Setting Time, Workability and Strength Properties of Alkali Activated Fly Ash and Slag Based Geopolymer Concrete Activated with High Silica Modulus Water Glass

Vikas, G; Rao, T. D. Gunneswara

doi:10.1007/s40996-021-00598-8

Cited by 34 publications

(19 citation statements)

References 17 publications

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“…For the 100% BFS mixture, the slump value was reduced around 40% at 120 min, while these reductions were lower than 20% for 85% BFS and 70% BFS. Therefore, the rate of decrease in a slump over time decreased with the higher amount of fly ash due to the slower setting of fly ash compared to slag [ 45 ].…”

Section: Resultsmentioning

confidence: 99%

“…In addition, the reaction between Ca 2+ dissolving from slag grains and silicate anions from the alkaline activators also played an important role in the setting and calorimetry in these systems, as previously observed in Figure 1 and Figure 4 . A driving force was provided by the formation of the gel to accelerate the chemical reaction leading to larger strength of alkali-activated binders cured at room temperature [ 5 , 45 ].…”

Section: Resultsmentioning

confidence: 99%

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Influence of the Fly Ash Content on the Fresh and Hardened Properties of Alkali-Activated Slag Pastes with Admixtures

Hita

Criado

2022

Materials

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A study on the influence of the inclusion of slag or fly ash and five types of superplasticizers on the fresh and hardened properties of alkali-activated cements is presented. Three alkali-activated slag formulations with different fly ash content (0, 15, and 30%) in the presence of five admixtures (vinyl copolymer, melamine, and three polycarboxylates with different chain lengths) were assessed for fluidity control and setting adjustment without loss of mechanical properties. Solid sodium metasilicate was used as an alkaline activator. Their fresh and hardened properties were studied through slump, setting time, isothermal calorimetry, mechanical strengths, and porosity tests. The results showed that the increase of fly ash content delayed the reaction and improved workability but reduced compressive strengths. Concerning the admixtures, these maintained fluidity especially for the one based on polycarboxylate with very long chains. The melamine and polycarboxylate with very long chain admixtures did not have a drastic impact on mechanical properties at early ages; even a gain of flexural and compressive strength was noted.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Influence of the Fly Ash Content on the Fresh and Hardened Properties of Alkali-Activated Slag Pastes with Admixtures

Hita

Criado

2022

Materials

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“…Beton endüstrisi, sera gazı salımının önemli miktarından sorumludur [1]. Araştırmalar 1 ton Portland çimentosu üretimi için doğaya yaklaşık olarak 1 ton karbondioksit salımı yapıldığını ortaya koymuştur [2]. Türkiye Çimento Sanayicileri Birliği'nin istatistiklerine göre 2018, 2019 ve 2020 yıllarında ülkemizde yaklaşık olarak 72.5, 57.0 ve 72.3 milyon ton çimento üretimi yapılmıştır [3].…”

Section: Gi̇ri̇ş (Introduction)unclassified

The Effect of Aggregate Type on Geopolymer Concrete High Temperature Resistance

2023

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Beton, dünyada en çok kullanılan yapı malzemesidir. Ancak çimento üretimi sırasında yüksek miktarda enerji tüketilmekte ve karbondioksit salımı yapılmaktadır. Çimentoya alternatif bağlayıcıların üretilmesi, uzun süredir üzerinde çalışılan bir konudur. Geopolimerler, çimentoya alternatif olma potansiyeli taşıyan malzemelerdir. Geopolimerlerin iyi bir yüksek sıcaklık direncine sahip oldukları bilinmektedir. Ancak hem geleneksel hem de geopolimer betonların yüksek sıcaklık dirençleri, kullanılan agreganın türü ve özelliklerinden önemli ölçüde etkilenmektedir. Bu çalışmada kireçtaşı, dere, bazalt ve cüruf agregaları kullanılarak üretilen geopolimer betonların 600 ve 900°C yüksek sıcaklık etkisine karşı dirençleri basınç dayanımı kayıpları kıyaslanarak tespit edilmiştir. 900°C sıcaklık etkisinde, kireçtaşı ile üretilen geopolimer beton tamamen parçalanırken dere, bazalt ve cüruf agregaları ile üretilen betonların %32.9, 48.5 ve 53.6 oranında basınç dayanımı kaybına uğradıkları tespit edilmiştir.

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“…Among these, sodium hydroxide plus a water-glass solution was thought to be the best alkali activator for the mechanical property of geopolymer, for which activation was higher than the others [22,23]. Current research shows that the water-glass module is the critical factor that generates high strength [24,25].…”

Section: Introductionmentioning

confidence: 99%

Effects of a Water-Glass Module on Compressive Strength, Size Effect and Stress–Strain Behavior of Geopolymer Recycled Aggregate Concrete

Wang

Bian

et al. 2022

Crystals

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Geopolymer recycled aggregate concrete (GRAC) was prepared by replacing cement with geopolymer and natural aggregate with waste concrete. The effect of the water-glass module on the mechanical properties of GRAC was studied. It was found that water-glass has a double-layer structure. The low module water-glass leads to a thicker diffusion layer and more Na+ and OH− in the solution, which activates more CaO, SiO2, and Al2O3 in the raw material, and improves the strength of GRAC. Moreover, two kinds of gel structures, namely layered C-A-S-H (calcium silicate hydrate) and networked N-A-S-H (zeolite), were found in the products of geopolymer. As the water-glass module changed, the phase of zeolite changed significantly, whereas the calcium silicate hydrate did not change, indicating that the decrease in the water-glass module contributes to the formation of more N-A-S-H gel. The compressive strengths of GRAC with the sizes of 200, 150, and 100 mm3 were in line with Bazant’s size effect theoretical curve. Through the segmented fitting method, the relationship of the size conversion coefficient of GRAC (α), the critical strength (fcr), the critical dimension (Dcr), and the water-glass module (ε) were determined. It was found that ε = 1.5 is the segmented point of the three equations. The elastic modulus and peak stress of GRAC are inversely proportional to the water-glass module, and the peak strain is proportional to the water-glass module, indicating that by reducing the water-glass module, the strength of GRAC can be improved, but the brittleness is increased. The constitutive equation of GRAC with only the water-glass module as a variable was also established. It was found that the polynomial mathematical model and rational fraction mathematical model are optimal for the rising-stage and falling-stage, respectively, and the relationship between the parameters of the rising-stage (a) and the falling-stage (b), and the water-glass module, is given.

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Setting Time, Workability and Strength Properties of Alkali Activated Fly Ash and Slag Based Geopolymer Concrete Activated with High Silica Modulus Water Glass

Cited by 34 publications

References 17 publications

Influence of the Fly Ash Content on the Fresh and Hardened Properties of Alkali-Activated Slag Pastes with Admixtures

Influence of the Fly Ash Content on the Fresh and Hardened Properties of Alkali-Activated Slag Pastes with Admixtures

The Effect of Aggregate Type on Geopolymer Concrete High Temperature Resistance

Effects of a Water-Glass Module on Compressive Strength, Size Effect and Stress–Strain Behavior of Geopolymer Recycled Aggregate Concrete

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