• Title/Summary/Keyword: cementless mortar

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Evaluation on the Shrinkage and Durability of Cementless Alkali-Activated Mortar (무(無)시멘트 알칼리 활성(活性) 모르타르의 수축(收縮) 및 내구성(耐久性) 평가(評價))

  • Koh, Kyung-Taek;Ryu, Gum-Sung;Lee, Jang-Hwa;Kang, Hyun-Jin
    • Resources Recycling
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    • v.20 no.3
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    • pp.40-47
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    • 2011
  • In this study, we investigated the strength, shrinkage and durability of alkali-activated mortar using blast furnace slag only, and admixed with blast-furnace slag and fly ash as cementious materials in oder to develop cementless alkali-activated concrete. In order to compare with the alkali-activated mortar, the normal mortar using ordinary portland cement was also test. In view of the results, we found out that strength development, the resistance to shrinkage and freezing-thawing of the cementless alkali-activated mortar have better than the mortar using ordinary portland cement. Especially, using the combined with blast furnace slag and fly ash develop high strength of above 60 MPa, reduce shrinkage of about 40% and improve freezing-thawing durability of approximately 20%, but promote the velocity of carbonation of 2~3 times.

Analiysis of Micro-structure of Cementless Mortar Using Fly Ash and Blast Furnace Slag (플라이애시와 고로슬래그를 사용한 무시멘트 모르타르의 미세구조 분석)

  • Kang, Hyun-Jin;Ryu, Gum-Sung;Ko, Kyung-Taek;Kang, Su-Tae;Park, Jung-Jun;Lee, Seoung-Tae
    • Proceedings of the Korea Concrete Institute Conference
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    • 2010.05a
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    • pp.363-364
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    • 2010
  • Recently, various researchers have studied alkali-activated concrete that do cementless as the binder. This study analyzed the effect on cementless mortar by flay ash and blast furnace slag of blast slag as the binder with no use of cement, by observing compressive strength and micro-structure.

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Effect of Superplasticizers and Admixtures on the Fluidity and Compressive Strength Development of Cementless Mortar Using Hwangtoh Binder (혼화제·재가 무시멘트 황토 모르타르의 유동성 및 압축강도 발현에 미치는 영향)

  • Yang, Keun-Hyeok;Hwang, Hey-Zoo;Kim, Sun-Young;Song, Jin-Gyu
    • Journal of the Korea Concrete Institute
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    • v.18 no.6 s.96
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    • pp.793-800
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    • 2006
  • This paper reports test results to assess the influence of superplasticizers and different admixture on the flow and compressive strength development of cementless mortar using developed hwangtoh binder. Test specimens were classified into four groups: series for I the mixing ratio of superplasticizers, series II for a kind and replacement level of admixtures according to the variation of water/hwangtoh binder ratio, series III for the specific surface area and replacement level of ground granulated blast-furnace slag and series IV for the replacement level of powered superplasticizer agent developed to improve slump loss of concrete. The proper replacement level of each admixture is proposed for enhancement the flow and compressive strength of the hwangtoh binder mortar.

Properties of Cementless Loess Mortar Using Eco-Friendly Hardening Agent (친환경 무기질 고화재를 사용한 무시멘트 황토모르타르의 특성)

