Assessment of important parameters involved in the synthesis of geopolymer composites: A review

Farhan, Khatib Zada; Johari, Megat Azmi Megat; Demirboğa, Ramazan

doi:10.1016/j.conbuildmat.2020.120276

Cited by 110 publications

(88 citation statements)

References 223 publications

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“…However, the majority of the early studies on the geopolymer focused on the mortar and paste. Numerous investigations have been conducted on the influence of various parameters on geopolymer concrete (GPC), such as alkali precursor (such as fly ash) ratio, Si/Al ratio, alkali concentration, and the properties of the coarse aggregate [22,23]. The physical and mechanical properties of fly ash-based geopolymer concrete, compared to those of Portland cement concrete were studied by [24].…”

Section: Introductionmentioning

confidence: 99%

Effect of Size of Coarse Aggregate on Mechanical Properties of Metakaolin-Based Geopolymer Concrete and Ordinary Concrete

et al. 2021

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Geopolymer binders are a promising alternative to ordinary Portland cement (OPC) because they can significantly reduce CO2 emissions. However, to apply geopolymer in concrete, it is critical to understand the compatibility between the coarse aggregate and the geopolymer binder. Experimental studies were conducted to explore the effect of the size of the coarse aggregate on the mechanical properties and microstructure of a metakaolin-based geopolymer (MKGP) concrete and ordinary concrete. Three coarse aggregate size grades (5–10 mm, 10–16 mm, and 16–20 mm) were adopted to prepare the specimens. The microstructure of the concretes was investigated with scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS) and mercury intrusion porosimetry (MIP). Results showed an opposite coarse aggregate size effect between OPC and MKGP specimens in terms of compressive strength. SEM/EDS analysis indicated that the MKGP concrete has a weaker microstructure compared to OPC concrete induced by a higher porosity. The differences in mechanical properties and pore structure between the MKGP and OPC concrete are attributed to the greatly differing shrinkages triggered by the large surface area and penny-shaped particles of metakaolin. The findings in this work help tailor the mechanical properties and microstructure of MKGP concrete for future engineering applications.

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Section: Introductionmentioning

confidence: 99%

Effect of Size of Coarse Aggregate on Mechanical Properties of Metakaolin-Based Geopolymer Concrete and Ordinary Concrete

et al. 2021

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“…The total content of SiO 2 and Al 2 O 3 is greater than 95%. Many studies illustrated that the combination of NaOH and Na 2 SiO 3 solutions could be the best choice for the polymerization of aluminosilicate sources [11,17,22] because NaOH could dissolve aluminosilicate sources and Na 2 SiO 3 continuously, providing more Na + and Si 4+ for polymerization. However, great difficulties in the transit and storage of NaOH and Na 2 SiO 3 solutions and ecological environment protection are always likely to be encountered in engineering practices.…”

Section: ) Gbmentioning

confidence: 99%

“…Geopolymer binder (GB) is an inorganic alkali-activated material touted for high strength and durability, low energy consumption, and low CO 2 emission [7,8]. Many studies indicated that the raw materials of GB could be metakaolin (MK), fly ash (FA), glass waste (GW), red mud (RM), and combinations of two or more of these materials, and the alkali activator (AA) could be R x OH, R x CO 3 , R x HCO 3 , R x O•(n)SiO 2 , or other alkaline metal oxides (R x O) in which R x represents an alkaline ion, such as Na + , K + , Li + , or Ca 2+ [9][10][11]. Despite the fact that properties of different raw materials and alkaliactivated conditions could affect the dissolution process and subsequent reaction directly, resulting in GB exhibiting a wide variety of physical and mechanical properties, the fundamental chemical and structural characteristics derived from coupled alkali-mediated dissolution and precipitation reactions are the same [9].…”

Section: Introductionmentioning

confidence: 99%

Silty Clay Stabilization Using Metakaolin-Based Geopolymer Binder

Wang

et al. 2021

Front. Phys.

