scholarly journals Alkali-activated binders based on ground granulated blast furnace slag and phosphogypsum

2019 ◽  
Vol 215 ◽  
pp. 371-380 ◽  
Author(s):  
Katrijn Gijbels ◽  
Remus Ion Iacobescu ◽  
Yiannis Pontikes ◽  
Sonja Schreurs ◽  
Wouter Schroeyers
2021 ◽  
Vol 5 (2) ◽  
pp. 59
Author(s):  
Dhruv Sood ◽  
Khandaker M. Anwar Hossain

Alkali-activated binders (AABs) are developed through the activation of aluminosilicate-rich materials using alkaline reagents. The characteristics of AABs developed using a novel dry-mixing technique incorporating powder-based reagents/activators are extensively explored. A total of forty-four binder mixes are assessed in terms of their fresh and hardened state properties. The influence of mono/binary/ternary combinations of supplementary cementitious materials (SCMs)/precursors and different types/combinations/dosages of powder-based reagents on the strength and workability properties of different binder mixes are assessed to determine the optimum composition of precursors and the reagents. The binary (55% fly ash class C and 45% ground granulated blast furnace slag) and ternary (25% fly ash class C, 35% fly ash class F and 40% ground granulated blast furnace slag) binders with reagent-2 (calcium hydroxide and sodium sulfate = 2.5:1) exhibited desired workability and 28-day compressive strengths of 56 and 52 MPa, respectively. Microstructural analyses (in terms of SEM/EDS and XRD) revealed the formation of additional calcium aluminosilicate hydrate with sodium or mixed Ca/Na compounds in binary and ternary binders incorporating reagent-2, resulting in higher compressive strength. This research confirms the potential of producing powder-based cement-free green AABs incorporating binary/ternary combinations of SCMs having the desired fresh and hardened state properties under ambient curing conditions.


2016 ◽  
Vol 865 ◽  
pp. 107-113 ◽  
Author(s):  
Pavel Mec ◽  
Jana Boháčová ◽  
Josef Koňařík

Alkali activated systems are materials formed by alkali-activation of latent hydraulic or pozzolanic materials. The outcome is a polymeric structure with properties comparable to materials based on cement.The principle of the experiment is to compare selected properties of alkali-activated materials based on blast furnace slag and using various types of activator (sodium water glass, potassium water glass, DESIL AL and sodium metasilicate) to binders based on white and Portland cements of the highest quality. The samples were left for one year in environments simulating the conditions in the interior and exterior. Selected physical-mechanical properties were evaluated and compared.


2011 ◽  
Vol 287-290 ◽  
pp. 1275-1279
Author(s):  
Yong Jia He ◽  
Lin Nu Lu ◽  
Shu Guang Hu

Compound binding material was prepared by the alkali activation of metakaolin and ground granulated blast furnace slag. Hydration product components, microstructure and mechanical properties of the hardened paste were investigated by IR, XRD, SEM, MIP, and compressive strength measurement. Results indicated that hydration products included C-S-H and geopolymer, and both of them were amorphous although there were differences in their structure and morphology. When the dosage of slag was less than 50%, the compressive strength of hardened paste increased as the dosage increased, which was mainly because C-S-H produced by the reaction of GGBFS and alkali filled void in geopolymer phase, and part of unreacted slag particles acting as microaggregate to prevent from extension of microcrack in the hardened paste, so the porosity of hardened paste decreased and compressive strength increased.


2018 ◽  
Vol 163 ◽  
pp. 06001
Author(s):  
Miroslav Komljenović ◽  
Nataša Džunuzović ◽  
Violeta Nikolić

Durability of binders, mortars and concretes in aggressive environments is of crucial importance for their commercial application. In this paper the resistance to external sulfate attack of two different alkaliactivated binders (AABs), based either on blast furnace slag (BFS) or fly ash/blast furnace slag (FA/BFS) blend, was compared with two different commercially available Portland cement (CEM II) blended either with BFS or with FA and BFS. Comparison of sulfate resistance was based on compressive strength testing (the loss of strength) of mortar samples exposed to sodium sulfate attack up to 180 days and samples cured under controlled conditions for the same period of time. Furthermore, the evolution of microstructure of alkali-activated binders and pH of sodium silicate solution during testing were also analyzed. Despite different gel chemistry being involved, both alkali-activated binders based either on BFS or FA/BFS blend showed excellent resistance to external sulfate attack and even better than selected Portland cements tested under the same experimental conditions.


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