Effects of Microwave Energy on Fast Compressive Strength Development of Coal Bottom Ash-Based Geopolymers

Hong, Sungil; Kim, Hyo

doi:10.1038/s41598-019-52160-2

Cited by 21 publications

(3 citation statements)

References 43 publications

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“…In the late 1970s, Davidovits introduced the expression "geopolymer" to characterize the inorganic polymeric system created through the metakaolin alkali activation [8]. Today, it stands as the most widely used term to refer to this material [9]. As per Davidovits [10], this innovative binder was produced through a modification of the techniques employed by the Romans and Egyptians.…”

Section: Introductionmentioning

confidence: 99%

Comprehensive Analysis of Geopolymer Materials: Properties, Environmental Impacts, and Applications

Sbahieh,

McKay,

Al-Ghamdi

2023

Materials

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The advancement of eco-friendly technology in the construction sector has been improving rapidly in the last few years. As a result, multiple building materials were developed, enhanced, and proposed as replacements for some traditional materials. One notable example presents geopolymer as a substitute for ordinary Portland concrete (OPC). The manufacturing process of (OPC) generates CO2 emissions and a high energy demand, both of which contribute to ozone depletion and global warming. The implementation of geopolymer concrete (GPC) technology in the construction sector provides a path to more sustainable growth and a cleaner environment. This is due to geopolymer concrete’s ability to reduce environmental pollutants and reduce the construction industry’s carbon footprint. This is achieved through its unique composition, which typically involves industrial byproducts like fly ash or slag. These materials, rich in silicon and aluminum, react with alkaline solutions to form a binding gel, bypassing the need for the high-energy clinker production required in OPC. The use of such byproducts not only reduces CO2 emissions but also contributes to waste minimization. Additionally, geopolymer offers extra advantages compared to OPC, including improved mechanical strength, enhanced durability, and good stability in acidic and alkaline settings. Such properties make GPC particularly suitable for a range of construction environments, from industrial applications to infrastructure projects exposed to harsh conditions. This paper comprehensively reviews the different characteristics of geopolymers, which include their composition, compressive strength, durability, and curing methods. Furthermore, the environmental impacts related to the manufacturing of geopolymer materials were evaluated through the life-cycle assessment method. The result demonstrated that geopolymer concrete maintains positive environmental impacts due to the fact that it produces fewer carbon dioxide CO2 emissions compared to OPC concrete during its manufacturing; however, geopolymer concrete had some minor negative environmental impacts, including abiotic depletion, human toxicity, freshwater ecotoxicity, terrestrial ecotoxicity, and acidification. These are important considerations for ongoing research aimed at further improving the sustainability of geopolymer concrete. Moreover, it was determined that silicate content, curing temperature, and the proportion of alkaline solution to binder are the major factors significantly influencing the compressive strength of geopolymer concrete. The advancement of geopolymer technology represents not just a stride toward more sustainable construction practices but also paves the way for innovative approaches in the field of building materials.

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Section: Introductionmentioning

confidence: 99%

Comprehensive Analysis of Geopolymer Materials: Properties, Environmental Impacts, and Applications

Sbahieh,

McKay,

Al-Ghamdi

2023

Materials

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“…The raw materials were coal bottom ash and sodium hydroxide solution. After 24 h in an oven at 75 • C and subjected to microwaves with a power level of 200 W for a few minutes, a compressive strength greater than 65 MPa was achieved [37]. Another synthesis of geopolymers with the help of microwave curing was reported by UI Haq et al In this paper, there was no oven curing before microwaving.…”

Section: Introductionmentioning

confidence: 76%

Effect of Microwaves on the Rapid Curing of Metakaolin- and Aluminum Orthophosphate-Based Geopolymers

Aschoff,

Partschefeld,

Schneider

et al. 2024

Materials

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This paper deals with the influence of microwaves on the hardening and curing of geopolymer binders synthesized from metakaolin or aluminum orthophosphate with sodium silicate solution as the activator. Pure geopolymer pastes as well as geopolymer mortars were considered. The variable parameters were the modulus of the sodium silicate solutions (molar ratio of SiO2 to Na2O: 1.5, 2.0 and 2.5) and the Si/Al ratio (3/1 and 2/1). Selected samples were cured in a microwave oven until hardening, so the curing time depended on the mixture. For comparison some samples were cured at ambient temperature. To investigate the influence of microwave radiation on the reaction kinetics, isothermal heat flow calorimetry, ultrasonic velocity measurements and rheological investigations into the variation of curing temperature were used. In addition, the mechanical properties of the cured samples were characterized. The results show that microwave curing only takes a few minutes, so it is the most time-saving method. Key factors influencing the geopolymer reaction under microwave radiation are the raw materials as well as the Si/Al ratio. Metakaolin-based geopolymer binders are more stable than those based on aluminum orthophosphate, especially regarding their salt efflorescence. Microwave radiation is an efficient method to accelerate the geopolymer reaction.

