The effectiveness of different superplasticizers in ambient cured one-part alkali activated pastes

Alrefaei, Yazan; Wang, Yanshuai; Dai, Jian‐Guo

doi:10.1016/j.cemconcomp.2018.12.027

Cited by 123 publications

(42 citation statements)

References 36 publications

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“…In many existing studies on the durability and mechanical properties of AAS geopolymers regardless of "two-part" (i.e., liquid activators) or "one-part" (i.e., solid activators) mixing approaches, the use of GGBS and FA combination with a certain ratio as an aluminosilicate precursor achieves a geopolymer binder that can roughly meet the engineering requirements (Ismail et al, 2014;Bernal et al, 2015Bernal et al, , 2016Alrefaei and Dai, 2018;Alrefaei et al, 2019). The incorporation of highcalcium materials (i.e., to seed calcium species) with low-calcium raw materials (i.e., main source of alumina and silica) greatly affects the formation of the main binding gels (Bernal et al, 2016).…”

Section: Effect Of "Impurities" In Aas Geopolymermentioning

confidence: 99%

Silico-Aluminophosphate and Alkali-Aluminosilicate Geopolymers: A Comparative Review

2019

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Chemically activated materials (often termed as geopolymer) have received attracting attentions in civil, material and environmental research fields as a toolkit alternative to traditional Portland cement in specific applications. This paper presents a comparative review on silico-aluminophosphate (SAP) geopolymers in terms of definition, chemistries involved during geopolymerization, mechanical performance, durability, environmental impacts, and their potentials in applications relative to conventional alkali-aluminosilicate (AAS) geopolymers. Recommendations for future applications are also highlighted. It is found that S-A-P gels with six-coordinated aluminum environment dominate in SAP geopolymers, while the aluminum in N-A-S-H gels formed in the AAS geopolymers is characterized by four-coordinated features. Besides, the slow performance development of SAP geopolymer matrix under ambient temperature curing can be compensated through incorporating additional countermeasures (e.g., metal sources) which allow the tailored design of such geopolymers for certain in-situ applications. Generally, the calcium-bearing C-(A)-S-H gels co-existing with N-A-S-H gels are dominant in AAS geopolymers, while the S-A-P gels enhanced by phosphate-containing crystalline/amorphous phases are the main products in SAP geopolymers. The SAP geopolymers show their environmental friendliness relative to the AAS geopolymers due to the utilization of phosphate activators that require lower production energy relative to silicate-containing activators. However, the higher cost of phosphate activators may confine the applications of SAP geopolymers in some exquisite or special fields.

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Section: Effect Of "Impurities" In Aas Geopolymermentioning

confidence: 99%

Silico-Aluminophosphate and Alkali-Aluminosilicate Geopolymers: A Comparative Review

2019

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“…The authors concluded that for the investigated one-part geopolymer formulation lignosulfonate, melamine, and naphthalene-based SPs were more effective than polyacrylate and polycarboxylate-based SPs. Alrefaei et al [37] investigated the effect of different SPs in a one-part geopolymer made of fly ash (50% w / w ) and slag (50% w / w ) as the source material and sodium silicate powder (8% w / w ) as the solid activator with different water contents. They found that polycarboxylate-based SP was more effective for mixtures with high water content (i.e., water/precursor ≥ 0.36), while naphthalene-based SP was more effective for mixtures with low water content (i.e., water/precursor ≤ 0.36).…”

Section: Introductionmentioning

confidence: 99%

Efficiency of Different Superplasticizers and Retarders on Properties of ‘One-Part’ Fly Ash-Slag Blended Geopolymers with Different Activators

