초기구렬(初期龜裂)이 있는 강직유보강(綱織維補强) 콘크리트의 파괴특성(破壞特性)

곽기주 ( Kwak Kee Ju ) 한국농공학회 1992 韓國農工學會誌 : 전원과 자원 Vol.34 No.3

To investgate the fracture behavior of the steel fiber reinforced concreate, the specimens with different steel fiber contents of 0.0%, 0.5%, 1.0%, 1.5%, were made and notched with differents notch depth retios of 0.0, 0.2, 0.4, 0.6, and the three point bend tests were followed. Test results of 16different types of above combined specimens were summarized as follows. 1. The load line deflection contents were found to increase 5%, 16%, 19%, respectively compared to the unnotched specimen with the increased of initial notch depth ratio to 0.2, 0.4, 0.6, respectively. 2. The frexural strength were found to decrease 14%, 16%, 21%, respectively, compared to the unnotched specimen with increase of initial notch depth ratio to 0.2, 0.4, 0.6, respectively 3. The stress intensity factors of the steel fiber reinforced concrete were found to increase 1.1 1.5 1.9 times, respectively, compared to the concrete with no steel fiber content with the increase of fiber content to 0.5%, 1.0%, 1.5%, respectively 4. The influence of the mass of the steel fiber reinforced concrete to the whole fracture energy was found to be minor with 6~8% contribution. 5. The fracture energy of the steel fiber reinforced concrete, considering the load-deflection curve and concrete mass was found to be approximately 350-380kg·m/m² 6. The regression analysis through the relationship between the compressive(σ_c)/tensile(σ_T) strength and fracture energy(G_f) showed that the fracture energy of the steel fiber reinforced concrete could be predicted as follows.

실라카흄을 사용한 고강도 콘크리트의 기초적 성질

곽기주 ( Kwak Kee Ju ),이경동 ( Lee Kyeong Dong ),곽동림 ( Kwak Dong Lim ) 한국농공학회 1997 韓國農工學會誌 : 전원과 자원 Vol.39 No.1

An experimental study of the application of Silica fume for the high strength concrete was conducted. Nine specimens with three different contents of silica fume, 0%, 10%, 20% and with three water-cement ratio 30%, 40%, 50% were tested. Results shows that 10% of silica fume and 30% of water-cement ratio has a maximum strength with 700kg/cm² of compressive strength and 64kg/cm² of splitting tensile strength and 100kg/cm² of flexural strength. Slump value of the tested samples decreases with increasing water-cement ratio and elapsed time of silica fume. Splitting tensile strength(□□)and flexural strength(□□)and static modulus of elasticity(E) can be correlated with compressive strength(□□)from a regression analysis.

피라미드형 전단열결재를 갖는 합성보의 변형거동과 S-N 곡선

이경동(Kyeong Dong Lee),곽기주(Kee Ju Kwak) 한국강구조학회 1995 韓國鋼構造學會誌 Vol.7 No.3

A steel plate-concrete composite slab system has been widely used in place of conventional reinforced concrete slabs for the reason that they have various advantages such as structural performance, safety and reduction of time and labors in field construction. In this paper, a series of bending fatigue tests was carried out on several types of PSC beams under various cross-sections and loading conditions. The results are as follows : (1) the fatigue failure of PSC beams results from the tensile fracture of bottom steel plate, and (2) fatigue strength of the plate for two million cycles can be estimated at 940kgf/㎠ from the S-N curves.

콘크리트 균열성장에 관한 연구

곽기주,송정근 순천대학교 공업기술연구소 1987 工業技術硏究所論文集 Vol.1 No.-

Experimental results are reported of a series of tests on concrete crack­line wedge loaded double cantilever beams. Those tests was conducted to predict fracture parameters characterizing mode I cracking in concrete. The development is reported of replica technique that provides an easy and accurate method for determining the total extend of cracking in concrete specimens. And it is shown that the fracture process zone continues to increase in length with increasing load.

콘크리트의 炭酸化에 關한 硏究

곽기주 順天大學校 1996 論文集 Vol.15 No.1

The results for examination of carbonation in the concrete are as follows; 1. The alkali components in cement was accelerated carbonation and the concrete of blast furnace slag inclusion was a factor in carbonatization. 2. The alkali components in cement was an excellent factor than water-cement ratio. 3. The movement of pore water in concrete was accelerated carbonation and its effects was shown considerably promoting substitution ratio of blast furnace slag.

