Assessing the shrinkage and creep of alkali-activated concrete binders

Wallah, Steenie E.; Hardjito, Djwantoro

doi:10.1533/9781782422884.2.265

Cited by 4 publications

(3 citation statements)

References 25 publications

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“…Recent investigations confirmed this pore related explanation (Mobili et al, 2016). However, AACB shrinkage is also dependent on the curing conditions being that curing with temperature is associated with a lower autogenous shrinkage (Wallah and Hardjito, 2014). Recent investigations showed that slag-fly ash AACB composites with a higher content of slag are associated with higher drying shrinkage (Gao et al, 2016).…”

Section: Introductionmentioning

confidence: 87%

Shrinkage Performance of Fly Ash Alkali-activated Cement Based Binder Mortars

2017

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Some authors reported that Alkali-activated Cement Based Binder (AACB) mortars can have much higher drying shrinkage than Portland cement based composites. Its worth remember that shrinkage performance is a very important property for reinforced concrete composites just because a high shrinkage performance is associated to cracking tendency that leads to future durability problems. Usually shrinkage is assessed under unrestrained conditions. However, the use of a restrained ellipse ring test is especially interesting for materials that will be used in restrained conditions like repair mortars. This paper provides results on restrained and unrestrained shrinkage performance of fly ash AACB mortars. The restrained shrinkage was assessed with an elliptical ring that provides a faster and more reliable assessment of the cracking potential than circular rings. The results show that the mixtures with lower sodium silicate content are associated to a lower unrestrained shrinkage. Mixtures with lower sodium silicate content showed reduced average crack width under restrained conditions. The results also show that the reduction of sodium silicate content delays the appearance of cracks and is also associated to lower crack width. The use of AACB mortars in restrained conditions requires the use of a reduced sodium silicate content or else the use of fibres to prevent crack appearance.

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Section: Introductionmentioning

confidence: 87%

Shrinkage Performance of Fly Ash Alkali-activated Cement Based Binder Mortars

2017

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“…On the other hand, a reduction in the mechanical properties was reported when >25% of basic oxygen furnace (BOF) slag aggregate was used in the concrete mixture [7,13,14]. Moreover, some drawbacks such as high drying shrinkage and volumetric instability compared to OPC concrete have been observed in alkali-activated concretes [15,16,17,18]. The utilisation of BOF slag as aggregates is limited by its excessive free calcium oxide (f-CaO), which easily reacts with water or CO 2 , forming Ca(OH) 2 or CaCO 3 and causing severe expansion and volume instability [19].…”

Section: Introductionmentioning

confidence: 99%

Using Carbonated BOF Slag Aggregates in Alkali-Activated Concretes

et al. 2019

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This experimental study aimed to develop alkali-activated concretes containing carbonated basic oxygen furnace (BOF) slag aggregates. In the first stage, the impacts of replacing normal aggregates with carbonated BOF slag aggregates in different alkali-activated concretes were determined by assessing mechanical properties (compressive and flexural strengths), morphology, thermogravimetric analyses (TGA), differential thermogravimetry (DTG) and the crystalline phases using X-ray diffraction analysis. Second, the developed plain alkali-activated concrete was reinforced by different fibre types and dosages to limit the negative impacts of the drying shrinkage and to improve strength. Therefore, the effects of using different fibre contents (1% and 1.5% in Vol.) and types (Polyvinyl alcohol [PVA], Polypropylene [PP], basalt, cellulose and indented short-length steel) on hardened state properties were evaluated. These evaluations were expressed in terms of the compressive and flexural strengths, ultrasonic pulse velocity, mass changes, drying shrinkage and efflorescence. Then, the impacts of aggressive conditions on the hardened properties of fibre-reinforced alkali-activated concretes were evaluated under carbonation, high temperature and freeze/thaw tests. The results showed that using carbonated BOF slag aggregates led to obtain higher strength than using normal aggregates in alkali activated concretes. Moreover, the maximum enhancement due to reinforcing the mixtures was recorded in alkali-activated concretes with steel fibres.

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“…Also, more recent investigations have confirmed this pore-related explanation (Mobili et al, 2016). However, geopolymer shrinkage is also dependent on the curing conditions because curing with heat is associated with a lower shrinkage (Wallah and Hardjito, 2014). Recent investigations have shown that slag-fly ash geopolymers with a higher content of slag are associated with higher drying shrinkage (Gao et al, 2016;Lee et al, 2014).…”

Section: Introductionmentioning

confidence: 92%

Drying shrinkage of fly ash geopolymeric mortars reinforced with polymer hybrid fibres

Kheradmand

Abdollahnejad

Pacheco-Torgal

2017

Proceedings of the Institution of Civil Engineers - Constructio

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Drying shrinkage performance is a very important factor for reinforced concrete composites because a high shrinkage performance is associated with a high cracking tendency, which leads to future durability problems. Geopolymeric mortars show much higher drying shrinkage than Portland cement-based composites because they use a low amount of structural water and thus have a higher pore content than ordinary Portland cement composites. Therefore, the use of fibres is especially interesting to counteract the drying shrinkage tendency of geopolymeric mortars. This paper provides results on the restrained and unrestrained shrinkage performance of fly ash-based geopolymeric mortars reinforced with short polymer hybrid fibres (SPHF). The results show that SPHF reduces the shrinkage cracking tendency. A content of SPHF as low as 0•08% was able to reduce the average crack width by four times when compared with non-reinforced mortars. Increasing the content of SPHF from 0•08 to 0•8% reduces the time of appearance of the first crack by 25 h and reduces the average crack width by two times.

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Assessing the shrinkage and creep of alkali-activated concrete binders

Cited by 4 publications

References 25 publications

Shrinkage Performance of Fly Ash Alkali-activated Cement Based Binder Mortars

Shrinkage Performance of Fly Ash Alkali-activated Cement Based Binder Mortars

Using Carbonated BOF Slag Aggregates in Alkali-Activated Concretes

Drying shrinkage of fly ash geopolymeric mortars reinforced with polymer hybrid fibres

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