• Title/Summary/Keyword: rapid hardening cement

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On the Rapid Hardening Cement (I) (초속경시멘트 제조에 관한 연구 (제1보 시멘트 제조))

  • 한기성;최상흘;한상목;서일영
    • Journal of the Korean Ceramic Society
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    • v.12 no.2
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    • pp.21-25
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    • 1975
  • As the major alumina source, domestic alunite was applied to synthesize the clinker for rapid hardening cement. The main minerals of the clinker were found to be C3S, C11A7-CaF2 and some C4AF by means of chemical treatment, x-ray diffraction analysis and microscopic observation. Rapid hardening cement was made of the clinker by adding suitable amount of hemi-hydrite and anhydrite. The setting time of the cement was regulated with citric acid as setter.

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An Experimental Study on the Properties of Ultra Rapid Hardening Mortar Using Magnesia-Phosphate Cement (마그네시아 인산염 시멘트를 사용한 보수용 초속경 모르타르의 특성에 관한 실험적 연구)

  • Ahn, Moo-Young;Jung, Sang-Jin
    • Journal of the Korea Institute of Building Construction
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    • v.7 no.4
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    • pp.109-116
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    • 2007
  • Building structures are generally large in size and have a long life, and the construction of such structures requires the investment of a huge amount of money and social infrastructure. Furthermore, building structures are closely related to people's life. Recently, however, the rapid development of society has been worsening air pollution, which is in turn accelerating the degradation of building structures. Thus, the safety of building structure is emerging as a critical issue. To cope with this problem, the government enacted "The Special Act on Safety Control for Infrastructure" but we need engineers' higher concern over the maintenance and reinforcement of existing structures. Recently researches are being made actively on repair mortar using ultra rapid hardening cement for recovering the performance of structures. The present study conducted an experiment on the basic physical properties of ultra rapid hardening mortar for repairing and reinforcing building structures using magnesia cement and mono-ammonium phosphate. In the experiment, we changed the water-cement ratio and carried out replacement at different ratio of MAP/MgO(%). We used retarder to have working life, and made comparative analysis through evaluating working life and fluidity and measuring strength by age.

A Study on Design of High Early Strength Cement and Concrete for Road Way Pavements (신속개방형 콘크리트 도로포장재의 설계를 위한 실험실적 평가 연구)

  • 임채용;엄태선;신국재;이종열;엄주용;조윤호
    • Proceedings of the Korea Concrete Institute Conference
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    • 2001.05a
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    • pp.295-300
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    • 2001
  • In road pavements, it is known that cement concrete pavement has superior durability, safety in compared with asphalt concrete pavement. But in reparing 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 mixied concrete because of rapid setting time, high slump loss and other restrictions. We aim to develope specific cement and concrete developing 1 day strength of over 300 kg/$cm^{2}$ to open the road within one day and workable time is maintained over 1 hour that can be used as ready mixed concrete. In this study, we Produced cement using rapid-hardening cement, Hauyne clinker, anhydride gypsum and accelerator and studied on its properties. The concrete strength was over 300 kg/$cm^{2}$ at 1 day and 550 kg/$cm^{2}$ at 28 day and workable time was maintained for over 1 hour.

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A Study on Evaluation of High Early Strength Concrete as Pavement Overlay Materials for Early Traffic Opening(2) (신속개방형 콘크리트 도로포장재의 설계를 위한 평가 연구(2))

  • 엄태선;임채용;유재상;이종열;엄주용;조윤호
    • Proceedings of the Korea Concrete Institute Conference
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    • 2001.11a
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    • pp.233-238
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    • 2001
  • In road Pavements, it is known that cement concrete pavement has superior durability, safety compared with asphalt pavement. 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 aim to develope special cement and concrete developing 1 day strength of over 300 kg/$\textrm{cm}^2$ to open the road within one day and workable time is maintained over 1 hour that can be used as ready mixed concrete. In this study, we produced cement using rapid-hardening cement, Hauyne clinker, anhydride gypsum and accelerator and studied on its properties. The comperssive strength was over 400 kg/$\textrm{cm}^2$ and tensile at 1 day and workable time was maintained for over 1 hour.

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Study on the Strength Development of cement paste using High-Early-Strength Cement and Hardening Accelerator (조강시멘트와 경화촉진제가 압축강도에 미치는 영향에 대한 실험적 연구)

  • Min, Tae-Beom;Jo, In-Seong;Lee, Han-Seung
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2013.05a
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    • pp.56-58
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    • 2013
  • In order to develop concrete generating compressive strength of 15MPa~30MPa aging for 6~12 hours in the room temperature curing, Hardening accelerator containing Ca2+ mixed with rapid hardening portland cement containing C3S in quantity. The result was that the more addictive contents of Hardening accelerator is, the more greatly early compressive strength was improved. That s because the composition of Ca(OH)2 was mass-produced at early-ages.