실리카 흄을 이용한 콘크리트의 강도특성

곽기주,이경동 순천대학교 공업기술연구소 1995 工業技術硏究所論文集 Vol.9 No.-

The influences on the strength of various silica fume content 0%,10%,20% concrete have been investigated. The results indicated that a target value of slump was obtained by incorporation a fine silica fume without increasing unit water in concretes, The compressive strength of concrete increased with increasing silica contents and curing temperatures. It has been also found that higher compressive strength of concrete resulted in increased modulus of elasticity. From a regression analysis on modulus of elasticity and compressive strength, a general relationship for the modulus of elasticity was derived as follows. E = 0.003946σ_c + 0.679289

各種 纖維補强콘크리드 强度特性에 관한 硏究

郭基柱 순천대학교 공업기술연구소 1991 工業技術硏究所論文集 Vol.5 No.-

This study aims at investigating the strength properties of fiber reinforced concrete. Specimens were made from concrete reinforced by various kinds of fiber and the failure test was performed. The results analyzed are as follow: 1. As the fiber content was increased, the flexural strength of various kinds of fiber reinforced concrete was increased and the order of an increasing rate was steel fiber, glass fiber, vinylon fiber and carbon fiber. 2. As the fiber content was increased, the slump of various kinds of fiber reinforced concrete was increased and the order of an increasing rate was steel fiber, glass fiber, vinylon fiber and carbon fiber. 3. As the fiber content was increased, the air of various kinds of fiber reinforced concrete was increased. Especially in case of 1% fiber content, the order of an increasing rate was glass fiber, carbon fiber, vinylon fiber and steel fiber. 4. As the fiber content was increased, the flexural strength and the toughness index of the vinylon fiber reinforced concrete was increased and the increasing rate of the toughness index was still larger than that of the flexural strength.

微少 모르터르供試體의 引張强度 特性

곽기주 順天大學校 師範大學 附屬 科學敎育硏究所 1996 科學과 敎育 Vol.4 No.-

To study characteristics of tensile strength of exopsed surface of mortar, strength test and measurement of pore volume of mortar specimens with different contents and sizes of fly ash were conducted with the following conclusions. (1) Tensile strength of mortar hardened in water for 91 days is 2.8 times stronger than in humid atmosphere. (2) Tensile strength of mortar hardened in 50% relative humidity is decreased as the size of the specimen increases. On the contrary the tensile strength curing in 25% relative humidity is constant irrespective the size of the specimen. (3) Tensile strength of the mortar decreased as the total pore volume increases. (4) Tensile strength of the mortar hardened in sea water increased as the size of the specimen increases. Tensile strength of the mortar 5 cm diameter increased with the hardening period. Mortar hardened 28days and 91 days is 1.6 times, 1.9 times stronger than 7days hardening. (5) Tensile strength of the mortar decreased with increasing fly ash contents. The tensile strength of the mortar with the contents of 8% and 15% fly ash is 0.87 times and 0.75 times than 7 days hardening.

실리카흄을 이용한 고강도 콘크리트의 기초적 성질

곽기주,이경동,곽동림 순천대학교 기초과학연구소 1996 基礎科學硏究誌 Vol.7 No.-

An experimental study of the application of silica fume for the high strength concrete was conducted. Nine specimens with the variation of the contents of silica fume Owt%, 10wt%, 20wt% and that of water-cement ratio 30%, 40%, 50% were tested. Results show that 10% of silica fume and 30% of water-cement ratio has a maximum strength with 700kg/㎠ of compressive strength and 64kg/㎠ of splitting tensile strength and 100kg/㎠ of flexural strength. Slump value of the tested samples decreases with increasing water-cement ratio and elapsed time of silica fume. Splitting tensile strength(σ_t) and flexural strength(σ_f) and static modulus of elasticity (E) can be correlated with compressive strength(σ_c) from a regression analysis.

減水劑를 添加한 큰크리트의 强度特性에 關한 硏究

郭基柱 順天大學校 1985 論文集 Vol.4 No.1

This study on the purpose of investigating the strength properties of high strength conrete was set about with the failure test after making the specimen with concrete added by water reducing agent. The results of studying are as follows; The use of water reducing agent resulted in the possiblity of reducing the water cement ratio of which slump is 10㎝~13cm Concrete by under the rate of 40% Using water reducing agent 1 can raise the compressive strength which is 28days of material age to 800㎏/㎠ The rate between the compressive strength and tensible strength of the high strength concrete was approximately 16 Material age from 28days to one year of which the growth rate of Compressive strength was 20%, which was highest in the time of standard curing.