• Journal of Construction Engineering and Project Management
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• v.2 no.2
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• pp.53-60
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• 2012

Accurate assessment of $CO_2$ emission from buildings requires gathering $CO_2$ emission data of various construction materials. Unfortunately, the amount of available data is limited in most countries. This study was conducted to present the $CO_2$ emission data of concrete, which is the most important construction material in Korea, by conducting a statistical analysis of the concrete mix proportion. Finally, regression models that can be used to estimate the $CO_2$ emission of concrete in all strengths were developed, and the validity of these models was evaluated using 24 and 35MPa concrete data. The validation test showed that the error ratio of the estimated value did not exceed a maximum of 5.33%. This signifies that the models can be used in acquiring the $CO_2$ emission data of concrete in all strengths. The proposed equations can be used in assessing the environmental impact of various construction structural designs by presenting the $CO_2$ emission data of all concrete types.

• Advances in concrete construction
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• v.4 no.1
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• pp.49-69
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• 2016

This work investigates the mechanical properties of conventional concrete (CC) and self compacting concrete (SCC) using fine rubber and silpozz were accompanied by a comparative study between conventional rubberized concrete (CRC) and self compacting rubberized concrete (SCRC). Fine rubber (FR) from scrap tires has replaced the fine aggregate (FA) and Silpozz has been used as a replacement of cement at the proportions of 5, 10 and 15%. Silpozz as a partial replacement of cement in addition of superplasticiser (SP) increases the strength of concrete. Fresh concrete properties such as slump test, compaction factor test for CRC, whereas for SCRC slump flow, $T_{500}$, V-funnel, L-box, U-box, J-ring tests were conducted along with the hardened properties tests like compressive, split tensile and flexural strength test at 7, 28 and 90 days of curing. The durability and microstructural behavior for both CRC and SCRC were investigated. FR used in the present study is 4.75 mm passing with fineness modulus 4.74.M30 grade concrete is used with a mix proportion of 1:1.44:2.91 and w/c ratio as 0.43. The results indicate that as FR quantity increases, workability of both CRC and SCRC decreases. The results also show that the replacement of natural fine aggregate (NFA) with FR particles decreases the compressive strength with the increase of flexural strength observed upto 5% replacement of FR. Also replacement of cement with silpozz resulted enhancement of strength in SCRC.

• Advances in concrete construction
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• v.11 no.2
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• pp.89-98
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• 2021

Investigations on the dynamic behavior of concrete members, incorporating steel fibers with different aspect ratios, are limited so far and do not covered comprehensively in prior studies. Present endeavor is devoted to examine the dynamic response of the steel fibrous concrete beams and slabs under the influence of impact loading. These members were reinforced with steel fibers in different length of 25 mm and 50 mm. Four concrete mixes were designed and used based on the proportion of long and short fibers. Twenty-four slabs and beams were fabricated with respect to the concrete mix and these specimens were tested in impact load experiment. Testing observations revealed that the maximum dynamic deflection or ductility of the member can be achieved with increasing the fiber length. Structural behavior of the tested structures was predicted using nonlinear finite element analysis with specific material constitutive relationships. Eight nodes plate elements have been considered in the present dynamic analysis. Dynamic fracture energy of the members was calculated and agreement ratio, of more than 70%, was noticed between the experimental and analysis outcomes.

• Journal of the Korea Institute of Building Construction
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• v.2 no.4
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• pp.169-176
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• 2002

To study of binder and fine aggregate a lot of replacement fly-ash concrete, initial characteristics, standard environment of curing temperature $20^{\circ}C$, hot-weather environment, cold weather environment of curing temperature $5^{\circ}C$. Flash concrete tested slump, air contest, setting and Hardening concrete valuated setting period of form, day of age 3, 7, 28 compression strength in sealing curing. Underwater curing specimen compression strength of age 3. 7, 28day used strength change accordingly fly-ash concrete curing temperature. Purpose of study is consultation materials in field that variety of fly-ash replacement concrete mix proportion comparison and valuation. (1) Setting test result, fly-ash ratio of replacement higher delay totting time. Same volume of fly-ash ratio of replacement is lower fly-ash ratio of replacement fine aggregate delay setting time. Setting test in curing temperature $35^{\circ}C$ over twice fast setting in curing temperature $20^{\circ}C$ and all specimen setting delay in curing temperature $5^{\circ}C$. F40 specimen end of setting about 30 time. (2) Experiment result age 28day compression strength more fisher plan concrete then standard environment in curing temperature $20^{\circ}C$, cold weather environment in curing temperature $5^{\circ}C$, most strength F43 is hot-weather environment in curing temperature $35^{\circ}C$ replacement binder 25%, fine aggregate 15%. (3) Hot-weather environment replacement a mount of fly-ash is a same of plan concrete setting period of form. Age 28day compression strength replacement a mount of fly-ash more hot-weather concrete then plan concrete.

• Journal of the Korea Concrete Institute
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• v.20 no.2
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• pp.165-173
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• 2008

One of the most important requirements for reinforced concrete constructions is the bond behavior between concrete and reinforcement. For practical application, it is very important to study bond behavior of reinforcing bars in recycled aggregate concrete (RAC). Thirty six pull-out tests were carried out in order to investigate the bond behaviour between recycled coarse aggregate concrete (RCAC) and deformed bars. RCA replacement ratios (i.e., 0%, 30%, 60% and 100%) and positions of deformed bar (i.e., vertical and horizontal position) were considered as variables in this paper. Each specimen was in the form of a cube, with edges of 150 mm in length and for the pull-out tests, a deformed bar, 13 mm in diameter, was embedded in the center of each specimen. Based on the test results, the bond strength between the RCAC and deformed bars were influenced by both RCA replacement ratios and positions of deformed bars. It was found that under the equivalent mix proportion (i.e., the mix proportions are the same, except for different RCA replacement ratios), the bond strength between the RCAC and the ribbed bar has no obvious relation with the RCA replacement ratio, whereas the positions of deformed bars have a significant effect on the bond behavior between the RCAC and deformed bars. Under the condition of same RCA replacement ratio, the specimen of horizontal reinforcement at upper position (HU type) appear considerably low bond stress.

