• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 가을 학술발표회 논문집
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• pp.269-272
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• 2003

This study is intended to investigate the properties of concrete using AE Water Reducing Agent of Early-Strength Type. According to the results, as for the replacing method of mineral admixture, setting time is shortened faster in order of replacement for fine aggregate, combination and replacement for cement, and when AE Water Reducing Agent of Early-Strength Type is used, it is shortened by about 4 hours, compared with normal AE Water Reducing Agent Compressive strength is lower in the case of replacement for fine aggregate, but higher in the other case than that of plain concrete. And When AE Water Reducing Agent of Early-Strength Type is used, early compressive strength is very high in comparison to normal AE Water Reducing Agent. Early strength development is very favorable by the use of AE Water Reducing Agent of Early-Strength Type regardless of the replacing method of mineral admixture at $20^{\circ}C$, but at $l0^{\circ}C$, it is effective for Early strength development that W/B is lowered to below 45%, BS of 20% is replaced for fine aggregate, and AE Water Reducing Agent of Early-Strength Type is used.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2007년도 추계 학술논문 발표대회
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• pp.57-60
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• 2007

This study is to discuss the effect of the liquid type high early strength agent considering early strength, developing strength, and economics of the concrete using admixtures. The powder type high early strength agent does not helpful because the field application is not available such as the problem of mixing process and rack of economics. To make up these subjects, the plain mixture contains the standard type AE water reducing agent, and the types of the agents are the standard type AE water reducing agent(P),liquid type high early strength agent(AD),poly carboxylate high early strength type AE water reducing agent(E1), and naphthalene + melamine high early strength type AE water reducing agent(E2). As the Contents of the agents, E1 and E2 is two types each cases, and P is one type to satisfy the target fluidity and air content, AD is three types as 0.5, 1.0,and 1.5%. In the case that AD is mixed, the fluidity is decreased, but air content is increased. For increasing strength of the early age, using OPC is more effective than FA and BS for increasing the early strength of the concrete, and if the air content is secure as plain, the effect of the developing strength can be increased because the air content is increased about 2% in the case that AD is used.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2013년도 추계 학술논문 발표대회
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• pp.80-81
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• 2013

There is the increasing number of constructing soil or structure on the soft ground during public works. Usually cement or slag cement has been the traditional material for surface soil stabilization method. Recently, early strength development properties of hardening agent is required for driving abilities of execution equipment and shortening of the construction time. Therefore, the purpose of this study is to develop the early compressive strength hardening agent for surface soil stabilization. The study was confirmed performance and availability of hardening agent using early strength type cement and industrial by-product minerals through early strength development properties in accordance with water cement ratio, content of hardening agent for soft soil.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2004년도 학술.기술논문발표회
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• pp.1-4
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• 2004

In this paper. applicability of high early strength type AE water reducing agent(HESAEWA) developed by the authors is discussed by applying Mock-up test. For fresh concrete properties, concrete using existing AE water reducing agent(EAEWRA) and HESAEW A meets the target slump and air content at jobsite. Setting time of concrete using HESAEWA is shorter than that using EAEWRA. Remarkable variance of bleeding and settlement is not observed with type of AE water reducing agent. For hardened concrete properties, use of HESAEW A results in higher strength development compared with that of EAEWRA at standard curing and in field curing condition. Reaching time to accomplish 5MPa of compressive strength. which is possible to remove side form. is taken using HESAEWA earlier than that of EAEWRA by 1day. Therefore, it is confirmed that use of HESAEWA can meet the requirements of general quality of concrete and achieve high early strength development as well as has a desirable field applicability.

• 한국구조물진단유지관리공학회 논문집
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• 제5권2호
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• pp.191-197
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• 2001

In this study, the admixtures for agents for enduring cold weather used widely are collected and applied to cement mortar to analyze the strength development due to variation of curing temperature at early age. The test results show that anti-freezing admixture have some problems due to high chloride content, which may cause the corrosion of reinforcement embedded in concrete. However, the mortar applied by accelerator and another kind of agent for enduring cold weather produced by S company lead to delay of strength development in low temperature. Also, it is clarified that there are no significant problems for cement mortar in strength development due to low temperature if a suitable kind of agent enduring cold weather is used and cement mortar is cured for more than $7.5^{\circ}D.D$ at early age.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(II)
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• pp.309-312
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• 2005

Admixture compounds for shortening setting time and accelerating early strength development of EVA polymer powder-modified mortars were made by mixing various quick setting agents. As a result, the quick setting agents contribute to strength development of the mortars in the early curing age of 168h or less. In the viewpoint of early strength development of EVA polymer powder-modified mortars, an quick setting agent content of 20$\%$ is recommended. Early strength of EVA polymer powder-modified mortars expresses the excellent strength with 5$\%$, 10$\%$ of rates of polymer mixing. The rate of polymer mixing was able to be adjusted and flexural strength which is a predeterminded initial strength was also able to satisfy 3MPa(s).

