• 콘크리트학회지
• /
• 제11권2호
• /
• pp.85-94
• /
• 1999

플라이애쉬 대체량에 따른 변화, 양생방법이 미치는 영향 그리고 조기강도를 높이기 위해 첨가된 화학 혼화제가 시멘트-플라이애쉬 페이스트의 특징 및 콘크리트 강도에 미치는 영향을 알아보았다. 시멘트-플라이애쉬 페이스트의 압축강도는 시멘트로만 만들어진 페이스트보다 낮았으며, 플라이애쉬의 대체량이 증가할수록 강도차이가 증가하였다. 그러나 증기양생시 시멘트-플라이애쉬 페이스트는 수중양생시보다 압축강도가 증가하였으며, 특히 조기강도가 크게 향상되었다. 조기강도 증진을 목적으로 혼입한 활성화제($Na_2SO_4$)의 첨가는 시멘트-플라이애쉬 페이스트 조기강도를 증진시켰으며, 또한 $Na_2SO_4$와 플라이애쉬를 30% 함유한 플라이애쉬 콘크리트의 강도도 월등히 향상되었다.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2016년도 춘계 학술논문 발표대회
• /
• pp.185-186
• /
• 2016

Four mortar mixes tested to evaluate the early-age compressive strength of magnesia-phosphate composite with phosphate type. Monopotassium phosphate, dipotassium phosphate, ammonium dihydrogen phosphate and diammonium phosphate used as phosphate. Test results show that the compressive strength of mortar used monopotassium phosphate as phosphate was highest, while compressive strength of mortars used dipotassium phosphate and diammonium phosphate as phosphate were not developed.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2018년도 춘계 학술논문 발표대회
• /
• pp.197-198
• /
• 2018

As part of the effort to shorten the construction period, this study examined the strength expression characteristics at the early age of concrete using high fineness cement and blast furnace slag. accordingly to provide a basic data on how to solve the problem that the initial strength is lowered.

• Advances in Computational Design
• /
• 제1권1호
• /
• pp.27-35
• /
• 2016

The influences of chloride-free components of the cement additive: triethanolamine, triisopropanolamine, sodium hyposulfite and calcium gluconate on the 1d, 3d and 28d compressive strength of cement were investigated by response surface methodology. It found the early strength activators, triethanolamine and sodium hyposulfite could enhance the 1d strength of cement effectively but they did not contribute to the 3d strength enhancement, and further their interaction was able to decrease the 28d strength of cement. Calcium gluconate was not that effective for the strength enhancement on 3 and 28 days when it's simply dosed. However the interaction effect of calcium gluconate with triisopropanolamine could strongly favor the strength enhancement of cement after 3 days. Results indicated it was necessary to focus attention on the potential interactions among the chemical components. And for the concern of four chemicals studied in this paper, it was feasible to formulated a kind of chloride-free cement additive that can be effective for the early strength of cement and its the strength after 3 days.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2003년도 학술.기술논문발표회
• /
• pp.99-102
• /
• 2003

This study discusses the determination of removal time of forms with early strength development in high strength concrete. According to the results, as W/B increases by 10％, the setting time is shortened by about 2 hours. The time when compressive strength of 8 MPa is gained is about 20 hours. Bond strength between form and concrete is highest around final setting time, but decreases drastically after that. Amount of concrete sticking on the form is large before setting, but after that, it is little. The rebound value of P type schmidt hammer is measured faster by 2-3 hours than compressive strength. It is also confirmed that the removal of forms is possible when the rebound value of P type schmidt hammer is more than 34

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
• /
• pp.607-612
• /
• 2002

In road pavements, it is known that cement concrete pavement has superior durability, safety compared. But in repairing pavement, cement concrete pavement is not usually applied because of the length of time while the road is interrupted when using Ordinary and Rapid-hardening Portland Cement. And Super High Early Strength Cement and Ultra Super High Early Strength Cement are not favorable for ready mixed concrete because of rapid setting time, high slump loss and other restrictions. We developed special cement developing 1 day strength of over 30.0N/mm$^2$ to open the road within 1 day and workable time is maintained over 1 hour so that it can be used as ready mixed concrete. We performed experimental overlay construction with the cement and evaluated the mechanical property and the durability. At curing temperature of 8-l8$^{\circ}C$,the flexural strength was 6.4N/mm$^2$at 1 day, so that the road can be open to traffic within 1 day. In durability test, the hardened concrete showed higher durability than Portland cement concrete.

