• Proceedings of the Korea Concrete Institute Conference
• /
• 1998.10c
• /
• pp.83-86
• /
• 1998

Recently, underwater concrete constructions are increasing. Therefore it is considered important to control the quality of underwater concrete. In this paper, we have an intention of evaluating fundamental properties of underwater concrete using the Ground Granulated Blast Furnace Slag (GGBF Slag). Thus, it has been investigated that the slump flow of the concrete, pH value and suspended solids in solution, compressive strength on both of specimens made above and below water. Also the percentage of GGBF Slag was found to alter the filling-up in underwater concrete.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.36 no.1
• /
• pp.75-83
• /
• 2016

In case of underground construction affected by groundwater, CIP (Cast-In-Place Pile) method is generally used to resolve the geo-hydraulic problem. However, as this method has poor connectivity between piles, an auxiliary method for cut-off is needed in many cases. In this study, a new concept earth retaining wall method (H-CIP) with no auxiliary method, by using surfactant grout (Hi-FA) which improves antiwashout and infiltration ability, is introduced, and its field applicability is evaluated. CIP and H-CIP piles were installed with same ground conditions, and field and laboratory tests were conducted to verify the performance. As results, newly contrived H-CIP method shows higher field performance for cut-off and strength than conventional CIP method.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1993.04a
• /
• pp.47-52
• /
• 1993

Admixtures for concrete placed underwater have been developed to the stage that they are now widely used. The use of this type of product allows concrete to be placed underwater with far less risk than was previously possible. One of the problems facing users of underwater concreting admixtures is how does one test such products in order to access their performance initially while minimizing the expense of carrying out site trials. This paper will introduce three categories of laboratory test for underwater concrete listed next : fluidity test, non-segregation test, strength test. Trial underwater concretes were ordinary Portland cement. Strength and workability development and segregation resistance properties of the concrete under the coexistence of some kinds of superplasticizer were studied for this laboratory tests.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2004.05a
• /
• pp.786-789
• /
• 2004

Corrosion of reinforced concrete structures in marine environment is one of the most important mechanism of deterioration. However, conventional rehabilitation techniques in tidal zone, which consist of removing delaminated areas of concrete, cleaning affected steel and patching with portland cements mortar, have proven to be ineffective for marine structures. Also, repairs are often repeated every several years. The purpose of this report is to announce appropriate repair method of highway bridge damaged by chloride attack in marine environment (application of cathodic protection) using FRP and antiwashout underwater mortar.

• Journal of the Korea Concrete Institute
• /
• v.12 no.5
• /
• pp.13-23
• /
• 2000

In this study, an flexural test on half-scale spliced PSC-I girder was conducted to verify the efficiency of the long span spliced girder as suggested by the Korean Highway Design Specification. The experimental results showed that the specimens developed a complex failure mode due to flexural-compression and torsional stress. The cracking moment of each girder was higher the experiment than was calulated by the ACI and the ultimate strength were the almost same. To estimate the safety and the structural efficiency of the spliced girder, the proposed Yielding Resistance Index(YRI) and ductility index by American Concrete Institutes were used based on the energy concept. The proposed YRI defined the ratio of crack resisting energy and the total energy calculated from load-displacement relationship. Based on the analysis of YRI and ductility index, the flexural behavior of the spliced girder was found to be efficient. Through the experimental results, the structural behavior of proposed spliced PSC I-type girder for long span bridge was found to be more efficient than the exsisting PSC I-type girders.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2000.04a
• /
• pp.113-117
• /
• 2000

The objective of this study is to find the long-age strength property and the compressive strength of age which is used as the specified concrete strength. The W/W ratio (45%, 50%, 55%, 60%) fine aggregate of useful river sand or blended sand(river sane : sea sand=1:1) were chosen as the experimental parameters. the experimental results show that pH(it means the material segregation resistance) & suspension were increased larger, so W/C become larger, and slump flow was increased as W/C increased (except W/C=60%), air-contents were decreased as W/C became increase and all of this results are satisfied with the under of 40%. The compressive strength ( a case use only river sand as fine aggregate) is showed less than the case of blended asnd. Because the unit weight of the blended sand is more heavy than the unit weigh of the river sand. The results of the case which haven been used only river sand, and the case have been used blended sand), both case have considered W/C. So it's possible to use the compressive strength of age 28 day like the case of plain concrete.