Relation between drying shrinkage behavior and the microstructure of metakaolin-based geopolymer

Chen, Shikun; Wu, Chenglin; Yan, Dongming; Ao, Yu; Ruan, Shengqian; Zheng, Wenbin; Sun, Xingliang; Lin, Hao-Tzu

doi:10.1631/jzus.a2000513

Cited by 15 publications

(3 citation statements)

References 53 publications

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“…Trincal et al 57 observed a 1.1% mass loss in the geopolymer during the initial drying phase, resulting in significant shrinkage. Additionally, Chen et al 58 noted a substantial escalation in drying shrinkage when water loss exceeded a critical threshold (approximately .29-.50 g/mL).…”

Section: Conductive Mechanism Of Geopolymer Under Cycling Heatingmentioning

confidence: 99%

Electrothermal effect of carbon fiber and graphite reinforced metakaolin‐based geopolymer

Zhang,

Lin,

Chen

et al. 2024

Int J Applied Ceramic Tech

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This paper investigates the influence of carbon fiber and graphite on the cyclic electrothermal performance of geopolymers (inorganic polymers). It was observed that carbon fibers, graphite, and the carbon fiber/graphite composite could form a stable conductive network at low voltage (3 V). However, under high voltages (9 and 12 V), the current of the geopolymer exhibited a peak shape in the first cycle, with higher voltages resulting in larger peak values and decreased conductivity in subsequent cycles. While graphite improved electrical and thermal conductivity, it weakened the microstructure, leading to an increase in microcracks and voids, and a reduction in the strength of geopolymers. The cumulative energy during the electrothermal process was calculated. The failure mechanism of the conductive network in the geopolymer during cyclic electrical heating was explained, highlighting the disruptive effect of gel shrinkage due to water loss on conductive networks.

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Section: Conductive Mechanism Of Geopolymer Under Cycling Heatingmentioning

confidence: 99%

Electrothermal effect of carbon fiber and graphite reinforced metakaolin‐based geopolymer

Zhang,

Lin,

Chen

et al. 2024

Int J Applied Ceramic Tech

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“…Based on the authors' experience, the shrinkage level reported by Duran et al [42] should be perceptible to the naked eye in any reinforced concrete beam, as the crack strain is lower than this value. [44] Class C FA 56 DS~6.2‰ Ma and Ye [45] Class F FA 28 DS~0.5-2.5‰ Saha and Rajasekaran [46] FA 28 TSD~1.2-2.5‰ Zhang [47] MK --DS~4-6‰ Yang et al [48] MK --DS~4-6‰ Campopiano et al [49] MK --DS~2-4‰ Palumbo et al [50] MK --DS~2-4‰ Chen et al [51] MK --DS~2-4‰ Xiang et al [7] MK --DS~2-4‰ Mobili et al [52] MK --DS~1-2‰ Tonnayopas et al [53] MK ~100-200 DS~0.5-0.6‰ Trincal et al [54] MK --DS~1-2‰ Eisa et al [19] MK --DS < ~0.6‰…”

Section: Shrinkagementioning

confidence: 99%

Influence of Curing Temperature on the Strength of a Metakaolin-Based Geopolymer

Lopes,

Pinto

2023

Materials

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The present work focuses on the further development of a new family of geopolymers obtained by the alkaline activation of a binder. The aim is to find a viable alternative to concrete that can be used in civil construction. Regarding the influence of the curing temperature on this type of mixture, the recommendations in the existing literature are different for fly ash, ground granulated blast-furnace slag, and metakaolin-based geopolymers. While for fly ash and slag, increasing the curing temperature above 60 °C is reported to be advantageous, for metakaolin geopolymers, the opposite is reported. In this context, the objective of this work is to evaluate the mechanical strength of several metakaolin-based geopolymer specimens subjected to different curing temperatures (10, 15, 20, 30, 40 and 50 °C). Furthermore, several stress-strain diagrams are also shown. Based on the results, we recommend using curing temperatures below 30 °C in order to avoid reducing the strength of metakaolin-based geopolymers. Curing at 50 °C, relative to room temperature, results in a reduction of more than 35% in flexural strength and a reduction of more than 60% in compressive strength. Regarding the behavior of the geopolymers, it was found that the strain, at the ultimate stress, is about 2 to 2.5 times the strain of an equivalent cement mortar.

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“…The first three properties are related to one of the most dominant characteristics of geopolymers, i.e., the porous structure (Chen et al 2019 ; Zhang et al 2010 ; Ma et al 2013 ) which develops on different size scales and is introduced into the material framework without the need for costly structural directing agents. The porosity percentage range (measured by mercury intrusion porosimetry) of the traditional metakaolin-based geopolymer is 34–44 (Chen et al 2021 ), and it is higher than that of ordinary Portland cement, for which a water/cement ratio larger than 0.6 is required (Haga et al 2005 ), which is not commonly used in construction. In addition, the micro pores in geopolymers are usually finer than in ordinary Portland cement (Provis et al 2011 ; Rovnaník 2010 ), and it causes a correlation with the sorption and capillary condensation and also contributes to the thermal insulation of geopolymers.…”

Section: Introductionmentioning

confidence: 99%

Long-term durability of discarded cork-based composites obtained by geopolymerization

Poggetto,

Barbieri,

D’Angelo

et al. 2024

Environ Sci Pollut Res

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Geopolymers are amorphous aluminosilicate inorganic polymers synthesized by alkaline activation characterized by a lower carbon footprint, greater durability, and excellent mechanical properties compared to traditional concrete, making them promising building materials for sustainable construction. To develop sustainable lightweight geopolymer-based building materials useful as fire resistant thermal insulation materials, we added 5 and 10 wt% of discarded cork dust, a readily available industrial by-product, to metakaolin before and after the alkaline activation with sodium hydroxide 8 M and sodium silicate solutions. We followed the chemical, microstructural, antibacterial, and physical properties of the resulting composites for up to 90 days in order to monitor their long-term durability. The presence of cork does not interfere with the geopolymerization process and in fact reduces the density of the composites to values around 2.5 g/cm3, especially when added after alkaline activation. The composites resulted in chemically stable matrices (less than 10 ppm of cations release) and filler (no hazardous compounds released) with a bacterial viability of around 80%. This study provides valuable insights into the tailoring of discarded cork-based composites obtained by geopolymerization with a porosity between 32 and 48% and a mechanical resistance to compression from 15 to 5 MPa, respectively, suggesting their potential as durable interior panels with low environmental impact and desirable performance.

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Relation between drying shrinkage behavior and the microstructure of metakaolin-based geopolymer

Cited by 15 publications

References 53 publications

Electrothermal effect of carbon fiber and graphite reinforced metakaolin‐based geopolymer

Electrothermal effect of carbon fiber and graphite reinforced metakaolin‐based geopolymer

Influence of Curing Temperature on the Strength of a Metakaolin-Based Geopolymer

Long-term durability of discarded cork-based composites obtained by geopolymerization

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