• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.1A
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• pp.95-100
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• 2009

This study proposed mix proportions of early strength pavement concrete for large size area using calcium nitrate. Therefore, we used type III cement with calcium nitrate. Laboratory tests conducted to air content, slump loss test, setting time test, compressive strength test and flexural strength test. Our early strength pavement concrete mixture proportion proposed in this study for large size area attained the required compressive strength of 21 MPa and a flexural strength of 3.8 MPa, which allowed it to be opened to traffic within 8 hours. Based on test results, we suggested optimum mix proportions of early strength pavement concrete for large size area using calcium nitrate.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.369-370
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• 2009

This study aims to find an optimum mix proportions for high-performance shotcrete using industrial by-product from power plants. Compressive strengths of various mix proportions with varying amount of fly ash were verified if they meet the required limits.

• Journal of the Korea Institute of Building Construction
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• v.8 no.5
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• pp.85-91
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• 2008

Prepacked concrete has recently been used in the special constructions fields such as underwater concrete work, heavy-weight concrete work, underground structure work, partial repair works for damaged reinforced concrete structures. and polymer-modified mortars have been employed as grouting mortars for the prepacked concrete. The purpose of this study is to recommend the optimum mix design of polymer-modified grouting mortars for prepacked concrete. Polymer-modified mortars using SBR and EVA emulsions as admixture of grouting mortars for prepacked concrete are prepared with various mix proportions such as sand-binder ratio, fly ash replacement ratio, polymer-binder ratio. and tested for flowability, viscosity of grouting mortars, bleeding ratio, expansion ratio, flexural and compressive strengths of grouting mortars and compressive and tensile strengths of prepacked concretes. From the test results, it is apparent that polymer-modified mortars can be produced as grouting mortars when proper mix design is chosen. We can design the mix proportions of high strength mortars for prepacked concrete according to the control of mix design factors such as type of polymer, polymer-binder ratio, sand-binder ratio and fly ash replacement ratio. Water-binder ratio of plain mortars for a constant flowability value are in the ranges of 43% to 50%. SBR-modified mortar has a little water-binder ratios compared to those of plain mortar, however, EVA-modified mortar needs a high water-binder ratio due to a high viscosity of polymer dispersion. The expansion and bleeding ratios of grouting mortars are also controlled in the proper value ranges. Polymer-modified grouting mortars have good flexural. compressive and tensile strengths, are not affected with various properties with increasing fly ash replacement to cement and binder-sand ratio. In this study, SBR-modified grouting mortar with a polymer-binder ratio of 10% or less, a fly ash replacement of 10% to cement and a sand-binder ratio of 1.5 is recommended as a grouting mortar for prepacked concrete.

• Journal of The Korean Society of Agricultural Engineers
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• v.55 no.3
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• pp.25-33
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• 2013

In this study, the optimum mix proportions of rain garden structure concrete were decided and the mechanical properties were evaluated. Experimental parameters were blast furnace slag, hwang-toh, recycled aggregates and natural jute fibers. The target compressive strength and chloride ion penetration were more than 24 MPa and less than 1000 coulombs, respectively. The response surface method was used for statistical optimization of experimental results. The optimal mixing ratios of the blast furnace slag, hwang-toh, recycled coarse aggregate and jute fiber volume fraction were determined 59.98 %, 8.74 %, 12.12 % and 0.2 %, respectively. The compressive strength, flexural strength and chloride ion penetration test results of optimum mix ratio showed that the 24.56 MPa, 3.88 MPa and 999.08 columbs, respectively.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10a
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• pp.356-361
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• 1998

Permeable polymer cement concrete in this study is one of the invironment conscious concretes that can be applied at roads, side walks, parking lots, interlocking block and river embankment, etc. In this study, permeable polymer cement concretes using polymer dispersion(St/Ac) with water-cement ratios of 25, 30, 35 and 40%, polymer-cement ratios of 0, 5, 10, 15 and 20%, and a ratio of cement to aggregate (by weight), 1 : 3.5(about 415kg/㎥), 1 : 4.0(about 375 kg/㎥), and 1 : 4.5(about 345kg/㎥) are prepared, and tested for compressive, flexural and tensile strength, and permeability. From the test results, increase in the strengths of permeable polymer cement concrete are clearly observed with increasing polymer-cement ratio, we can obtain the maximum strengths at water-cement ratio of 35%. The optimum permeable polymer cement concrete according to application and location of work can be selected in various mix proportions.

• Journal of the Korea Institute of Building Construction
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• v.7 no.1 s.23
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• pp.57-62
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• 2007

Generally, the strength of concrete depends on factors of materials, mix proportions, compaction, manufacturing methods and curing and so on. And recently, it has increased the using of crushed sand for concrete due to the exhaustion of good natural aggregate. In case of Korea, in 2004, the using ratio of crushed sand occupies about 28% of whole fine aggregate. This is an experimental study to compare and analyze the influence of W/B ratio and replacement ratio of crushed sand on the fluidity and compressive strength of high strength concrete. For this purpose, the mix proportions of concrete according to the W/B (31.5, 27.5, 23.5%) and replacement ratio of crushed sand (0, 20, 40%) was selected. And then air content, slump-flow, a-lot, compressive strength test were performed.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.45-48
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• 2006

Generally, the strength of concrete depends on factors of materials, mix proportions, compaction, manufacturing methods and curing and so on. This is an experimental study to compare and analyze the influence of cementitious material type on the compressive strength of ultra high strength concrete. For this purpose, the mix proportions of concrete according to the type of cementitious materials(Fly ash, blast furnace slag, silica fume) and W/B(31.5, 27.5%) was selected. And then air content, slump-flow, O-lot, compressive strength test were performed.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.437-440
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• 2006

Generally, the strength of concrete depends on factors of materials, mix proportions, compaction, manufacturing methods and curing and so on. And recently, it has increased the using of crushed sand for concrete due to the exhaustion of good natural aggregate. This is an experimental study to compare and analyze the fluidity and compressive strength of ultra-high strength concrete according to the replacement ratio of crushed sand. For this purpose, the mix proportions of concrete according to the W/B ratio and replacement ratio of crushed sand was selected. And then air content, slump-flow, O-lot, compressive strength test were performed.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.11a
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• pp.101-103
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• 2011

Various desired performances of concrete cannot be always obtained by current conventional mix proportion methods for recycled aggregate concrete (RAC). This paper suggests a new design method of mix proportion for RAC to reduce the number of trial mixes using genetic algorithm (GA) which has been an optimization technique to solve the multi-object problem. In mix design method by GA, several fitness functions for the required properties of concrete, i.e., slump, strength, price, and carbonation speed coefficient were considered based on conventional data or fitness function. As a result, various optimum mix proportions for RAC that meet required performances were obtained and the risk evaluation was also conducted for selected mixtures.

• 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.