• Title, Summary, Keyword: 초지연제

Search Result 19, Processing Time 0.032 seconds

Prediction of Setting Time of Concrete Using Fly Ash and Super Retarding Agent (초지연제 및 플라이애쉬를 사용한 콘크리트의 응결시간 예측)

  • Han, Min-Cheol
    • Journal of the Korea Concrete Institute
    • /
    • v.18 no.6
    • /
    • pp.759-767
    • /
    • 2006
  • This paper presents a method to estimate the setting time of concrete using super retarding agent(SRA) and fly ash(FA) under various curing temperature conditions by applying maturity based on equivalent age. To estimate setting time, the equivalent age using apparent activation energy($E_a$) was applied. Increasing SRA content and decreasing curing temperature leads to retard initial and final set markedly. $E_a$ at the initial set and final set obtained by Arrhenius function showed differences in response to mixture type. It is estimated to be from $24{\sim}35KJ/mol$ in all mixtures, which is smaller than that of conventional mixture ranging from $30{\sim}50KJ/mol$. Based on the application of $E_a$ to Freisleben-Hansen and Pederson's equivalent age function, equivalent age is nearly constant, regardless of curing temperature and SRA contents. This implies that the concept of maturity is applicable in estimating the setting time of concrete containing SRA. A high correlation between estimated setting time and measured setting time is observed. Multi-regression model to determine appropriate dosage of SRA reflecting FA contents and equivalent age was provided. Thus, the setting time estimation method studied herein can be applicable to the concrete containing SRA and FA in construction fields.

Setting md Mechanical Properties of Concrete Using Saccharic Type Super Retarding Agent (당분류의 초지연제를 이용한 콘크리트의 응결 및 역학적 특성)

  • 한천구;한민철;윤치환;심보길
    • Journal of the Korea Concrete Institute
    • /
    • v.14 no.4
    • /
    • pp.589-596
    • /
    • 2002
  • In this paper, setting and strength performances of concrete containing saccharic type super retarding agents are investigated under various kinds and contents of super retarding agents. According to test results, as super retarding agents contents increase, slump shows to be increased, while air contents decrease about 1∼2%. Setting time shows to be retarded considerably with increase of super retarding agents. It takes 20 days after mixing to reach final setting in case of concrete containing gluconic acid more than 0.3%. And 10 days after mixing in case of enhancing sucrose, white and brown sugar. Compressive strength of concrete containing super retarding agents is lower than that of plain concrete at early age. However, it keeps up with and exceeds the compressive strength of plain concrete at later age. White sugar md brown sugar shows positive performances in delaying setting time and strength compared to existing super retarding agents. n further investigations on durability are conducted, it is thought that application of white sugar as super retarding agent is available.

Field Application of Setting Time Difference Method Using SRA for Reduction of Hydration Heat of Mass Concrete (매스콘크리트의 수화열저감을 위한 초지연제 응결시간차 공법의 현장 적용 -대전 가오지구 코오롱 하늘채 아파트 현장-)

  • Jeon Chung-Keun;Kim Jong;Shin Dong-An;Yoon Gi-Won;Oh Seon-Gyo;Han Cheon-Goo
    • Proceedings of the Korean Institute of Building Construction Conference
    • /
    • /
    • pp.21-24
    • /
    • 2005
  • In this paper, field application of mass concrete using setting time difference of super retarding agent is reported to reduce hydration heat of concrete placed at newly constructed apartment house in Daejeon. Horizontal placing lift is applied. According to test results,: slump and air content meets the requirement of target values. For compressive strength, it exceeds the nominal strength ordered by the costumer. For temperature history, maximum temperature of center at top section shows $25.6^{\circ}C$, and at bottom section, $35.4^{\circ}C$. According to naked eye's investigation, no hydration heat crack is observed at the surface of concrete.

  • PDF

Construction Considering the Difference of Setting Time of Super Retarding Agent for Reduction of Hydration Heat of Footing Mass Concrete (기초 매스콘크리트의 수화열 저감을 위한 초지연제 응결시간차 공법의 현장 적용)

  • 황인성;배정렬;윤석명;김기철;오선교;한천구
    • Proceedings of the Korean Institute of Building Construction Conference
    • /
    • /
    • pp.95-98
    • /
    • 2003
  • This paper presents the results of field experiment to apply the difference of setting tine method using super retarding agent for reducing hydration heat of mass concrete of foundation. According to the results, as the properties of fresh concrete, base concrete satisfies aimed slump and air content, and there is no difference of slump and air content with mixture of super retarding agent. The mixing ratio of super retarding agent is determined for setting time to be retarded by 12 hours in comparison with base concrete, but because the temperature of the air and concrete is low, the difference of setting time is retarded to 24 hours. In man concrete of foundation to which the difference of setting time method is applied, crack by hydration heat is not seen because the lower concrete of super retarding agent generates heat after generation of hydration heat of the upper concrete.