• Journal of the Korea Concrete Institute
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• v.17 no.5 s.89
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• pp.709-716
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• 2005

The objective of this study is to develop a high ductile fiber reinforced mortar, ECC(Engineered Cementitious Composite) with using raw material commercially available in Korea. A single fiber pullout test and a wedge splitting test were employed to measure the bond properties in a matrix and the fracture toughness of mortar matrix respectively, which are used for designing mix proportion suitable for achieving strain-hardening behavior at a composite level. Test results showed that the properties tended to increase with decreasing water-cement ratio. A high ductile fiber reinforced mortar has been developed by employing micromechanics-based design procedure. Micromechanical analysis was initially peformed to properly select water-cement ratio, and then basic mixture proportion range was determined based on workability considerations, including desirable fiber dispersion without segregation. Subsequent direct tensile tests were performed on the composites with W/C's of 47.5% and 60% at 28 days that the fiber reinforced mortar exhibited high ductile uniaxial tension property, represented by a maximum strain capacity of 2.2%, which is around 100 times the strain capacity of normal concrete. Also, compressive tests were performed to examine high ductile fiber reinforced mortar under the compression. The test results showed that the measured value of compressive strength was from 26MPa to 34 MPa which comes under the strength of normal concrete at 28 days.

• Korean journal of food and cookery science
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• v.32 no.5
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• pp.593-599
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• 2016

Purpose: The aim of this study was to investigate the quality characteristics of pancake mix containing Dioscorea batatas powder. In order to optimize the formulation ratio of the pancakes, steaming process was used to develop health-oriented products by adding D. batatas saponin and improved blood circulation. Methods: D. batatas powder was substituted into pancake at 0%, 10%, 20%, 30% and 40% of the total weight of wheat flour. Results: The viscosity of batter tended to increase as the ratio of D. batatas powder increased whereas the measures of spreadability were not significantly changed. In addition, the L-value and b-values decreased gradually while a-value increased. Among the textural characteristics cohesiveness tended to increase in proportion to the amount of D. batatas powder. Conclusion: The results of the sensory evaluation showed that pancake made with 20% D. batatas powder was the most preferable in appearance, flavor, taste, texture, and overall acceptability.

• Korean Journal of Construction Engineering and Management
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• v.1 no.2 s.2
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• pp.63-70
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• 2000

Since inorganic pigment, among admixtures used for cement composites, can raise the esthetic value of a building due to its effect of coloring, it can be assumed that the quantity consumed is expected to increase in connection with the recent trend of emphasizing the beautiful sights of the city. We carried out a flow test by changing the mix proportion of the cement mortar mixed with an inorganic pigment, water-cement ratio and pigment mixing ratio in order to present the basic materials for utilizing colored cement mortars. In construction by exploring the effect of inorganic pigments on the workability of cement mortar. In case of red pigment mortar and yellow pigment mortar, the workability was found to be rapidly decreased. To secure proper workability, it is necessary to increase the amount of mixing water, or to use superplasticizer. In case of green pigment mortar, however, it recorded $-2.4{\~}6.9{\%}$, showing that there was almost no change in flow. In case of black pigment mortar, it was also confirmed that there is no need to consider workability.

• Journal of the Korea Concrete Institute
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• v.26 no.6
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• pp.671-677
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• 2014

In this research, flow experiments and simulation of highly flowable concrete has been attempted using a viscoplastic particle method varying with dosages of SP admixture and water-cement (W/C) ratios. Rheological and flow characteristics of flowable concrete manufactured in domestic products of cement, aggregates, and SP admixtures were investigated by experimental programs varying with mix proportions. From experiment, the predictive model of rheological characteristics of flowable concrete has been newly proposed considering with the effects of the W/C ratio and the dosage of SP admixture, and the effect of mixing proportion has also been incorporated into shear stress and strain rate curve of flowable concrete in the current method. A series of L-box flow test of highly flowable concrete varying with dosages of SP admixture and W/C ratios was compared with the proposed model.

• Journal of the Korea Concrete Institute
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• v.29 no.3
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• pp.315-322
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• 2017

The purpose of this study is to investigate experimentally the construction performances and economical evaluation of the self-compacting concrete in actual site work after selecting the optimum mix proportions according to cementitious materials. Slag cement type of 46.5% slag powder and belite cement of 51.4% $C_2S$ content, lime stone powder as binders are selected for site experiment including water cement ratio. Also, test items for optimum mix proportion are as followings ; (1) Slump flow, 500 mm reaching time, V-type flowing time and U-box height (2) Setting time, bleeding, shortening depth and adiabatic temperature rising (3) Mixing time in plant (4) Concrete quantity and cost, quality control in actual concrete work. As test results, (4) Optimum water-cement ratio ; Slag cement type 41.0% and belite cement 51.0% (2) Setting time and bleeding finishing time of slag cement are faster, bleeding content of slag cement is higher, shortening depth and adiabatic temperature rising of belite cement type are lower (3) Optimum mixing time in batcher plant is 75 seconds and concrete productive capacity is about $100{\sim}110m^3/hr$. (4) Belite cement type is lower than slag cement type in material cost 14.0%, and concrete quantity in actual concreting work save 3.3% in case of belite cement type. Therefore, self-compacting concrete of belite cement type is definitely superior to that of slag cement type in various test items without compressive strength development.