• Proceedings of the Korean Institute of Building Construction Conference
• /
• 한국건축시공학회 2009년도 춘계 학술논문 발표대회 산업계
• /
• pp.65-68
• /
• 2009

Recently, the knowledge access about concrete might be 2 methods. One is approach about advanced and new technical development through the institute journal, the other is construction technology which is using at construction fields. However, there is no research for the interrelationship between them. So, this paper investigates the demands on construction fields at the ready mixed concrete plants on the 4 cities, the characteristics of the products like the maximum size of coarse aggregate and slump, and the extension of market on the high strength and flow ability concrete in 2000 and 2008. Moreover, this study would like to propose the investigation about diversification of construction materials for the fine construction cultures and development of the ready mixed concrete to the engineers at the construction fields.

• Magazine of the Korea Concrete Institute
• /
• 제6권6호
• /
• pp.135-142
• /
• 1994

The quality characteristics of concrete using super plasticizer in dornestlc rnarket are evaluat ed in order to put to practical use of high performance concrete with high mobility. high strength ard high durability. For this purpose, rune kmds of super plasticizer are compared and analyzed for the slump, air content. unit weight, water reducing percent and ratios of compressive strength wth admixture content. As a result, the optimum quantity of admixture content were obtained for ordinary and high strength concrete using super plasticizer.

• Proceedings of the Korea Concrete Institute Conference
• /
• 한국콘크리트학회 2009년도 춘계 학술대회 제21권1호
• /
• pp.543-544
• /
• 2009

The fiber(NY, PP) known to the effective material on improvement of the fire-resistance of HSC(high strength concrete) has a difference for fluidity according to the variation of a length and contents of fiber. In this study, to analyze the effect of a length and contents of the fiber on the fluidity of HSC and fheological characteristics, we calculated a viscosity of mortar by mini slump-flow, simple V-lot and viscometer. With the test results, the fluidity characteristic showed a moderate difference by a length and contents of the fiber, but showed a significant difference by increase of the fiber contents. ${\ast}$ AFR Concrete (Advenced Fire Resistant Concrete)

• Proceedings of the Korea Concrete Institute Conference
• /
• 한국콘크리트학회 2008년도 추계 학술발표회 제20권2호
• /
• pp.405-408
• /
• 2008

This study, as mock-up test for applying Polylon Fiber engineering method to the field, analyzed the fundamental characteristics and the fireproof characteristics of high strength concrete mixed with Polylon Fiber 0.05% and the results are summarized as followings. From the characteristic of the fresh concrete, both slump flow and air content were appeared to satisfy target range. And from the characteristic of hardened concrete, all compressive strengths according to the curing conditions were appeared to satisfy design standard strength of 60 MPa. From the fireproof characteristic, small scaling and spalling phenomenon were partially appeared on the surface part of specimens, but generally the excellent fireproof capacities were appeared. From the characteristic of temperature hysteresis, the highest temperature and the average temperature of reinforcing part after fire-resistant test for 3 hours were $531^{\circ}C$ and $405{\circ}C$, respectively and then satisfied fireproof standard of the Ministry of Land Transportation and Maritime Affairs.

• Korean Chemical Engineering Research
• /
• 제50권6호
• /
• pp.1076-1081
• /
• 2012

For the purpose of development of the latex suitable for latex modified concrete, experimental researches on the preparation of carboxylated styrene butadiene latex by the method of the two-step emulsion polymerization and application to concrete were performed. Sodium dodecylbenzene sulfonate and sodium salt of lauryl sulfonate were selected as anionic emulsifiers, and nonylphenoxy poly(ethyleneoxy) ethanols (n=10, 20, 40) as latex stabilizer. Potassium persulfate and sodium bisulfite were used as redox initiator, besides $Na_2HPO_4$ and $K_2CO_3$ as electrolytes. Polymerization recipe of latex suitable for latex modified concrete were suggested from the experimental researches on the effects of anionic emulsifiers and their concentration on the polymerization stability, and the effect of electrolytes concentration on the particle size of latex. Physical properties, such as slump, air contents, compressive and flexural strength, of latex prepared by suggested polymerization recipe were examined. The experimental results showed that latex modified concrete satisfied the quality standards in slump and air contents. Furthermore, it was turned out that the compressive and the flexural strength of latex modified concrete with 28 days curing time showed appreciably improvements.

