• Title/Summary/Keyword: admixture

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An Experimental Study on the Freezing Temperature of Admixture Agent for Concrete (콘크리트용 혼화제의 동결온도에 관한 실험적 연구)

  • 한경익;이건철;이진규;윤기원;한천구
    • Proceedings of the Korea Concrete Institute Conference
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    • 1996.04a
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    • pp.48-51
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    • 1996
  • Recently, frost damage of storage tank for admixture agent caused by low temperature in winter and quality deterioration of admixture agent ofen happened. But, many problems are caused because of no applicable regulations of admixture agent facility and so on. Therefore, this study presents the reference data about using and quality control of admixture agent in practice and the judgement data about working out a counter plan of suitable heat insulation of injecion equipment of admixture agent exposed at outside in winter by measuring the freezing point of admixture agent for concrete.

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Development of Self Waterproofing Admixture for Concrete Using Inorganic Admixture (무기질 혼화재를 이용한 콘크리트용 구체방수재의 개발)

  • 한천구;박상준
    • Journal of the Korea Concrete Institute
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    • v.13 no.6
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    • pp.527-535
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    • 2001
  • The watertight property of concrete was examined, that is affected by the sort of self waterproofing admixture and the change of the addition ratio of admixture. Various self waterproofing admixtures were made by changing the mixing ratio of silica fume, zinc stearate and silica sand. The result showed as follows. As the adding ratio of self waterproofing admixture increases, the fluidity is increased and the setting time is delayed. While compressive strength of concrete with self waterproofing admixture A which is currently using is increased until the adding ratio of self waterproofing admixture reached 18kg/㎥ and decreased over 24 kg/㎥, that with self waterproofing admixture B, C and D which are developed are higher than that of A. Absorption is decreased as the adding ratio of self waterproofing admixture and the increasing of age in concrete. Especially, when self waterproofing admixture has a lot of zinc stearate, absorption is decreased manifestly. The property of permeability is similar to that of absorption; permeability is decreased as the adding ratio of self waterproofing admixture and the increasing of age in concrete. Consequently, when the ratio of silica fume, zinc stearate and silica sand in self waterproofing admixture is 1 : 2 : 1 and addition ratio of self waterproofing admixture is 6kg/㎥, the high quality concrete is obtained comparing to the concrete with existent self waterproofing admixture.

A Study on Watertightness Effect of Waterproofing Admixture Mixed Redispersible (재유화형 분말수지계와 규산질계 혼합형 구체방수재의 방수효과에 관한 연구)

  • 김무한;오상근;배기선;박선규;김용로
    • Journal of the Korea Concrete Institute
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    • v.12 no.3
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    • pp.39-46
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    • 2000
  • This study is to investigate the watertightness properties of waterproofing admixture mixed redispersible polymer and siliceous powder. Series I deals with change in micro-structure of mortar by waterproofing admixture according to the water/cement ratios of 0.5, 0.6, 0.7 and 0.8 Crystal growth in micro-structure was observed through SEM to estimate on the watertightness effect of it. SeriesII deals with watertightness properties of waterproofing admixture on water permeability coefficient, crack restoration capacity and carbonation depth. SeriesII deals with watertightness properties of waterproofing admixture on water permeability coefficient, crack restoration capacity and carbonation depth. The result of this study can be summarized as follows. 1) Fluidity of mortar and concrete was increased by adding waterproofing admixture. 2) From observation through SEM. Crystals grew larger and denser in micro-structure as fiberic crystalization. 3) Waterproofing admixture is good watertightness properties in a level of high water/cement ratios and long limit of time. 4) Crack restoration capacity was appeared and durability was progressed by waterproofing admixture.

Autogenous shrinkage of ultra high performance concrete considering early age coefficient of thermal expansion

  • Park, Jung-Jun;Yoo, Doo-Yeol;Kim, Sung-Wook;Yoon, Young-Soo
    • Structural Engineering and Mechanics
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    • v.49 no.6
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    • pp.763-773
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    • 2014
  • The recently developed Ultra High Performance Concrete (UHPC) displays outstanding compressive strength and ductility but is also subjected to very large autogenous shrinkage. In addition, the use of forms and reinforcement to confine this autogenous shrinkage increases the risk of shrinkage cracking. Accordingly, this study adopts a combination of shrinkage reducing admixture and expansive admixture as a solution to reduce the shrinkage of UHPC and estimates its appropriateness by evaluating the compressive and flexural strengths as well as the autogenous shrinkage according to the age. Moreover, the coefficient of thermal expansion known to experience sudden variations at early age is measured in order to evaluate exactly the autogenous shrinkage and the thermal expansion is compensated considering these measurements. The experimental results show that the compressive and flexural strengths decreased slightly at early age when mixing 7.5% of expansive admixture and 1% of shrinkage reducing admixture but that this decrease becomes insignificant after 7 days. The use of expansive admixture tended to premature the setting of UHPC and the start of sudden increase of autogenous shrinkage. Finally, the combined use of shrinkage reducing admixture and expansive admixture appeared to reduce effectively the autogenous shrinkage by about 47% at 15 days.

Study on the Development of High Strength Admixture using Paper Sludge Ash (제지 애쉬를 사용한 고강도 혼화재 개발에 관한 연구)

  • 이재환;서형남;김창률;민경소
    • Proceedings of the Korea Concrete Institute Conference
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    • 1998.10c
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    • pp.87-92
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    • 1998
  • The purpose of this study is to use paper sludge ash as a material in manufacturing high strength admixture. The reactivity of paper sludge ash as iteself is low for the crystallized non-reactive $SiO_2$, but when the $SiO_2$ was removed, the phase component is mainly composed of glass phase which could react with cement hydrates. In this study, we manufactured high strength admixture using separated paper sludge ash, and examined the strength of mortar, spun concrete with and without this high strength admixture in steam curing. The strength of spun concrete with high strength admixture including paper sludge ash was more higher than that of spun concrete without admixture. As a result, it was found that paper sludge ash could be used to a pozzolanic material in manufacturing high strength admixture.