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Solidification/stabilization of Hazardous Wastes Using Cementitious Materials(III) (특수시멘트 고형화재를 이용한 지정폐기물의 고형화/안정화(III))

  • Lim, Chae-Yong;Ku, Ki-Dae;Um, Tae-Sun;Lee, Jong-Ryul;Choi, Long;Oh, Byoung-Hwan
    • Proceedings of the Korea Concrete Institute Conference
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    • 2001.05a
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    • pp.289-294
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    • 2001
  • This study concerns the cement-solidification/stabilization of the waste with high concentration heavy metals. Compressive strength and leaching test of heavy metals were evaluated for ing types of cements and the effect of the additives of Hauyne clinker and slag were also cussed. Using ordinary portland cement, rapid hardening portland cement and the cement with additives solidification materials, it shows that the strength and stability of concrete is satisfactory and superiority is in the order of rapid hardening portland cement > the cement with additives > nary portland cements.

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A Study on the Characteristics of Cement, Concrete from kinds of Admixture for Rapid Hardening (조기강도 발현을 위한 혼화제별 시멘트 콘크리트의 특성 연구)

  • Lee, Won-Am;Um, Tai-Sun;Lee, Jong-Ryul
    • Proceedings of the Korea Concrete Institute Conference
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    • 2006.11a
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    • pp.469-472
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    • 2006
  • The use of admixture(PNS type & PC type) played a important role in the development of rapid hardening concrete. This paper presents an experimental study on the effect of a kinds of admixture on hydration characteristics, mini slump, apparent viscosity of fresh cement pastes and workability, compressive strength properties of hardened concrete for rapid hardening. Measurements have showed that their characteristics depends on the type of the admixture. As a result, the excellent quality was obtained, also being widely used for the construction field is expected.

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Effects of H$_2$BO$_3$ on the Hydration of $C_4$A$_3$S Blended Rapid Hardign Cement (CSA계 혼합 시멘트 수화에 미치는 Boric Acid 의 영향)

  • Yoo, K.S.;Lee, K.H.;Kim, N.H.;Lee, Y.S.;Hun, K.H.;Lee, J.W.;Yim, Going
    • Journal of the Korean Ceramic Society
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    • v.35 no.6
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    • pp.583-593
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    • 1998
  • The study was carried on the influence of {{{{ { {H }_{3 }BO }_{3 } }} for hydration of blended rapid hardening cement which was composed of {{{{ {{C }`_{4 } ^{ }A }_{3 } }} Adding {{{{ { {H }_{3 }BO }_{3 } }} to the mortar of blended rapid hardening cement delayed the setting time and increased the flow of the mortar. When {{{{ { {H }_{3 }BO }_{3 } }} added to the blended rapid hardening cement mono-sulfate was produced rather than ettringite and the existing time of monosulfate also prolonged. After hours monosulfate was converted to ettringite through being producted like gels. This monosulfate phase in-fluences on the setting time and flow of fresh mortar.

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Compressive and Adhesive Strengths of Mortars using Re-emulsification Type Polymer and Ultra-Rapid-Hardening Cement (재유화형 분말수지와 초속경 시멘트를 혼입한 모르타르의 압축강도 및 접착강도 특성)

  • Lee, Kwang-Il;Yoon, Hyun-Sub;Yang, Keun-Hyeok
    • Journal of the Korea Institute of Building Construction
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    • v.18 no.4
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    • pp.329-335
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    • 2018
  • The objective of this study is to develop a mortar mixture with high workability and adhesive strength for section jacketing in seismic strengthening technology of existing concrete structures. To achieve targeted requirements of the mortars (initial flow exceeding 200 mm, compressive strength of 30MPa, and adhesive strength exceeding 1MPa), step-by-step tests were conducted under the variation of the following mixture parameters: water-to-binder ratio, sand-to-binder ratio, polymer-to-binder ratio, dosage of viscosity agent, and content of ultra-rapid-hardening cement. The adhesive strength of the mortars was also estimated with respect to the various surface treatment states of existing concrete. Based on the test results, the mortar mixture with the polymer-to-binder ratio of 10% and the content of ultra-rapid-hardening cement of 5% can be recommended for the section jacketing materials. The recommended mortar mixture satisfied the targeted requirements as follows: initial flow of 220 mm, high-early strength gain, 28-day compressive strength of 35MPa, and adhesive strength exceeding 1.2MPa.

Mechanical and Durability Characteristics of Latex-Modified Concrete Using Ultra Rapid Hardening Cement (초속경 시멘트를 이용한 라텍스 개질 콘크리트의 역학성능과 내구성능)

  • Park, Sang-Hyun;Jung, Si-young;Kim, Hyun-yu;Choi, Kyoung-Kyu
    • Journal of the Architectural Institute of Korea Structure & Construction
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    • v.35 no.5
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    • pp.153-160
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    • 2019
  • The purpose of this study was to investigate the mechanical and durability characteristics of latex-modified concrete using ultra rapid hardening cement : four types of mechanical tests including compressive strength, modulus of elasticity, flexural strength and bond strength were performed; and seven types of durability tests including resistance of concrete to chloride ion penetration, freeze-thaw resistance, scaling resistance, coefficient of thermal expansion, cracking tendency, abrasion resistance and drying shrinkage were performed. Required material performance of each test was determined in accordance with the Korea specification for repair of concrete and pavement repairing materials. The test results satisfied the required material performances, and presented a good mechanical and durability characteristics. In particularly, the materials showed early development of compressive strength, flexural strength and bond strength at 3 and 4 hours after curing. SEM photos were also taken to investigate the micro structures of the materials after chloride ion penetration test.