The Effect of Microwave Curing on the Strength Development of Class-F Fly Ash-Based Geopolymer Mortar

Year 2021, Volume: 37 Issue: 1, 118 - 129, 28.04.2021

Faidhalrahman Khaleel , Cengiz Atiş , Uğur Durak , Serhan İlkentapar , Okan Karahan

Abstract

This study investigates the influence of microwave (MW) curing on the strength development of geopolymer. Since applying conventional oven heat curing makes the heat moves from outer edge to the center of specimen and leads to a non-uniform of distributing heat within the specimen, which effects on the mechanical properties of the geopolymer. On the other hand, the use of MW reduces the curing time and allows to uniform heat distribution within samples and provides higher mechanical properties in a short period. The influence of conventional heat curing and MW curing on class F fly ash based geopolymer activated with sodium hydroxide and sodium metasilicate was investigated. The conventional heat curing was applied at 75 and 90°C for 6 and 24 hours; on the other hand, additional MW curing was applied for a different period (5-60 minutes) and different energy level (100, 180 and 300W) on hardened geopolymer samples cured with conventional oven curing. The results show that the use of conventional heat curing for 6 hours followed by MW curing gave higher or equivalent strength compared to only conventional heat curing. While 24 hours conventional heat curing result with a geopolymer having 39.1 MPa compressive strength, 6 hours conventional heat curing followed by 1 hour MW curing at 180W energy level results with a geopolymer with compressive strength in the order of 80 MPa.

Keywords

Fly ash, geopolymer, microwave curing, strength

The Effect of Microwave Curing on the Strength Development of Class-F Fly Ash-Based Geopolymer Mortar

Abstract

Bu çalışmada, mikrodalga (MW) kürünün geopolimerin dayanım gelişimi üzerindeki etkisi araştırılmıştır. Geleneksel ısıyla fırın küründe, ısı numunenin dış kenardan numune merkezine doğru hareket etmekte ve bu durum numune üzerine üniform olmayan bir ısınmaya neden olarak geopolimerlerin mekanik özelliklerini etkilemektedir. Öte yandan, MW kullanımı numuneler içinde homojen ısı dağılımına olanak sağlayarak kürleme süresini azaltmakta ve kısa sürede daha yüksek mekanik özellikler elde edilmesini sağlamaktadır.
Çalışmada sodyum hidroksit ve sodyum metasilikat ile aktive edilmiş F sınıfı uçucu kül bazlı geopolimerler üzerinde geleneksel ısıl kür ve MW kürü etkileri araştırılmıştır. Geleneksel ısıl kür 75 ve 90°C'de 6 ve 24 saat süreyle numunelere uygulanmıştır. Mikrodalga kürü ise geleneksel ısıl kür ile kürlenen sertleştirilmiş geopolimer numunelere farklı süre (5-60 dakika) ve farklı enerji seviyelerinde (100, 180 ve 300W) ilave olarak uygulanmıştır.
Elde edilen sonuçlara göre 6 saat boyunca geleneksel ısıl kür ile sertleşen numunelere MW kürü uygulanması durumunda, yalnızca geleneksel ısıl kür ile dayanım kazanan numunelere kıyasla daha yüksek veya eşdeğer bir dayanım elde edildiği görülmüştür. 24 saat geleneksel ısıl kür sonucu 39,1 MPa basınç dayanımına ulaşan bir geopolimer, 6 saat geleneksel ısıl kür sonrası 180W enerji seviyesinde 1 saat MW kürüne tabi tutulduğunda 80 MPa civarında basınç dayanımı elde edilmiştir.

Keywords

Uçucu Kül, Geopolymer, Microwave curing, Strength

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