• 한국건설순환자원학회논문집
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• 제6권2호
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• pp.94-99
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• 2018

본 연구에서는 현장의 골조공사에 주로 활용되고 있는 설계기준강도 21~27MPa 범위의 콘크리트를 대상으로 $10^{\circ}C$ 온도조건의 범위에서 기존 조강형 혼화제를 사용한 것 대비 경화촉진제를 복합사용하여 추가 첨가할 경우 1종 보통포틀랜드를 사용한 콘크리트의 초기 강도발현에 미치는 영향을 검토하고자 하였으며, 조강형 혼화제에 경화촉진제를 단일 첨가한 기존 자료와 촉진 효과가 우수한 3가지의 경화촉진제를 선정하여 이에 대한 복합사용에 대한 검토를 수행하였다. 본 연구의 실험결과 $CaBr_2+NaSCN+DEA$를 복합사용한 경우 $CaBr_2$, NaSCN의 단일사용에 비하여 시멘트량 및 혼화제의 사용에 따라 강도발현율이 증가되는 경향이 나타났으며, 단위 시멘트량 $330kg/m^3$ 이상의 조건에서 복합형태의 경화촉진제를 첨가하게 되면 기존 조강형 혼화제 또는 경화촉진제를 단일 사용한 것에 비하여 5MPa 발현시점이 12시간 정도 단축할 수 있는 것으로 확인되었다.

• Environmental Engineering Research
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• 제21권4호
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• pp.341-349
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• 2016

To improve the utilization rate of construction waste as mine backfilling materials, this paper investigated the feasibility of using recycled powder as mine paste backfilling cementitious material, and studied the pozzolanic activity of recycled construction waste powder. In this study, alkali-calcium-sulfur served as the activation principle and an orthogonal test plan was performed to analyze the impact of the early strength agent, quick lime, and gypsum on the pozzolanic activity of the recycled powder. Our results indicated that in descending order, early strength agent > quick lime > gypsum affected the strength of the backfilling paste with recycled powder as a cementitious material during early phases. The strength during late phases was affected by, in descending order, quick lime > gypsum > early strength agent. Using setting time and early compressive strength as an analysis index as well as an extreme difference analysis, it was found that the optimal ratio of recycled powder cementitious material for mine paste backfilling was recycled powder:quick lime:gypsum:early strength agent at 78%:10%:8%:4%. X-ray diffraction analysis and scanning electron microscope were used to show that the hydration products of recycled powder cementitious material at the initial stages were mainly CH and ettringite. As hydration time increased, more and more recycled powder was activated. It mainly became calcium silicate hydrate, calcium aluminate hydrate, etc. In summary, recycled powder exhibited potential pozzolanic activities. When activated, it could replace cementitious materials to be used in mine backfill.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.663-668
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• 2002

In this paper, insulating effects and strength development of concrete placed at mock up model structure are discussed using anti freezing agent and insulating forms. According to test results, concrete containing 8% of anti freezing agent shows lower freezing temperature, earlier setting time and higher strength development than plain concrete. As for the temperature history of mock up structures, when plain concrete is placed at euro form, the temperature drops to -4${\circ}$ before early 24 hours, and when concrete containing anti freeze agent at euro form, it to -3${\circ}$ before early 24 hours. Nevertheless, when concrete containing anti freeze agent is placed at insulating form, it does not go below zero, and the concrete containing anti freeze agent enhances higher strength development.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회논문집(I)
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• pp.571-574
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• 2000

When fresh concrete is exposed to low temperature, the concrete may suffer from the frost damage at early ages and the strength development may be delayed. To solve such problems of cold weather concreting admixtures called agent for enduring cold climate are developed to prevent the fresh concrete from being frozen at early ages. In this study, the experiments are carried out on several kinds of agent for enduring cold climate to present their performance. According to experimental results, most kinds of agent for enduring cold climate show the strength development in the range $-5^{\circ}C$ of curing temperature, it tends to be delayed at long term maturity without agents for enduring cold climate. while it gains high strength maturity when agents for enduring cold climate is applied.