폐주불사를 혼입한 콘크리트의 내구성에 관한 연구

김태경,박정호,이정호,이주형,박제선,김연경,윤경구 강원대학교 석재복합신소재제품연구센터 1998 석재연 논문집 Vol.3 No.-

콘크리트 구조물은 자연적인 혹은 인위적인 온도의 상승, 강하로 인하여 동결-융해 작용을 받게 되어 구조물의 성능저하를 야기시킨다. 현대에 들어서면서 콘크리트의 내구특성을 파악하기 위한 연구적 요구가 증가되고 있다. 따라서 폐주물사 콘크리트를 실제 구조물에 적용하기 위해서는 내구특성에 대한 연구가 반드시 이루어져야 한다. 폐주물사를 혼입한 콘크리트의 내구특성을 파악하기 위한 동결-융해 실험은 폐주물사의 잔골재 치환율, 물-시멘트비, AE제 사용 여부를 주요 변수로 하여 실시하였다. 원형공시체를 제작하여, 동결-융해 시험기에 넣어 -18∼4℃로 급속 동결-융해를 진행시키면서 매 23싸이클마다 동탄성계수를 측정하였다. 실험결과 AE제를 첨가했을 때 물-시멘트비가 적을수록, 폐주물사의 치환율이 클수록 전반적으로 강도가 증가하는 것으로 나타났으며, 물-시멘트비가 증가함에 따라, AE제를 사용한 콘크리트가 동결-융해 저항성이 증가하는 것으로 나타났다. 특히 폐주물사 치환율이 50%일 때가 동결-융해 저항성이 가장 좋은 것으로 나타났으며 그 다음으로 25, 0% 순으로 저항성이 좋은 것으로 나타났다. 따라서 폐주물사 콘크리트가 내구성이 우수한 것으로 나타나 폐주물사를 콘크리트에 재활용 할 수 있는 것으로 나타났다. Concrete structures has been deteriorated by the freezing and thawing due to temperature gap. This study was conducted to evaluate durability of concrete which are increasingly demanded recently. Therefore the research of durability must be executed for application of waste foundry sand concrete real structures. Concrete durability properties incorporating waste foundry sand was performed with the variable of W/C ratio, Sand/Waste foundry sand ratio and Air entrainment-Non air entrainment. Cylinder specimens were made and subjected to freezing and thawing cycle at -18℃ and 4℃. Dynamic modulus of elasticity were evaluated as F/T cycle increase. The results show that strength of concrete is increased the W/C ratio decrease, the Sand/Waste foundry sand ratio increase when the concrete contains AE agent and decreasing W/C ratio and AE concrete makes improved resistance of freezing and thawing improved. Especially, resistance of freezing and thawing is improved by Fine aggregate/Waste foundry sand ratio which is 50%, 25%, 0% in a row. Therefore it is turn out the waste foundry sand could be applied to concrete from the experiment.

라텍스 개질 콘크리트의 강도발현 및 내구특성

윤경구,홍창우,이주형,이종명 강원대학교 석재복합신소재제품연구센터 2001 석재연 논문집 Vol.6 No.-

본 연구는 라텍스 혼입률이 5%, 10%, 15%, 20%로 변화할 때 라텍스 개질 콘크리트의 내구 특성을 평가하는데 있다. 라텍스를 콘크리트에 혼입한 라텍스 개질 콘크리트는 보통 콘크리트의 색상과 성형성, 작업성를 갖으며, 약 20%~35%의 단위수향이 감소된다. 그리고 양생후, 콘크리트는 시멘트수화물과 라텍스 입자의 필름막에 의해 연결된 골재로 구성된다. 일반적으로 라텍스 양이 증가하면 콘크리트의 휨강도는 증가하는데, 이것은 라텍스가 시멘트 수화물과 골재사이의 점착력을 증가시키기 때문으로 판단된다. 라텍스 개질 콘크리트와 보통콘크리트와의 상대투수성을 측정하기 위하여 염소이온투과시험법을 사용하였다. 그 결과 라텍스 개질 콘크리트의 투수성은 보통콘크리트의 투수성보다 매우 낮음을 알 수 있었다. 이것은 라텍스가 미세공극을 충진하고 라텍스 입자의 필름막에 의해 골재와 시멘트수화물이 연결 때문이다. 또한 라텍스가 공극주위로 필름막을 형성하기 때문에 공기량이 투수성에 영향을 미치지 못한다는 것을 알 수 있었다. 보통콘크리트에서는 동결융해저항성을 증가시키기 위해 공기연행제를 필요로 하지만, 라텍스 개질 콘크리트에서는 적절한 양생이 이루어지면 추가적인 공기연행제는 요구되지 않는다. 또한 라텍스 혼입률이 증가함에 따라 추가적인 동결융해저항성의 증가는 나타나지 않았다. This study focused on the investigation of strength development and durability of latex modified concrete(LMC) as the latex content variated such as 5%, 10%, 15%, and 20%. When latex was added to concrete, the workability of LMC was quietly increased, compared to that of conventional concrete. This resulted in the decrease of the required water as 20% to 35% in order to obtain a same slump. In general, increasing the amount of latex decreased compressive strength a little but increased flexural strength quite a lot. This might be due to interconnection by a film of latex particles between hydrated cement and aggregates. This, also, might attribute to bonding between the hydrated cement and aggregates. The rapid chloride permeability test was used to evaluate the relative permeability of latex-modified concretes and conventional concretes. The results showed that the permeability of latex-modified concretes was considerably lower than that of conventional concretes tested, which might be due to the latex filled in voids and interconnections of hydrated cement and aggregates by a film of latex particles. Because of latex formed film surrounding the air void, air contents and voids does not effect to the permeability of latex modified concrete.