  • Jung, Yong-Wook;Kim, Sung-Hyun;Lee, Dong-Gyu
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.3 no.4
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    • pp.355-365
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    • 2015
  • This study examined the fluidity and strength properties, water resistance, durability, and freeze-thaw of cementless loess mortar using an eco-friendly hardening agent. The experimental result indicates that 28 days compressive and flexural strength of the loess mortar was increased regardless of the weathered granite soil and loess mixture ratio as the replacement ratio of the hardening agent increases. The strengths were significantly increased until 14 days regardless of the hardening agent, while the effect on the strengths increasement was relatively low after 14 days. Thus, the strength development of loess mortar concrete was found to be faster than that of the normal concrete. In addition, when the hardening agent of 10% was used, the average flexural strength was 1.7MPa which is insufficient compared to the 28-day flexural strength of 4.5MPa for the paving concrete. However, the flexural strengths of the loess mortar concrete using the hardening agents of 20% and 30% were 4.0MPa and 5.3MPa, respectively. Thus, the hardening agent need to be at least 20% so that the loess mortar can be used for paving concrete. The experiment for water resistance shows that the repeated absorption and dry reduced mass regardless of the mixing ratio of the loess. The maximum length change also decreased with increasing the substitution rate loess mixture ratio and the hardening agent. The result of the freeze-thaw resistance test indicates that the relative dynamic modulus of elasticity at 300 cycle freeze-thaw with the hardening agents of 20% and 30% were 75% and 79%, relatively. Thus, the hardening agent of at least 20% is required to obtain the relative dynamic modulus of elasticity of 60% for the loess mortar.

Flowability and Compressive Strength of Cementless Alkali-Activated Mortar Using Blast Furnace Slag (고로슬래그를 사용한 무시멘트 알칼리 활성 모르타르의 유동성과 압축강도)

  • Koh, Kyung-Taek;Ryu, Gum-Sung;Lee, Jang-Hwa;Kang, Hyun-Jin;Jeon, Yong-Su
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.6 no.1
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    • pp.63-71
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    • 2011
  • Portland cement production is under critical review due to high amount of $CO_2$ gas released to the atmosphere. Attempts to increase the utilization of a by-products such as fly ash and ground granulated blast-furnace slag to partially replace the cement in concrete are gathering momentum. But most of by-products is currently dumped in landfills, thus creating a threat to the environment. Many researches on alkali-activated concrete that does not need the presence of cement as a binder have been carried out recently. In this study, we investigated the influence of alkali activator and superplasticizer on the flowability and compressive strength of the alkali-activated mortar in oder to develop cementless alkali-activated concrete using blast furnace slag. In view of the results, we found out that the type and mixture ratio of alkali activator, the type and adding order of superplasticizer results to be significant factors. When cementless alkali-activated mortar using blast furnace slag manufactured with 1:1 the mass ratio of 9M NaOH and sodium silicate, and added superplasticizer before alkali activator in the mixer, we can be secured workability with 180 mm of flow during 1 hours and compressive strength of about 50 MPa under $20^{\circ}C$ curing condition at age of 28days.

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Properties of the Flowability and Strength of Cementless Alkali-Activated Mortar Using the Mixed Fly Ash and Ground Granulated Blast-Furnace Slag (플라이애쉬와 고로슬래그 미분말의 혼합 사용한 무시멘트 알칼리 활성 모르터의 유동성 및 강도 특성)

  • Koh, Kyung-Taek;Ryu, Gum-Sung;Lee, Jang-Hwa
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.5 no.4
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    • pp.114-121
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    • 2010
  • Portland cement production is under critical review due to high amount of CO2 gas released to the atmosphere. Attempts to increase the utilization of a by-products such as fly ash and ground granulated blast-furnace slag to partially replace the cement in concrete are gathering momentum. But most of by-products is currently dumped in landfills, thus creating a threat to the environment. Many researches on alkali-activated concrete that does not need the presence of cement as a binder have been carried out recently. However, most study deal only with alkali-activated ground granulated blast furnace slag or fly ash, as for the combined use of the both, little information is reported. In this study, we investigated the influence of mixture ratio of fly ash/ blast furnace slag tand curing condition on the flowability and compressive strength of mortar in oder to develop cementless alkali-activated concrete. In view of the results, we found out that the mixture ratio of fly ash/blast furnace slag always results to be significant factors. But the influence of curing temperature in the strength development of mortar is lower than the contribution due to other factors. At the age of 28days, the mixture 50% fly ash and 50% ground granulated blast furnace slag activated with 1:1 the mass ratio of 9M NaOH and sodium silicate, develop compressive strength of about 65 MPa under $20^{\circ}C$ curing.