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“…Yani, mikrodalgada kritik bir kür süresi mevcuttur ve bu sürenin ötesinde, Şekil 3'te gösterildiği gibi, özellikler olumsuz yönde etkilenmektedir. Mikrodalganın yoğun ve doğrudan malzeme çekirdeğine nüfuz edici ısıtma özellikleri nedeniyle, jeopolimer numunelerin sıcaklığı birkaç dakikalık mikrodalga ışıması ile 200℃'nin çok üzerine çıkabilir [48,49]. Isıtma sırasında, nispeten düşük bir sıcaklık aralığında (ortam sıcaklığı ila 100℃) fiziksel olarak bağlı su kolayca bünyeden uzaklaşmaktadır.…”

Section: Kür Koşulları (Curing Conditions)unclassified

Doğal puzolan-esaslı jeopolimer üretiminde mikrodalga kürünün rolü

Ekiz Barış

2024

Gazi Üniversitesi Mühendislik Mimarlık Fakültesi Dergisi

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Jeopolimer üretiminde uygulanan geleneksel kür yöntemlerinde, yeterli özelik kazanımı için uzun bir kür süresi gerekmektedir. Özeliklerin daha kısa sürede geliştirilmesi amacıyla farklı kür yöntemleri arayışı sürmektedir. Bu araştırmanın amacı, doğal puzolan-esaslı jeopolimer malzeme özeliklerinin mikrodalga kürüyle daha kısa sürede ve daha az enerji harcanarak geliştirilebilmesi olanaklarını değerlendirmektir. Alüminosilikat kaynağı olarak Türkiye’nin Datça Yarımadası’nda bulunan volkanik tüf, dolgu maddesi olarak standart kum ve alkali aktivatör olarak potasyum hidroksit ve sodyum silikat kullanılmıştır. Numuneler dört farklı yöntemle kürlenmiştir: (i) Geleneksel ısı kürü; (ii) Mikrodalga kürü; (iii) Isı+mikrodalga kürü; (iv) Mikrodalga+ısı kürü. Araştırma sonucunda, doğal puzolan-esaslı jeopolimer özeliklerinin mikrodalga kürüyle, geleneksel ısı kürüne nazaran daha kısa sürede ve daha az enerji harcanarak geliştirilebilmesinin mümkün olduğu belirlenmiştir. Isı+mikrodalga veya mikrodalga+ısı kürü (kombine kür yöntemleri), yalnızca ısı veya mikrodalga kürüne nazaran daha yüksek fiziksel ve mekanik özeliklerin elde edilmesini sağlamıştır. En yüksek reaksiyon derecesi, fiziksel ve mekanik özellikler 90 °C’de 24 saat ısı+15 dakika mikrodalga kürüyle elde edilmiştir. Reaksiyonların gelişiminde ilk 12 saatteki etkinliğin daha yüksek olduğu ve 24 saat ısı kürü yerine 12 saat kür süresinin yeterli olduğu belirlenmiştir. Kombine kür yöntemlerinin birlikte uygulanması, diğer yöntemlere nazaran nispeten daha yüksek enerji tüketimine yol açmasına rağmen, malzemenin mekanik özeliklerini yaklaşık iki kat geliştirmesi bakımından önemlidir.

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Effects of Microwave Energy on Fast Compressive Strength Development of Coal Bottom Ash-Based Geopolymers

Cited by 21 publications

References 43 publications

Comprehensive Analysis of Geopolymer Materials: Properties, Environmental Impacts, and Applications

Comprehensive Analysis of Geopolymer Materials: Properties, Environmental Impacts, and Applications

Effect of Microwaves on the Rapid Curing of Metakaolin- and Aluminum Orthophosphate-Based Geopolymers

Doğal puzolan-esaslı jeopolimer üretiminde mikrodalga kürünün rolü

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