• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 1999년도 봄 학술발표회 논문집(I)
• /
• pp.259-264
• /
• 1999

The aim of this study of to compare the development of compressive strength of high-strength concrete with maturity and investigate the applicability the strength prediction models. An experiment was attempted on the high-strength concrete mixes using portland cement replaced by silica fume of 10% by weight of cement, the water-binder ratios of mixes being 0.30 and 0.35, the curing temperatures being 30, 20, 10, 5$^{\circ}C$. Test results of mixes are statistically analyzed to infer the correlation coefficient between the maturity and the compressive strength of high-strength concrete. The constant of strength prediction equation were determined from test results, and the equation was adopted to predict the strength of slab(W80$\times$D100$\times$H20cm). The slab was cast in the laboratory from the same batch water-binder ratio of 0.30, and cores were cut from slab in order to estimate the actual strength. These values are used to compare with predicted value. The present study allows more realistic determination of early age compressive strength of high-strength concrete and can be efficiently used to control the quality in actual construction.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 1994년도 가을 학술발표회 논문집
• /
• pp.167-170
• /
• 1994

To reduce the size of structural members, high strength concrete has recently been utilized for structure such as ultra-high-rise buildings and prestressed concrete bridges in North America, and its compressive strength has gone up to 1300kg/$\textrm{cm}^2$. In Japan, research on high-strength concrete has been undertaken on a large scale by the national enterprise so-called New RC Project. And high-strength concrete with a design compressive strength over 450kg/$\textrm{cm}^2$ has recently been employed for high rised reinforced concrete building. As a result of the serious land availability situation of metropolitan areas in the world, buildings will become taller, and even higher strengths will be required. In the future, the utilization of high-strength concrete will spread widely through the development of new structural concepts, application of steels of a higher yield stress, silica fume, and other new materials. Considering these circumstance, the aim of this experimental study is to develop ultra-high-strength concrete with compressive strength over 1800kg/$\textrm{cm}^2$ with domestic current materials. There are so many factors which influence the manufacturing of ultra-high-strength concrete. The experimental factors selected in this study are mixing methods, curing methods, water-binder ratio, maximum size of coarse by silica fume. The results of this experimental study show that it is possible to develop the ultra-high-strength concrete with compressive strength over 1700kg/$\textrm{cm}^2$ at 28days, 1800kg/$\textrm{cm}^2$ at 56 days.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 1994년도 가을 학술발표회 논문집
• /
• pp.171-174
• /
• 1994

To reduce the size of structural members, high strength concrete has recently been utilized for structure such as ultra-high-rise buildings and prestressed concrete bridges in North America, and its compressive strength has gone up to 1300kg/$\textrm{cm}^2$. In Japan, research on high-strength concrete has been undertaken on a large scale by the national enterprise so-called New RC Project. And high-strength concrete with a design compressive strength over 450kg/$\textrm{cm}^2$ has recently been employed for high rised reinforced concrete building. As a result of the serious land availability situation of metropolitan areas in the world, buildings will become taller, and even higher strengths will be required. In the future, the utilization of high-strength concrete will spread widely through the development of new structural concepts, application of steels of a higher yield stress, silica fume, and other new materials. Considering these circumstance, the aim of this experimental study is to develop ultra-high-strength concrete with compressive strength over 1800kg/$\textrm{cm}^2$ with domestic current materials. There are so many factors which influence the manufacturing of ultra-high-strength concrete. The experimental factors selected in this study are mixing methods, curing methods, water-binder ratio, maximum size of coarse by silica fume. The results of this experimental study show that it is possible to develop the ultra-high-strength concrete with compressive strength over 1700kg/$\textrm{cm}^2$ at 28days, 1800kg/$\textrm{cm}^2$ at 56 days.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2005년도 춘계 학술기술논문발표대회 논문집
• /
• pp.93-98
• /
• 2005

The purpose of this study was to analyze the compression strength research by aerated concrete as mixing ratio This Study used foaming-agent and produced aerated concrete by pre-foam way that is used in construction site. An experiment changes unit cement amount, w/c and the glass fiber mixing rate and 'measured capacity change, unit capacity weight and compressive strength. The results obtained from experimental study are as following; Research to reduce unit capacity weight in condition more than unit cement amount 500kgf is considered should be gone side by side. The highest compressive strength result appeared in aerated concrete that cement amount 600kgf and w/c ratio $45\%$, $50\%$. compressive strength was increased maximum $34%$ when glass fiber $0.7\%$ addition cause by coherence enlargement to enlargement of cement paste and glass fiber addition per unit volume