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Strength Development Properties of Alkali-Activated Slag Mortar by Autoclave Curing (오토클레이브 양생에 의한 알칼리활성슬래그 모르타르의 강도발현 특성)

  • Song, Jin-Gyu;Kim, Byeong-Jo;Oh, Myeong-hyeon
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • 2015.07a
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    • pp.218-219
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    • 2015
  • Precast concrete produced in the industry is advantage that easy to manage, and it save construction period in the field. The specimens according to the type of activator for AAS(Alkali-Activated Slag) mortar cured in an autoclave. The specimens of AAS mortar with sodium was shown the high rate of increase of the compressive strength.

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Compressive Strength and Shrinkage Strain of Slag-Based Alkali-Activated Mortar with Gypsum (석고가 첨가된 슬래그 기반 알카리활성 모르터의 압축강도 및 건조수축 변형률)

  • Yang, Keun-Hyeok;Sin, Jae-Il
    • Journal of the Korea Institute of Building Construction
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    • v.8 no.1
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    • pp.57-62
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    • 2008
  • Twelve mortars were mixed and tested to explore the effect of gypsum on the compressive strength development and shrinkage strain of alkali-activated mortars. Powder typed sodium silicate and ground granulated blast-furnace slag were employed as alkaline activator and source material, respectively, to produce cementless mortar. The main variables investigated were alkali quality coefficient combining the concentration of activator and main compositions in source material, and the adding amount of gypsum ranged between 1 and 5% with respect to the weight of binder. Initial flow, compressive strength development, modulus of rupture, and shrinkage strain behavior of mortar specimens were measured. In addition, the hydration production of alkali-activated pastes with gypsum was traced using X-ray diffraction and energy-dispersive X-ray analysis combined with scanning electron microscope image. Test results showed that the initial flow of slag-based alkali-activated mortar was little influenced by the adding amount of gypsum. On the other hand, the effect of gypsum on the compressive strength of mortar specimens was dependent on the alkali quality coefficient, indicating that the compressive strength increased with the increase of the adding amount of gypsum until a certain limit, beyond which the strength decreased slowly. Shrinkage strain of mortar tested was little influenced by the adding amount of gypsum because no ettringite as hydration product was generated. However, the adding of gypsum had a beneficial effect on reducing the microcrack in the alkali-activated mortar.

The Mechanics Characteristics of Alkali-Activated Mortar by Brain of Blast Furnace Slag (고로슬래그 분말도에 따른 알칼리 활성 모르타르의 역학적 특성)

  • Kang, Hyun-Jin;Ko, Kyung-Taek;Ryu, Gum-Sung;Kang, Su-Tae;An, Gi-Hong;Lee, Jang-Hwa
    • Proceedings of the Korea Concrete Institute Conference
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    • 2009.05a
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    • pp.393-394
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    • 2009
  • Recently, various researchers have studied alkali-activated concrete that do cementless as the binder. This study analyzed the effect on alkali-activated mortar by fineness of blast slag as the binder with no use of cement, by observing workability and compressive strength.

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The Effect on the Alkali-Activator Mixing Ratio of Cementless Mortar Using Fly Ash and Blast Furnace Slag (알칼리 활성화제 혼합비가 플라이애시와 고로슬래그를 사용한 무시멘트 모르타르에 미치는 영향)

  • Kang, Hyun-Jin;Ko, Kyung-Taek;Ryu, Gum-Sung;Kang, Su-Tae;Park, Jung-Jun;Lee, Jang-Hwa
    • Proceedings of the Korea Concrete Institute Conference
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    • 2010.05a
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    • pp.315-316
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    • 2010
  • The purpose of this study is to observe the effect of mixture ratio of alkali-activator on workability and compressive strength of alkali-activated mortar that using fly ash and blast furnace slag.

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