Elevated temperature, freezing-thawing and wetting-drying effects on polypropylene fiber reinforced metakaolin based geopolymer composites

Aygörmez, Yurdakul; Canpolat, Orhan; Al-mashhadani, Mukhallad M.; Uysal, Mücteba

doi:10.1016/j.conbuildmat.2019.117502

Cited by 146 publications

(48 citation statements)

References 132 publications

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“…Adding materials such as QZ and SF into the FA geopolymers can enhance the mechanical properties of the composite geopolymers at high temperature. Fine filler Researchers Tchakoute et al [76] Lahoti et al [77] Aygörmez et al [78] Duan et al [43] Duan et al [79] Rovnaník anď Safránková [53] Duan et al [60] Zhang et al [80] Roviello et al…”

Section: Chemical Compositionsmentioning

confidence: 99%

Thermal and Mechanical Properties of Geopolymers Exposed to High Temperature: A Literature Review

Dai

Wang

2020

Advances in Civil Engineering

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Geopolymers are prepared by alkali solution-activated natural minerals or industrial waste materials, which have been widely used as new sustainable building and construction materials for their excellent thermal and mechanical properties. The thermal and mechanical properties of geopolymers at high temperature have attracted great attention from many researchers. However, there are few systematic works concerning these two issues. Therefore, this work reviewed the thermal and mechanical behaviors of geopolymers at high temperature. Firstly, the thermal properties of geopolymers in terms of mass loss, thermal expansion, and thermal conductivity after high temperature were explained. Secondly, the mechanical properties of residual compressive strength and stress-strain relationship of fly ash geopolymers and metakaolin geopolymers after high temperature were analyzed. Finally, the microstructure and mineralogical characteristics of geopolymers upon heating were interpreted according to the changes of microstructures and compositions. The results show that the thermal properties of geopolymers are superior to cement concrete. The geopolymers possess few mass loss and a low expansion ratio and thermal conductivity at high temperature. The thermal and mechanical properties of the geopolymers are usually closely related to the raw materials and the constituents of the geopolymers. Preparation and testing conditions can affect the mechanical properties of the geopolymers. The stress-strain curves of geopolymer are changed by the composition of geopolymers and the high temperature. The silicon-type fillers not only improve the thermal expansion of the geopolymers but also enhance mechanical properties of the geopolymers. But, they do not contribute to reducing the thermal conductivity. the different raw materials, aluminosilicate precursor and reinforcement materials, result in different geopolymer damage during the heating. However, phase transitions can occur during the process of heating regardless of the raw materials. The additional performance enhancements can be achieved by optimizing the paste formulation, adjusting the inner structure, changing the alkali type, and incorporating reinforcements.

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Section: Chemical Compositionsmentioning

confidence: 99%

Thermal and Mechanical Properties of Geopolymers Exposed to High Temperature: A Literature Review

Dai

Wang

2020

Advances in Civil Engineering

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“…The anomalous gel and capillary pores’ alterations did not directly reflect the material degradation caused by F-T loads, but might indicate the pore refinement induced by the continual polymerization of the materials immersed in water. A literature survey indicated that the first few F-T cycles may enhance the geopolymerization process, which helps refine the pore structure and even increase the strength [ 47 , 48 , 49 ]. The products of geopolymerization filled the coarse pores, which thus decreased the capillary pore fractions of MKG-4 and MKG-5 shown in Figure 9 f.…”

Section: Freezing-thawing Damagesmentioning

confidence: 99%

Compositional Dependence of Pore Structure, Strengthand Freezing-Thawing Resistance of Metakaolin-Based Geopolymers

et al. 2020

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The understanding of the composition dependent properties and freezing-thawing (F-T) resistance of geopolymer materials is vital to their applications in cold regions. In this study, metakaolin-based geopolymer (MKG) mortars were fabricated by controlling the Si/Al ratio and the Na/Al ratio. The pore structure and strength were measured by mercury intrusion porosimetry and compression tests, respectively, which both showed obvious correlations with the material composition. Mass loss, strength loss, visual rate, and microscopic observation were adopted to assess the changes of the material properties and microstructure caused by F-T loads. The results showed that the strength-porosity relationship roughly followed a linear plot. Increases of the Si/Al ratio increased the capillary pore volume, but decreased the gel pore volume and the F-T resistance. Increases of the Na/Al ratio decreased the gel pore, but roughly enhanced the F-T resistance. The MKG mortar at the Na/Al ratio of 1.26 showed the lowest total pore volume and the best F-T resistance. The mechanisms of our experimental observations were that the abundantly distributed air voids connected by the capillary pores facilitated the relaxation of hydraulic pressures induced by the freezing of the pore liquid. The findings of this work help better clarify the compositional dependence of the pore structure, strength, and freezing-thawing resistance of MKG materials and provide fundamental bases for their engineering applications in cold regions.