소포제를 이용한 초속경 LMC의 특성 개선연구

윤경구,김성환,정원경,권혁찬 강원대학교 부설 석재복합신소재 제품연구센터 2003 석재연 논문집 Vol.8 No.-

본 논문은 콘크리트 배합시 발생하는 과도한 기포 발생 문제점을 해결하기 위하여 최적의 소포제 종류 및 혼입률 범위를 산정하여 초속경 라텍스개질 콘크리트 성능을 개선하는 것이다. 초속경 라텍스개질 콘크리트 실험은 2종류의 소포제 A, C와 혼입률 0, 1, 2, 3%을 주요 변수로 하여 공기량 시험, 압축강도 및 휨강도 시험을 수행하였다. 또한, 내구성 평가를 위하여 염소이온 투과실험도 수행하였다. 초속경 라텍스 개질 콘크리트의 공기량시험 결과 소포제 종류에 상관없이 소포제 혼입률 1%이상 첨가시 공기량은 50%이상 감소하였다. 또한, 소포제 첨가에 의한 기포 발생량 감소에 의해서 압축강도의 증진을 이루었다. 초속경 라텍스개질 콘크리트 실험은 A, C 소포제로 선정하여 실험을 수행하였다. 초속경 라텍스개질 콘크리트의 강도 특성에서는 A 소포제 혼입률 1%에서 압축강도 235kgf/㎠ , 휨강도는 조기 교통개방에 요구되는 휨강도 기준 45kgf/㎠를 초과하는 49kgf/㎠를 나타내었다. The purpose of this study was to remove the excessive air foaming which was produced in mixing the RSLMC(latex-modified concrete with rapid-setting cement) by choosing the best antifoam agent type and the optimized quantity for performance improved RSLMC. The main experimental variables such as antifiamer types(A, C), antifoamer contents(0, 1, 2, 3%), and latex contents(15%). Air content test and compressive, flexural tests were carried out to measure the improved properties of RSLMC. the rapid chloride permeability was carried out to estimate a durability of RSLMC. The results of RSLMC showed that the decrease of 50% air content was obtained by admixturing a antifoam agent by 1%. Two kinds and the optimized quantities of antifoam agent were selected for using in RSLMC. The results of RSLMC were obtained at a latex content of 15% and a antifoam agent quantity of 1% with antifoamer A type. The compressive strength and flexural strength at 3 hours after RSLMC placement were 235kgf/㎠ and 49kgf/㎠, respectively, which exceeded the flexural strength criterion of 45kgf/㎠ in order to open the RSLMC placed to traffic.

라텍스 개질 콘크리트의 건조수축특성

윤경구,홍창우,이주형 江原大學校 産業技術硏究所 2001 産業技術硏究 Vol.21 No.B

Drying shrinkage cracking which may be caused by the relatively large specific surface is a matter of grave concern for latex modified concrete(LMC) overlay and rapid-setting cement latex modified concrete(RSLMC) overlay. Therefore, the purpose of this dissertation was to study the drying shrinkage properties of LMC and RSLMC with the main experimental variables such as cement types(ordinary portland cement, rapid setting cement), latex contents(0, 5, 10, 15, 20%), W-C ratios, and curing days at a same controlled environment of 60% of relative humidity and 20℃ of temperature. Test results revealed that the drying shrinkage of latex modified concrete(LMC), rapid-setting cement latex modified concrete(RSLMC) was considerably lower than that of ordinary portland cement concrete(OPC), rapid-setting cement concrete(RSC), respectively. This may be attributed to the interlocking of hydrated cement and aggregates by a film of latex particles, water retention due to hydrophobic and colloidal properties of the latexes, resulting in reduced water evaporation.

