Drying shrinkage of alkali-activated cements: effect of humidity and curing temperature

Hojati, Maryam; Rajabipour, Farshad; Radlińska, Aleksandra

doi:10.1617/s11527-019-1430-1

Cited by 37 publications

(12 citation statements)

References 37 publications

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“…Therefore, the organic admixtures have a significant mitigation effect on the early-age shrinkage of MKG paste. The autogenous shrinkage of MKG mainly depends on the matrix wettability, internal moisture distribution and stress characteristics but is not so associated with the water loss, which is consistent with the findings by other studies [78][79][80].…”

Section: Discussionsupporting

confidence: 91%

Early-age deformation of hydrophobized metakaolin-based geopolymers

Ruan

Chen

Liu

et al. 2023

Cement and Concrete Research

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Section: Discussionsupporting

confidence: 91%

Early-age deformation of hydrophobized metakaolin-based geopolymers

Ruan

Chen

Liu

et al. 2023

Cement and Concrete Research

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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%

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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“…Strain resulting from autogenous shrinkage, creep and water loss is normally larger for alkali-activated materials, as compared to Portland cement [9][10][11], and may lead to micro-cracking that affects the overall performance. Cracking may appear upon drying shrinkage occurring by loss of water in the hardened state [11,14,15].…”

Section: Introductionmentioning

confidence: 99%

Assessing the dimensional stability of alkali-activated calcined clays in the fresh state: a time-lapse X-ray imaging approach

Valentini

Mascarin

2021

Mater Struct

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Alkali-activated calcined clays are promising candidates for playing a prominent role in the future construction industry. These binders may achieve excellent mechanical performance, but one issue deserving attention is the proneness to plastic shrinkage and surface cracking. Tackling this issue requires the deployment of laboratory techniques that allow shrinkage-inducing mechanisms to be quantitatively assessed. Here, we demonstrate that time-lapse X-ray imaging can be used to quantify shrinkage immediately after mixing, when the binder is still in its fresh state, with excellent time and space resolution. The numeric quantification of strain is complemented by the real time visual inspection of the displacing sample interface and of the bleed aqueous solution layer that may form. Implementation of this method to a set of alkali-activated cement pastes, prepared by combining calcined clays having different mineralogical composition with sodium silicate activating solutions having different $$\hbox {SiO}_2$$ SiO 2 /$$\hbox {Na}_2\hbox {O}$$ Na 2 O ratios, suggests that two main mechanisms control the early dimensional stability of alkali-activated calcined clays. These mechanisms are: (a) volumetric contraction occurring in response to capillary stress arising from water evaporation and (b) segregation by particle settling, favoured in the water-saturated regime.

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Drying shrinkage of alkali-activated cements: effect of humidity and curing temperature

Cited by 37 publications

References 37 publications

Early-age deformation of hydrophobized metakaolin-based geopolymers

Early-age deformation of hydrophobized metakaolin-based geopolymers

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

Assessing the dimensional stability of alkali-activated calcined clays in the fresh state: a time-lapse X-ray imaging approach

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