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“…Bunun yanı sıra birim NaOH ve KOH ile üretilen numuneler arasındaki birim ağırlık farkı fazla belirgin değildir. [44]. Bu sebeple boşluk miktarının artışı ile birlikte su emme özelliğinin de artış gösterdiği bilinmektedir [35,37].…”

Section: Birim Ağırlık Deney Sonuçları şEkil 4 Numunelerin Birim Ağıunclassified

“…NaOH'un, KOH' a kıyasla daha fazla aktivasyon özelliği göstermesinden dolayı, NaOH ile üretilen numunelerde, KOH ile üretilen numunelere kıyasla daha fazla yayılma değeri gözlenmiştir. Bu durum NaOH ile üretilen numunelerde işlenebilirliğin daha fazla olmasından kaynaklanmaktadır [44].…”

Section: Introductionunclassified

“…Başka bir çalışmada ise C sınıfı UK ile üretilen geopolimer harçlarda birim ağırlığın 1,77-1,97 gr cm -3 , F sınıfı UK ile üretilen geopolimer harçlarda ise birim ağırlığın 1,57-2,05 gr cm -3 arasında değiştiği belirtilmiştir [37]. NaOH, KOH'a kıyasla daha etkin aktivasyon özelliği göstermekte ve daha kuvvetli bağ yapısı oluşturmaktadır [44]. Bu sebeple NaOH ile üretilen numunelerin birim ağırlıkları KOH ile üretilen numunelerin birim ağırlıklarından daha büyüktür.…”

Section: Introductionunclassified

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Yüksek ve Düşük Kalsiyum İçeren Uçucu Küller ile Üretilen Geopolimer Harçların Fiziksel ve Mekanik Özelliklerinin İncelenmesi

Kaya¹

2020

Türk Doğa Ve Fen Dergisi

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Bu çalışmada, C sınıfı ve F sınıfı uçucu külün birlikte kullanılarak geri dönüşümlerinin sağlanması ve ekonomiye kazandırılması amacıyla üretilen geopolimer harçların fiziksel ve mekanik özellikleri incelenmiştir. C sınıfı uçucu kül (UK) ile F sınıfı UK 'nın %0,%10, %20, %30, %40 ve %50 oranlarında birbirleri ile yer değiştirilmesi ile oluşturulan bağlayıcı, sodyum hidroksit (NaOH) ve potasyum hidroksit (KOH) ile ayrı ayrı aktive edilmiştir. Aktivatör/bağlayıcı oranı %10 olarak kullanılmıştır. Likit/bağlayıcı oranı 0,35, agrega/bağlayıcı oranı 3 olarak belirlenmiştir. UK, kum, aktivatör ve suyun standart çimento mikserinde karıştırılması ile hazırlanan harç numuneler, 40mm×40mm×160 mm boyutlu standart kalıplara yerleştirildikten sonra 100 °C' de 24 saat süre ile aktivasyon sıcaklığına maruz bırakılmıştır. Daha sonra numuneler 28 gün boyunca hava kürüne (22±2°C) tabi tutulmuşlardır. Hava kürünü takiben fiziksel ve mekanik deneyler gerçekleştirilmiştir. Sonuç olarak %60 C sınıfı ve %40 F sınıfı UK içeren ve NaOH ile üretilen numunelerde 3,8 MPa eğilme dayanımı, 28 MPa basınç dayanımı elde edilmiştir.

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Elevated temperature, freezing-thawing and wetting-drying effects on polypropylene fiber reinforced metakaolin based geopolymer composites

Cited by 146 publications

References 132 publications

Thermal and Mechanical Properties of Geopolymers Exposed to High Temperature: A Literature Review

Thermal and Mechanical Properties of Geopolymers Exposed to High Temperature: A Literature Review

Compositional Dependence of Pore Structure, Strengthand Freezing-Thawing Resistance of Metakaolin-Based Geopolymers

Yüksek ve Düşük Kalsiyum İçeren Uçucu Küller ile Üretilen Geopolimer Harçların Fiziksel ve Mekanik Özelliklerinin İncelenmesi

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