요인 실험분석에 의한 SB 라텍스 개질 콘크리트의 강도예측

윤경구,이주형,홍창우 江原大學校 産業技術硏究所 2001 産業技術硏究 Vol.21 No.B

The purpose of this study was to provide the evaluation and prediction of strengths of SB latex modified concrete(LMC) using a statistical method and factorial experimental design method. The main experimental variables were as follows; W/C(4 levels ; 31, 33, 35, 42%), S/a(2 levels ; 55, 58%) and L/C(2 levels ; 5, 15%). The compressive strength and flexural strength of LMC were selected as a factor of response. The statistical method was carried out to analyze the results, together with factorial experimental design method and response surface method. The analysis showed that if L/C had been 15%, W/C appeared to be around 33% to achieve the design strength of 350kgf/cm2. In this case, the flexural strength and the slump came to around 68kgf/cm2 and 18cm, respectively. Eventhough the L/C varied, the design strength and W/C could be predictable together with slump value and flexural strength. As a result of series of experiments in this study, W/C and L/C were proved to be the main factors influencing on the compressive and flexural strength of LMC. Both of strength and slump values could be predictable from the mixing proportion of LMC.

초속경 LMC의 시험시공을 위한 시방배합 및 현장배합 연구

윤경구,김성환,정원경,최성욱 강원대학교 부설 석재복합신소재 제품연구센터 2002 석재연 논문집 Vol.7 No.-

본 논문은 콘크리트 배합시 발생하는 과도한 기포 발생 문제점을 해결하기 위하여 최적의 소포제 종류 및 혼입률 범위를 산정하여 초속경 라텍스 개질 콘크리트 성능을 개선하는 것이다. 초속경 라텍스 개질 모르타르 실험은 4종류의 소포제 A, B, C, D와 혼입률 0, 1, 2, 3%을 주요 변수로 하여 실험을 수행하였으며, 초속경 라텍스 개질 모르타르 및 콘크리트의 특성을 분석하기 위하여 공기량 시험, 압축강도 및 휨강도 시험을 수행하였으며, 투수특성을 분석하기 위해서 염화이온 투과시험을 수행하였다. 초속경 라텍스 개질 모르타르의 공기량시험 결과 소포제 종류에 상관없이 소포제 혼입률 1%이상 첨가시 공기량은 50%이상 감소하였다. 또한, 소포제 첨가에 의한 기포발생량 감소에 의해서 압축강도의 증진을 이루었다. 초속경 라텍스 개질 콘크리트 실험은 모르타르 실험에서 우수한 특성을 나타낸 A, C 소포제로 선정하여 실험을 수행하였다. 초속경 라텍스 개질 콘크리트의 강도 특성에서는 A 소포제 혼입률 1%에서 압축강도 235 kgf/㎠, 휨강도는 조기 교통개방에 요구되는 휨강도 기준 45kgf/㎠를 초과하는 49kgf/㎠를 나타내었다. 초속경 라텍스 개질 콘크리트의 투수성을 분석하기 위한 염화이온투과시험에서 A 소포제는 각각 혼입률 1%, 2%에서 가장 우수한 투수저항성을 나타내어 재령 28일에서는 통과전하량이 100쿨롱 이하를 나타내어 불투수성을 나타내었다. The purpose of this study was to remove the excessive air foaming which was produced in mixing the RSLMC(latex-modified concrete with rapid-setting cement) by choosing the best antifoam agent type and the optimized quantity for performance improved RSLMC. A series of RSLMM(latex-modified mortar with rapid-setting cement) experiments were carried out as the basic for RSLMC with the main experimental variables such as antifiamer types (A, B, C, D), antifoamer contents (0, 1, 2, 3%), and latex contents (15%). A series of RSLMC experiments, also, were carried out with the similar main experimental variables but with the selected antifoamer types (A, C). Air content test and compressive, flexural tests were carried out to measure the improved properties of RSLMM and RSLMC. Chloride ion permeability test was carried out to estimate water permeability resistance. The results of RSLMM showed that the decrease of 50% air content was obtained by admixturing a antifoam agent by 1%. Two kinds and the optimized quantities of antifoam agent were selected for using in RSLMC. The results of RELMC were obtained at a latex content of 15% and an antifoam agent quantity of 1% with antifoamer A type. The compressive strength and flexural strength at 3 hours after RSLMC placement were 235 kgf/㎠ and 49kgf/㎠, respectively, which exceeded the flexural strength criterion of 45 kgf/㎠ in order to open the RSLMC placed to traffic. The rapid chloride permeability test was used to evaluate the permeability of RSLMC. The optimited quantity of antifoamer A and C type were 1% and 2% for the permeability test, respectively. The chloride permeability using A and C antifoamer at 28 days were below 100 coulombs, which was the permeability rating of negligible according to ASTM.

