Alkali-activated materials

Provis, John L.

doi:10.1016/j.cemconres.2017.02.009

Cited by 1,222 publications

(463 citation statements)

References 69 publications

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“…Since the present study focused on the chloride-binding capabilities of the samples, the results of the strength tests are presented in this section. The strength development of the samples similarly followed the alkaliactivated binders reported in previous studies [11][12][13]17,23,31]. The specimens that fractured after the compressive strength tests were finely ground for chloride content tests and XRD.…”

Section: Sample Preparationmentioning

confidence: 99%

“…These phases are the resultant zeolites after binding the chloride. Note that geopolymeric gel resembles zeolites in terms of structure on the nanometer scale [13,31], and thus the presence of Cl-chabazite and Cl-sodalite may indicate that a portion of the geopolymeric gel in the FSW sample is very similar to them in terms of structure and composition. Therefore, these types of geopolymeric gels are likely to chemically hold a portion of the chloride in the FSW sample.…”

Section: Xrd For the Fsw Samplementioning

confidence: 99%

“…As reaction products, the FSW sample produced geopolymer, which manifests itself in the form of an amorphous hump at 28-35° in XRD [12,13,43], with several crystalline zeolite phases. At 7 days, besides geopolymeric gel, zeolite Y (Al71Na71O384Si121) and Cl-sodalite (Al6Cl2Na8O24Si6) are only visible.…”

Section: Xrd For the Fsw Samplementioning

confidence: 99%

“…As reaction products, the FSW sample produced geopolymer, which manifests itself in the form of an amorphous hump at 28-35 • in XRD [12,13,43] Zeolites X and Y are very similar zeolites that belong to faujasite. Their main difference is simply the Si/Al ratio [44].…”

Section: Xrd For the Fsw Samplementioning

confidence: 99%

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A Comparison Study for Chloride-Binding Capacity between Alkali-Activated Fly Ash and Slag in the Use of Seawater

Jun

Yoon

2017

Applied Sciences

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Featured Application: The results of this study can be applied to the production of cementless concrete using seawater.Abstract: This study aimed to investigate the chloride-binding capacity of alkali-activated fly ash (denoted as FSW) and slag (denoted as SSW) samples and their synthesized Cl-bearing phases, which are capable of binding and immobilizing chloride when seawater is used as the mixing water. This study also examined the progressive changes in the pore structures of the FSW and SSW samples over time. The results show that the SSW sample is significantly more effective in the uptake of chloride ions compared to the FSW sample at 28 days of curing. While the FSW sample forms Cl-bearing zeolites (Cl-chabazite and Cl-sodalite) (possibly with similar types of geopolymeric gels), the SSW sample synthesizes Cl-bearing, layered double hydroxides (LDH) (Cl-hydrocalumite and Cl-hydrotalcite). Although both samples involve Cl-binding phases, the FSW sample is likely to be less efficient because it largely produces zeolites (or similar geopolymeric gels) with no Cl-binding capability (i.e., zeolites X and Y). Meanwhile, the SSW sample produces Cl-bearing LDH phases as well as C-S-H(I), which can physically adsorb chloride. The SSW sample exhibits both pore-size refinement and porosity reduction over time, while the FSW sample only exhibits pore-size refinement. Therefore, the SSW system is more advantageous in the use of seawater because it more effectively prevents Cl ingression due to greater impermeability.

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Section: Sample Preparationmentioning

confidence: 99%

Section: Xrd For the Fsw Samplementioning

confidence: 99%

Section: Xrd For the Fsw Samplementioning

confidence: 99%

Section: Xrd For the Fsw Samplementioning

confidence: 99%

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A Comparison Study for Chloride-Binding Capacity between Alkali-Activated Fly Ash and Slag in the Use of Seawater

Jun

Yoon

2017

Applied Sciences

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“…One promising approach is based on aluminosilicate raw materials such as blast furnace slag derived from the iron making process, which can be reacted with an alkali source to produce binding materials known as alkali-activated cements [1,2].…”

Section: Introductionmentioning

confidence: 99%

Influence of slag composition on the stability of steel in alkali-activated cementitious materials

et al. 2017

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Among the minor elements found in metallurgical slags, sulfur and manganese can potentially influence the corrosion process of steel embedded in alkali-activated slag cements, as both are redox-sensitive. Particularly, it is possible that these could significantly influence the corrosion process of the steel. Two types of alkali-activated slag mortars were prepared in this study: 100% blast furnace slag and a modified slag blend (90% blast furnace slag ? 10% silicomanganese slag), both activated with sodium silicate. These mortars were designed with the aim of determining the influence of varying the redox potential on the stability of steel passivation under exposure to alkaline and alkaline chloride-rich solutions. Both types of mortars presented highly negative corrosion potentials and high current density values in the presence of chloride. The steel bars extracted from mortar samples after exposure do not show evident pits or corrosion product layers, indicating that the presence of sulfides reduces the redox potential of the pore solution of slag mortars, but enables the steel to remain in an apparently passive state. The presence of a high amount of MnO in the slag does not significantly affect the corrosion process of steel under the conditions tested. Mass transport through the mortar to the metal is impeded with increasing exposure time; this is associated with refinement of the pore network as the slag continued to react while the samples were immersed.

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Multistep Crystallization Pathways in the Ambient‐Temperature Synthesis of a New Alkali‐Activated Binder

Maslyk

Gäb

Matveeva

et al. 2021

Adv Funct Materials

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Concrete is the most prevalent manufactured material that has shaped the built environment, but the high-temperature production of cement, the main component of concrete, has a massive carbon footprint. It is shown that CO 2 emissions during clinker production of cement can be circumvented by a metathesis reaction at room temperature in ball-mills, where the cement clinker is replaced by non-calcined limestone and alkali-activated binders/ geopolymers. An amorphous intermediate (aNaSiCC) containing a random mixture of the ionic constituents in "molecular" dispersion is formed by mechanochemical activation of CaCO 3 and Na 2 SiO 3 . This allows molecular transport during crystallization and low activated reactions, as precipitation of solids from liquids (nucleation limited and kinetically controlled) and solid-state transformations (diffusion-limited and thermodynamically controlled) have equal weight. Several steps of the hydration reaction could be resolved. Activating the amorphous aNaSiCC precursor with NaOH leads to a CSH-like phase with a C/S ratio of ≈1 containing some sodium. The carbonate components pass through a multistep crystallization from aNaSiCC via pirssonite and gaylussite to monohydrocalcite. The findings help unravel the interplay between thermodynamics and kinetics in complex reactions of alkali-activated binders and for CaCO 3 crystallization in industrial and geochemical settings, where dissolved silicate is always involved.

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Alkali-activated materials

Cited by 1,222 publications

References 69 publications

A Comparison Study for Chloride-Binding Capacity between Alkali-Activated Fly Ash and Slag in the Use of Seawater

A Comparison Study for Chloride-Binding Capacity between Alkali-Activated Fly Ash and Slag in the Use of Seawater

Influence of slag composition on the stability of steel in alkali-activated cementitious materials

Multistep Crystallization Pathways in the Ambient‐Temperature Synthesis of a New Alkali‐Activated Binder

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