• Journal of the Korea Concrete Institute
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• v.19 no.3
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• pp.377-383
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• 2007

In recent years the field application of high performance concrete has been increased to improve the quality and reliability of concrete structures. The mix design of the high performance concrete includes the 2 set-off mixture theory of mortar and coarse aggregate and that of paste and aggregate. The 2 set-off mixture theory of mortar and coarse aggregate has a problem of having to determine its value through repeated experiments in applying the rheological characteristics of mortar. The 2 set-off mixture theory of paste and aggregate has never been applied to high performance concrete since it doesn't take into account the relationship between optimum fine aggregate ratio and unit volume of powder nor does it consider the critical aggregate volume ratio. As the mixture theory of these high performance concretes, unlike that of general concrete, focuses on flowability and charge-ability, it does not consider intensity features in mix design also, the unit quantity of the materials used is determined by trial and error method in the same way as general concrete. This study is designed to reduce the frequency of trial and error by accurately calculating the optimum fine aggregate ratio, which makes it possible to minimize the aperture of aggregate in use by introducing the maximum density theory to the mix design of high performance concrete. Also, it is intended to propose a simple and reasonable mix design for high performance concrete meeting the requirements for both intensity and flowability. The mix design proposed in this study may reduce trial and error and conveniently produce high performance concrete which has self-chargeability by using more than the minimum unit volume of powder and optimum fine aggregate with minimum porosity.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.549-554
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• 2002

In Powder System, SCC demands high dosage of superplasticizer and a lage amout of powder for suitable fluidity and viscosity. Okamura's method of most representative mixing design method in SCC of Powder-System is unfavorable economically because of using a large amount of powder. In addition, many ready-mixed concrete plants do not use his mix design method and procedure due to complexity for practical application. Therefore, Nan Su proposed more simple mix design method than Okamura's. It had an advantage in simplicity in practical application and required a smaller amount of powders compared with Okamura's method. This paper proposed an optimal mixture proportion of SCC with consideration of Nan Su's method. The new and modified mix design method required a smaller amount of powder than that of Nan Su's. To check the properties of SCC, considered with the requirements specified by the Japanese Society of Civil Engineering.(JSCE)

• Proceedings of the Korean Institute of Building Construction Conference
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• 2001.11a
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• pp.40-45
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• 2001

The purposes of this study were mix design and quality control of high strength concrete for the construction of high rise complex structure. Desired performances of this high strength concrete were slump flow 50$\pm$10cm, air content 4.5$\pm$1.5% and design strength 400kgf/$cm^2$. Experimental flow was that optimal mix design was selected in the indoor experiment and after that, producing test was done in the batcher plant. Excel lent results of experiment was obtained from binder content 475kg/$m^2$ with replacement ratio 10% of fly ash. The results of field application of high strength concrete was sufficiently satisfied both flowability and compressive strength.

• Journal of the Korean housing association
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• v.25 no.6
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• pp.27-37
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• 2014

The purpose of this study was to identify the perception on social mix of managers and residents in the mixed housing complexes for sale and rental apartment. For the research purpose, concept and background of social mix, relevant policies, preceding research trend of social mix were organized through the literature analysis. In addition, observation study was executed to examine physical aspects of three selected sites as research subjects. Also, current state and awareness for social mix were conducted by using in-depth interview with 6 managers and 30 residents in selected areas with semi-structured questionnaires from June 3 to 7, 2013. The results of the study are as following: In the aspect of management, managers said that the biggest issue of mix-housing complex was dualization of management subject such as delegate of residents and tenants. Therefore, legislation which is suitable for unique features of mix-housing complex is required. To decrease disharmony between condominium and rental apartment, controlling the distribution ratio between condominium and rental apartment can be a good way. Accommodating middle class in mixed-housing complex is considered to reduce the social gap. Socially, multilateral and continuous effort through government, industry and academic area is required to inspire positive awareness on social mix among residents in mixed housing complex.

• Proceedings of the Korea Concrete Institute Conference
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• 1994.10a
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• pp.115-120
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• 1994

Recently super-flowing concrete has been developed and used in many construction sites in Japan. It is believed that super-flowing concrete will change the construction method and contribute to the durability of concrete structures. In this study the effect of mix proportion on the flowing characteristics of super-flowing concrete was investigated to establish the mix design method. From the result we have found that self-compactability of super-flowing concrete was greatly affected by the unit gravel volume and paste/gravel volume ratio. Therefore the two parameters can be used in mix design of super flowing concrete.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.6A
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• pp.561-572
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• 2010

This paper is a study about application of recently proposed Performance Based Mixture Design (PBMD) for design of high strength concrete (HSC) to obtain HSC mix proportion that satisfies required performances. The PBMD method which uses Satisfaction curve based on a Bayesian method is a performance oriented concrete mix proportion design procedure easily applicable to any condition and environment for a possible replacement to the current prescriptive design standards. Based on extensive experimental results obtained for various materials and performance parameters of HSC, the application feasibility of the developed PBMD procedure for HSC has been verified. Also, the proposed PBMD procedure has been used to perform application examples to obtain desired target performances of HSC with optimum concrete mixture proportions using locally available materials, local environmental conditions, and available concrete production technologies. The validity and precision of HSC mix proportion design obtained using the PBMD method is verified with the experimental and ACI presented results to check the feasibility for actual design usage.

• 한국도로학회:학술대회논문집
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• 2004.10a
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• pp.53-60
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• 2004

• 한국도로학회:학술대회논문집
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• 2003.10a
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• pp.249-254
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• 2003

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.10
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• pp.4832-4836
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• 2012

In general, there are needed lots of time and experiments for determination of optimum asphalt content and mix design. The experimental results are highly depended on the skill of testers. Bailey suggested the proper aggregate gradation of hot mix asphalt are a function of special size and passing percent of the specified aggregate to reduce the test errors. In this paper, the asphalt mix designs of 19mm dense graded mix and PA-20mm for FHWA were carried out, using Bailey's method. The use of Bailey method can cut down the testing times to get the proper aggregate gradation for asphalt mix design. In case of 19mm dense graded asphalt mixture, the measured values of CA, $FA_c$, $FA_f$ are 0.724, 0.440, and 0.455, which are within the suggested values by Bailey. Also, in case of PA-20 graded asphalt mixture, the measured values of CA, $FA_c$, $FA_f$ are 0.646, 0.476, and 0.450, respectively.

• International Journal of Highway Engineering
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• v.19 no.2
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• pp.75-85
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• 2017

PURPOSES : The purpose of this study was to determine the optimum mix design of the content of 100 % reclaimed asphalt pavement (RAP) for spray injection application with different binder types. METHODS : Literature review revealed that spray injection method is the one of the efficient and economical methods for repairing a small defective area on an asphalt pavement. The Rapid-Setting Polymer modified asphalt mixtures using two types of rapid setting polymers-asphalt emulsion and a quick setting polymer asphalt emulsion-were subjected to the following tests to determine optimum mix designs and for performance comparison: 1) Marshall stability test, 2) Retained stability test, 3) Wet track abrasion test, and 4) Dynamic stability test. RESULTS and CONCLUSIONS : Type A, B, and C emulsions were tested with different mix designs using RAP aggregates, to compare the performances and determine the optimum mix design. Performance of mixtures with Type A emulsion exceeded that of mixtures with Type B and C emulsion in all aspects. In particular, Type A binder demonstrated the highest performance for WTAT at low temperature. It demonstrated the practicality of using Type A mixture during the cold season. Furthers studies are to be performed to verify the optimum mix design for machine application. Differences in optimum mix designs for machine application and lab application will be corrected through field tests.