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혼화재의 치환방법에 따른 콘크리트의 초기 강도발현 특성에 관한 연구
김광화(Jin Guang-Hua),김기정(Kim Ki-Jeong),황인성(Hwang Yin-Seong),이승훈(Lee Seung-Hoon),한천구(Han Cheon-Goo) 한국구조물진단유지관리학회 2003 한국구조물진단학회 학술발표회논문집 Vol.- No.-
This study is investigate the strength development of concrete with the replacing method of admixture at the early age. As a result, the setting time is retarded in comparison with plain concrete in the case of replacement of admixture for cement. And in the case of replacement of admixture for cement and fine aggregate, the setting time of FA replacement is retarded, but that of BS replacement is shortened.
김광화,한민철,한천구 청주대학교 산업과학연구소 2004 産業科學硏究 Vol.21 No.2
In this paper, tests are carried out using the concrete incorporating shrinkage reducing admixture(SRA) to reduce drying shrinkage. According to test results, for fresh concrete properties, increase of SRA content leads to reduce the fluidity and air content sharply. For setting time, use of SRA cause concrete to accelerate setting time. For compressive strength, FA10 concrete(incorporating 10% of fly ash) shows remarkable drop in compressive strength compared to that of plain concrete, meanwhile, slight decrease of compressive strength of BS 20 concrete(incorporating 20% of blast furnace slag) is found with the increase of SRA content. For drying shrinkage, concrete shows decline tendency in drying shrinkage with increase of SRA content. In the scope of this paper, the use of SRA 10% has optimum effects on the concrete properties such as reducing drying shrinkage reasonably as well as enhancing mechanical properties except fluidity.
시멘트 제조사 및 W/C 변화에 따른 콘크리트의 초기 강도발현 특성
金光華,裵正烈,김규도,이승훈,한천구 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.1(구조계)
This study is to investigate the influence of cement manufacturing company and W/C on the properties of fresh concrete, strength of hardened concrete and rebound value of P type Schmidt hammer. According to the result, setting time of concrete is shortened with and increase of W/C, and when cement made in A and B corporation is used in concrete, the final setting time is measured at about 10 hours and 13 hours. Compressive strength increases with elapse of time and decrease of W/C, and concrete using cement made in A corporation shows higher compressive strength and rebound value until 24 hours, but from 3rd day, the contrary tendency is shown. As for the properties of early strength, the strength develop fast with decrease of W/C, and the time when compressive strength of 5MPa is gained and the form can be removed, is about 15, 18, 21 hours and 20, 22, 27 hours at the W/C 40, 45, 50% in concrete using cement made in A and B Co. respectively. The correlativity between compressive strength and the rebound value, which a coefficient of correlation is over 0.97, is very favorable. Therefore this method is effective to estimate the strength of removing the form.
金光華,김종,한민철,정평유,한천구 대한건축학회 2004 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.24 No.1(구조계)
The objective of this paper is to investigate the physical and mechanical properties of concrete incorporating shrinkage reducing admixture(SRA) and mineral admixture(MA) such as fly ash and blast furnace slag powder. According to results, for fresh concrete properties, increase of SRA content leaded to reduce the fluidity and air content sharply. For setting time, use of SRA caused concrete to accelerate setting time, and compared with plain concrete it retarded by incorporating MA. Compressive strength decreased with an increase in SRA content, and when incorporating MA, compared with plain concrete, it shows lower compressive strength in early age but similar or increase by the elapse of age due to the pozzolanic and latent hydration reaction. For drying shrinkage, concrete shows decline tendency with an increase in SRA content due to the relaxation effect at the capillary tension in concrete by SRA. In the scope of this paper, it is found that the use of SRA with 1.0% has optimum effects on the various properties of concrete, and the combinations of SRA and fly ash will ensure the stability for drying shrinkage.
트리에탄올아민의 혼입률 변화에 따른 콘크리트의 초기 강도발현 특성
황인성,金光華,김규동,이승훈,한천구 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.1(구조계)
In this study, the influence of TEA on early strength development of concrete is discussed in order to reduce a construction period in RC structure by early removal of forms. According to the results, as for the properties of fresh concrete, fluidity of concrete shows no difference, and air content increases with an increase of the mixing ratio of TEA. Setting time is shortened upto mixing ratio of 0.025%, but is retarded above the mixing ratio of 0.025%. The time when compressive strength gains 5MPa is fast in about 2 hours in the case of the mixing ratio of 0.05%, but it is retarded above the mixing ratio of 0.05%. The relativity between compressive strength and the rebound value of P-type Schmidt hammer is also favorable at early age, and compressive strength of 5MPa, which the side forms can be removed, is estimated at the rebound value of 23.
회수수 안정화제를 사용한 콘크리트의 공학적 특성에 관한 연구
김기정,金光華,이문환,이세현,한천구 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.2
In this study is investigated the engineering properties of concrete using stabilizing agent of recycling water in order to suggest a practical use of recycling water. According to the results. as stabilizing agent is added. fluidity and air content varies slightly with W/C, but does not make a big difference. Bleeding is reduced by adding stabilizing agent, and so it decreases by about 40% at the adding ratio of 0.15%. When stabilizing agent is not added, compressive strength decreases in comparison with plain concrete, but increases by adding stabilizing agent, so it is largest at adding ratio of 0.30%(W/C 30%) and 0.15%(W/C 40, 50%). Length change by drying shrinkage is larger than plain concrete in the case of no adding of stabilizing agent, but decreases by the use of stabilizing agent. Therefore, it is thought that when stabilizing agent is added to recycling water, quality deterioration of concrete is prevented, moreover, quality of concrete can be improved.
수축저감제 혼입률 변화에 따른 콘크리트의 공학적 특성에 관한 연구
한민철,金光華,정규문,정평유,윤성노,한천구 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.2
In this paper, tests are carried out using concrete incorporating shrinkage reducing agent(SR) in order to investigate the engineering properties of concrete. The contents of SR and W/C are varied. According to test results, as for fresh concrete, as SR content increases, slump and air content shows decline tendency, and setting time is accelerated with increase of SR content and decrease of W/C. As for compressive strength, as SR contents increases compressive strength shows to be decreased. As for the effect of SR on drying shrinkage, it shows to be reduced with increase of SR content. This is due to the reduced surface tensile strength of water and tensile strength of capillary pore in concrete.