• 콘크리트학회논문집
• /
• 제23권6호
• /
• pp.757-763
• /
• 2011

콘크리트의 효율적인 조기강도 확보를 위해 시멘트의 성능 향상에 주안점을 두고 연구를 진행하였다. 이 연구는 선행 연구인 시멘트 생산 공정 중 부수적으로 발생되는 크기가 작은 시멘트(이하 미립자 시멘트, FC라 함)를 이용하는 콘크리트의 조기강도 발현 특성 연구에 대한 후속 연구로서 내구성 검토를 실시하였다. 실험 결과 굳지 않은 콘크리트에서는 각 배합별 목표 범위를 모두 만족하는 것으로 나타났고, 미립자 시멘트를 혼입하였을 때 응결시간은 촉진되었고 압축강도는 증진되었으며 수화열은 유사한 수준인 것으로 평가되었다. 특히, 내구성 측면에서는 미립자 시멘트 혼입 유 에 따라 모든 실험 항목에서 유사한 수준인 것으로 평가되었다.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2009년도 추계 학술논문 발표대회
• /
• pp.157-160
• /
• 2009

The decision of the Form removal time which leads the early assuring strength of the concrete from Apartment construction is the fact which is important from Reducing the period of works and the economical efficiency side. Especially, with Complex building of recent times the same Tall building and Multiple Apartment Site which only follows in upgrade of interior construction of apartment site and shortening the frame construction period becomes very, importantly is the actual condition where the effort which is various for this is attempted. But is caused by with limit and economical efficiency problem of case concrete early strength revelation of most and is not put to practical use is the actual condition. Develops concrete mixture which is a utility from the research which sees hereupon and the effect which is economic leads construction duration shortening under maximizing boil.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
• /
• pp.269-272
• /
• 2004

After concrete casts, temperature decent and shrinkage bring volume changes of concrete pavement. Microcracking and cracking in concrete pavement are caused by these volume changes. As a result, durability of concrete pavement is deteriorated. Recently, Very-Early Strength Latex Modified concrete(below:VESLMC) from the beginning of High-Way is used as urgent repair material for bridge deck. The advantage of VESLMC is that compressive and flexural strength at 3 hours age are 4.5MPa and 21MPa respectively. It allows the traffic to open in 3 hours. But, this material has the problem which is early-age shrinkage cracking caused by water self-dissipation with rapid hydration reaction and water evaporation with body dry. Unfortunately, until now, the research about early-age shrinkage of VESLMC leaves something to be desired. Therefore, the purpose of this study is to present the early-age shrinkage of VESLMC respect to latex contents and shrinkage ratio to maximum length change that can help field engineers' skill. Latex contents of 0, 5, 10, 15, $20\%$ in standard of same workability in VESLMC are selected by experimental variables. After initial set, shrinkage value was measured with 10mm LVDT for 3 days. The results of maximum shrinkage ratio were 0.019, 0.017, 0.023, $0.027\%$ respectively.

• 한국농공학회지
• /
• 제33권2호
• /
• pp.61-72
• /
• 1991

This study was carried out to research the strength drop of concrete in dry environment. The mixing ratio of cement-fine aggregate was 1: 1, 1 : 2, 1: 3 and 1 : 4. The curing was compared standard curing with dry curing immediately after casting. It is analysis of strength change by water-proof mixing. The curing age of cement mortar was 3days, 7days, l4days and 28days. The result obtained from this study are summarized as follows. 1. The compressive and bending strength change by increasing the curing age, dry curing mortar the increasing rate of strength was decreased than standard curing mortar. 2. The compressive and bending strength change in early curing, strength difference between standard curing mortar and dry curing motar was gradually closed by increasing the W/C. 3. The dry curing mortar was decreased than standard curing mortar in decreasing rate of compressive and bending strength by increasing the W/C. 4. The compressive strength of water-proof mortar in early curing, liquid water-proof mortar was shown high strength in dry curing than standard curing. The powder and liquid water-proof mortar have a small effect in dry environment. The liquid water-proof mortar was high strength without relation change of curing age in dry environment than standard curing. 5. The compressive strength of liquid water-proof mortar in poverty mix, dry curing was shown high strength than standard curing. 6. The bending strength was increased than compressive strength by decreasing the volume of cement in early curing. The increasing rate of bending strength was decreased to compressive stength by increasing the curing age.