2019

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Currently, there are a very limited number of studies on the effect of admixtures on properties of ‘one-part’ geopolymers. This paper reports the effects of different superplasticizers and retarders on fresh and hardened properties of one-part fly ash-slag blended geopolymers made by different solid activators. Two different grades of sodium silicate, namely anhydrous sodium metasilicate powder (nSiO2/nNa2O = 0.9) and GD Grade sodium silicate powder (nSiO2/nNa2O = 2.0) were used as the solid activators. Five different commercially available superplasticizers, including three modified polycarboxylate-based superplasticizers (denoted as PC1, PC2, and PC3) and two naphthalene-based superplasticizers (denoted as N1 and N2), as well as three different retarders, including sucrose, anhydrous borax and a commercially available retarder, were investigated. Workability, setting time and compressive strength of the mixtures without and with addition of each ‘individual’ admixture were measured. The results showed the effect of admixtures on the properties of the one-part geopolymers significantly depended on the type of solid activator and the type of admixture used. When GD Grade sodium silicate powder was used as the solid activator, all investigated admixtures not only had no positive effect on the workability and setting time, but also significantly reduced the compressive strength of the mixture. However, when anhydrous sodium metasilicate powder was used as the solid activator, the PC1 and sucrose were the best performing superplasticizer and retarder, respectively, causing no reduction in the compressive strength, but significant increase in the workability (up to + 72%) and setting time (up to + 111%), respectively as compared to the mixture with no admixture. In addition, the results also showed that addition of ‘combined’ admixtures (i.e., PC1 in the presence of sucrose) significantly increased the workability (up to + 39%) and setting time (up to + 141%), but slightly reduced the compressive strength (−16%) of the mixture activated by anhydrous sodium metasilicate powder, as compared to the mixture with no admixture.

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“…Alrefaei et al [33] The effect of different SPs on Alkali Activated Pastes PC was effective for relatively high W/P ratio (≥0.36). In contrast, N had better performance in the case of low W/P ratio in AAMs containing Na 2 SiO 3 .…”

Section: Author Aim Resultsmentioning

confidence: 99%

“…The laboratory observation indicated that the compatibility of cement and admixtures are deeply attributed to molarity ratio of chemical combinations, such as C 3 A, C 2 S/C 3 S, participating in concrete structure and specific surface area available in cement, as well as the superplasticizer type utilized in this case. Similarly, in another attempt, Alrefaei et al [33] presented the investigations to point out the effect of various SPs involving naphthalene (N), melamine (M) and polycarboxylate (PC) on workability, and compressive strength of the concrete mixtures consisted of alkaline-activated material (AAM), such as FA, which was considered a sustainable contender for OPC. The results showed that SP type along with water/precursor (W/P) ratio were two dominate factors affecting on the improvement of compressive strength concrete workability.…”

Section: Factors On Workability Of Gpc and Pccmentioning

confidence: 99%

A Mini Review on Properties of Portland Cement Concrete with Geopolymer Materials as Partial or Entire Replacement

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Mostofizadeh

2021

Infrastructures

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The main aim of this paper is to review recent studies over the past 10 years investigating the influencing factors for improving the mechanical properties of concrete. This focuses on concrete comprising of pozzolanic materials, partially or entirely replacing ordinary Portland cement, in the concrete mixture. Firstly, the effectiveness of main factors such as temperature, water to solid (W/S) ratio, and alkaline solution ratio was briefly discussed. Next, the effects of significant factors such as different superplasticizer and alkaline solutions and combinative materials on the improvement of concrete workability were reviewed and compared. Eventually, other concrete properties such as water absorption and durability were discussed in the last section. After reviewing all types of concrete additives, including mineral or chemical materials, the influence of these admixtures under different laboratory conditions were highlighted to objectively evaluate the benefits of each factor. As a whole, the significant reasons of such experimental tests arising from the usage of these materials, in accordance with the laboratory results obtained from these investigations, are discussed.

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The effectiveness of different superplasticizers in ambient cured one-part alkali activated pastes

Cited by 123 publications

References 36 publications

Silico-Aluminophosphate and Alkali-Aluminosilicate Geopolymers: A Comparative Review

Silico-Aluminophosphate and Alkali-Aluminosilicate Geopolymers: A Comparative Review

Efficiency of Different Superplasticizers and Retarders on Properties of ‘One-Part’ Fly Ash-Slag Blended Geopolymers with Different Activators

A Mini Review on Properties of Portland Cement Concrete with Geopolymer Materials as Partial or Entire Replacement

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