• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.525-528
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• 2005

This study determines the best composite grade to minimize the void of aggregate mixture based on the maximum density theory in an attempt to suggest a mix proportion method design for asphalt mixtures. Study results show that the grading curve with the maximum mass per unit capacity of each aggregate mixture satisfied the KS standards and the optimum AP content to meet the optimal asphalt mixture void rate of 4$\%$ was 5.7$\%$, less than the optimum AP content of 6.5$\%$ suggested in the Marshal mix proportion method design. At the same time, the asphalt mixture produced based upon the suggested mix proportion method had a flow value 17$\%$ lower than that of asphalt mixture produced according to the Marshal method, while its density was greater by 0.06$\～$0.09. This suggests that the introduced mix proportion method design helps to improve the shape flexibility and crack-resistance of asphalt concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 1991.04a
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• pp.29-32
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• 1991

This is the study on the performance of workability and engneering properties of flowing concrete using the superplasticizers, which are being used for control of the consistency of fresh concrete without modifying the properties of the hardened concrete and for production of high quality concrete at a low water-cement ratio. It is the aim of this study to analyze and investigate workability and engineering properties of flowing concrete according to the addition rate in poor and rich mix proportions of base concrete. Base on this fundamental investigation for the development of flowing concrete mix design, it could be drawn that the workability and engineering properties of flowing concreteare influenced greatly by mix proportion and dosage of superplasticizers.

• Journal of Ceramic Processing Research
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• v.19 no.6
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• pp.509-513
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• 2018

This study uses fly ash for non-shrinkage grout in order to develop strength of grout and improve its durability. We grind fly ash to the extent of $7,000cm^2/g$ and use ground fly ash and raw fly ash respectively at the proportion of 10%, 20%, 30% instead of OPC and compare the results drawn on the condition of each proportion. As a mixed material of grout, EVA and water-reducing agent is added in order to prevent bleeding and improve segregation resistance, CSA is added with a view to preventing drying shrinkage and improving early strength property. In regard to flow and flow time test for analyzing and evaluating workability, it is revealed that grouts of all mix proportions except raw fly ash 30% mix proportion satisfy all performance criteria. With regard to length change rate, grout with no admixture shows the highest shrinkage rate, but the rate is 0.0005%, extremely insignificant rate. As material age increases, compressive strength of two grouts, that is to say ground fly ash 10% and 20%-used grouts, exceed that of grout with no admixture or show high-level compressive strength.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.05a
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• pp.131-132
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• 2011

This study analyzes the yearly-best delivered size range of truck mixer based on the specified mix, Water to Binder Ratio, aggregate proportion and unit amount with statistical method targeting on Kyeongi and Kyeongsang province and compares with the similar materials of Japan to propose as a basic standard for the quality control of mixer truck. As a result, in case of the Water to Binder Ratio of these areas, it is higher than Japan's due to the excessive safety rate reflecting the changes of differential value impact and unit amount, and the unit amount's standard deviation is very large by reflecting the changes of the amount used and chemical admixture susceptibility. In case of aggregate proportion, the frequency rate is about 50%, which is very similar value with Japan's one.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10a
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• pp.262-268
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• 1998

This research is to examine the selected method of optimal mixing proportion and cost analysis in the super flowing concrete. As confined water $ratio($\beta_p$)$ and K is introduced, itis to establish optimal mixing design of super flowing concrete according to the steps of paste, mortar and concrete. From paste and mortar test, it was led to $$\beta_p$$ and $K_p$satisfying the optimum condions depending on the kinds of binders. Then $$\beta_p$$ and $K_p$ is reflected to the mix condition of super flowing concrete. The result of test, the mix condition of super flowing concrete satisfied the quality performance of concrete with adjustment of additional rate of the superplasticizer. Besides, in case of design strength $350kg/\textrm{cm}^2$ of concrete, material cost in super flowing concrete is able to be reduced 5~16% in replacement of fly ash 30% in ordinary portland cement and slag cement.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.275-280
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• 2001

Recently, self-compacting concrete is applied in order to achieve workability improvement and rationalization in construction. But self-compacting concrete using viscosity agent has a difficulty in practical use because viscosity agent is invested small quantity and by man-power. Therefore in this paper we have been focused on the development and practical use of self-compacting concrete by hydraulic composition containing the segregation-reducing agent. According to mix variable, we find out right quantity of water, binder and rate of admixture replacement, and also we find out the optimum mix proportion. In the result, self-compacting concrete by hydraulic composition containing the segregation reducing agent gave satisfaction with standard and its demand will increase in the future.

• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.4
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• pp.349-357
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• 2019

Controlled low strength material(CLSM) has been developed using variety of material such as excavated soil, industrial by-product and industrial waste. But theses research limited at laboratory test and failed at commercialization. So in this paper evaluates CLSM used excavated soil characteristics such as flowability, bleeding rate, early strength for following process and 28day strength for re-excavatability. Also, various mix proportion of CLSM by water-binder ratio and soil-binder ratio were evaluated in laboratory. And derive the optimized CLSM mix proportion for using at field application test by movable batch plant. After applying CLSM at trench, evaluate core sample strength and excavatability by shovel, pickax and excavator for verify re-excavation. Furthermore, measure the level change after casting CLSM to inspect subsidence stability. As results of these assessments, not only confirmed the characteristics of CLSM at field but the fillability around pipe and subsidence stability.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.30-31
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• 2021

This study aims to build a deep learning model that can predict the value of concrete mixing properties according to a given concrete strength value. A model was created for a total of 1,291 concrete data, including 8 characteristics related to concrete mixing elements and environment, and the compressive strength of concrete. As the deep learning model, DNN-3L-256N, which showed the best performance on the prior study, was used. The average value for each characteristic of the data set was used as the initial input value. In results, in the case of 'curing temperature', which had a narrow range of values in the existing data set, showed the lowest error rate with less than 1% error based on MAE. The highest error rate with an error of 12 to 14% for fly and bfs.

• Journal of the Korea Concrete Institute
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• v.27 no.4
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• pp.331-341
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• 2015

The main purpose of this study is reducing the cost and effort for characterization of tensile strength of fiber reinforced concrete, in order to use in structural design. For this purpose, in this study, test for fiber reinforced concrete was carried out. Because fiber reinforced concrete is consisted of diverse material, it is hard to define the correlation between mix proportions and strength. Therefore, compressive strength test and tensile strength test were carried out for the range of smaller than 100 MPa of compressive strength and 0.25~1% of steel fiber volume fraction. as a results of test, two types of tensile strength were highly affected by compressive strength of concrete. However, increase rate of tensile strength was decreased with increase of compressive strength. Increase rate of tensile strength was decreased with increase of fiber volume fraction. Database was constructed using previous research data. Because estimation equations for tensile strength of fiber reinforced concrete should be multiple variable function, linear regression is hard to apply. Therefore, in this study, we decided to use the ANN(Artificial Neural Network). ANN was constructed using multiple layer perceptron architecture. Sigmoid function was used as transfer function and back propagation training method was used. As a results of prediction using artificial neural network, predicted values of test data and previous research which was randomly selected were well agreed with each other. And the main effective parameters are water-cement ratio and fiber volume fraction.

• KIEAE Journal
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• v.15 no.1
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• pp.155-160
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• 2015

The annual average of energy sources is continuously increasing at a rate of 5.8%, and particularly, the power generation proportion of new/renewable energy is increasing significantly. Furthermore, South Korea has established a national energy master plan for 2008-2030 and is aiming at obtaining approximately 11% of total energy production from the wind turbine sector. Although offshore wind turbines are similar to wind turbines installed on land, they require materials with excellent dynamic properties and durability to prevent damage due to seawater at the lower parts and connecting parts. The lower parts of wind turbines are submerged in seawater, and the upper and lower parts are connected by filling the connecting part with grout. This paper describes the test results of the process of determining the mix ratios to develop ultra-high grout for offshore wind turbines. There is virtually no relevant technology regarding grout for offshore wind turbines in South Korea that can be referenced for the process of determining the mix ratios. Therefore, tests were conducted for determining compression strength, elastic modulus, flexural strength, density, constructability (floor test), and early strength by referencing a high-performance grout produced in South Korea, and the mixing process for achieving the goal strengths was described using the Korean Industrial Standards (KS) as the reference.