• Journal of IKEEE
• /
• 제14권3호
• /
• pp.173-181
• /
• 2010

The high flowability performance evaluation device for the concrete is the device which was designed to compensate from the incorrect data detection of the viscosimetry examination of the existing concrete. As for the existing concrete viscosimetry method, the measuring data for a viscosity are very irregular by the point of view of an experimenter and a supervisor, Therefore there were some problems to have many different opinions by a small numerical value difference according to the job characteristic. In this paper, we suggested some mechanism to compensate the problem and some driving electronics including the related algorithm, and the communication structure with wireless sensor network between the devices and users are also presented. The effectiveness of the suggested method was verified with a real experiment.

• Journal of the Korean Recycled Construction Resources Institute
• /
• 제3권1호
• /
• pp.58-63
• /
• 2015

Several researches on cement zero concrete using alkali-activators have been conducted to investigate its fundamental material properties such as slump, strength and durability, however, research on the structural behavior of relevant members involving the elastic modulus, stress-strain relationship is essential for the application of this cement zero concrete to structural members. In this paper the shear behavior of reinforced concrete beams using 50 MPa-alkali activated slag concrete was experimentally evaluated. To achieve such a goal, six reinforced concrete beam specimens were fabricated and their shear behaviors were observed. The maximum difference between test results and analysis results in crack shear stress for beam specimens without stirrups is 31%, while that for beam specimens with stirrup is 15%. Furthermore, it is also found that the shear strength of alkali activated slag concrete is by 22~57% greater than the nominal shear strength calculated by design code, implying that shear design equations would provide conservative results on the safety side.

• Journal of the Korean Recycled Construction Resources Institute
• /
• 제4권1호
• /
• pp.19-24
• /
• 2016

Several researches on high volume fly ash concrete have been conducted to investigate its fundamental material properties such as slump, strength and durability and however, research on the structural behavior of bond strength is essential for the application of this high volume fly ash concrete to structural members because of the necessity of reinforcement. But the exact design code for application and researches on the bond behavior of high volume fly ash concrete lack yet. To achieve such a goal, this paper evaluates experimentally the bond behavior of high volume fly ash concretes by direct pull-out test and compares between the current test results and existing research results. By the test results, it is shown that the bond behavior of high volume fly ash concrete is similar to that of general concrete. And by the comparison between test and existing research, it is shown that bond stress of high volume fly ash concrete is underestimated, as the embedment length gets longer.

• Proceedings of the Korea Concrete Institute Conference
• /
• 한국콘크리트학회 2008년도 춘계 학술발표회 제20권1호
• /
• pp.1073-1076
• /
• 2008

This study shows some results of concrete mixing design has 100 years life time. The ratios of ternary blended cement are 4 types. the ratios of blast furnace slag cement are 3 types. In this case study, 40%, 50% and 60% replacement ratio of blast furnace slag(BSF) to OPC are used, also 35:45:20, 30:35:35, 30:40:30 and 35:40:25 ratio of OPC:BSF:FA are used. The mixing design tests include slump, air content, compressive strength and thermal properties of concrete. The compressive strength tests are executed at the age of 3, 7, 28, 56, and 91 days. The coefficient of chloride diffusion is determined by NT Build 492 method. The purpose of this study is to shows the results of case studies as the ratio of blended cement varies.

• Journal of the Korea Concrete Institute
• /
• 제25권3호
• /
• pp.339-345
• /
• 2013

This study is to derive from the required performances and the optimum mix proportion of the roof concrete placed in the in-ground LNG storage tank with a capacity of 200000 $m^3$, and propose the actual data for site concrete work. The concrete placing work without sliding and segregation in the fresh concrete condition is very important because the slope of domed roof is varied in the large range by its curvature. Also the control of hydration heat and the strength development at test ages are classified with massive section about 1.4 m thick and considered to the pre-stressing work and removal of air support after concrete placing work. Considering above condition, slump range is selected $100{\pm}25$ mm under the slope $20^{\circ}$ and $150{\pm}25$ mm over the slope $20^{\circ}$ s until 60 minutes of elapsed time. Also, the roof concrete is satisfied with compressive strength range including design strength at 91 days (30 MPa), pre-stressing work at 7 days (10 MPa), air support removal work at 21 days (14 MPa). Replacement ratio of limestone powder is determined by confined water ratio test and main design factors include water-cement ratio (W/C), sand-aggregate ratio and dosage of admixture. As test results, the optimum mix proportion of the roof concrete used low heat cement is as followings. 1) Replacement ratio of limestone powder 25% by confined water ratio test 2) Water-cement ratio 57.8% 3) Sand-aggregate ratio 42.0%. Also, test results for the adiabatic temperature rising test is satisfied with its criteria and shown the lower value compared to preceding storage tank (TK-13, 14). These required performances and the optimum mix proportion is to apply the actual construction work.