• Magazine of the Korean Society of Agricultural Engineers
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• v.42
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• pp.78-84
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• 2000

Permeable polymer concrete can be applied to roads, sidewalks, river embankment, drain pipes, conduits, retaining walls, yards, parking lots, plazas, interlocking blocks, etc. This study is to explore a possibility of utilizing industrial by-products, a blast furnace slag and a fly ash, as fillers for permeable polymer concrete. Different mixing proportions are tried to find an optimum mixing proportion of permeable polymer concrete. The tests are carried out at 20$\pm$1$^{\circ}C$ and 60$\pm$2$^{\circ}C$ relative humidity. At 7 days of curing, compressive, flexural and splitting tensile strengths and water permeability ranged between 239~285kgf/$\textrm{cm}^2$, 107~133kgf/$\textrm{cm}^2$, 37~46kgf/$\textrm{cm}^2$ and 4.612~5.913$\ell$/$\textrm{cm}^2$/h, respectively. It is concluded that the blast furnace slag and fly ash can be used in permeable polymer concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10b
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• pp.1063-1068
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• 2000

Latex modified concrete (LMC) has grown to be accepted as a standard material of construction overlaying bridge decks in America due to its superior physical and chemical properties. The properties of latex, combined with the low water-cement ratio, produce a concrete that has improved flexural, tensile, and bond strength, lower modulus of elasticity, increased freeze-thaw resistance, and reduced permeability compared to conventional concrete of similar mix design. LMC overlays have been service in excellence for 30 years on thousands of bridge in U.S.A. This may, also, prolong the life cycle of bridge deck once it is adopted in Korea. The self-contained, mobile, continuous mixer is most appropriate particularly for concrete quality assurance. Assuring quality on a bridge deck overlay project should begin in the design phase and continue after the construction is completed. Quality should be the concern of everyone involved-owner, designer, and contractor.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.11a
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• pp.19-20
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• 2023

The pre-qualification system related to floor impact noise is considered ineffective, and thus, the introduction of a post-verification system is being prepared. This is because the performance, which was notarized in the qualification test due to various reasons, was not uniformly confirmed on building construction fields. Industry practitioners perceive that this is due to the influence of factors such as the flatness, levelness and/or thickness of the floor. However, it is very difficult to confirm such facts in a short period of time on the fields, and since the practical application of technology to measure and evaluate quantitatively and the establishment of a system are insufficient, it cannot be said to be a problem that can be brought to the surface. In fact, even when considering the conventional measurement of the dynamic modulus of elasticity, measurements are performed under controlled variables, such as placing a 200mm×200mm buffer material on a flat test-floor. However, in the fields, it is common to lay down larger productions(for example, 900mm×600mm) on the bare floor where significant variables are not controlled, and to construct finishing layers corresponding to the pre-qualified floor system without separately confirming the realization of the dynamic modulus of elasticity in the field conditions. In this study, spatial information of the bare floor on the field was measured and evaluated through a laser scanner. Technical methods for assessing the smoothness, flatness, and thickness of construction surfaces were reviewed, providing key insights for grading the quality of construction based on these criteria. Through further detailed and thorough investigations, it is expected that results suitable for practical application and systematization will be derived.

• International Journal of Concrete Structures and Materials
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• v.11 no.2
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• pp.315-325
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• 2017

The purpose of the paper is to determine the influence of two widely used steel fibers and polypropylene fibers on the sulphate crystallization resistance, freeze-thaw resistance and surface wettability of ultra-high performance concrete (UHPC). Tests were carried out on cubes and cylinders of plain UHPC and fiber reinforced UHPC with varying contents ranging from 0.25 to 1% steel fibers and/or polypropylene fibers. Extensive data from the salt resistance test, frost resistance test, dynamic modulus of elasticity test before and after freezing-thawing, as well as the contact angle test were recorded and analyzed. Fiber hybridization relatively increased the resistance to salt crystallization and freeze-thaw resistance of UHPC in comparison with a single type of fiber in UHPC at the same fiber volume fraction. The experimental results indicate that hybrid fibers can significantly improve the adhesion properties and reduce the wettability of the UHPC surface.

