Robustness to water and temperature, and activation energies of metakaolin-based geopolymer and alkali-activated slag binders

Lahalle, Hugo; Benavent, Virginie; Trincal, Vincent; Wattez, Thomas; Bucher, Raphaël; Cyr, Martin

doi:10.1016/j.conbuildmat.2021.124066

Cited by 14 publications

(13 citation statements)

References 59 publications

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“…Various studies have found that an S/L ratio around 0.8 provided an optimal mechanical strength while retaining satisfactory workability [17][18][19]. Similarly, a W/B ratio below 0.55 is often used to attain high-strength geopolymers [20][21][22][23]. In this work, geopolymers with W/B ratios between 0.75 and 0.95 were designed (Table 2).…”

Section: Design Of Recipementioning

confidence: 99%

Strength and Microstructure Characteristics of Metakaolin-Based Geopolymer Mortars with High Water-to-Binder Ratios

2022

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Geopolymers and other alkali-activated materials were investigated in detail as alternatives to ordinary Portland cement because of their reduced CO2 emissions, high (radionuclide) binding capacities, and low permeabilities. The last two properties make them potential materials for the immobilization of several types of chemical waste. In this context, the direct immobilization of liquid waste streams would be a useful application. This study aimed to develop geopolymers with high water-to-binder ratios, but with good mechanical strengths, while elucidating the parameters that dictate the strengths. Three potential metakaolin geopolymer recipes were cast and cured for 28 days, after which their strengths, mineralogy, and microstructures were determined. The results show that it is possible to attain acceptable mechanical strengths at water-to-binder ratios that vary from 0.75 to 0.95, which is a significant increase from the ratio of 0.55 that is commonly used in the literature. It was found that the most important parameter that governs the mechanical strength is the dilution of the activating solution, which is represented by the H2O/Na2O ratio, while the microstructure was found to benefit from a high SiO2/Al2O3 ratio.

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Section: Design Of Recipementioning

confidence: 99%

Strength and Microstructure Characteristics of Metakaolin-Based Geopolymer Mortars with High Water-to-Binder Ratios

2022

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“…Many researchers have conducted research to identify the complex and unclear contraction mechanism of AASC. It has been reported that the shrinkage behavior of AASC is affected by diverse and complex factors, such as humidity [32,36,37], the nature of raw materials [17,31,33], temperature [38,39], the drying history [40], the curing regime [41][42][43][44], pore size [33], the activator type and dosage [7,22,23,[45][46][47], aggregate properties [48,49], and the exposure period [50]. Additionally, experiments and research have been conducted to study contraction prediction models for various AACs [27,34,51].…”

Section: Introductionmentioning

confidence: 99%

“…Various methods have been attempted to reduce the drying shrinkage of AAS. For example, the addition of fiber [60][61][62][63], pozzolanic material [57][58][59][60][61][62][63][64][65][66][67], an expansion agent [68][69][70], nano-materials [57,[71][72][73], a shrinkage-reducing agent (SRA) [32,34,[74][75][76][77], superabsorbent polymer [78,79], and methods for increasing the curing temperature [23,42,58,80,81] have been attempted. Previous studies on drying shrinkage reduction experiments and studies have shown a certain level of shrinkage reduction effect.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the Effect of Blended Aggregate on the Strength and Drying Shrinkage Characteristics of Alkali-Activated Slag Mortar

Kang,

Park,

Kim

2024

Materials

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To reduce drying shrinkage of AASC mortar (AASM), mixed aggregate mixed with river sand (RS) and silica sand in three sizes was used to investigate the effect of the physical properties of mixed aggregate on shrinkage reduction. A mixture of river sand (0.2–0.8 mm), S1 (2.5–5.0 mm), S2 (1.6–2.5 mm), and S3 (1.21–160 mm) had river sand–silica sand mean diameter ratios (dr) of 7.68 (S1/RS), 3.75 (S2/RS), and 3.02 (S3/RS). The compressive strength and drying shrinkage characteristics of mixed aggregates according to fineness modulus, surface area, bulk density, and pore space were investigated. It had the highest bulk density and lowest porosity at a substitution ratio of 50%, but the highest strength was measured at a substitution ratio of 50% or less. High mechanical properties were shown when the fineness modulus of the mixed aggregate was in the range of 2.25–3.75 and the surface area was in the range of 2.25–4.25 m2/kg. As the substitution rate of silica sand increased, drying shrinkage decreased. In particular, the drying shrinkage of RS + S1 mixed aggregate mixed with S1 silica sand, which had the largest particle size, was the smallest. When silica sand or river sand was used alone, the drying shrinkage of the sample manufactured only with S1, which has the largest particle size of silica sand, was the smallest among all mixes. Compared to RS, at a 5% activator concentration, drying shrinkage was reduced by approximately 40% for S1, 27% for S2, and 19% for S3. At a 10% concentration, S1 showed a reduction effect of 39%, S2 by 28%, and S3 by 13%. As a result of this study, it was confirmed that the drying shrinkage of AASM could be reduced simply by controlling the physical properties of the aggregate mixed with two types of aggregate. This is believed to have a synergistic effect in reducing drying shrinkage when combined with various reduction methods published in previous studies on AASM shrinkage reduction. However, additional research is needed to analyze the correlation and influencing factors between the strength, pore structure, and drying shrinkage of AASM using mixed aggregate.

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“…In the meantime, the large shrinkage for AAS is due to the fine pore structure [23][24][25] and its gel characteristic of hydration products [2,26]. Most of studies concentrated on the impacts of raw materials [10,27], curing regime [28,29] and the type and dosage of alkali activator [18,[30][31][32] on the shrinkage of alkali-activated slag. The drying shrinkage of AAS would gradually increase with the increase of alkali content.…”

Section: Introductionmentioning

confidence: 99%

“…on the shrinkage is also related with the alkali concentration [34]. Moreover, Lahalle et al [29] and Ye et al [13] also investigated the effect of curing temperature on the shrinkage. A high curing temperature is beneficial to reduce the shrinkage, but could sharply decrease the setting time which brings another challenge in site construction.…”

Section: Introductionmentioning

confidence: 99%

Long-term (2 years) drying shrinkage evaluation of alkali-activated slag mortar: Experiments and partial factor analysis

Wang

Yang

et al. 2023

Case Studies in Construction Materials

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Robustness to water and temperature, and activation energies of metakaolin-based geopolymer and alkali-activated slag binders

Cited by 14 publications

References 59 publications

Strength and Microstructure Characteristics of Metakaolin-Based Geopolymer Mortars with High Water-to-Binder Ratios

Strength and Microstructure Characteristics of Metakaolin-Based Geopolymer Mortars with High Water-to-Binder Ratios

Investigation of the Effect of Blended Aggregate on the Strength and Drying Shrinkage Characteristics of Alkali-Activated Slag Mortar

Long-term (2 years) drying shrinkage evaluation of alkali-activated slag mortar: Experiments and partial factor analysis

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