  • PDF

Fundamental Properties of Low-Heat Concrete According to the Mixing Rate of Super Retarding Agent (초지연제 혼입률에 따른 저발열 콘크리트의 양생온도별 기초물성평가)

  • Park, Byoung-Joo;Choi, Yoon-Ho;Hyun, seung-Yong;Kim, Jong;Han, Min-Cheol;Han, Cheon-Goo
    • Proceedings of the Korean Institute of Building Construction Conference
    • /
    • /
    • pp.90-91
    • /
    • 2020
  • As the construction site has become narrower recently, the importance of mass concrete is naturally being highlighted as skyscrapers become popular. However, it is not possible to install the entire volume per day if the mass concrete is installed due to the Remicon 8⦁5 system and the 52-hour workweek system. When the mass concrete base is divided into several days, cold joints occur because the consolidation of joints is not integrated due to different degree of hardening in the case of the previous layer and the next day. As a result, existing research has shown that if super retarding agent are mixed into Ready Mixed Concrete (hereinafter referred to as Remicon) using sugar as a raw material to delay the curing time of concrete, cold joints are inhibited and cracks are inhibited by reducing the initial hydration heat.

  • PDF

Field Application of Mass Concrete Using Setting Time Difference of Super Retarding Agent for Reduction of Hydration Heat (초지연제의 응결시간차를 이용한 매스 콘크리트의 수화열 저감을 위한 현장 적용)

  • 전충근;심보길;손성운;신동안;오선교;한천구
    • Proceedings of the Korean Institute of Building Construction Conference
    • /
    • /
    • pp.11-14
    • /
    • 2004
  • In this paper, field application of mass concrete using setting time difference of super retarding agent is reported to reduce hydration heat of concrete placed at newly constructed apartment house in Busan. Horizontal placing lift is applied. According to test results. slump and air content meets the requirement of target values. For compressive strength, it exceeds the nominal strength ordered by the costumer. Compressive strength of concrete cured in place is achieved more than the values of nominal strength at l4days. For temperature history, maximum temperature of center at top section shows 58.5$^{\circ}C$, and at bottom section, 62.6$^{\circ}C$. According to naked eye's investigation, no hydration heat crack is observed at the surface of concrete.

  • PDF

Estimation of the Strength Development of the Super Retarding Concrete Incorporating Fly Ash and Blast Furnace Slag (플라이애시와 고로슬래그를 조합 사용한 초지연 콘크리트의 강도증진)

  • Han, Min-Cheol
    • Journal of the Korea Institute of Building Construction
    • /
    • v.8 no.5
    • /
    • pp.119-125
    • /
    • 2008
  • In this paper, the estimation of super retarding concrete incorporating mineral admixtures at the same time including fly ash(FA), blast furnace slag(BS) are studied based on maturity method. The setting time was retarded, as super retarding agent contents increase and curing temperature decreases. In addition, apparent activation energy by Arrhenius function was ranged from $24\sim35$ KJ/mol with slightly difference along with mixture proportion. This value is smaller than existing value $30\sim50$ KJ/mol. Based on strength development estimation. it exhibited comparable relativity between prediction value and measurement value. Therefore, this study provided effective strength development prediction value with super retarding agent contents and mineral admixture combination. Strength development prediction equation provided herein is possibly valid for estimating accurate strength development of the super retarding concrete at the job site.

Estimation of the Setting Time of the Super Retarding Concrete Combining Mineral Admixtures (혼화재를 조합 사용한 초지연 콘크리트의 응결시간 추정)

  • Han, Min-Cheol
    • Journal of the Korea Institute of Building Construction
    • /
    • v.8 no.3
    • /
    • pp.111-117
    • /
    • 2008
  • This study provides the setting time prediction method of super retarding concrete incorporating mineral admixtures at the same time including fly ash(FA), blast furnace slag(BS) based on maturity method. The setting time was retarded, as super retarding agent contents increase and curing temperature decreases. In addition, apparent activation energy by Arrhenius function was ranged from $24{\sim}35KJ/mol$ with slightly difference along with mixture proportion. This value is smaller than existing value $30{\sim}50KJ/mol$. It is Indicated that equivalent age using setting time can be a proper method to predict setting time and it also exhibited comparable relativity between prediction value and measurement value. Therefore, this study provided setting time prediction value with super retarding agent contents and mineral admixture combination. Setting time prediction equation provided herein is possibly valid for estimating precise setting time of the super retarding concrete at the job site.