• Title/Summary/Keyword: alkali activated slag mortar

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Influence of Blended Activators on the Physical Properties of Alkali-activated Slag Mortar (알칼리 활성화 슬래그 모르타르의 특성에 미치는 혼합 활성화제의 영향)

  • Kim, Tae Wan;Park, Hyun Jae;Seo, Ki Young
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.16 no.6
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    • pp.26-33
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    • 2012
  • This paper reported on the effect of blended activator on the physical properties of alkali-activated slag mortar. Five different activators(caustic alkalis) were used: sodium hydroxide(NaOH, A Case), calsium hydroxide($Ca(OH)_2$, B Case), magnesium hydroxide($Mg(OH)_2$, C Case), aluminum hydroxide($Al(OH)_3$, D Case), and potassium hydroxide(KOH, E Case). We blended five caustic alkalis with sodium carbonate($Na_2CO_3$). The dosage of five caustic alkalis was 3M and sodium carbonate was 1M, 2M and 3M. The result of flow and setting time was decrease as the dosage of sodium carbonate increase. But the compressive strength was increase as the dosage of sodium carbonate increase. It was shown that there is a good effect of blended caustic alkalis with sodium carbonate in alkali-activated slag mortar.

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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Effect of the Combined Using of Fly Ash and Blast Furnace Slag as Cementitious Materials on Properties of Alkali-Activated Mortar (결합재(結合材)로 플라이애시와 고로(高爐)슬래그의 혼합사용(混合使用)이 알칼리 활성(活性) 모르타르의 특성(特性)에 미치는 영향(影響))

  • Koh, Kyung-Taek;Kang, Su-Tae;Park, Jung-Jun;Ryu, Gum-Sung;Lee, Jang-Hwa;Kang, Hyun-Jin
    • Resources Recycling
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    • v.19 no.4
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    • pp.19-28
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    • 2010
  • Attempts to increase the utilization of a by-products such as fly ash and 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 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/slag, type of alkaline activator and curing condition on the workability 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/slag and the type of alkaline activator 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% 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.

Strength and Pore Characteristics of Alkali-activated Slag-Red Mud Cement Mortar used Polymer According to Red Mud Content (레드머드 대체율에 따른 폴리머 혼입 알칼리활성화 슬래그-레드머드 시멘트모르타르의 강도 및 기공특성)

  • Kwon, Seung-Jun;Kang, Suk-Pyo
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.20 no.2
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    • pp.26-33
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    • 2016
  • The alkali-slag-red mud(ASRC) cement belongs to clinker free cementitious material, which is made from alkali activator, blast-furnace slag(BFS) and red mud in designed proportion. This study is to investigate strength and pore characteristics of alkali-activated slag cement(NC), clinker free cementitious material, and ordinary portland cement(C) mortars using polymer according to red mud content. The results showed that the hardened alkali-activated slag-red mud cement paste was mostly consisted of C-S-H gel, being very fine in size and extremely irregular in its shape. So the hardened ASRC cement paste has lower total porosity, less portion of larger pore and more portion of smaller pore, as compared with those of hardened portland cement paste, and has higher strength within containing 10 wt.(%) of alkali-activated slag cement(NC) substituted by red mud.

Influence of Silica Fume on Strength Properties of Alkali-Activated Slag Mortar (실리카 퓸이 알칼리 활성화 슬래그 모르타르의 강도특성에 미치는 영향)

  • Kim, Tae-Wan
    • Journal of the Korea Concrete Institute
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    • v.25 no.3
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    • pp.305-312
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    • 2013
  • This paper reports the results of an investigation into the effects of silica fume on strength properties of alkali-activated slag cement (AASC) with water-binder (W/B) ratio and replacement ratio of silica fume content. The W/B ratio varied between 0.50 and 0.60 at a constant increment of 0.05. The silica fume content varied from 0% to 50% by weight of slag. The activators was used sodium hydroxide (NaOH) and the dosage of activator was 3M. The strength development with W/B ratio has been studied at different ages of 1, 3, 7 and 28 days. For mixes of AASC mortars with varying silica fume content, the flow values were lower than the control mixes (without silica fume). The flow value was decrease as the content of silica fume increase. This is because the higher surface areas of silica fume particles increase the water requirement. The analysis of these results indicates that, increasing the silica fume content in AASC mortar also increased the compressive strength. Moreover, the strength decreases with the W/B ratios increases. This is because the particle sizes of silica fume are smaller than slag. The high compressive strength of blended slag-silica fume mortars was due to both the filler effect and the activated reaction of silica fume evidently giving the mortar matrix a denser microstructure, thereby resulting in a significant gain in strength.