• 한국농공학회지
• /
• 제23권4호
• /
• pp.53-59
• /
• 1981

This experiment was carried out to find out the effectiveness of soil cement stabilization about the Song-I in Cheju province. The results are summarized as follows; 1.The increasing ratio of unconfined compressive strength according to the increment of cement content was markedly low compared with the weathered granite soil, so the effect of stabilization was low. 2.The moisture content of the sample of Song-I indicates the maximum unconfined compressive strength showed at the 5% or so of dry side than the optimum moisture content and the change of the unconfined compressive strength according to the change of moisture content was not sensitive compared with the weathered granite soil. 3.Generally the primary strength of curing age within 7 days of the sulfate resisting cement was low compared with the normal portland cement and the strength of 28 curing days showed a similar tendency, especially in case of Song-I, and it seemed that the sulfate resisting cement was a little more effective than the normal portland cement. 4.As the unconfined compressive strength of grain size controlled Song-I was low compared with the weathered granite soil, so the rate of weight loss by the durability test was great, therefore it was thought that the durability was weak.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
• /
• pp.157-162
• /
• 2002

This study is intended to present a reference data for effective quality control of concrete through comparing the rebound value of P type schmidt hammer with the compressive strength with variation of mix proportion and curing condition. According to the results, the air-curing specimen shows the higher rebound value than standard specimen except high strength in the whole. Also the vertical stroke shows higher rebound value than horizontal stroke in standard specimen, however, the rebound value of the two does not show prominent difference in air-curing specimen. The estimation equation of compressive strength derived from this experiment estimates the compressive strength more largely than the estimation equation in P type schmidt hammer manual. Therefore it is thought that the new estimation equation that fits our condition will have to be presented.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
• /
• pp.684-687
• /
• 2004

The purpose of this study is to obtain basic data on the properties of the development of lightweight mortar contained foam agent for various applications in the field. In the experiment, as a result of measurement the specific gravity by the change of the W/C and the foam agent into a variable and measuring the compressive strength of mortar, specific gravity checked that a compressive strength therefore increased. Mortar is using lightweight foam agent having the change of specific gravity, the water cement ratio $50\%,\;40\%,\;30\%$. This paper present extensive data on the characteristics of strength of the lightweight mortar and also presents the mechanical characteristics of the lightweight according to specific gravity.

• KCI Concrete Journal
• /
• 제14권4호
• /
• pp.139-144
• /
• 2002

Concrete filled FRP tube has lately attracted attention as the member that can substitute the conventional reinforced concrete. Glass fiber and carbon fiber are some of available materials for FRP tube. Carbon tube is filament wound with specified winding angle to meet the appropriate capacity demands. Confinement effect of carbon tube is varied according to winding angle. In this study, a total 4 of large scale circular specimens of 30cm diameter and 60cm height is tested. To estimate the effect of winding angle and thickness of carbon tube on the increased confined compressive strength, the test tube are wound with $\pm45^{\circ}\;and\;\pm30^{\circ}$ with two types of thickness, 2mm and 3mm, respectively. It is shown that effectively increased confined strength and ductility are observed from the specimens with $\pm45^{\circ}$ winding angle than $\pm30^{\circ}$ winding angle. Increasing thickness is not as effective as adjusting winding angle for the confinement of concrete core.

• 한국구조물진단유지관리공학회 논문집
• /
• 제5권1호
• /
• pp.161-168
• /
• 2001

The use of composite members to improve the compressive strength of steel structure is a common practice these days and its efficiency has already been proved by several researches and experiments. The result of concrete filled circular tubular(CFCT) stub column tests is introduced in this paper. The main parameter of this test is the ratio of diameter to thickness of circular hollow section. From the test results, the effect of concrete filled in steel tube on the ultimate strength, the deformation capacity and initial stiffness are discussed. The purpose of this paper is to investigate the effect of various parameters and evaluate the compressive strength of confined concrete. It would contribute to a better understanding of CFT structure, further laboratory experimentations are needed for better accurate estimation on its effect.

• 한국세라믹학회지
• /
• 제43권9호
• /
• pp.537-543
• /
• 2006

Length change, hydration heat, setting time and compressive strength of OPC were measured by adding KCl and replacing limestone powder so as to examine the influence of limestone powder on hydration of the OPC contained much chloride. In general, the chloride modified cement was high in heat of hydration, short in its setting time, low in its fluidity and low in its strength at 28 days due to the sudden hydration in its initial stage. As a result of the experiment, it has been demonstrated that heat of hydration, became low as one replaced limestone powder to the chloride modified cement, and the fluidity and shrinkage rate of mortar decreased without change in setting time; furthermore, the compressive strength at 28 days was improved.