Relative Importance of Al(V) and Reinforcement to the Flexural Strength of Geopolymer Composites

Metakaolinite-based geopolymer binder was prepared at room temperature by mixing calcined claystone and potassium alkaline activator. Various granular inorganic fillers were added, amounting to 65 vol % to form geopolymer composites. The effect of four types of fillers (sand quartz, chamotte, cordierite, and corundum) on the thermo-mechanical properties of metakaolinite-based geopolymer composites were investigated. The samples were also examined by an X-ray diffraction method to determine their phase composition. The pore size distributions were determined by a mercury intrusion porosimeter. The XRD revealed the crystallization of new phase (leucite) after thermal exposure at 1000 °C and higher. Geopolymer binders had low mechanical properties (flexural strength 2.5 MPa and compressive strength 45 MPa) and poor thermo-mechanical properties (especially high shrinkage—total shrinkage 9%) compared to geopolymer composites (flexural strength up to 13.8 MPa, compressive strength up to 95 MPa and total shrinkage up to 1%). The addition of fillers reduced the shrinkage of geopolymers and improved their mechanical properties. The results have shown that the compressive strength tested in situ and after exposure to high temperature are in conflict. Geopolymer composites with the addition of chamotte had the best mechanical properties before and after thermal exposure (compressive strength up to 95 MPa). The average pore size diameters increased with the increasing temperature (from 10 nm to approx. 700 nm). The fillers addition decreased the pore volume (from 250 mm3/g to approx. 100 mm3/g).

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High-flexural-strength of geopolymer composites with self-assembled nanofiber networks

Ceramics International ◽

10.1016/j.ceramint.2021.08.014 ◽

2021 ◽

Author(s):

Sifan Zhang ◽

Xiang Ji ◽

Wei Zhou ◽

Xinghong Liu ◽

Qiao Wang ◽

...

Keyword(s):

Flexural Strength ◽

Self Assembled ◽

Geopolymer Composites

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Influence of elevated temperatures on the residual and quasi in-situ flexural strength of strain-hardening geopolymer composites (SHGC) reinforced with PVA and PE fibers

Construction and Building Materials ◽

10.1016/j.conbuildmat.2021.125649 ◽

2022 ◽

Vol 314 ◽

pp. 125649

Author(s):

Ana Carolina Constâncio Trindade ◽

Marco Liebscher ◽

Iurie Curosu ◽

Flávio de Andrade Silva ◽

Viktor Mechtcherine

Keyword(s):

Flexural Strength ◽

Strain Hardening ◽

Elevated Temperatures ◽

Geopolymer Composites

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Synthesis, Characterization, and Recyclability of a Functional Jute-Based Geopolymer Composite

Frontiers in Built Environment ◽

10.3389/fbuil.2021.631307 ◽

2021 ◽

Vol 7 ◽

Author(s):

Mazen Alshaaer

Keyword(s):

Mechanical Properties ◽

Reference Material ◽

Flexural Strength ◽

Circular Economy ◽

Reinforced Composite ◽

Jute Fibers ◽

Geopolymer Matrix ◽

High Elongation ◽

Geopolymer Composites ◽

Geopolymer Material

This study describes the properties of geopolymer composites reinforced with bidirectional jute fibers. Their flexural strength is 12 MPa, four times higher than the strength of non-reinforced reference geopolymers. The bidirectional jute-reinforced geopolymer composite (JGC) is characterized by ductility and high elongation as well as strain hardening with a modulus of 66 MPa. It is found that the introduction of bidirectional jute fibers in the geopolymer matrix increases the adsorption capacity of Cr ions from 2.7 to 6.4 mg/g (pH = 5). The JGC can be recycled by grinding the material, and then using both the geopolymer material and the jute micro-fibers as filler and reinforcement for a new geopolymer matrix. The micro-fiber jute-reinforced composite obtained showed noteworthy mechanical properties, with strength three times higher than that of the reference material, when 2.5 wt% filler was added. Moreover, the ductility of the composite can be substantially enhanced by increasing (up to 10 wt%) the proportion of recycled jute-based geopolymer filler. These composites are therefore proposed as candidate materials for applications in the context of a circular economy.

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Evaluation of Hybrid Melamine and Steel Fiber Reinforced Geopolymers Composites

Materials ◽

10.3390/ma13235548 ◽

2020 ◽

Vol 13 (23) ◽

pp. 5548

Author(s):

Patrycja Bazan ◽

Barbara Kozub ◽

Michał Łach ◽

Kinga Korniejenko

Keyword(s):

Compressive Strength ◽

Fly Ash ◽

Flexural Strength ◽

Hybrid System ◽

Steel Fiber ◽

Base Material ◽

Steel Fibers ◽

Polymer Fibers ◽

Single Type ◽

Geopolymer Composites

This study investigated the influence of the steel and melamine fibers hybridization on the flexural and compressive strength of a fly ash-based geopolymer. The applied reinforcement reduced the geopolymer brittleness. Currently, there are several types of polymer fibers available on the market. However, the authors did not come across information on the use of melamine fibers in geopolymer composites. Two systems of reinforcement for the composites were investigated in this work. Reinforcement with a single type of fiber and a hybrid system, i.e., two types of fibers. Both systems strengthened the base material. The research results showed the addition of melamine fibers as well as steel fibers increased the compressive and flexural strength in comparison to the plain matrix. In the case of a hybrid system, the achieved results showed a synergistic effect of the introduced fibers, which provided better strength results in relation to composites reinforced with a single type of fiber in the same amount by weight.

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Fly-Ash-Based Geopolymers Reinforced by Melamine Fibers

Materials ◽

10.3390/ma14020400 ◽

2021 ◽

Vol 14 (2) ◽

pp. 400 ◽

Cited By ~ 1

Author(s):

Barbara Kozub ◽

Patrycja Bazan ◽

Dariusz Mierzwiński ◽

Kinga Korniejenko

Keyword(s):

Fly Ash ◽

Flexural Strength ◽

Thermal Radiation ◽

Bending Strength ◽

Melamine Resin ◽

Density Measurements ◽

Temperature Resistance ◽

Pure Matrix ◽

Radiation Measurements ◽

Geopolymer Composites

This paper presents the results of research on geopolymer composites based on fly ash with the addition of melamine fibers in amounts of 0.5%, 1% and 2% by weight and, for comparison, without the addition of fibers. The melamine fibers used in the tests retain their melamine resin properties by 100% and are characterized by excellent acoustic and thermal insulation as well as excellent filtration. In addition, these fibers are nonflammable, resistant to chemicals, resistant to UV radiation, characterized by high temperature resistance and, most importantly, do not show thermal-related shrinking, melting and dripping. This paper presents the results of density measurements, compressive and flexural strength as well as the results of the measurement of thermal radiation changes in samples subjected to a temperature of 600 °C. The results indicate that melamine fibers can be used as geopolymer reinforcement. The best result was achieved for 0.5% by weight amount of reinforcement, approximately 53 MPa, compared to 41 MPa for a pure matrix. In the case of flexural strength, the best results were obtained for the samples made of unreinforced geopolymer and samples with the addition of 0.5% by weight of melamine fibers, which were characterized by bending strength values above 9 MPa, amounting to 10.7 MPa and 9.3 MPa, respectively. The thermal radiation measurements and fire-jet test did not confirm the increasing thermal and fire resistance of the composites reinforced by melamine fiber.

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