logical method for establishing sustainable dwellings both in terms of monetary and ecological reasons. Prior to the construction at Mae-Hae, Thailand, series of experimental tests on the strength of rammed earth were performed off site at our university and also brought soil samples from the actual job site at Mae-Hae for detailed soil analysis. Through the tests, integrity of the earth and characteristics of the soil were established to build a small senior citizen center as an example. This appropriate technology is expected to contribute to the sustainable construction at Mae-Hae.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2006.05a
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• pp.155-158
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• 2006

Deduction of compressive strength in concrete members is very important to decide stability of structures. In this study, we compare the compressive strength of concrete between nondestructive test done to the building which was to be demolished at residential reconstruction site and destructive test of core specimen from the site. The result is more reliable because ore can compare the measurement of nondestructive tell with the result from destructive test using drilled cores. Compressive strength of each material was calculated with the result of rebound number test. In addition, we performed ultrasonic test for another result of compressive strength. And we made a comparative study of compressive strength of concrete drawn from both nondestructive and destructive tests.

• Journal of the Korea Concrete Institute
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• v.23 no.4
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• pp.421-430
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• 2011

As a fundamental study to introduce the reliability-based design code, a statistical study is conducted for the material strength data collected from domestic construction sites. In order to develop a rational design code based on statistics and reliability theory, it is essential to obtain the statistical properties of material strength. Material strength data for concrete, reinforcing bars, and prestressing strands which are used in domestic construction sites are collected and statistically analyzed. Then, the statistical properties are compared with those used in the process of the reliability-based calibration of internationally leading design codes. The statistical properties of the domestic data are such that the bias factor is relatively uniform between 1.13 and 1.20 and the coefficient of variation is below 0.10. Reinforcing bar data show difference among different manufacturers but there is not much difference among re-bar diameters. In the case of tendons, which are high strength materials, both of the domestic and foreign data show smaller values of the bias factor and the coefficient of variation than those of concrete and re-bar. Statistical distribution of all the material strength can be properly assumed as normal, log-normal, or Gumbel distribution after analyzing the classified data by individual construction site and manufacturer rather than the mixed data obtained from different sources in order to express the individual distribution of each structure.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.160-163
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• 2004

In domestic, various repair materials and method systems to keep up with these reinforced concrete deteriorated due to salt damage, carbonation, chemical decay et. developed and applied. However, on-site quality control of various repair materials and method systems isn't achieved desirably because it is depend completely on a men of experience' opinions above all else regardless of various on-site environments. In this background, mock up test with due regard to real on-site environments was performed to secure fundamental data for establishment of desirable on-site quality control. Mock up test using repair mortar analyzed from angles of construction methods, mechanical spraying pressures, W/M. Construction methods were designed manpower method and spraying method, spraying pressures were designed 32, 42, 52 psi, W/M were designed 14.4, 15.4, $16.4\%$. And compressive strength, Chloride ion diffusion coefficient, bond strength, SEM. of mock up test specimens were evaluated. In conclusion, we confirmed excellency of mechanical spraying pressures, fined extremely excellency of condition of spraying pressure 42 ps, W/M $14.4\%$ within this study. therefore the results of this study will be useful to provide fundamental data for establishment of desirable on-site quality control.

• Magazine of RCR
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• v.16 no.3
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• pp.39-44
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• 2021

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2008.04a
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• pp.399-404
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• 2008

The objective of this study is to develop the predicting method of concrete strength when remove concrete form-work without making cement test piece at construction site. For this purpose, this study catches the Maturity Method by using RFID, the usability of which is now being emphasized at site, accumulates and record the strength data, which can be gained with the results of existing Maturity Method method that is accompanied with strength estimation study, in database, and finally proposes the system structure which can check the estimated strength by Maturity Method. The merits of this method by using of Maturity Method are as follows; More objective, precise, and rapid decision can be made to the concrete strength and about the maintaining period of concrete form and form support. More efficient control of integrated material management system can be possible. Architectural field example using RFID can be suggested more concretely. RFID applicability can be extended by using DB of material integration management system.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04b
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• pp.719-724
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• 1998

It is proposed in this paper to develop the rational mix design system of High-strength concrete which is adjusted in the domestic circumstances. 1) Collect a lots of data in order to introduce the optimum mix design which has relation among material variables which compose High-strength concrete and run by using SAS (Statistical analysis system) which is one of multivariate statistical analysis method. 2) Select the important material variables for mix design of High-strength concrete by major component analysis and propose the standard range of each material variable along the target strengths. From the results of this study, it was proposed the range of proper material variables in domestic circumstance, which are W/C, S/A, air and admixture amounts, etc, at the target strengths for concrete kind. Also it was developed the optimum mix design program of High-strength concrete according to target strength and size of aggregate and made mix design ease in domestic construction site.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.05b
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• pp.63-66
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• 2011

The aim of this study is to estimate the field applicability of PBFM to replace in-site soil with pile backfill used to replace the existing cement paste. As results, the flowability, segregation and bleeding, and bond strength of PBFM was a good performance than that of the existing cement paste. But the skin friction of pile by Pile Driving Analyzer (PDA) and compressive strength was slightly decreased than that of the existing cement paste. However, as pile backfill materials, and in terms of economics and environment, the applicability of PBFM is considered very effective.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.1017-1024
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• 2009

In the past few decades, the rockfill embankment dam, which has superior workability and economy, has become a major trend. In Korea, most of the embankment dams are rockfill dams, but recently, in response to the demand for sustainable development and environmentally-friendly water resource development, the sand and gravel in streams has become a major construction material for dams, rather than the non-economic rockfill, and its application examples have also increased. In this study, a large triaxial test was performed, with construction samples of different maximum sizes, in parallel with the grading method at the 'B Dam' construction site in Korea, and the effects of the different maximum sizes on the strain of the dam construction material and on the shear strength characteristics were analyzed to provide the basic data for determining the strength characteristics of the coarse-grained materials by the maximum size.