• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.157-165
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• 1997

In this experiment, there is a purpose to analysis the relationship of feature of compressive strength after fixing of remarkable element under the condition of initial curing temperature. According to this experiment, we get to the fallow result. In case of highest curing temperature, 3-day-strength become high but last revelation of strength become low among the condition of initial curing temperature, the highest curing temperature have an effect on revelation of strength by the application of cumulative temperature, we can get the shape of revelation of strength.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.475-480
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• 2003

Latex modification of concrete provides the material with higher flexural strength. This increase in flexural strength can attribute to the crack-arresting action of polymer in concrete, and also to the bonding they provide between the matrix and aggregates. This experimental study presents the fracture behavior of 12 flexural reinforced concrete beams repaired or strengthened by latex-modified concrete with the main experimental variables such as overlay thickness, strength thickness, and shear reinforcement. The results are as follow: All beam specimens having shear reinforcement were failed by delamination rupture at concrete interface at about 80% of ultimate loading after flexural cracking. All specimens overlayed and strengthened by latex-modified concrete (LMC) showed higher ultimate flexural strength than OPC control specimen, but lower than LMC control specimen. This increase in flexural strength could attribute to the high bonding they provide between the matrix and aggregates. All specimens except two shear unreinforced showed quite similar and consistent displacement behavior. The effect of overlay and strength thickness on the load-displacement relationship were a small at this study.

• Architectural research
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• v.20 no.3
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• pp.75-82
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• 2018

The aim of the study is to evaluate the concrete shear strength and structural behavior of two general beams and eight shape memory alloys (SMAs)-reinforced beams under the flexural test. This work compares the existing reference formula for concrete shear strength with test result to provide the basic data for the design of highly intelligent reinforced concrete (hereinafter, HIRC) beams. The evaluation of the concrete shear strength was performed with effective depth (d=65, 70, 80), SMA diameter change (ø=2.0, 2.5) as the main variables of the specimens. For the relationship between the effective depth and the $V_{\exp}/V_{cal}$, the test result shows that the concrete shear strength gradually approaches 1.0 as the effective depth length increase. For the AIJ formula, the specimens are approached evenly for comparison between $V_{\exp}/V_{cal}$ and the by-product (garnet, fly-ash) reinforced specimen; however, other formulas indicate a deviation.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2005.10a
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• pp.361-366
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• 2005

Since most soils exist above the ground water table, negative pore pressure exist in unsaturated soils. Negative pore water pressure in unsaturated soil affects the soil structure and degree of saturation and it is important for accurate evaluation of unsaturate flow and behavior. This negative pore pressure is called a matric suction which causes an increased shear strength. Therefore, it is required that the effect of increase in the shear strength should be included in a geotechnical analysis. From the test result, the influence of net confining pressure and matric suction on the shear strength was analyzed and strength parameter was increased with matric suction increase and a unliner relationship was found to relate matric suction and shear strength.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2006.05a
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• pp.89-92
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• 2006

To investigate the properties of high flowing and high strength concrete with crushed sand and fly ash for CFT structure, many batches were performed by a trial-error method. In the experiment W/B was set up three levels as 0.25, 0.30 and 0.35. Also the variables of the experiment were a substitution ratio of fly ash, a blend ratio of crushed sand and the ages of specimens(3, 7, 28 days). The results of this study are summarized as the follows; 1) The effect a substitution ratio of fly ash on the compressive strength was not consistent with age. For twenty-eight day compressive strength, the best result was come out when cement was substituted by 10% of fly ash. 2) The decrease of the water binder ratio, the increase of compressive strength and elastic modulus. Also the relationship is very similar to the case of a normal concrete

• Journal of the Korea Concrete Institute
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• v.11 no.4
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• pp.157-167
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• 1999

Among several non-destructive testing methods, ultrasonic pulse velocity method and rebound index method have been widely used for the evaluation of concrete strength. However, such methods might not provide accurate estimated results since factors influencing the relationship between strength and either ultrasonic pulse velocity or rebound index are not considered. In this paper, the evaluation method of concrete strength using rod-wave velocity measured by impact-resonance method is proposed. A basic equation is obtained by the linear regression of velocity vs, strength data at specific age and then, aging factor is employed in the equation to consider the difference of the increasing rate between wave velocity and strength. Strengths predicted by the proposed equation agree well with test results. Furthermore, the combined method of rod-wave velocity and rebound index is proposed.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.517-520
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• 2005

This study is basic experiment for estimating influence of strength by curing temperature of concrete's heat of hydration and estimate relationship of compressive strength development by initial curing temperature factor, and then asume temperature factor which influence compressive strength development and for showing basic document of quality control. According to the result of cement mortar by the curing temperature factor high-curing temperature shows high strength on 3 day compare with low curing-temperature, shows higher strength than the piece of high curing temperature.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.489-492
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• 2004

Compressive strength of self-compacting concrete with waste concrete powder(SCCWCP) linearly decreased as the containing ratio of WCP increas. When granulated blast furnace slag(SG) was contained for improving the rheological properties of SCCWCP, compressive strength of concrete with $15\%$ SG and $15\%$ WCP was increased in comparison with that of concrete with $30\%$ WCP. Splitting tensile strength of SCCWCP higher increased than that of CEB-FIP at same compressive strength. Relationship between compressive strength and elastic modulus of SCCWCP indicated a similar function with CEB-FIP fuction.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.703-706
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• 2004

This study is basic experiment for estimating influence of strength by curing temperature of concrete's heat of hydration and estimate relationship of compressive strength development by initial curing temperature factor, and then asume temperature factor which influence compressive strength development and for showing basic document of quality control. According to the result of cement mortar by the curing temperature factor high-curing temperature shows high strength on 3 day compare with low curing-temperature, shows higher strength than the piece of high curing temperature.

• Journal of the Korea Furniture Society
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• v.17 no.4
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• pp.49-57
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• 2006

Larix kaemferi is now a major economic kind of trees and is produced in large quantity every year. Thus, the study of Larix kaemferiis conducted to acquire the basic date of measures for the reasonable use, clarifying the relation with the compression strength parallel to grain according to anatomical properties by heartwood and sapwood, and earlywood and latewood. As the length of an earlywood tracheid and the radial wall thickness of earlywood and latewood tracheids increased, the compression strength rose, and as the height of uniseriate ray in cell number increased, the compression strength parallel to grain fell. The major anatomical factors effecting on the compression strength parallel to grain of heart wood were the radial wall thickness of a latewood tracheid and the length of a latewood tracheid, while in sapwood, the length of an earlywood tracheid and the radial wall thickness of earlywood and latewood tracheids were the major factor on it.