• Journal of the Korean Ceramic Society
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• v.47 no.5
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• pp.412-418
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• 2010

This paper presents the results of experimental work on both mechanical properties and durability of concrete or mortar incorporating silica fume. The aim of this study was to investigate the effect of replacement of silica fume on the performance of hardened concrete or mortar. The replacement levels of silica fume that replaced cement in this work were 0%, 5%, 10% and 15%, respectively. The results of this study indicate that both mechanical properties and durability of concrete are greatly dependent on the replacement levels of silica fume. As the replacement level of silica fume increased, the mechanical properties including compressive and flexural strengths, and static modulus of elasticity were proportionally enhanced. Furthermore, it was found that silica fume had some beneficial effects on the resistances to both chloride ions penetration and sodium sulfate attack. However, it exhibited poor resistances to both freezing-thawing action and magnesium sulfate attack.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.461-464
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• 2006

An experimental study is conducted to charaterize the mechanical properties of a fiber-reinforced, lightweight concrete (FRLAC) that is produced without an autoclave process. The FRLAC enhances the strength of lightweight cellular concrete by adding polypropylene fibers. A series of compressive strength tests on cylindrical specimens are carried out to characterize the compressive strength and the modulus of elasticity of the FRLAC. Specifically, various mixing rates of a foam agent are applied in casting of the specimens to investigate the influence of the mixing rate of the foam agent on the performance of the FRLAC and to determine the optimal mixing rate of the foam agent.

• Magazine of the Korean Society of Agricultural Engineers
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• v.41 no.3
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• pp.66-72
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• 1999

The purpose of this experiment is to estimate freezing and thawing resistance of rice straw ash concrete. Test results show that mass, pulse velocity and relative synamic modulus of elasticity are gradually decreased with increase of freezing and thawing cycle. The durability factor(DF) is in the range of 85.48 ∼86.33 in the rice straw ash comcrete with 2.5% , 5% 7.5%, rice straw ash and higher than that of thenormal cement concrete. But, DF of 10% , 12.5%, 15% rice straw ash filled rice straw ash concrete is in the range of 41.26∼65.34 and lower than that of the normal cement concrete.

• Structural Engineering and Mechanics
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• v.80 no.6
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• pp.689-699
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• 2021

The present study aims to understand the behaviour of low-strength masonry prisms constructed with locally-produced low-strength hollow concrete blocks. Compression tests were conducted on masonry prisms constructed with three different mortar grades of cement-sand ratios of 1:3, 1:4.5 and 1:6 representing strong, moderately strong and weak mortar. Stress-strain curves were generated from the test results for the masonry prisms. The hollow concrete masonry units employed in this study are some of the weakest as compared to other masonry units employed by other researchers. The compressive strengths for masonry prisms with mortar grades 1:3, 1:4.5 and 1:6 are 2.21 MPa, 2.19 MPa and 2.25 MPa respectively. The results indicate that the masonry compressive strength of such low-strength hollow concrete block masonry prisms is not influenced by the mortar strength. Simple relationships to estimate the modulus of elasticity and compressive strength of masonry prisms is also proposed.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.05a
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• pp.65-67
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• 2011

This research analyzed the mechanical properties of high strength concrete produced by limestone aggregate, and summarized the result as follows: Due to the property of unhardened concrete, slump flow value increased more or less according to the increase in LG replacement, but didn't show a big difference while clear tendency of air content couldn't be found. Due to the property of hardened concrete, there appeared an increase in the rate of compressive strength the more LG replacement increased, and the modulus of elasticity also showed a tendency similar to the increase rate of compressive strength.

• Computers and Concrete
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• v.19 no.6
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• pp.617-623
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• 2017

This work is conducted with the aim of using waste material to reserve the natural resources. The objective is accomplished by conducting experimentation and verify by modeling based on fuzzy logic. In experimentation, concrete is casted by using natural/river sand as fine aggregate and termed as control specimen. Natural sand is conserved by replacing it with used foundry sand (UFS) by an amount of 10, 20 and 30% by weight. Fresh and hardened properties of concrete are investigated at different ages. It is observed that compressive strength and modulus of elasticity reduced with the increase in amount of UFS. Furthermore, concrete compressive strength is predicted by using fuzzy logic model and verified at different replacement ratio and age with experimental observations.