Effects of Moisture Absorption Coefficient of Alkali-Activated Slag-Red Mud Cement on Efflorescence (알칼리활성화 슬래그-레드머드 시멘트 모르타르의 흡수계수가 백화발생에 미치는 영향)

  • Kang, Hye Ju;Kim, Byeong gi;Kim, Jae Hwan;Kang, Suk Pyo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2016.05a
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    • pp.130-131
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    • 2016
  • In this study, moisture absorption coefficient and efflorescence properties of Ordinary Portland cement and alkali-activated slag cement mortar were assessed according to their red mud substitution ratio. Tests were conducted to determine the cause of efflorescence, which is a significant obstacle to the recycling of red mud as a sodium activator in alkali-activated slag cement, and to find a method to control efflorescence.

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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 Strength Properties of Alkali-Activated Slag Mortars by Combined Caustic Alkali with Sodium Carbonate as Activator (가성알칼리와 탄산나트륨을 혼합한 활성화제를 사용한 알칼리 활성화 고로슬래그 모르타르의 강도 특성)

  • Kim, Tae-Wan
    • Journal of the Korea Concrete Institute
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    • v.24 no.6
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    • pp.745-752
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    • 2012
  • This paper studies the effect of the compressive strength for combined alkali-activated slag mortars. The effect of activators such as alkali type and dosage factor on the strength was investigated. The alkalis combinations made using five caustic alkalis (sodium hydroxide (NaOH, A series), calcium hydroxide ($Ca(OH)_2$, B series), magnesium hydroxide ($Mg(OH)_2$, C series), aluminum hydroxide ($Al(OH)_3$, D series), and potassium hydroxide (KOH, E series)) with sodium carbonate ($Na_2CO_3$) were evaluated. The mixtures were combined in different dosage at 1M, 2M, and 3M. The study results showed that the compressive strength of combined alkali-activated slag mortars tended to increase with increasing sodium carbonate. The strength of combined alkali-activated slag mortars was better than that of control cases (without sodium carbonate). The result from scanning electron microscopy (SEM) analysis confirmed that there were reaction products of calcium silicate hydrate (C-S-H) and alumina-silicate gels from combined alkali-activated slag specimens.

Pore and Efflorescence Characteristics of Alkali Activated Slag-Red Mud Cement Mortar depending on Red Mud Content (레드머드 대체율에 따른 알칼리활성화 슬래그-레드머드 시멘트 모르타르의 기공 및 백화특성)

  • Kang, Suk-Pyo;Kang, Hye-Ju
    • Journal of the Korea Institute of Building Construction
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    • v.17 no.3
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    • pp.261-268
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    • 2017
  • Red mud is an inorganic by-product obtained from the mineral processing of alumina from Bauxite ores. A highly alkali inorganic waste product with a pH level over 11, red mud in its original state negatively impacts the ecosystem, so appropriate treatment is necessary. The development of alkali activated slag-red mud cement can be a representative study aimed at recycling the strong alkali of the red mud as a construction material. However, Alkali-activated binders that use sodium activators have been reported to be more vulnerable to efflorescence. Therefore, in this study, the compressive strength, pore characteristics, water absorption, elution characteristics, and efflorescence properties of alkali-activated slag cement mortar were assessed according to their red mud substitution ratio.

Effect of Adding Gypsum in Blast-Furnace-Based Mortar's Fundamental Properties (이수석고가 고로슬래그 미분말 활용 무시멘트 모르타르의 기초물성에 미치는 영향)

  • Lu, Liang Liang;Kim, Jun Ho;Park, Jun Hee;Huang, Jin Guang;Baek, Byung Hoon;Han, Cheon Goo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2013.11a
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    • pp.137-138
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    • 2013
  • Nowadays, research about using recycled aggregate as alkali activator has been investigated. By the mechanism of Alkali activation, blast furnace slag's potential hydraulis property would be activated. Thee application of this technique is considered as fit for low strength concrete, so it's suitable in concrete secondary production such as bricks and blocks. Aside alkali activator, sulfate could also activate blast furnace slag's potential hydranlis property. In this research, gypsum(CaSO4·2H2O)has been added with blast furnace slag. Fundamental experiment such as flow and strength has been tested to evalnate effect of gypsum's activation property.

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