줄눈콘크리트 포장의 줄눈 거동 측정

윤경구,김동호,홍창우,이주형 江原大學校 産業技術硏究所 2001 産業技術硏究 Vol.21 No.B

In this research, the early-age movements of joint at JPCP(Jointed Plain Concrete Pavement) were measured by field tests. The field tests were carried out for 5 days just after concrete placement, for 1 day after 52 and 72 days on Chung-Ang Expressway construction site in Dan-Yang on the 28th and 29th of May 2001. The joint movements were measured by demec gauge and clip gauge. The results of regression analysis for the data measured during early 5 days showed that the joints of No.4, No.5, No.6, No.10, No.13, and No.15 could be considered as a moving joint. From data analysis on July 20, the joints of No.2, No.9, and No.10 showed the significant correlations from the minus value of coefficient of regression. As a result of regression data on August 8, joint movements occurred at all joints. Joint freezing and closure could be judged from the regression analysis using joint opening and total temperature measured at field tests.

VES-LMC 덧씌우기를 이용한 콘크리트 포장 보수

정원경,김용곤,김기헌,윤경구 강원대학교 산업기술연구소 2005 産業技術硏究 Vol.25 No.B

Since in 1970, the length of concrete pavements(JCP, JRCP and CRCP) are growing rapidly at both of main highways and local roads. Many of them are deteriorated and old enough to be repaired or replaced. The pavement is more important than the other infrastructures and it is very difficult to go around or block the traffic during the rehabilitation. The very-early strength latex-modified concrete(VES-LMC)may offer the advantages of high-early-strength, higher flexural strength, higher bond strength, and improved durability. The VES-LMC could be used at a kind of fast track ofr early opening to the traffic after 3 hours of concrete placement. The installation of VES-LMC overlay at Jung-Boo highway was successfully done from April 28 to 29, 2005. The traffic was closed at 07:00 PM and opened to traffic at 08:30 AM. The compressive and flexural strength of VES-MC were more than 28MPa, 6.2MPa after 4 hours, respectively.

라덱스 혼입률에 따른 철근콘크리트의 휨파괴 거동특성

정원경,김동호,이주형,임홍범,윤경구 江原大學校 産業技術硏究所 2002 産業技術硏究 Vol.22 No.A

Reinforced concrete(R/C) is commonly used to structures because they have many merits that compressive strength, economy and so on. However, reinforced concrete has a crack at the tensile section which is due to the relatively lower tensile strength than its compressive strength. Latex modified concrete(LMC) has higher tensile and flexural strength than the ordinary portland cement, due to the interconnections of hydrated cement and aggregates by a film of latex particles. The purpose of this study was to investigate the flexural behavior of reinforced concrete beam with latex modified concrete, having the main experimental variables such as concrete types(ordinary portland cement concrete, latex modified concrete), latex contents(0%, 15%), flexural steel ratios(0.012, 0.0235), and with/without shear reinforcement. The beam of LMC showed considerably higher initial cracking loads and ductility than that of OPC, but, similar to ultimate strength and deflection. This might be attributed to the interlocking of hydrated cement and aggregates by a film of latex particles, water retention due to hydrophobic, and colloidal properties of the latexes resulting in reduced water evaporation. The beam with latex modified concrete could be adopted at field for controlling and reducing the tensile crack due to its higher tensile strength.

콘크리트 공극 분석을 위한 평면간격계수의 제안

정원경,최성용,김성환,윤경구 江原大學校 産業技術硏究所 2005 産業技術硏究 Vol.25 No.A

Air void systems in hardened concrete has an important influence on concrete durability such as freeze-thaw resistance, water permeability, surface scaling resistance. Linear traverse method and point count method described at ASTM are the routine analysis of the air void system that have been widely used to estimate the spacing factor in hardened concrete. Recently, many concretes often have a spacing factor higher than the generally accepted 200-250㎛ limit for the usual range of air contents. This study is proposed to estimate the plane spacing factor by calculation of simplicity. The plane spacing factor need two parameters that are air content and numbers of air voids in the hardened concrete. Those obtained from the standard air-void system analysis of the ASTM C 457. The equation is valid for all values of paste-to-air ratio because the estimation of paste content is unnecessary at the using ASTM C 457. The plane spacing factor yields a similar estimate of the standard spacing factor.