Uçucu Kül Esaslı Geopolimer Harçların Fiziksel ve Mekanik Özelliklerine NaOH Molaritesi, Kür Sıcaklığı ve Kür Süresinin Etkisi

Abstract

Bu çalışmada, F sınıfı uçucu kül esaslı geopolimer harçlarda NaOH molaritesinin ve kür sıcaklığının işlenebilirlik, ultrases geçiş hızı (UGH), eğilme dayanımı ve basınç dayanımı üzerindeki etkileri araştırılmıştır. Bu amaçla 6, 8 ve 10 M NaOH çözeltileri kullanılarak geopolimer harçlar üretilmiş ve numuneler 80°C ve 100°C sıcaklıklarda 24 saat süreyle ısıl küre tabi tutulmuştur. Isıl kür işleminin ardından numuneler oda koşullarında muhafaza edilmiş ve deneyler 1, 7 ve 28 günlük yaşlarda gerçekleştirilmiştir. Taze haldeki harçların işlenebilirliği yayılma tablası deneyi ile belirlenirken, sertleşmiş numunelerde UGH, eğilme dayanımı ve basınç dayanımı deneyleri gerçekleştirilmiştir. Elde edilen sonuçlar NaOH molaritesindeki artışın geopolimer harçların işlenebilirliğini azalttığını göstermiştir. Buna karşılık, kür sıcaklığının artırılması UGH ile mekanik özellikleri olumlu yönde etkilemiştir. En yüksek UGH değeri 100°C’de kürlenen 10 M karışımında elde edilmiştir. Eğilme ve basınç dayanımı sonuçları, optimum NaOH molaritesinin uygulanan kür sıcaklığına bağlı olarak değişebileceğini ortaya koymuştur. 80°C’de kürlenen numunelerde en yüksek dayanım değerleri 8 M karışımında elde edilirken, 100°C’de kürlenen numunelerde en yüksek dayanımlar 10 M karışımında belirlenmiştir. Ayrıca kür süresinin uzaması tüm karışımlarda dayanım gelişimini olumlu yönde etkilemiştir. Sonuç olarak, uçucu kül esaslı geopolimer harçların performansının geliştirilmesinde NaOH molaritesi ve kür sıcaklığının birlikte değerlendirilmesi gerektiği belirlenmiştir.

Keywords

• Geopolimer harç
• uçucu kül
• NaOH molaritesi
• ısıl kür
• mekanik dayanım

Effects of NaOH Molarity, Curing Temperature, and Curing Duration on the Physical and Mechanical Performance of Fly Ash-Based Geopolymer Mortars

Abstract

This study investigated the effects of NaOH molarity and curing temperature on the workability, ultrasonic pulse velocity (UPV), flexural strength, and compressive strength of Class F fly ash-based geopolymer mortars. For this purpose, geopolymer mortars were produced using 6, 8, and 10 M NaOH solutions and subjected to thermal curing at 80°C and 100°C for 24 h. Following thermal curing, the specimens were stored under laboratory conditions and tested at the ages of 1, 7, and 28 days. The workability of fresh mortars was evaluated using the flow table test, while UPV, flexural strength, and compressive strength tests were performed on hardened specimens. The results indicated that increasing NaOH molarity reduced the workability of geopolymer mortars. In contrast, higher curing temperatures positively influenced both UPV and mechanical properties. The highest UPV value was obtained in the 10 M mixture cured at 100°C. Flexural and compressive strength results revealed that the optimum NaOH molarity may vary depending on the applied curing temperature. The highest strength values were achieved with the 8 M mixture at 80°C, whereas the 10 M mixture exhibited the best mechanical performance at 100°C. Furthermore, increasing curing age contributed positively to strength development in all mixtures. Overall, the findings demonstrate that NaOH molarity and curing temperature should be considered together to optimize the performance of fly ash-based geopolymer mortars.

Keywords

• Geopolymer mortar
• fly ash
• NaOH molarity
• thermal curing
• mechanical strength

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