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Geopolymer binders are adjudged as the latest wave of sustainable alkali-activated materials for soil stabilization due to their excellent bonding properties. This study applied metakaolin as a precursor for synthesizing the geopolymer binder by employing the mixture of quicklime and sodium bicarbonate as an alkali activator. The optimal mass mixing ratio of the alkali activator, metakaolin, and silty clay was determined by unconfined compression tests. The stabilization mechanisms of the geopolymer binder were measured by x-ray diffraction and Fourier transform infrared spectroscopy. The microstructural characteristics of the geopolymer-stabilized silty clay were observed by scanning electron microscopy with an energy dispersive x-ray spectroscopy and mercury intrusion porosimetry test for understanding the strengthening mechanism of the silty clay after the treatment. Results indicate that the optimal mass mixing ratio of the alkali activator, metakaolin, and silty clay is 1:2:17, and the unconfined compressive strength of the geopolymer-stabilized silty clay reaches the maximum value of 0.85 MPa with adding 15 wt% of the geopolymer binder. Diffraction patterns show an insufficient polymerization of the geopolymer binder in the silty clay in the early days but a rapid synthesis of aluminosilicate gels after that. The new asymmetrical stretching vibration peaks signified the formation of aluminosilicate networks and are responsible for the strength improvement of the silty clay. Microstructural analyses further confirm the formation of aluminosilicate gels and their positive impacts on the structure of the silty clay over curing age.

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“…Hu et al [13], geopolimerlerin aderans ve aşınma dirençlerinin çimento esaslı onarım malzemesinden daha iyi olduğunu ve Sakkas et al [14] ayrıca, geopolimerlerin genellikle seramik benzeri mikro yapıları ve özelliklerinden dolayı yüksek sıcaklıklara maruz kaldıktan sonra iyi termalfiziksel ve mekanik özelliklere sahip olduğunu ifade etmişlerdir [15]. Geopolimerler ile ilgili son yıllarda yapılan derleme çalışmalarında detaylı bilgi mevcuttur [1,[16][17][18] [25], perlit esaslı geopolimerlerde kür süresi ve kür sıcaklığının etkisini araştırmışlar ve sonuç olarak en iyi dayanımı veren karışım; 15,5 NaOH molaritesinde, 24 saatlik kür süresi ve 110ºC'de elde edilmiş olup bu değer 46,76 MPa olarak belirlenmiştir. Fakat bu çalışmada yalnızca ısı kürünün hemen sonrası dayanım özellikleri mevcut olup ileri yaş dayanımları bulunmamaktadır.…”

Section: Normalunclassified

Erzurum Pasinler Bölgesi Perlitinin Geopolimer Üretiminde Kullanımının Araştırılması

Akbulut

Polat

Karagöl

2021

Türk Doğa Ve Fen Dergisi

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Öz: Küresel ısınma ve iklim değişikliğine sebebiyet veren en önemli sera gazlarından birisi CO 2 'dir. Bu gazın salınımının önemli bir miktarı (%6-8), çimento üretiminden kaynaklanmaktadır. Bu sebeple yaklaşık yirmi yıldır araştırmacılar, çimentoya alternatif sürdürülebilir bağlayıcı malzeme olan geopolimer üzerinde yoğun olarak çalışmaktadırlar. Geopolimer üretimi temel olarak, atık yan ürünler (uçucu kül, yüksek fırın cürufu vb.) veya doğal mineral malzemeler (volkanik kül, kil, pomza vb.) gibi bir alümino-silikat kaynağı ve NaOH, Na 2 SiO 3 vb. aktivatörlerden oluşmaktadır. Bu çalışmada ise, Erzurum Pasinler bölgesinde önemli miktarda bulunan ve alümino silikat içeren perlit, bağlayıcı olarak kullanılıp geopolimer üretimi araştırılmıştır. Karışımlarda alkali aktivatör olarak yalnızca NaOH kullanılmıştır ve üretilen numunelere yapılan ön deneyler sonucunda 90°C'de 72 saat ısıl kür uygulanmıştır. Üretilen numunelerin su emme oranları, birim hacim ağırlıkları ve 3, 7, 28 ve 150 günlük basınç dayanımları tespit edilmiştir. Ayrıca numuneler %5 konsantrasyonlu HCl ve MgSO 4 çözeltilerine, 50 çevrimlik donma-çözünme etkisine ve 300°C, 500°C ve 700°C yüksek sıcaklıklara maruz bırakılmıştır ve numunelerin mekanik ve fiziksel özellikleri tespit edilmiştir. Sonuç olarak, perlit esaslı geopolimer üretiminde NaOH tek başına kullanılarak maksimum 21,14 MPa basınç dayanımı elde edilmiştir.

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Assessment of important parameters involved in the synthesis of geopolymer composites: A review

Cited by 110 publications

References 223 publications

Effect of Size of Coarse Aggregate on Mechanical Properties of Metakaolin-Based Geopolymer Concrete and Ordinary Concrete

Effect of Size of Coarse Aggregate on Mechanical Properties of Metakaolin-Based Geopolymer Concrete and Ordinary Concrete

Silty Clay Stabilization Using Metakaolin-Based Geopolymer Binder

Erzurum Pasinler Bölgesi Perlitinin Geopolimer Üretiminde Kullanımının Araştırılması

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