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A Study on the Properties of Concrete Mixed with Pozzolan Inorganic Polymer(PIP) Waterproof Admixture (인공 무기계 구체방수재를 혼입한 콘크리트의 물성에 관한 연구)

  • Chung, Jee-Seung;Shin, Hwa-Cheol;Kim, Jin-Gu
    • Journal of the Korean Society of Safety
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    • v.31 no.4
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    • pp.82-89
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    • 2016
  • In this paper, various of experiments were performed for checking the usefulness of Pozzolan Inorganic Polymer(PIP) Waterproof Admixture. The results of the experiment enabled to set the optimum mixture ratio of PIP waterproof admixture as 3.5%. Then, the test specimen mixed with PIP waterproof admixture was produced and consider whether meeting the quality standard of waterproofing admixture for concrete (KS F 4926) From the results, all the items such as mechanical properties and durability were meet the quality standard of KS. The PIP waterproof admixture concrete shows the high resistance of absorption, permeability and chloride ion penetration thanks to its internal components such as siliceous powder, zinc stearate and dispersive polymer.

Effect of Addition of Special Admixture to ERCO, on the Quality of Normal Strength Mortar (ERCO에 특수혼화제 첨가가 보통강도 모르타르의 품질에 미치는 영향)

  • Kim, Tae-Woo;Baek, Cheol;Lee, Jea-Hyeon;Kim, Jong;Han, Min-Cheol;Han, Cheon-Goo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2017.11a
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    • pp.75-76
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    • 2017
  • In this study, it is speculated that the special admixture can be mixed with ERCO beforehand to prevent adsorption of cement and AE at the time of contamination together with water, and the change in the amount of special admixture preliminarily added to ERCO We will try to analyze the influence on normal strength mortar. As a result, the flow quantity, the air quantity, the compressive strength and the flexural strength were improved as the added amount of the special admixture was increased, and When the special admixture with the addition amount of ERCO 3% was added, the strength was rather lowered. Therefore, it was found that the optimum amount of special admixture added to ERCO was 2%.

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Influence of Air Void Characteristic on Chloride Diffusion Coefficient and Compressive Strength of Concrete using Urea and Sulfur (요소와 유황을 첨가한 콘크리트의 압축강도와 염화물 확산계수에 대한 공극특성의 영향)

  • Kim, Jae Hyun;Hong, Ki Nam;Jeon, Byeong Gu
    • Journal of the Korean Society of Safety
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    • v.31 no.4
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    • pp.75-81
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    • 2016
  • This study presents the effect of urea and sulfur admixture on compressive strength, chloride diffusion coefficient, and internal void distribution of concrete. Compressive strength of concretes with urea admixture by 5% increased by 5% relative to Control. However, that of concretes with urea admixture over 10% decreased. Chloride diffusion coefficient of concrete with urea and sulfur admixture decreased by 40% relative to Control. Additionally, the volume of internal void of concrete with urea and sulfur admixture decreased by 20% relative to Control. Therefore, it can be mentioned from test results that the use of adequate urea and sulfur admixture improves the mechanical properties and durability of concrete.

A Study on the Early-Age Strength Property of Concrete Using Liquid Admixture (액상형 조강제를 사용한 콘크리트의 초기강도 특성에 관한 연구)

  • Song, Tae-Hyeob;Lee, Sea-Hyun;Ryu, Deug-Hyun;Park, Cho-Bum
    • Proceedings of the Korea Concrete Institute Conference
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    • 2006.05b
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    • pp.469-472
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    • 2006
  • Amount used of admixture fare is increasing for concrete economic efficiency and ability security. Security of economic efficiency and ability can expect by use of this admixture fare but is displaying a lot of problems on early age strength hold by hydrate delay relatively. Specially, in the case of construction site, concrete strength can speak that interrelation is high with mold removal of forms time. Therefore, is economical and need examination of plan that can secure robber within 3 days using admixture fare such as fly ash and blast furnace slage differential speech to secure function. In this study, adding liquid admixture within 1% of a binding agent quantity to examine these problem with physical characteristic after hardening ago specially, strength change at standard and air dry curing of observed change in priority. Air dried and water curing total strength enhancement effects appeared by thing which is in case of add test result liquid admixture by below 1% and strength deputy by passage of age could know is not big.

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A Study on the Chemical Admixture According to Target Slump Value by Crushed Sand Replacement Rate (부순모래 치환율별 목표슬럼프 값 고정에 따른 화학혼화제의 특성에 관한 연구)

  • Ryu, Hyun-Gi;Cho, Myeong-Ken
    • Journal of the Korea Institute of Building Construction
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    • v.8 no.4
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    • pp.87-93
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    • 2008
  • With an increased use of alternative aggregate due to exhaustion of quality aggregate resources, the amount of used crushed aggregates have been increased and as a result, development of admixture materials has also been improved and its amount of use is increasing from day to day in order to secure quality in concrete. Accordingly, the purpose of this study is to make concrete of good quality by using chemical admixture developed in this study by replacement rate of fine aggregate. At first, susceptibility, compressive strength ratio and length change ratio in both fresh and hardened concrete were evaluated according to corresponding regulation. As for high performance related regulation, APC NO.3 and PC series were going to rule, and as for AE agent regulation, replacement ratio of fine aggregate of high performance chemical admixture was 10:0 and other chemical admixture met quality regulation for AE agent.